Insecticide Sprays Research Articles

Integrated Pest Management Programs for Pear Psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), Using Kaolin Clay and Reflective Plastic Mulch.

Pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), is the most economically important pest of pears grown in Washington State. Standard conventional management programs involve season-long broad-spectrum insecticide sprays. Although the industry uses some tools that are not disruptive to biological control, such as kaolin clay and selective insecticides, they are additions to broad-spectrum insecticides instead of replacements. Conventional sprays suppress pear psylla through the spring and early summer; however, disruption of biological control leads to pear psylla outbreaks near harvest. In 2018 and 2019, we tested two season-long programs that used only selective approaches. The programs began with either kaolin clay or reflective plastic mulch and were followed by identical spray programs using only selective insecticides. Programs were compared with an industry standard conventional program that used numerous broad-spectrum insecticides throughout the season, and a check program with no insecticides for pear psylla. Experiments were conducted using replicated 40-tree plots in a research orchard near Wenatchee, WA with high pear psylla pressure. In both years, selective programs had similar pear psylla densities to the industry standard program and all had lower pear psylla densities and fruit injury than the check. Both selective programs had lower fruit injury than the industry standard in the first year, and similar injury to the industry standard in the second year. Our results suggest kaolin clay and reflective mulch can effectively suppress pear psylla populations and injury in the early season and support season-long selective management programs without the use of broad-spectrum insecticides.

Potentiality of intercropping in managing Diamondback moth (Plutella xylostella)

The present experiment was conducted at horticulture farm of Rajasthan College of Agriculture, Udaipur, Rajasthan, during two winter (rabi) seasons 2019–20 and 2020–21. The treatments include, cabbage + marigold, cabbage + onion, cabbage + garlic, cabbage + marigold + insecticides spray, cabbage + onion + insecticides spray, cabbage + garlic + insecticides spray, cabbage + insecticides spray and cabbage sole without insecticide spray as untreated control. The insecticidal treatments scheduled with two sprays, viz. first spray of chlorfenapyr 10% sc @200 g a.i./ ha and spinosad 45% sc @45 g a.i./ha. During both years, cabbage intercropped with marigold + insecticides spray proved to be the best treatment with the lowest mean DBM larval population (0.73 and 0.47 larvae/plant) and highest benefit-cost ratio (6.69 and 6.88). Additionally, the intercrops treatments, viz. cabbage + marigold, cabbage + onion and cabbage + garlic also significantly reduced the number of DBM larvae per plant as compared to the untreated sole cabbage. The different intercrops combinations evaluated had a positive effect on the cabbage crop in reducing the pest and can be taken to manage DBM in a sustainable way.

Effect of acaricide and insecticide mixtures against citrus leprosis vector, Brevipalpus yothersi, under laboratory and field conditions

The intense spraying of insecticides has negatively affected the management of the leprosis vector mite, Brevipalpus yothersi, requiring additional acaricide applications. Therefore, the main objective of this study was to assess the toxicity of the acaricide spirodiclofen and several insecticides, alone or combined, on different developmental stages of B. yothersi in the laboratory and field. Additionally, the concentration of the active ingredient spirodiclofen was quantified in the spray solutions. The efficacy of spirodiclofen on the eggs and adults of B. yothersi was drastically reduced when spirodiclofen was sprayed in a mixture with cypermethrin, phosmet, or imidacloprid, with 65.4%, 57.2%, and 53.4% of reduction in eggs mortality, and 24.4%, 57.7%, and 17.6% of reduction in adult mortality, respectively. In the field, the addition of insecticides to the spirodiclofen solution decreased the period for reinfestation of the mites by the acaricide from 127 days with spirodiclofen alone to 42 (cypermethrin), 43 (phosmet), and 52 (imidacloprid) days. There was no significant reduction in the spirodiclofen concentration when mixed with insecticides. Our results indicate that the insecticides cypermethrin, phosmet, and imidacloprid antagonize the efficacy of spirodiclofen on eggs and adults of B. yothersi.

