Durability monitoring of insecticide-treated nets (ITNs) containing a pyrethroid in combination with a second active ingredient (AI) must be adapted so that the insecticidal bioefficacy of each AI can be monitored independently. An effective way to do this is to measure rapid knock down of a pyrethroid-susceptible strain of mosquitoes to assess the bioefficacy of the pyrethroid component and to use a pyrethroid-resistant strain to measure the bioefficacy of the second ingredient. To allow robust comparison of results across tests within and between test facilities, and over time, protocols for bioefficacy testing must include either characterisation of the resistant strain, standardisation of the mosquitoes used for bioassays, or a combination of the two. Through a series of virtual meetings, key stakeholders and practitioners explored different approaches to achieving these goals. Via an iterative process we decided on the preferred approach and produced a protocol consisting of characterising mosquitoes used for bioefficacy testing before and after a round of bioassays, for example at each time point in a durability monitoring study. We present the final protocol and justify our approach to establishing a standard methodology for durability monitoring of ITNs containing pyrethroid and a second AI.

Pyrethroid resistance is widespread in malaria vectors. However, differential mortality in discriminating dose assays to different pyrethroids is often observed in wild populations. When this occurs, it is unclear if this differential mortality should be interpreted as an indication of differential levels of susceptibility within the pyrethroid class, and if so, if countries should consider selecting one specific pyrethroid for programmatic use over another. A review of evidence from molecular studies, resistance testing with laboratory colonies and wild populations, and mosquito behavioural assays was conducted to answer these questions. Evidence suggests that in areas where pyrethroid resistance exists, different results in insecticide susceptibility assays with specific pyrethroids currently in common use (deltamethrin, permethrin, α-cypermethrin and λ-cyhalothrin) are not necessarily indicative of an operationally relevant difference in potential performance. Consequently, it is not advisable to use rotation between these pyrethroids as an insecticide resistance management strategy. Less commonly used pyrethroids (bifenthrin and etofenprox) may have sufficiently different modes of action, though further work would be needed to examine how this may apply to insecticide resistance management.

Toxicological studies have shown that the cockroach Periplaneta americana is a classical model for studying the mode of action of commonly used insecticides. In a previous study, we demonstrated that thiamethoxam and clothianidin decreased locomotor activity and decreased the locomotor activity in an open-field-like apparatus. Here, we tested the effect of the neonicotinoid acetamiprid when applied orally, topically, or injected into the haemolymph. We found that acetamiprid decreased locomotor activity in the open-field-like apparatus. When treated with acetamiprid, a strong alteration in locomotor activity was observed 1 h, 24 h and 48 h after haemolymph and topical applications. Oral application of acetamiprid demonstrated that it impaired locomotor activity at 24 h and 48 h. A comparison of the present data with our previously published results showed that neonicotinoids were more active when injected into the haemolymph compared to oral and topical applications. These findings increased our understanding of the effect of neonicotinoid insecticides on insect locomotor activity, and demonstrated that the cyano-substituted neonicotinoid, acetamiprid, was able to alter cockroach locomotor activity.

Increased levels of insecticide resistance in major malaria vectors such as Anopheles funestus threaten the effectiveness of insecticide-based control programmes. Understanding the landscape features impacting the spread of resistance makers is necessary to design suitable resistance management strategies. Here we examined the influence of the highest mountain in West Africa (Mount Cameroon; 4,100 meters elevation) on the spread of metabolic and target-site resistance alleles in An. funestus populations. Vector composition varied across the four localities surveyed along the altitudinal cline with major vectors exhibiting high parity rate (80.5%). Plasmodium infection rates ranged from 0.79% (An. melas) to 4.67% (An. funestus). High frequencies of GSTe2R (67% - 81%) and RdlR (49% - 90%) resistance alleles were observed in An. funestus throughout the study area, with GSTe2R frequency increasing with altitude whereas the opposite is observed for RdlR. Patterns of genetic diversity and population structure analyses revealed high levels of polymorphisms with 12 and 16 haplotypes respectively for GSTe2 and Rdl. However, the reduced diversity patterns of resistance allele carriers revealed signatures of positive selection on the two genes across the study area irrespective of the altitude. Despite slight variations associated with the altitude, the spread of resistance alleles suggest that control strategies could be implemented against malaria vectors across mountainous landscapes.

Experiments were conducted in 2020 and 2021 in College Station, TX; Stoneville, MS; and Blackville, SC, to evaluate the potential of grain sorghum to serve as a trap crop for H. zea, a nursery crop for natural enemies of H. zea, and source of HearNPV for H. zea management in cotton. The experiments consisted of 3 treatments, including cotton-only, non-treated cotton-sorghum, and HearNPV-treated cotton-sorghum. Variables, including percentage of damaged fruiting forms, parasitized H. zea larvae, egg density, H. zea larval density, beneficial arthropod numbers, and HearNPV prevalence, were compared between treatments. Growing cotton in an intercropping system with grain sorghum did not result in a consistent increase in H. zea control and beneficial arthropod density relative to the cotton-only treatment. Additionally, our results did not show sufficient evidence that grain sorghum interplanted with cotton can serve as a source of HearNPV that can favor H. zea control in cotton. However, we found that, if maintained in the cotton canopy, HearNPV may favor some level of H. zea suppression in cotton. Based on our PCR analyses, insects in the families Chrysopidae, Coccinellidae, Pentatomidae, Reduviidae, Formicidae, Anthocoridae, and spiders appeared to be carrying HearNPV. The virus was detected consistently in specimens of coccinellids, pentatomids, and reduviids across both years of the study. We suggest that further investigation on virus efficacy against H. zea in cotton using the sorghum-cotton system as well as the ability of grain sorghum to serve as a H. zea trap crop and source of H. zea natural enemies be considered in future studies.

