Semi-field Conditions Research Articles

Curcumin/d-mannitol as photolarvicide: induced delay in larval development time, changes in sex ratio and reduced longevity of Aedes aegypti.

Resistant populations of Ae. aegypti have been a major problem in arboviruses epidemic areas, generating a strong demand for novel methods of vector control. In this regard, our group has demonstrated the use of curcumin as an efficient photoactive larvicide to eliminate Ae. aegypti larvae. This work was aimed to evaluate the Ae. aegypti (Rockefeller) development under sublethal conditions, using a curcumin/d-mannitol (DMC) formulation. The photolarvicidal efficacy under semi-field and field conditions (wild populations) was also analyzed, as well as the photobleaching and residual activity of DMC. A delay in development time when larvae were exposed to sublethal concentrations of DMC was observed, followed by significant changes in sex ratio and reduction in longevity. DMC also presented a low residual activity when compared to usual larvicides, and had a substantial photolarvicidal activity against wild populations in field trials, achieving 71.3% mortality after 48 h. Overall, these findings are of great biological importance for the process of enabling the implementation of DMC as a new product in the control of Ae. aegypti larvae, and contributes to the improvement of new plant-based larvicides. © 2021 Society of Chemical Industry.

Assessment of the impacts of microbial plant protection products containing Bacillus thuringiensis on the survival of adults and larvae of the honeybee (Apis mellifera)

This study was aimed at evaluating the effect of a microbial pest-controlling product (MPCP) with the active substance Bacillus thuringiensis ssp. aizawai (strain: ABTS-1857) on adults and larvae of honeybees. To determine the contamination levels of Bt spores in different matrices, a colony-feeding study under semi-field conditions was performed. Furthermore, two chronic adult trials and a chronic larval study were conducted under laboratory conditions to test the effects of different concentrations of the plant protection product (PPP) on the development and mortality. Possible modifications of the chronic oral toxicity test were assessed by additional pollen feeding. Our results showed that Bt spores were detected in all matrices over the entire test duration in different concentrations, decreasing over time. The survival of adult bees and larvae was negatively affected in laboratory conditions after a chronic exposure to the MPCP depending on the tested concentrations. Moreover, the earliest sign of bee mortality, resulting from exposure to ABTS-1857, was recorded only after 96 h at the highest tested concentration. Pollen feeding to adults significantly increased the survival of the treated bees. In conclusion, the PPP with the Bt strain ABTS-1857 showed an effect on the mortality of adults and larvae under laboratory conditions. Further studies with Bt-based PPPs under realistic field conditions are necessary to evaluate the potential risk of those MPCPs on honeybees.

Predicting the impact of outdoor vector control interventions on malaria transmission intensity from semi-field studies

BackgroundSemi-field experiments with human landing catch (HLC) measure as the outcome are an important step in the development of novel vector control interventions against outdoor transmission of malaria since they provide good estimates of personal protection. However, it is often infeasible to determine whether the reduction in HLC counts is due to mosquito mortality or repellency, especially considering that spatial repellents based on volatile pyrethroids might induce both. Due to the vastly different impact of repellency and mortality on transmission, the community-level impact of spatial repellents can not be estimated from such semi-field experiments.MethodsWe present a new stochastic model that is able to estimate for any product inhibiting outdoor biting, its repelling effect versus its killing and disarming (preventing host-seeking until the next night) effects, based only on time-stratified HLC data from controlled semi-field experiments. For parameter inference, a Bayesian hierarchical model is used to account for nightly variation of semi-field experimental conditions. We estimate the impact of the products on the vectorial capacity of the given Anopheles species using an existing mathematical model. With this methodology, we analysed data from recent semi-field studies in Kenya and Tanzania on the impact of transfluthrin-treated eave ribbons, the odour-baited Suna trap and their combination (push–pull system) on HLC of Anopheles arabiensis in the peridomestic area.ResultsComplementing previous analyses of personal protection, we found that the transfluthrin-treated eave ribbons act mainly by killing or disarming mosquitoes. Depending on the actual ratio of disarming versus killing, the vectorial capacity of An. arabiensis is reduced by 41 to 96% at 70% coverage with the transfluthrin-treated eave ribbons and by 38 to 82% at the same coverage with the push–pull system, under the assumption of a similar impact on biting indoors compared to outdoors.ConclusionsThe results of this analysis of semi-field data suggest that transfluthrin-treated eave ribbons are a promising tool against malaria transmission by An. arabiensis in the peridomestic area, since they provide both personal and community protection. Our modelling framework can estimate the community-level impact of any tool intervening during the mosquito host-seeking state using data from only semi-field experiments with time-stratified HLC.Graphical