Attractive targeted sugar bait phase III trials in Kenya, Mali, and Zambia

BackgroundLong-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) target night-time indoor biting mosquitoes and effectively reduce malaria transmission in rural settings across Africa, but additional vector control tools are needed to interrupt transmission. Attractive targeted sugar baits (ATSBs) attract and kill mosquitoes, including those biting outdoors. Deployment of ATSBs incorporating the insecticide dinotefuran was associated with major reductions in mosquito density and longevity in Mali. The impact of this promising intervention on malaria transmission and morbidity now needs to be determined in a range of transmission settings.Methods/designWe will conduct three similar stand-alone, open-label, two-arm, cluster-randomized, controlled trials (cRCTs) in Mali, Kenya, and Zambia to determine the impact of ATSB + universal vector control versus universal vector control alone on clinical malaria. The trials will use a “fried-egg” design, with primary outcomes measured in the core area of each cluster to reduce spill-over effects. All household structures in the ATSB clusters will receive two ATSBs, but the impact will be measured in the core of clusters. Restricted randomization will be used. The primary outcome is clinical malaria incidence among children aged 5–14 years in Mali and 1–14 years in Kenya and Zambia. A key secondary outcome is malaria parasite prevalence across all ages. The trials will include 76 clusters (38 per arm) in Mali and 70 (35 per arm) in each of Kenya and Zambia. The trials are powered to detect a 30% reduction in clinical malaria, requiring a total of 3850 person-years of follow-up in Mali, 1260 person-years in Kenya, and 1610 person-years in Zambia. These sample sizes will be ascertained using two seasonal 8-month cohorts in Mali and two 6-month seasonal cohorts in Zambia. In Kenya, which has year-round transmission, four 6-month cohorts will be used (total 24 months of follow-up). The design allows for one interim analysis in Mali and Zambia and two in Kenya.DiscussionStrengths of the design include the use of multiple study sites with different transmission patterns and a range of vectors to improve external validity, a large number of clusters within each trial site, restricted randomization, between-cluster separation to minimize contamination between study arms, and an adaptive trial design. Noted threats to internal validity include open-label design, risk of contamination between study arms, risk of imbalance of covariates across study arms, variation in durability of ATSB stations, and potential disruption resulting from the COVID-19 pandemic.Trial registrationZambia: ClinicalTrials.gov NCT04800055. Registered on March 15, 2021Mali: ClinicalTrials.gov NCT04149119. Registered on November 4, 2019Kenya: ClinicalTrials.gov NCT05219565. Registered on February 2, 2022

Insecticide spray regimes to manage Helicoverpa armigera (Hubner) and their impact on natural enemies in cotton under high density planting system

This study evaluated some new class insecticides viz., chlorantraniliprole 18.5SC, flubendiamide 480SC, spinosad 45%SC, indoxacarb 14.5SC and emamectin benzoate 5%SG in cotton under high density planting system (HDPS). These were evaluated against Helicoverpa armigera (Hubner) and their impact on natural enemies were also observed. Experiments were conducted at the ICAR-Central Institute for Cotton Research, Nagpur during 2013-14. Each of the new molecules were sprayed in eight different windows 60 days after sowing (DAS), 60 and 80 DAS, 60, 80 and 100 DAS, 60, 80 100 and120 DAS, 100 and 120 DAS, 80,100 and 120 DAS, 120 DAS and unsprayed control along with three replicates each were analysed in randomized complete block design. The damage by H. armigera was observed by counting healthy and damaged squares and bolls, and % worked out. The whole plant incidence was recorded in case of major predators sampled including spiders and coccinellids. The spray regime 2 (60 and 80 DAS), regime 3 (60, 80 and 100 DAS), regime 4 (60, 80, 100 and 120 DAS) and regime 6 (80, 100 and 120 DAS) were found superior in managing bollworms with by recording least square damage. The results on natural enemies’ populations (spiders and coccinellids) clearly revealed that, all spray regimes were more or less safe to the natural enemies. However, spray regime 1 (spray at 60 DAS), regime 2 (spray at 60 and 80 DAS) and regime 3 (spray at 60, 80 and 100 DAS) recorded maximum natural enemies. Maximum natural enemies was reported at 80 DAS in all the insecticidal spray regimes. Chlorantraniliprole, flubendiamide, spinosad, indoxacarb and emamectin benzoate through the spray regime 2 (spray at 60 and 80 DAS) was observed to be the best option against H. armigera by controlling it in early stage itself and to sustain natural enemies in the cotton ecosystem.