To mitigate pyrethroid resistance in mosquito vectors of emerging and re-emerging human pathogens, there is an urgent need to discover insecticides with novel modes of action. Natural alternatives, such as extracts derived from plants, may serve as substitutes for traditional synthetic insecticides if they prove to be sustainable, cost-effective, and safe for non-target organisms. Hemp (Cannabis sativa) is a sustainable plant known to produce various secondary metabolites with insecticidal properties, including terpenoids and flavonoids. The goal of this study was to assess the larvicidal activity of hemp leaf extract on 1st instar mosquito larvae from both pyrethroid-susceptible (PS) and pyrethroid-resistant (PR) strains of Aedes aegypti Another goal was to identify which components of the extracts were responsible for any observed larvicidal activity. We found that methanol extract of hemp leaves induced similar concentration-dependent larvicidal activity against PS (LC50: 4.4 ppm) and PR (LC50: 4.3 ppm) strains within 48 hours. Partitioning of the dried leaf extract between methanol and revealed that full larvicidal activity was restricted to the methanol fraction. Analysis of this fraction by gas chromatography-mass spectrometry and nuclear magnetic resonance showed it to be dominated by cannabidiol (CBD). Larvicidal assays using authentic CBD confirmed this compound was primarily responsible for the toxicity of hemp leaf extract against both strains. We conclude that hemp leaf extracts and CBD have the potential to serve as viable sources for the development of novel mosquito larvicides.

Imidacloprid, a neonicotinoid, has proven as efficacious against hemipterans including the brown planthopper, Nilaparvata lugens (Stål). Frequent use, however, has resulted in high levels of resistance to imidacloprid among brown planthopper populations. Endosymbionts of insects are important for host insect growth and development and seem to play a role in resistance to imidacloprid. In this study, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the bacterial and yeast-like-symbiont communities of imidacloprid-resistant and imidacloprid-susceptible brown planthopper populations. The Shannon-Weaver diversity index and the evenness index indicated that there were no differences in the composition of the symbiotic communities of resistant and susceptible with a similarity coefficient of 0.53 for bacterial symbionts and 0.56 for yeast-like symbionts for the two planthopper populations. Sequence comparison analysis showed that the numbers of bacterial species in the imidacloprid-resistant versus the imidacloprid-susceptible populations were not significantly different. The bacterial species in the susceptible population were members of the Enterobacteriaceae and Moraxellaceae, while these in the resistant population were members of the Enterobacteriaceae, Oxalobacteriaceae, Rhodobacteriaceae, and Sphingomonadaceae. The imidacloprid-susceptible population had more yeast-like symbiont species than the resistant population.

Accurately monitoring insecticide resistance in target mosquito populations is important to combating malaria and other vector-borne diseases, and robust methods are key. The “WHO susceptibility bioassay” has been used for +60 years: mosquitoes of known physiological status are exposed to a discriminating concentration of insecticide. Several changes to the test procedures have been made historically which may seem minor but could impact bioassay results. The published test procedures and literature for this method were reviewed for methodological details. Areas where there was room for interpretation in the test procedures or where the test procedures were not being followed were assessed experimentally for impact on bioassay results: covering or uncovering of the tube end during exposure, number of mosquitoes per test unit, and mosquito age. Many publications do not cite the most recent test procedures, methodological details are reported which contradict the test procedures referenced or methodological details are not fully reported. As a result, the precise methodology is unclear. Experimental testing showed that using fewer than the recommended 15-30 mosquitoes per test unit significantly reduced mortality, covering the exposure tube had no effect, and using mosquitoes older than 2-5 days old increased mortality, particularly in the resistant strain. Recommendations are made for better reporting of experimental parameters.

This study investigated the development of Aedes aegypti density in houses of the urban locality of Poblado Miguel Alemán Valdes, in the Sonora state of Mexico, after application of 1% propoxur paint as full wall coverage (IP) and targeted indoor painting (IP 1m) in comparison to IRS with propoxur 70% WP (full wall coverage). The 1% propoxur paint was applied by the homeowners by brushing and rolling at the recommended dose of 1L/8 m², equivalent to 1.5 g a.i./m², while IRS was conducted by professionals with Propoxur 70% WP at a dose of 1 g a.i./m². Adult mosquito surveys were conducted in a random sample of houses in each block one week before the interventions and at week 1, month 1 to 4, month 6, month 9 and month 12 post-interventions. All three propoxur based treatments provided similar reductions (43.7%, 44.9% and 41.3% for IP, IP 1m and IRS respectively) in the fraction of houses positive in female Aedes aegypti resting indoor and outdoor as one year average of 8 follow up surveys. Indoor resting density of Aedes females during the one-year evaluation was reduced by 77.5% through IP followed by IP 1m with 64.2% reduction and 30% reduction with IRS. Culex mosquitoes’ interior density was affected as well by the insecticide treatments with similar average reductions for IP 1m (50.0%) and IRS (57.8%) in comparison with control. Aedes breeding was impacted by the insecticide paint in similar extent for both interventions, expressed by a substantial reduction of the House Index (20.1% IP, 31.2% IP 1m) and especially the Container Index (51.8% IP, 61.7% IP 1m) during the one-year surveys in comparison to control. In contrast, IRS treated block experienced an increase in both indexes. However, despite IP and IP 1m impacted in Aedes adult and immature indexes with noticeable reductions, the differences in all cases were not significative among the different insecticide treatments. The low sample size and mosquito population levels may have influenced the statistical outcomes. More than 80% of the interviewed residents were satisfied with the effectiveness of the paint and IRS treatments. The determination of the blood cholinesterase activity of tested individuals after the use of the carbamate paint and IRS in this study did not exceed acceptable inhibition limits. This study suggests that the application of propoxur paint by homeowners as full house coverage or as targeted indoor painting can be a safe and accepted intervention method for density reduction of Aedes aegypti populations in urban environments.