Biological control of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) by Entomopathogenic fungi and their side effects on natural enemies

BackgroundThe Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an insect pest species responsible for damages of citrus fruit quality and tree health. This insect is a vector of bacteria ‘Candidatus Liberibacter’ spp. a putative causal agent of citrus greening disease known as Huanglongbing (HLB), considered one of the most destructive diseases of citrus orchards worldwide. Disease management is mainly based on vector control using pesticides which can affect natural enemies that play an important role in pest control. The entomopathogenic fungi (EPF) Beauveria bassiana (2067 and 2121) and Metarhizium anisopliae (2411) were achieved by applying a suspension of 1 × 107 spores against D. citri nymphs and artificially infected the citrus seedlings under controlled and semi-field conditions. Also, the activity of these EPFs on the coccinellid and lacewing predators was evaluated. The effects of the main chemicals used in citrus plantations on the selected fungi for possible combined use was also investigated.ResultsThe obtained results showed that under controlled conditions, the percentage of insect mortality produced by EPF varied between 82.8 and 85.9%. Under semi-field conditions, the infection and mortality of D. citri caused by the M. anisopliae 2411 strain was significantly higher than that of B. bassiana 2067, 78.9 and 51%, respectively. Non-significant effect of EPF on the natural enemies of D. citri was observed, suggesting that EPF and predators had compatible effects.ConclusionThis study clearly demonstrated that EPF were able to kill D. citri and can be explored as a promissory biocontrol candidate. Simultaneous use in an integrated pest management program could be possible by applying EPF combined with pesticides.

FIELD ASSESSMENT OF AUTODISSEMINATION OF PYRIPROXYFEN BY CONTAINER-INHABITING AEDES MOSQUITOES IN FLORIDA

Domestic mosquito control for container-inhabiting Aedes vectors of Zika, chikungunya, yellow fever, and dengue viruses is challenging, and novel methods are needed. Autodissemination strategies are one such method. In this control method, females are attracted to stations treated with an insect growth regulator (IGR), become treated, and subsequently deposit the IGR in natural oviposition sites, preventing pupal emergence. We developed and tested treatment stations in semi-field conditions based on number of captured mosquitoes in the treatment stations. The modified treatment station attracted gravid females with oak leaf infusion and mosquito passage through exit chutes granted access to sucrose and topical contamination of IGR (pyriproxyfen) for 25% of released mosquitoes. Although a majority of released mosquitoes were uncaptured (75%), sufficient amounts of pyriproxyfen contaminated female mosquitoes to result in 75% inhibition of adult emergence in larval bioassays. These stations were then used in a field experiment to test the efficacy using sentinel cups with mosquito larvae. Three treatments which included varied numbers of autodissemination stations (control, low density, and high density) were compared. Both low and high density of stations provided high inhibition of adult emergence from sentinel cups relative to controls. We did not observe differences in mosquito emergence inhibition whether sites contained low or high densities of stations (i.e., similar rates of mosquito inhibition). Two additional field trials showed that topically contaminated mosquitoes were traveling further than expected and causing mortality in sentinel cups at least as far as 80 meters from the autodissemination stations. The development and implementation of autodissemination of IGRs is an additional tool for use in integrated mosquito management.

Effect of Benzoylphenyl Ureas on Survival and Reproduction of the Lace Bug, Leptopharsa gibbicarina

Simple SummaryPestalotiopsis fungal complex is a disease that causes damages in oil palm (Elaeis guineensis), and the lace bug, Leptopharsa gibbicarina is the main insect pest that spread this disease. Application of neurotoxic insecticides has been a common method used to control L. gibbicarina for decades in Colombia and Venezuela. The effects of four benzoylphenyl ureas (BPUs) (lufenuron, novaluron, teflubenzuron, and triflumuron) were assessed against L. gibbicarina for toxicity, survival, and reproduction. Overall, the results show that novaluron, teflubenzuron, and triflumuron cause high mortality and reduce survival time, fecundity, and fertility. Thus, BPUs exhibit detrimental effects on L. gibbicarina and can be used as alternatives to other chemical insecticides.The lace bug, Leptopharsa gibbicarina is a vector of Pestalotiopsis fungal complex in oil palm crops in the Americas. The effects of four benzoylphenyl ureas (BPUs) (lufenuron, novaluron, teflubenzuron, and triflumuron) were evaluated against L. gibbicarina for toxicity, survival, reproduction, and mortality in semi-field conditions. Concentration-mortality bioassays demonstrated that novaluron (LC50 = 0.33 ppm), teflubenzuron (LC50 = 0.24 ppm), lufenuron (LC50 = 0.17 ppm), and triflumuron (LC50 = 0.42 ppm) are toxic to L. gibbicarina nymphs. The survival rate was 99% in control nymphs, decreasing to 50% in nymphs exposed to LC50 of triflumuron, 47% in nymphs treated with lufenuron, 43% in nymphs treated with teflubenzuron, and 43% in those treated with novaluron. Sublethal concentrations of BPUs showed detrimental effects on the adult emergence, longevity, fecundity, and fertility of this insect. The mortality of nymphs caused by these insecticides was similar in both laboratory and semi-field conditions. Our results suggest that novaluron, teflubenzuron, and triflumuron are highly effective against L. gibbicarina, and therefore, have potential applications for this oil palm pest.