Bean Leaf Beetle (Ootheca spp.) (Coleoptera: Chrysomelidae) Management via Planting Timing and Insecticides.

Simple SummaryBean leaf beetles (Ootheca spp.) (Coleoptera: Chrysomelidae) are a major pest of the common bean (Phaseolus vulgaris L.) in Africa, attacking the roots, leaves, floral parts, and young pods, and reducing grain yields significantly. However, there is no comprehensive program for managing bean leaf beetles. In Uganda, farmers typically try to reduce pest impacts by delaying bean crop sowing, and to a lesser extent, using insecticides, but there is no information on the impact of delayed planting and insecticide application on bean leaf beetles. We conducted a study to assess the effects of planting timing and insecticide spray regimes on bean leaf beetle abundance, foliar damage, and common bean grain yield in three agro-ecological zones. Bean leaf beetle abundance was highest in mid-planting compared to late and early planting, while foliar damage was highest in late planting in two of the three agro-ecological zones. However, marketable grain yield was highest in early-planted plots in all three agro-ecological zones. Insecticide application reduced foliar damage and increased marketable grain yield, with a combination of soil drench and foliar spray resulting in significantly less foliar damage and higher grain yield. Marketable grain yield was higher when insecticides were combined with early planting in all agro-ecological zones.Bean leaf beetles (Ootheca spp.) (Coleoptera: Chrysomelidae) are one of Africa’s most important pests of the common bean (Phaseolus vulgaris L.). Roots, leaves, floral parts, and young pods are all attacked, leading to a considerable loss in grain yield. In Uganda, there are no comprehensive prescribed management strategies for bean leaf beetles, but farmers typically try to control the pest by delaying bean crop sowing, and to a lesser extent, using insecticides. Although farmers have consistently implemented the two approaches, there is no information on the effects of the approaches in Uganda. To assess the impact of planting timing and insecticide spray regimes on bean leaf beetle populations, concomitant foliar damage, and grain yield, we set up trials in three agro-ecological zones with known presence of the beetles during the second rainy season of 2016 (2016) and the first rainy season of 2017 (2017). The first planting, coinciding with early planting, was conducted within one week after the onset of rains. The second planting, coinciding with mid planting, followed two weeks later, while the third planting, considered late planting in this study, was conducted one month after the second planting. A foliar application of cypermethrin commencing at 7 days after emergence (DAE), 14 DAE, 21 DAE, 28 DAE, and 35 DAE; a soil drench of imidacloprid at planting combined with a foliar spray starting at 7 DAE; and an untreated control were among the insecticide spray regimes evaluated. Higher bean leaf beetle abundance was recorded from mid-planting, while higher foliar damage was recorded from late planting in two of the three agro-ecological zones. However, higher marketable grain yield was recorded from early planting in all agro-ecological zones, suggesting that delayed planting may not be beneficial. Insecticide application reduced foliar damage and increased marketable grain yield, with a combination of soil drench and foliar spray resulting in much less foliar damage and, as a result, higher grain yield. However, this did not result in economic benefits. Furthermore, marketable grain yield was higher when insecticide spray regimes were combined with early planting in all agro-ecological zones during both seasons. Our findings suggest that the common bean should be planted early and that the control of the bean leaf beetle should target both the adults and the juvenile stages in the soil. Therefore, there is a need for farmers to be able to access less-expensive soil treatments.

Filling gaps between exposure modeling and the analysis of urinary biomarkers using personal air monitoring: An intervention study of permethrin used in home insecticide spray.