Aedes aegypti mosquito is a vector that could transmit various pathogens, such as viruses, bacteria, and parasites. Several human diseases transmitted by Ae. aegypti mosquito are dengue fever (DHF), Chikungunya, Yellow Fever and Zika. The occurance of resistance to various insecticides, including pyrethroid, is a current problem faced by various countries. In this research, a WHO bioassay test on Palembang and Jakarta Ae. aegypti was conducted using 0.25% permethrin pyrethroid insecticide. VGSC gene fragments associated with pyrethroid resistance (L982, S989, I1011, L1014, V1016 and F1534) of resistant and sensitive strains were amplified and analyzed. The test showed the presence of resistance in Ae. aegypti isolates from Palembang and Jakarta. From the results of VGSC gene fragment analyses, it was known that there were mutations (S989P and/or V1016G) on isolates from Palembang and (S989P and/or V1016G) on resistant isolates from Jakarta.

Indoor residual spray (IRS), mainly employing pyrethroid insecticides, is the most common intervention to prevent malaria transmission in many regions of Latin America; the use of long-lasting insecticidal nets (LLINs) has been more limited. Knockdown resistance (kdr) is a well-characterized target-site resistance mechanism associated with pyrethroid and DDT resistance. Most mutations detected in acetylcholinesterase-1 (Ace-1) and voltage-gated sodium channel (VGSC) genes are non-synonymous, resulting in a change of amino acid leading to non-binding of the insecticide. In the present study, we analyzed target-site resistance in Nyssorhynchus darlingi, the primary malaria vector in the Amazon, in multiple malaria endemic localities. We screened 988 wild-caught specimens of Ny. darlingi from three localities in Amazonian Peru and four in Amazonian Brazil. Collections were conducted between 2014-2021. Criteria were Amazonian localities with a recent history as malaria hotspots, primary transmission by Ny. darlingi and the use of both IRS and LLINs as interventions. Fragments of Ace-1 (456 bp) and VGSC (228 bp) were amplified, sequenced and aligned with Ny. darlingi sequences available in GenBank. We detected only synonymous mutations in the frequently reported Ace-1 codon 280 known to confer resistance to organophosphates and carbamates, but detected three non-synonymous mutations in other regions of the gene. Similarly, no mutations linked to insecticide resistance were detected in the frequently reported codon (995) at the S6 segment of domain II of VGSC. The lack of genotypic detection of IR mutations by sequencing the Ace-1 and VGSC genes from multiple Ny. darlingi populations in Brazil and Peru could be associated with low-intensity resistance, or possibly the main resistance mechanism is metabolic.

The mass production of mosquitoes at an industrial scale requires efficient sex separation, which can be achieved through mechanical, genetic or artificial intelligence means. Compared with others methods, the genetic sexing approach offers the advantage of limiting costs and space by removing females at larval stage. We recently developed a GSS in Aedes albopictus based on the sex linkage of the rdl gene to the M locus, conferring dieldrin resistance in males only. It has been previously reported that dieldrin ingested by larvae can be detected in adults and bioaccumulated in predators, raising the question of its use at a large-scale. In this context, we performed several experiments aiming at optimizing dieldrin selection by decreasing both dieldrin concentration and exposure time while maintaining a stable percentage of females averaging 1%. We showed that the previously used dieldrin exposure induced an important toxicity as it killed 60% of resistant males at larval stage. We could easily lower this toxicity by reducing the dose and/or the exposure time to recover nearly all resistant males. We then quantified the residues of dieldrin in resistant male adults and showed that dieldrin toxicity in larvae was positively correlated with dieldrin concentrations detected in adults. Interestingly, we showed that the use of reduced dieldrin exposure led to a dieldrin detection in adult males that was below the sensitivity threshold of the Gas Chromatography Mass Spectrometry detection method. Presented data show that dieldrin exposure can be adjusted to suppress toxicity in males while achieving efficient sexing and lowering the levels of dieldrin residues in adults to barely detectable levels.

Acetamiprid is a broad-spectrum neonicotinoid insecticide used in agriculture to control aphids. While recent studies have documented resistance to acetamiprid in several aphid species, the underlying mechanisms are still not fully understood. In this study, we analyzed the transcriptome and metatranscriptome of a laboratory strain of the pea aphid, Acyrthosiphon pisum (Harris, 1776), with reduced susceptibility to acetamiprid after nine generations of exposure to identify candidate genes and the microbiome involved in the adaptation process. Sequencing of the transcriptome of both selected (RS) and non-selected (SS) strains allowed the identification of 14858 genes and 4938 new transcripts. Most of the differentially expressed genes were associated with catalytic activities and metabolic pathways involving carbon and fatty acids. Specifically, the alcohol-forming fatty acyl-CoA reductase (FAR) and acyl-CoA synthetase (ACSF2), both involved in the synthesis of epidermal wax layer components, were significantly upregulated in RS, suggesting that adaptation to acetamiprid involves the synthesis of a thicker protective layer. Metatranscriptomic analysis revealed subtle shifts in the microbiome of RS. These results contribute to a deeper understanding of acetamiprid adaptation by the pea aphid and provide new insights for aphid control strategies.