Comparative infectivity and biocontrol potential of Acrobeloides k29 and entomopathogenic nematodes on the leopard moth borer, Zeuzera pyrina

The leopard moth, Zeuzera pyrina L. (Lepidoptera: Cossidae) is a serious pest of walnut trees in Iran. Due to special habitat of this cossid, the application of entomopathogenic nematodes (EPNs) may offer an efficient strategy in suppressing populations of this pest. The efficacy of two commercially available EPNs Steinernema carpocapsae and Heterorhabditis bacteriophora, as well as a local insect-killing nematode (Acrobeloides K29) were investigated against Z. pyrina larvae in laboratory, semi-field, and field conditions. Laboratory experiments included pathogenicity assessment of aforementioned nematodes in plates using a range of concentrations [5, 10, 20, 50 and 100 infective juveniles (IJs) per larva], as well as evaluation of their reproduction potential on Z. pyrina larvae with concentrations of 5 and 20 IJs per larva. Application of increasing concentrations of nematodes induced higher mortality on Z. pyrina larvae with mean mortality ranging from 28.3% to 100% after 72 h. All three nematodes successfully reproduced and recovered from pest’s cadavers. The highest reproduction was recorded for H. bacteriophora at 5 IJs larva−1 in Z. pyrina. Semi–field experiments using potted walnut seedlings and field trials in a heavily infested walnut orchard during two consecutive years revealed the ability of the aforementioned nematodes to infect and kill Z. pyrina larvae inside the galleries of walnut branches. Overall, this research highlights the ability of all three examined nematodes to find, invade, recycle and effectively infect Z. pyrina larvae; however, S. carpocapsae is comparatively more effective than H. bacteriophora and Acrobeloides K29 under laboratory, semi–field and field conditions. Of significance, the free-living nematode causes high to moderate levels of mortality in Z. pyrina larvae in laboratory and natural conditions.

Evaluation of Long-Lasting Insecticidal Nets (DuraNet®) Under laboratory and Semi-Field Conditions Using Experimental Huts Against Anopheles Mosquitoes in Jimma Zone, Southwestern Ethiopia

Background:Long-Lasting Insecticidal Nets (LLINs) efficacy could be compromised due to a lot of influences together with user compliance and vector population insecticide resistance status. Thus, this study was to assess the biological efficacy of DuraNet® with the help of the World Health Organization cone bioassay and field experimental hut.Methods:A laboratory and a semi-field conditions experimental huts against Anopheles Mosquitoes were conducted in southwestern Ethiopia from September 2015 to January 2016. The bio efficacy of DuraNet® was evaluated using the WHO cone bioassay test and then its field efficacy was evaluated using experimental huts against the malaria vector population.Results:World Health Organization cone bioassay tests against pyrethroid-resistant An. arabiensis led to mean percent mortality and knockdown of 78% and 93%, respectively. Washing of DuraNet® successively reduced its efficacy from 93% knockdown (0 wash) to 45% knockdown (20 washes). Similarly, mean mortality decreased from 84% (0 wash) to 47% (20 washes). A total of 1575 female mosquitoes were collected over 40 nights out of which 1373(87.8%) were An. gambiae s.l., 116 (7.4%) were Anopheles coustani and 107 (6.8%) were An. pharoensis. The mean blood-feeding rate was significantly lower (P < .001) in hut containing unwashed DuraNet® when compared to hut containing untreated DuraNet®. The mean mortality rate was significantly higher (P < .001) in hut containing DuraNet® when compared to hut containing untreated DuraNet®. Unwashed DuraNet® showed the highest personal protection 88.7% and 100% against An. Arabiensis and An. pharoensis, respectively.Conclusion:Both DuraNet® and PermaNet 2.0 moderate efficacy against a pyrethroid-resistant population of An. arabiensis from Ethiopia. The bio efficacy of DuraNet® was found below the WHO recommendation. Therefore, the real impact of the observed insecticide resistance against DuraNet® to be further studied under phase-III trials, the need for new alternative vector control tools remains critical.