Permethrin is one of the most widely used active ingredients in spray-type home insecticides. However, indoor permethrin exposure resulting from the use of home insecticides is not well-characterized, as measured permethrin concentrations in indoor environmental and biological media with a known application rate are scarce. We conducted an intervention study with four participants for seven days. We conducted personal air monitoring and collected 24-h urine samples in which we quantified time-weighted average (TWA) permethrin concentrations in indoor air (Cair ) and urinary concentrations of two permethrin metabolites, 3-phenoxybenzoic acid (3-PBA) and cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis/trans-DCCA). We also estimated (1) TWA Cair using a simple indoor air model and (2) urinary excreted (UE) mass using a simple excretion model with both estimated and measured TWA Cair . Measurements of TWA Cair from personal air monitoring were lower than those estimated from the indoor model by a factor of 2.9 to 49.4. The ratio of estimated to measured UE mass ranged 3.5-18.2 when using estimated TWA Cair and 1.1-2.9 when using measured TWA Cair . Smaller ratios in estimating internal permethrin exposure from personal air monitoring suggest that personal air monitoring could reduce uncertainties in permethrin exposure assessment resulting from the use of spray-type insecticides.

Microsporidia: a promising vector control tool for residual malaria transmission

Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) have resulted in a major decrease in malaria transmission. However, it has become apparent that malaria can be effectively transmitted despite high coverage of LLINs/IRS. Residual transmission can occur due toPlasmodium-carryingAnophelesmosquitoes that are insecticide resistant and have feeding and resting behavior that reduces their chance of encountering the currently deployed indoor malaria control tools. Residual malaria transmission is likely to be the most significant hurdle to achieving the goal of malaria eradication and research and development towards new tools and strategies that can control residual malaria transmission is therefore critical. One of the most promising strategies involves biological agents that are part of the mosquito microbiome and influence the ability ofAnophelesto transmitPlasmodium.These differ from biological agents previously used for vector control in that their primary effect is on vectoral capacity rather than the longevity and fitness ofAnopheles(which may or may not be affected). An example of this type of biological agent isMicrosporidia MB, which was identified in field collectedAnopheles arabiensisand caused complete inhibition ofPlasmodium falciparumtransmission without effecting the longevity and fitness of the host.Microsporidia MBbelongs to a unique group of rapidly adapting and evolving intracellular parasites and symbionts called microsporidia. In this review we discuss the general biology of microsporidians and the inherent characteristics that make some of them particularly suitable for malaria control. We then discuss the research priorities for developing a transmission blocking strategy for the currently leading microsporidian candidateMicrosporidia MBfor malaria control.

Microbial ecology of sand fly breeding sites: aging and larval conditioning alter the bacterial community composition of rearing substrates

BackgroundSand flies vector several human pathogens, including Leishmania species, which cause leishmaniases. A leishmaniasis vaccine does not yet exist, so the most common prevention strategies involve personal protection and insecticide spraying. However, insecticides can impact non-target organisms and are becoming less effective because of the evolution of resistance. An alternative control strategy is the attract-and-kill approach, where the vector is lured to a lethal trap, ideally located in oviposition sites that will attract gravid females. Oviposition traps containing attractive microbes have proven successful for the control of some mosquito populations but have not been developed for sand flies. Gravid female sand flies lay their eggs in decomposing organic matter on which the larvae feed and develop. Studies have demonstrated that gravid females are particularly attracted to larval conditioned (containing eggs and larvae) and aged rearing substrates. An isolate-based study has provided some evidence that bacteria play a role in the attraction of sand flies to conditioned substrates. However, the overall bacterial community structure of conditioned and aged substrates and how they change over time has not been investigated.MethodsThe goal of this study was to characterize the bacterial communities of rearing and oviposition substrates that have been shown to vary in attractiveness to gravid sand flies in previous behavioral studies. Using 16S rRNA amplicon sequencing we determined the bacterial composition in fresh, aged, and larval-conditioned substrates at four time points representing the main life-cycle stages of developing sand flies. We compared the diversity, presence, and abundance of taxa across substrate types and time points in order to identify how aging and larval-conditioning impact bacterial community structure.ResultsWe found that the bacterial communities significantly change within and between substrates over time. We also identified bacteria that might be responsible for attraction to conditioned and aged substrates, which could be potential candidates for the development of attract-and-kill strategies for sand flies.ConclusionThis study demonstrated that both aging and larval conditioning induce shifts in the bacterial communities of sand fly oviposition and rearing substrates, which may explain the previously observed preference of gravid female sand flies to substrates containing second/third-instar larvae (conditioned) and substrates aged the same amount of time without larvae (aged).Graphical