The European corn borer (ECB) and in a lesser extent the western corn rootworm (Diabrotica virgifera virgifera LeConte) are a threat to maize in the Po Valley (Northern Italy), and its control can require insecticide applications. The results of a study to assess the effects of insecticide sprays on the beneficial insect Trichogramma brassicae (Hymenoptera Trichogrammatidae) and aphid predators are reported. A three-year research was carried out in two study areas, in Lombardy. In area 1, crop rotation was a common practice, while in area 2, maize monoculture was practiced. The ordinary trend of ECB egg masses attacked by T. brassicae was affected and parasitism rates were reduced as a result of exposure to insecticides (chlorpyriphos methyl, cypermethrin, alphacypermethrine, teflubenzuron). Repeated maize crop and insecticides spraying increased the aphid population abundance and negatively affected the aphid predator community, which mainly included ladybirds, hoverflies, bugs and lacewings. In sprayed fields, managed according to repeated crop protocols, the predator community was dominated by hoverflies, whereas ladybirds and Orius spp. prevailed in maize fields managed according to crop rotation protocols. Crop rotation protocols help to prevent ECB outbreaks; when threshold limit can be at risk, inundative release of T. brassicae or microbial control (i.e. use of preparation of Bacillus thuringiensis) can integrate natural biocontrol, a valuable alternative to chemical insecticides.

Coffee berry borer (CBB), Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), is the pest that causes the most economic damage to coffee crops. Chemical control of this insect is based on the use of insecticides that can affect the environment and nontarget organisms. Despite the fact that caffeine has shown potential as an insecticide, a caffeine-based product for field use is currently not available on the market. As a new alternative to control CBB and other coffee pests, such as Monalonion velezangeli, a caffeine-oleate was developed. The caffeine oleate formulation showed laboratory efficacy by causing mortality of more than 90% of CBB adults in preventive tests in which the insecticide was sprayed prior to insect attack on the coffee fruits. In the curative tests, in which spraying occurred after CBB infested the fruits, the formulation caused 77% mortality of the insects. Under controlled field conditions, the product kept CBB infestation below 20%, reducing the number of fruits attacked by the insect by up to 70%. In addition, no phytotoxic effects were observed in coffee plants. The insecticide was also effective against M. velezangeli causing 100% mortality. A caffeine oleate formulation that could be part of a strategy for integrated CBB management as well as other pests of coffee was developed. The components of the insecticide are food grade; the product would provide greater security to the coffee ecosystem and coffee growers.

Growing resistance is reported to carbamate insecticides in malaria vectors in Cameroon. However, the contribution of acetylcholinesterase (Ace-1) to this resistance remains uncharacterised. Here, we established that the G119S mutation is driving resistance to carbamates in Anopheles gambiae populations from Cameroon. Insecticide bioassay on field collected mosquitoes from Bankeng, a locality in southern Cameroon, showed high resistance to the carbamates bendiocarb (64.8 ± 3.5 % mortality) and propoxur (55.71 ± 2.9 %) but a full susceptibility to the organophosphate fenithrothion. The TaqMan genotyping of the G119S mutation in field-collected adults revealed the presence of this resistance allele (39%). A significant correlation was observed between the Ace-1^R and carbamate resistance at allelic [(bendiocarb; OR = 75.9; P<0.0001) and (propoxur; OR= 1514; P<0.0001)] and genotypic [RR vs SS (bendiocarb; OR = 120.8; P<0.0001) and (propoxur; OR= 3277; P<0.0001) levels. Furthermore, the presence of the mutation was confirmed by sequencing an Ace-1 portion flanking codon 119. The cloning of this fragment revealed a likely duplication of Ace-1 in Cameroon as mosquitoes exhibited at least three distinct haplotypes. Phylogenetic analyses showed that the predominant Ace-1^R allele is identical to that from West Africa suggesting a recent introduction of this allele in Central Africa from the West. The spread of this Ace-1^R represents a serious challenge to future implementation of IRS-based interventions using carbamates or organophosphates in Cameroon

A long-term investigation of D. suzukii dynamics in wild blueberry fields from 2012 - 2018 demonstrates relative abundance is still increasing seven years after initial invasion. Relative abundance is determined by physiological date of first detection and air temperatures the previous winter. Date of first detection of flies does not determine date of fruit infestation. The level of fruit infestation is determined by year, fly pressure, and insecticide application frequency. Frequency of insecticide application is determined by production system. Non-crop wild fruit and predation influences fly pressure; increased wild fruit abundance results in increased fly pressure. Increased predation rate reduces fly pressure, but only at high abundance of flies, or when high levels of wild fruit are present along field edges. Male sex ratio might be declining over the seven years. Action thresholds were developed from samples of 92 fields from 2012 - 2017 that related cumulative adult male trap capture to the following week likelihood of fruit infestation. A two-parameter gamma density function describing this probability was used to develop a risk-based gradient action threshold system. The action thresholds were validated from 2016-2018 in 35 fields and were shown to work well in two of three years (2016 and 2017).