Hormetic and transgenerational effects in spotted-wing Drosophila (Diptera: Drosophilidae) in response to three commonly-used insecticides.

Although insecticide formulations and spray rates are optimized to achieve lethal exposure, there are many factors in agricultural settings that can reduce the effective exposure of insect pests. These include weather patterns, timing of application, chemical degradation/volatilization, plant structural complexity, and resistant populations. While sub-lethal exposure to insecticides can still have negative impacts on pest populations, they can also lead to stimulatory, or hormetic, responses that can increase the fitness of surviving insects. Sub-lethal concentrations may also produce increased tolerance in the offspring of surviving adults through transgenerational effects. Sub-lethal effects are pertinent for the invasive fruit pest, spotted-wing Drosophila, Drosophila suzukii (Matsumura), because its small size, diurnal movement patterns, and utilization of hosts with complex plant structures, such as caneberries and blueberries, make effective insecticide applications tenuous. In this study, we measured spotted-wing Drosophila survivorship, reproductive performance, and offspring tolerance in flies exposed to sub-lethal concentrations of three commonly-used insecticides (zeta-cypermethrin, spinetoram, and pyrethrin). We found some evidence for hormesis, with survival effects being sex- and concentration-dependent for all insecticides. Males were far more susceptible to insecticides than females, which in some cases exhibited higher eclosion success and reproductive rates when exposed to sub-lethal doses. We did not observe significant transgenerational effects at sub-lethal concentrations, despite trends of increased offspring viability for zeta-cypermethrin and spinetoram. More research, however, is needed to fully understand the role that sub-lethal effects may play in pest population dynamics, insecticide efficacy, and the development of genetic resistance.

Influence of insecticide spray regime and weed management methods on growth and yield of cowpea

ABSTRACT Cowpea (Vigna unguiculata L. Walp.) production in Nigeria is limited mainly due to weed and insect infestations. The effects of insecticide spray regime and weed control on the productivity of cowpea were evaluated in the early and late seasons of 2020. Two insecticide sprays produced increased growth and yield in the late cropping season. However, in the early cropping season, optimum growth and yield of cowpea were obtained with four insecticide sprays. Regardless of the cropping season, preemergence (PRE) application of metolachlor or propaben plus manual weeding (MW) provided 71–80% reduction in weed density and biomass and resulted in cowpea growth and yields similar to the weed-free control. In the late season, two MWs resulted in cowpea growth and yield similar to the weed-free control. However, in the early season treatment, two MWs resulted in 51% lower yield than the weed-free control. The results showed that four insecticide sprays in the early cropping season or two insecticidal sprays in the late cropping season integrated with metolachlor or propaben application plus MW improved the productivity of cowpea.

Evidence map of diagnosis, treatment, prognosis, prevention, and control in visceral leishmaniasis.