The research employs both literature and experimental data to develop reasonable strategies for melon fly control. The objects of research were sierozem soils of the Zhanakorgan region (Kyzylorda region), bentonite clays of the Sauran region (Turkestan region), vermicompost obtained at the production site of the Research Institute "Ecology" at the International Kazakh-Turkish University named after Khoja Ahmed Yasawi. The competitive agent 'Vermiserbent' was developed by combining sulphur-perlite-containing waste (SPCW), vermicompost (VC), and natural bentonite clay. When incorporated into the soil, it serves as both an insecticide and a fertiliser recovery agent. Disinfection and enrichment of barren Sierozem soils in southern Kazakhstan could provide an eco-friendly approach to protect cucurbits (melon, watermelon, and pumpkin) against the melon fly. The average yield of watermelon treated with vermiserbent increased by 2.3 t/ha compared to the control, melon by 4.6 t/ha, pumpkin by 5.6 t/ha. The marketability of gourds as watermelons and melon after treatment with fertilizer increased by 1.2 times, and pumpkin by 1.1 times. The findings of studies conducted in agricultural fields in the Turkestan and Kyzylorda regions have shown that it is possible to produce environmentally sound gourds using a mixture of vermicompost, bentonite, and SPCW.

Target pests of genetically engineered crops producing both defensive allelochemicals and Bacillus thuringiensis (Bt) toxins often sequentially or simultaneously uptake allelochemicals, Bt toxins, and/or insecticides. How the three types of toxins interact to kill pests remains underexplored. Here we investigated the interactions of Bt toxin Vip3A, plant allelochemical flavone, and insecticide emamectin benzoate in Spodoptera frugiperda. Simultaneous administration of flavone LC25 + Vip3A LC25, emamectin benzoate LC25 + Vip3A LC25, and flavone LC15 + emamectin benzoate LC15 + Vip3A LC15 but not flavone LC25 + emamectin LC25 yielded a mortality significantly higher than their expected additive mortality (EAM). One-day preexposure to one toxin at LC5 followed by 6-day exposure to the same toxin at LC5 plus another toxin at LC50 showed that the mortality of flavone LC5 + Vip3A LC50, emamectin benzoate LC5 + Vip3A LC50, and Vip3A LC5 + emamectin benzoate LC50, were significantly higher than their EAM, while that of flavone LC5 + emamectin benzoate LC50 was significantly lower than their EAM. No significant difference existed among the mortalities of Vip3A LC5 + flavone LC50, emamectin benzoate LC5 + flavone LC50, and their EAMs. The results suggest that the interactions of the three toxins are largely synergistic (inductive) or additive, depending on their combinations and doses.

Field studies were conducted in 2016, 2017, and 2020 in south-central and the Coastal Bend regions of Texas to determine the effects of various biostimulants and soil additives on corn growth and yield. In south-central Texas, the use of pop-up fertilizer (9-30-0 + Zn) either alone or in combination with either 2% N, bifenthrin, or bifenthrin + pyraclostrobin resulted in the greatest corn vigor but a yield response was only noted with pop-up fertilizer alone at 28062 or 46771 ml ha-1 in one year. In the Coastal Bend region, leaf tissue analysis showed that only Fe was affected with the use of any soil additive. Bacillus licheniformis + bacillus megaterium + bacillus pumilus increased Fe leaf tissue content by 20% over the untreated check. Radicoat seed coating at 438 ml ha-1 reduced corn plant stand by 10% and Pseudomonas brassicaceanum reduced corn height when compared with the untreated check; however, no differences in test weight or yield from the untreated check were noted with any soil additive. Little if any impacts of the use of biostimulants or soil amendments were seen in these studies.

With widespread resistance to a limited number of insecticides available for medical and veterinary pests, new insecticides and insecticide synergists are desperately needed in this market space. We assessed the topical toxicity of carvone, menthone, and fenchone compared to permethrin and methomyl against the yellow fever mosquito, Aedes aegypti, and the house fly, Musca domestica. We also evaluated the synergistic potential of the monoterpenoids with permethrin and methomyl. Additionally, we assessed the acetylcholinesterase inhibitory potential of each monoterpenoid compared to methomyl. While all three monoterpenoids performed relatively poorly as topical insecticides (LD50 > 4000 ng/mg on M. domestica; > 6000 ng/mg on Ae. aegypti), they synergized both permethrin and methomyl as well as or better than piperonyl butoxide (PBO). Carvone and menthone yielded synergistic co-toxicity factors (23 and 29, respectively), which were each higher than PBO at 24 h. Acetylcholinesterase inhibition did not appear to explain the toxic or synergistic effects of the three monoterpenoids with IC50 values greater than 1 mM for all, compared to the 2.5 and 1.7 µM for methomyl on Aedes aegypti and Musca domestica, respectively. This study provides valuable monoterpenoid toxicity and synergism data on two pestiferous insects and highlights potential for these chemistries in future pest control formulations.

The use of botanical extracts of the plant Jatropha curcas (Euphorbiaceae) represents a valuable alternative to control insect pests and avoid the detrimental effects on the environment and health that arise due to synthetic chemical insecticides. Thus, we conducted a systematic review to summarize the published evidence on the bioactivity of J. curcas against insect pests. Electronic databases were searched to identify studies that assessed J. curcas extracts against insect pests in various types of crops. We included 39 articles that reported the insecticidal and insectistatic activity of several botanical extracts from J. curcas against insects of eight different taxonomic orders. The evidence demonstrates that aqueous and methanolic extracts from seeds and leaves, seed oil, and petroleum ether seed extracts were effective against insect pests of stored grains, aphids of cabbage, sorghum, fruit flies, and desert locusts. The extracts caused high mortality, controlled the populations, reduced oviposition, diminished hatchability, and increased the antifeedant effect. However, the type of solvent used to obtain the botanical extract and the method of application (contact or food) are fundamental to increase its bioactivity. Therefore, botanical extracts from seeds and leaves of J. curcas should be considered as an alternative against insect pests and may be incorporated into integrative and sustainable management for insect control.

Ants of the genus Solenopsis are important invasive pests in the world. Due to their high dispersion capacity, aggressive behavior and because they feed on various sources of vegetable and animal protein, these insects have caused serious damage to public health and agriculture. The control has usually been carried out through the use of organosynthetic insecticides. However, due to the ecological and environmental impacts caused by the use these products, more sustainable alternatives have been sought for their control. Faced with these problems and due to the scarcity of registered products for the control of these insects, we aimed with this study to synthesize and evaluate the anticidal potential of carvacrol derivatives. The lethal and sublethal effects caused by these derivatives were compared with the essential oil of Lippia gracilis (50.7% carvacrol) and with the base molecule — carvacrol. Carvacryl benzoate was the most toxic derivative to Solenopsis sp. with an LD50 of 3.20 g/ mg. This compound was about 2 and 7.6 times, more toxic than carvacrol at the doses needed to kill 50 and 90% of populations, respectively. The workers of Solenopsis sp. showed a rapid reduction in survival when exposed to carvacrol (LT50 = 8.43h) and carvacryl benzoate (LT50 = 8.87h). Insects treated with sublethal doses of the compounds did not show significant effects on self-cleaning, allogrooming and aggregation, with the exception of those treated with L. gracilis essential oil. The oil increased self-cleaning and reduced allogrooming and aggregation. Ants treated with carvacrol and carvacryl benzoate showed greater distance and speed when compared to the control. These compounds decreased meanders and angular velocity. When live workers were exposed to dead individuals at the LD90 of the compounds, carvacryl benzoate was the derivative that most reduced insects survival, due to horizontal transfer. These results show the potential of the carvacrol derivative — carvacryl benzoate — for the alternative management of ants of the genus Solenopsis sp.

Background: Insecticide resistance in Anopheles gambiae s.l. is a major challenge for malaria vector control in Nigeria. Both target-site insensitivity and metabolic resistance have been im-plicated in resistance process, with the latter receiving little attention in Nigeria. Therefore, we investigated metabolic enzyme activities in Anopheles gambiae s.l populations resistant to Del-tamethrin and Diethyldichlorotriethylethane (DDT) in South-West Nigeria. Methods: Anopheles larvae were collected from Ibadan, Oyo and Badagry, Lagos. Adults were exposed to Deltamethrin and DDT using WHO method. Cohorts of populations were further exposed to Pyperonil Butoxide (PBO) and Deltamethrin. Insecticide-exposed and unexposed co-horts were examined for metabolic enzyme activities. Results were compared between exposed and unexposed samples ANOVA (P<0.05). Results: Mosquitoes were identified as An. gambiae (89%, Ibadan; 0%, Badagry) and An. coluzzii (11%, Ibadan; 100%, Badagry). The populations showed varied level of resistance to Deltamethrin (26%, Ibadan; 71%, Badagry) and DDT (2%, Ibadan; 44%, Badagry). Mortality to Deltamethrin in-creased from 26% to 64% (Ibadan) and 71% to 84% (Badagry) when populations were pre-exposed to PBO. Biochemical analysis revealed significant high levels (P<0.05) of cytochrome P450 and GST in exposed samples. Conclusions: Cytochrome P450 and GST are involved in Deltamethrin and DDT resistance in Anopheles gambiae s.l populations in South-West Nigeria.

The rearing temperature of the immature stages can have a significant impact on the life-history traits and the ability of adult mosquitoes to transmit diseases. This review assessed published evidence of the effects of temperature on the immature stages, life-history traits, insecticide susceptibility, and expression of enzymes in the adult Anopheles mosquito. Original articles published through 31 March 2021 were systematically retrieved from Scopus, Google Scholar, Science Direct, PubMed, ProQuest and Web of Science databases. After applying eligibility criteria, 29 studies were included. The review revealed that immature stages of Anopheles arabiensis were more tolerant (in terms of survival) to a higher temperature than An. funestus and An. quadriannulatus. Higher temperatures resulted in smaller larval size and decreased hatching and pupation time. The development rate and survival of Anopheles stephensi were significantly reduced at a higher temperature than a lower temperature. Increasing temperatures decreased the longevity, body size, length of the gonotrophic cycle and fecundity of Anopheles mosquitoes. Anopheles mosquitoes exposed at 18° or 30 °C had a higher risk of dying compared to those exposed at 25 °C. Increasing temperature also significantly increased NOS expression and decreased insecticide toxicity. Both extreme low and high temperatures affect Anopheles mosquito development and survival. Climate change could have diverse effects on Anopheles mosquitoes. There seems to be inconclusive evidence of the effects of temperature on the development and survival of Anopheles species, and more studies are needed to clarify this relationship.