ABSTRACTObjective.To develop an evidence map on visceral leishmaniasis prevention, control, diagnosis, treatment, and prognosis.Methods.Systematic reviews on visceral leishmaniasis were searched using MEDLINE/PubMed and Virtual Health Library. After selection, each included systematic review was assessed, characterized, and categorized by intervention type and by outcomes, according to the methodology offered by the PAHO/WHO Latin American and Caribbean Center on Health Sciences Information (BIREME). The methodological quality was assessed using the AMSTAR2 tool to determine the confidence level of the evidence obtained.Results.Among the prevention and control interventions, insecticide spraying, bednets, dog collars, and dog culling were the most assessed, emphasizing that insecticidal dog collars can reduce visceral leishmaniasis incidence in dogs. Regarding diagnosis, polymerase chain reaction (PCR), rK39 immunochromatographic test (rK39 ICT), and direct agglutination test (DAT) presented high sensitivity and specificity. As for treatment, pentavalent antimonials and amphotericin B were the most analyzed drugs and showed therapeutic success; however, serious adverse events can occur due to their use. The prognostic factors identified were anemia, edema, bleeding, jaundice, age, and HIV coinfection.Conclusions.The evidence map developed shows rK39 ICT and DAT as promising diagnostic alternatives and reinforces the efficacy of liposomal amphotericin B and pentavalent antimonials. Insecticide-impregnated dog collars appear as a promising measure for the control of visceral leishmaniasis, but there is also a need for future studies and reviews with higher methodological quality, especially on prevention and control interventions.

Comparison of entomological impacts of two methods of intervention designed to control Anopheles gambiae s.l. via swarm killing in Western Burkina Faso

Outdoor biting constitutes a major limitation of current vector control based primarily on long-lasting insecticidal nets and indoor residual spraying, both of which are indoor interventions. Consequently, malaria elimination will not be achieved unless additional tools are found to deal with the residual malaria transmission and the associated vector dynamics. In this study we tested a new vector control approach for rapidly crashing mosquito populations and disrupting malaria transmission in Africa. This method targets the previously neglected swarming and outdoor nocturnal behaviors of both male and female Anopheles mosquitoes. It involved accurate identification and targeted spraying of mosquito swarms to suppress adult malaria vector populations and their vectorial capacities. The impact of targeted spraying was compared to broadcast spraying and evaluated simultaneously. The effects of the two interventions were very similar, no significant differences between targeted spraying and broadcast spraying were found for effects on density, insemination or parity rate. However, targeted spraying was found to be significantly more effective than broadcast spraying at reducing the number of bites per person. As expected, each intervention had a highly significant impact upon all parameters measured, but the targeted swarm spraying required less insecticide.

Mitigating an Epidemic of Resistance with Integrated Disease Management Tactics: Conflicting Management Recommendations from Insecticide Resistance and Epidemiological Models.

Insect-transmitted plant pathogens threaten crop production worldwide. Because a single feeding bout may be sufficient for a vector to transmit a pathogen that kills the plant, treatment thresholds for vectors of plant pathogens are low. For many vector species, overreliance on chemical controls has resulted in evolution of insecticide resistance. Analysis of complementary insecticide resistance and epidemiological models indicated that tactics for delaying resistance evolution conflict with tactics for limiting pathogen spread. Insecticide resistance models support maintaining untreated refuges that serve as a source of susceptible insects that reduce the likelihood of mating among rare resistant insects. In contrast, epidemiological models indicate that movement of vectors from untreated areas to insecticide-treated areas contributes to pathogen spread. Accordingly, epidemiological models support area-wide insecticide spray programs, although resistance models indicate that such an approach is likely to lead to rapid resistance. To mitigate risk of insecticide resistance, additional management approaches must be integrated into plant disease management strategies. The resistance and epidemiological models were used to evaluate effects of integrating application of insecticides with two additional management strategies: deployment of partially resistant plants (plants that are not immune to infection but have lower acquisition and inoculation rates than susceptible plants) and mating disruption (reduced vector birth rate in mating disruption-treated areas). Deployment of partially resistant plants reduced the risk that untreated areas served as a source of inoculative vectors. Mating disruption reduced the risk of resistance by suppressing growth of insecticide-resistant populations and benefited disease management by reducing vector abundance. Simulation results indicated that by targeting multiple aspects of the plant-pathogen-vector system, pathogen spread could be suppressed and resistance delayed. Implementation of such an approach will require innovations in vector control and sustained efforts in plant breeding.