Culex quinquefasciatus is an important target for vector control because of its ability to transmit pathogens that cause disease. Most populations are resistant to pyrethroids and often to organophosphates, the two most common classes of active ingredients used by public health agencies. A knockdown resistance (kdr) mutation, resulting in a change from a leucine to phenylalanine in the voltage gated sodium channel, is one mechanism contributing to the pyrethroid resistant phenotype. Enzymatic resistance has also been shown to play a very important role. Recent studies have shown strong resistance in populations even when kdr is relatively low which indicates factors other than kdr may be larger contributors to resistance. In this study, we examined on a statewide scale (over 70 populations), the strength of the correlation between resistance in the CDC bottle bioassay and the kdr genotypes and allele frequencies. Spearman correlation analysis showed only moderate (-0.51) and weak (-0.29) correlation between the kdr genotype and permethrin and deltamethrin respectively. The frequency of the kdr allele was an even weaker correlate. These results indicate, in contrast to Aedes aegypti, assessing kdr in populations of Culex quinquefasciatus is not a good surrogate for phenotypic resistance testing.

Contact toxicity against Periplaneta americana has never been tested with S. collinsiae root extract. Hexane, dichloromethane, ethanol and water extracts were tested in final-instar nymphs and adult P. americana by topical application method. The dichloromethane extract showed the high-est potency of contact toxicity against the final-instar nymphs (41-100% corrected mortality at 48 hours), lowest LC50 (1.5±0.2 %w/v at 48 hours), and lowest LT50 (36.1±0.8 hours at 10%w/v) while the water crude extract lacked the contact toxicity (0-0% corrected mortality at 48 hours). Signs of toxicity, such as excited movement, trembling body, motionlessness, and swollen abdomen segment including irregularly extended foregut were found at the both stages of P. americana dropping with solutions of dichloromethane extract. Detection of didehydrostemofoline distri-bution using IMS revealed that didehydrostemofoline distributed in the tissue of the dead fi-nal-instar nymph and adult P. americana contacting with dichloromethane extract, but it was not found in tissue of euthanized P. americana which exposed to the water extract. Didehydrostemo-foline in the extract was a cause of toxicity signs and death of P. americana via a contact route. Thus, dichloromethane extract and didehydrostemofoline could be used as an active ingredient and chemical marker in aerosol and spray formulations for cockroach control.

Kiwifruit (Actinidia chinensis) cultivation is expanding worldwide being China, New Zealand and Italy the major producing countries. Halyomorpha halys, the brown marmorated stink bug, has been raising serious concerns to kiwifruit cultivation both in China and Italy. This study aimed at improving the chemical control efficacy against this pest by comparing two insecticide spray techniques (a conventional ray atomizer and a trumpet-modified atomizer adapted for localized spray application in kiwifruit). In fact, kiwifruit is often grown with a ‘pergola’ training system, which may reduce the effectiveness of insecticide penetration into the canopy. Experiments have been performed in naturally infested orchards of both Actinidia chinensis var. chinensis ‘Jintao’ and A. chinensis var. deliciosa ‘Hayward’ during two consecutive seasons. Furthermore, mesh cages, each containing three H. halys adults, were deployed in the orchards to assess the insects’ mortality at 1, 3, 7 and 10 days after the insecticide application with the two spray techniques. In the cultivar 'Jintao', the two systems performed similarly, while in the cultivar 'Hayward', an overall significantly higher insect mortality was recorded with the trumpet atomizer. The crop damage was also evaluated on both cultivars, simulating the grower insecticide applications with the two spray techniques. At harvest, no difference emerged between the spray techniques, which provided a significantly better protection compared to the untreated control. Further investigations in this direction are needed also considering the restriction of insecticidal active substances ongoing in European Union and the need to maximize the efficacy of the available tools.

Aedes aegypti transmits major arboviruses of public health importance, including dengue, chikungunya, Zika, and yellow fever. The use of insecticides represents the cornerstone of vector control, however insecticide resistance in Ae. aegypti has become widespread. Understanding the molecular basis of insecticide resistance in this species is crucial to design effective resistance management strategies. Here, we applied Illumina RNA-Seq to study the gene expression patterns associated with resistance to three widely used insecticides (malathion, alpha-cypermethrin and lambda-cyhalothrin) in Ae. aegypti populations from 2 sites (Manatí and Isabela) in Puerto Rico (PR). Cytochrome P450s were the most over-expressed detoxification genes across all resistant phenotypes. Some detoxification genes (CYP6Z7, CYP28A5, CYP9J2, CYP6Z6, CYP6BB2, CYP6M9, and two CYP9F2 orthologs) were commonly over-expressed in mosquitoes that survived exposure to all three insecticides (independent of geographical origin) while others including CYP6BY1 (malathion), GSTD1 (alpha-cypermethrin), CYP4H29 and GSTE6 (lambda-cyhalothrin) were uniquely overexpressed in mosquitoes that survived exposure to specific insecticides. The gene ontology (GO) terms associated with monooxygenase, iron binding, and passive transmembrane transporter activities were significantly enriched in 4 out of 6 resistant vs susceptible comparisons while serine protease activity was elevated in all insecticide resistant groups relative to the susceptible strain. Interestingly, cuticular-related protein genes (chinase and chitin) were predominantly downregulated, which was also confirmed in the functional enrichment analysis. This RNA-Seq analysis presents a detailed picture of the candidate detoxification genes and other pathways that are potentially associated with pyrethroid and organophosphate resistance in Ae. aegypti populations from PR. These results could inform development of novel molecular tools for detection of resistance-associated gene expression in this important arbovirus vector and guide the design and implementation of resistance management strategies.

Malaria is endemic in Nigeria and remains a major public health problem, taking its greatest toll on children under age 5 and pregnant women, although it is preventable, treatable, and curable. This study investigates the Impact of socio-economic factors and indoor mosquito control on malaria prevalent among pregnant women in Nigeria using logistic regression. To achieve this, secondary data obtained from 2015 Nigeria Malaria Indicator survey, executed by the National Malaria Elimination Programme (NMEP) and the National Population Commission (NPopC), with a nationally representative sample of more than 8,000 consisting of 7,745 households. The results from the logistic regression with odds ratio revealed that pregnant women are more like to be affected by malaria fever (though not significant) compared to women that are not pregnant. The income levels of the household does not significant reduce the incidence of malaria fever among pregnant women in Niger. Concerning the malaria presenting measure, only dwelling sprayed by private company significantly reduce the incidence of malaria fever among pregnant women (P-value=0.020<0.05) compared to dwelling sprayed by government and NGOs and also to Insecticide Treated Net. Also pregnant women in the urban centers are less likely to have malaria fever compared to pregnant women in rural communities in Nigeria. Also, pregnant women with atleast a secondary school level of education are less likely to be affected by malaria fever compared to pregnant women with no formal education. The fitted logistic model passed the goodness-of-test fit; the classification test for the logistic model was correctly classified at about 67.02%. Therefore, this study recommends that government and NGOs should intensify their efforts in the area of dwelling spraying, awareness campaign of the danger of malaria fever among pregnant women and infants, engaged in effective distribution of insecticide treated net in order to reduce the incidence of malaria fever among pregnant women living in rural communities in Nigeria.

The sweetpotato whitefly, Bemisia tabaci MEAM1, is a pest known to significantly impact tomato development and yields through direct damage and virus transmission. To manage this pest, the current study compared the effectiveness of various insecticide rotations. Field trials included rotations involving synthetic insecticides, biochemicals, and microbial agents, applied according to their labeled highest concentrations. Results indicated that while standard synthetic insecticides consistently reduced whitefly egg and nymph counts significantly, microbial biopesticide rotations also achieved reductions, although less consistently. This study demonstrated that while traditional chemical treatments remain highly effective, integrating microbial biopesticides containing Beauveria bassiana and Cordyceps javanica present a viable alternative that could mitigate resistance development and reduce environmental impact. The findings suggest the potential for optimizing integrated pest management (IPM) and Insecticide Resistance Management (IRM) strategies by incorporating a variety of modes of action to sustainably manage B. tabaci MEAM1 populations in agricultural settings.

Insecticides with novel modes of action are required to complement the pyrethroids currently relied upon for controlling malaria vectors. One example of this is the neonicotinoid clothianidin, which is found in SumiShield™ 50WG used in indoor residual spraying (IRS). In a preliminary experiment, mortality in insecticide susceptible and resistant An. gambiae adults exposed to SumiShield™ 50WG-treated filter papers reached 80% by 3-days post-exposure and 100% by 6-days post-exposure. Next, cement, wood, and mud tiles were treated with SumiShield™ 50WG or K-Othrine® WG250 (deltamethrin IRS formulation) and insecticide resistant and susceptible Anopheles and Aedes were exposed to these surfaces periodically for up to 18-months. Pyrethroid resistant Cx. quinquefasciatus were also exposed at 9 months. Between exposures tiles were stored in heat and relative humidity conditions reflecting those found in the field. On these surfaces, SumiShield™ 50WG was effective at killing both susceptible and resistant An. gambiae for 18 months post-treatment, while mortality amongst the resistant strains when exposed to deltamethrin (K-Othrine® WG250) IRS was not above that of the negative control. Greater efficacy of SumiShield™ 50WG was also demonstrated against insecticide resistant strains of An. funestus compared to deltamethrin, though the potency was lower when compared with An. gambiae. In general, a higher efficacy of SumiShield™ 50WG was observed on cement and mud compared to wood. SumiShield™ 50WG demonstrated poor residual activity against Aedes aegypti and Culex quinquefasciatus. Overall, the results suggest SumiShield™ 50WG is well suited for malaria control.

Chemosensory proteins (CSP) are found in the olfactory sensory organs (antennae and maxillary palps) and/or gustatory sensory organs (labellum and legs) and long been accepted to function through binding ‘odorants’. Yet, the same CSPs are also expressed in many tissues other than olfactory and gustatory organs, such as gut, brain, fat body, wing, epidermis, corpora allata, pheromone gland, prothoracic gland, etc. In this review, we suggested the rename “chemosensory protein (CSP)” to “4 Cysteines Soluble Protein (4CSP). To support our idea, we reviewed CSPs from several aspects: their primary sequences, existence of CSP in insects, hexapods, and bacteria, expression during development and in other tissues, evolution of CSP genes, genomic mining, their ancestral functions and lipoid binding, function outside the chemosensory/binding aspect, their intracellular function, and from structure to function. The scope of the review per se is broad, and this is especially true given the volume of data that has been gathered on CSP expressed in ways that are not consistent with the olfactory paradigm. We discuss the Mp10 story in aphids, our research on insecticide resistance, and other lipid transport and immunity-related processes. There is substantial evidence to support the non-chemosensory aspects of CSPs, which is where the majority of discussions lean. There are still very few, if any, statements outlining the aspects of CSPs’ chemosensory properties, specifically how they activate olfactory receptor neurons (ORNs). We present an analysis showing a stronger correlation between them and the actin complex family proteins, mucins, and translation initiation factors. An additional argument is the existence of CSPs outside of insects. Therefore, strong arguments in favor of renaming chemosensory proteins are becoming evident here, outweighing the drawbacks.