The resting behavior of malaria vectors in different ecological zones of Ghana and its implications for vector control

BackgroundIn sub-Saharan Africa there is widespread use of long-lasting insecticidal nets and indoor residual spraying to help control the densities of malaria vectors and decrease the incidence of malaria. This study was carried out to investigate the resting behavior, host preference and infection with Plasmodium falciparum of malaria vectors in Ghana in the context of the increasing insecticide resistance of malaria vectors in sub-Saharan Africa.MethodsIndoor and outdoor resting anopheline mosquitoes were sampled during the dry and rainy seasons in five sites in three ecological zones [Sahel savannah (Kpalsogo, Pagaza, Libga); coastal savannah (Anyakpor); and forest (Konongo)]. Polymerase chain reaction-based molecular diagnostics were used to determine speciation, genotypes for knockdown resistance mutations (L1014S and L1014F) and the G119S ace1 mutation, specific host blood meal origins and sporozoite infection in the field-collected mosquitoes.ResultsAnopheles gambiae sensu lato (s.l.) predominated (89.95%, n = 1718), followed by Anopheles rufipes (8.48%, n = 162) and Anopheles funestus s.l. (1.57%, n = 30). Sibling species of the Anopheles gambiae s.l. revealed Anopheles coluzzii accounted for 63% (95% confidence interval = 57.10–68.91) and 27% (95% confidence interval = 21.66–32.55) was Anopheles gambiae s. s.. The mean resting density of An. gambiae s.l. was higher outdoors (79.63%; 1368/1718) than indoors (20.37%; 350/1718) (Wilcoxon rank sum test, Z = − 4.815, P < 0.0001). The kdr west L1014F and the ace1 mutation frequencies were higher in indoor resting An. coluzzii and An. gambiae in the Sahel savannah sites than in the forest and coastal savannah sites. Overall, the blood meal analyses revealed that a larger proportion of the malaria vectors preferred feeding on humans (70.2%) than on animals (29.8%) in all of the sites. Sporozoites were only detected in indoor resting An. coluzzii from the Sahel savannah (5.0%) and forest (2.5%) zones.ConclusionsThis study reports high outdoor resting densities of An. gambiae and An. coluzzii with high kdr west mutation frequencies, and the presence of malaria vectors indoors despite the use of long-lasting insecticidal nets and indoor residual spraying. Continuous monitoring of changes in the resting behavior of mosquitoes and the implementation of complementary malaria control interventions that target outdoor resting Anopheles mosquitoes are necessary in Ghana.Graphical abstract

Management of the Common Vole in the Czech Lands: Historical and Current Perspectives

The integrated management of a serious agricultural pest, the common vole (Microtus arvalis), should be based on modern and empirically proven approaches. The aim of this paper was to map the historical development of the monitoring and control practices of the common vole in the Czech Republic (CR) territory. Published records of vole population outbreaks and heavy crop damage have been documented in the Czech literature since the turn of the 20th century, and even in crops planted in highly fragmented and diversified agricultural landscapes. In the CR, systematic state monitoring was introduced in 1955. In the 1930’s, there were more than 100 various rodent preparations against the common vole, which were formulated as smoke generators, gases, baits, dusts, toxic mushy mass, and insecticide sprays. Currently, there are only six preparations with three active ingredients registered in the CR. Zinc phosphide is the only active ingredient that has been used from the 1940s to the present, whereas anticoagulants were banned for vole control in 2011 owing to the high environmental risks. The poisoning of nontarget animals by rodenticides is not a new phenomenon tied to synthetic pesticides; poisoning by botanical extracts (strychnine) was documented more than 100 years ago. This review may provide both historical lessons for current practice and new incentives for future research.

Inferring the epidemiological benefit of indoor vector control interventions against malaria from mosquito data

The cause of malaria transmission has been known for over a century but it is still unclear whether entomological measures are sufficiently reliable to inform policy decisions in human health. Decision-making on the effectiveness of new insecticide-treated nets (ITNs) and the indoor residual spraying of insecticide (IRS) have been based on epidemiological data, typically collected in cluster-randomised control trials. The number of these trials that can be conducted is limited. Here we use a systematic review to highlight that efficacy estimates of the same intervention may vary substantially between trials. Analyses indicate that mosquito data collected in experimental hut trials can be used to parameterize mechanistic models for Plasmodium falciparum malaria and reliably predict the epidemiological efficacy of quick-acting, neuro-acting ITNs and IRS. Results suggest that for certain types of ITNs and IRS using this framework instead of clinical endpoints could support policy and expedite the widespread use of novel technologies.

Deciphering pollination implications of Apis cerana, Apis mellifera L. on yield of mango (Mangifera indica) in urban landscape

Honeybees play a significant role in the plant–pollinator interactions of many flowering plants. The ecological consequences in urban landscape have not been well studied. The efficacy of pollination by two honey bee species, Apis cerana and Apis mellifera, in mango flowers in the field condition was examined in the present study. The number of honeybees of these two species and other pollinators foraging on the open branches were also observed regularly during three different timings (i.e., 9.00 am, 12.00 pm, and 3.00 pm) in a day. Apis cerana population showed that it was directly proportional to the emergence of flowers and similar 33 phenomenon was observed at the shedding of flowers. Significantly higher fruit yield (78%) in open-pollinated branches than closed-branches (22%) was recorded. Moreover, fruit size and quality were better in open-pollinated branches than closed-branches (covered with muslin cloth). We concluded that A. cerana was more active than A. mellifera during flowering and shedding in mango. This study will help to manipulate the timings of insecticide spray because the populations of honey bees and other pollinators will not be affected if spray done in the late evening (18.00 pm to 19.00 pm).

Approaches to conservation of Nesidiocoris tenuis for biological control of pests in field-grown tomato in Senegal

Conservation biological control is a promising approach to natural pest control in both open field and protected crops. In sub-Saharan Africa, tomato crops are commonly damaged by several arthropod pests but can also host the predatory mirid bug, Nesidiocoris tenuis. Unfortunately, farmers do not currently take full advantage of this zoophytophagous and generalist biocontrol agent. We conducted field investigations in the Niayes area of Senegal, combined with laboratory experiments, to determine how to enhance natural regulation services provided by this natural enemy. We found that strong full-plant watering and insecticidal sprays, both conventionally applied in the Niayes area, had a detrimental effect on N. tenuis. We identified Sesamum radiatum (false or black sesame) as a promising insectarium plant that could also serve as a leaf vegetable and medicinal plant. This plant supports good N. tenuis development and reproduction, even without alternative food sources. Y-tube olfactometry indicated no attraction to odors of Sesamum radiatum, suggesting that N. tenuis would not abandon tomato plants for this insectarium plants when present in tomato fields. Our results suggest potential approaches to improve conservation of N. tenuis for biological control of Tuta absoluta and other tomato pests in Africa.

Regional pest suppression associated with adoption of Cry1Ac soybean benefits pest management in tropical agriculture.

Bacillus thuringiensis (Bt) crops have been adopted worldwide, providing high-level protection from insect pests. Furthermore, Bt crops preserve natural enemies, promote higher yield, and economically benefit farmers. Although regional pest suppression by widespread Bt crop adoption has been observed in temperate regions, this possibility remains uncertain in tropical areas due to the high diversity of alternative hosts and mild winters. Evidence of regional reduction in insecticide use across areas was observed in Brazil where Cry1Ac soybean has been grown since 2013, with up to 50% reduction in the number of insecticide sprays for managing lepidopteran pests on non-Bt soybean observed at specific locations from 2012 to 2019. Pest monitoring data from four mesoregions across 5 years of commercial plantings of Cry1Ac soybean from December 2014 to July 2019 showed reduced numbers of Chrysodeixis includens moths captured in pheromone traps across years at all locations. The number of Helicoverpa spp. moths captured also was reduced at three locations. We provide evidence for regional suppression of lepidopteran pests and reduced insecticide use with the widespread adoption of Cry1Ac soybean in Brazil, bringing economic, social and environmental benefits. © 2022 Society of Chemical Industry.