Efficacy and Residual Effect of Abamectin and Chlorpyrifos-Methyl against the Second Larval Instar of the Cotton Leafworm, Spodoptera littoralis (BOISD.) Under Field and Semi-Field Condition

The initial mortality and residual effect of abamectin and chlorpyrifos-methyl against the second instar larvae of the leafworm, Spodoptera littoralis (Boisduval) and beneficial arthropods were evaluated on tomato crop during 2019 and 2020 growing seasons under field and semi field conditions.The obtained data were revealed that Chlorpyrifos-methyl gave 100% initial mortality one to five days in 2019 and one to three days in 2020 growing season after application when the recommended rate was used in both seasons.Also, abamectin expressed 100 and 96% initial mortality during the first 24 hr after application in 2019 and 2020 growing seasons, respectively.When the recommended rate was applied,abamectin and chlorpyrifos-methylwere completely lost their toxic residues after 7.55 and 18.39 in 2019 and7.64 and 16.77 days during 2020 growing season of field application, respectively.On the other hand, abamectin had negatively effection on the population of predators at the first day after application then the population was turned back to its normal abundance after 48hr, particularly with half of the recommended rate as well as the field rate of application in both seasons. However, chlorpyrifos-methyl was showed negative impact on the predators, which resulted 100% reduction of predators' population within 96 hr post application, and then the percentage reduction continuously increased till day 13 then it decreased starting from day 14.Therefore, it could be recommended that using abamectin for controling Lepidopterous pests on vegetables to minimize the pre-harvest interval, which makes these crops edible for human use shortly after treatment and also to preserve beneficial predators.

Microbiota Composition in &lt;i&gt;Anopheles&lt;/i&gt; Mosquitoes After Amoxicillin Treatment via the Blood Meal

The microbiota of Anopheles mosquitoes influences malaria transmission. Antibiotics ingested during a blood meal impact the mosquito microbiome and malaria transmission, with substantial differences between drugs. Here, we assessed if amoxicillin affects the mosquito microbiota . We collected Anopheles larvae in Burkina Faso, kept them in semi-field conditions and offered a blood meal to adult females. We tested the impact of blood supplementation with two alternative amoxicillin preparations on microbiota composition, determined by high-throughput sequencing in individual gut samples. Our mosquitoes harbored four main genera, Elizabethkingia, Wigglesworthia, Asaia and Serratia . The antibiotic treatment significantly affected overall microbiota composition, with a specific decrease in the relative abundance of Elizabethkingia and Asaia during blood digestion. Besides its interest on the influence of amoxicillin on the mosquito microbiota, our study proposes a thorough approach to report negative-control data of high-throughput sequencing studies on samples with a reduced microbial load.

Relative toxicity of two natural compounds compared to abamectin against some soybean pests under period rates

A sustainable pest management in agro-ecosystems requires parallel assessments of pesticide and natural compounds to control target pests. In the present study, a semi-field experiment was conducted to evaluate the relative toxicity of abamectin (Abamax), humic acid, and Chitosan Nano-Particles (C.N.Ps) against four soybean pests:Tetranychus urticae,Eutetranychusorientalis,Bemisia tabaci, andPhenacoccus solenopsis. The experimental treatments were arranged in a split-plot design with three replicates, where treatments were assigned to main plots and pest populations under different periods in the subplots. The obtained results and graphs demonstrated that there were considerable differences between the total numbers of pests after different periods of treatment. Generally,E. orientalisrecorded the minimum pest number at all. Different tested compounds demonstrated a considerable correlation between the densities of the pests.T. urticaeexhibited a significant correlation with the other three pests (E. orientalis,B. tabaci, andP. solenopsis).E. orientalisdid not correlate withB. tabaciandP. solenopsis. The humic acid recorded the best effect onT. urticaeafter 3 days with a reduction of 85.45% andE. orientalisafter 7 days 65.55%. However, Chitosan Nano-Particles (C.N.Ps) was the best forE. orientalisafter 14 days (mortality 74.36%). In contrast, abamectin (Abamax) had a general mean of reduction of 91.17% againstT. urticae, whenever, these compounds are promising for controllingT. urticae,E. orientalis,B. tabaci, andP. solenopsis. These results may be a supporting method to overcome some soybean pests. The findings are discussed within the context of integrated management of soybean pests under semi-field conditions.

Impact on survivality and mortality of Apis mellifera L. brood and workers exposed to thiamethoxam treated mustard

The present study was aimed to find out the possible effect of thiamethoxam on growth, development and behaviour of Apis mellifera. The risk of thiamethoxam to broods and adult worker bees was assessed by exposing the honey bee colonies to thiamethoxam treated mustard crop under semi field (within cage) conditions. Observations regarding broods and adult worker bees mortality, brood emergence were taken at a regular interval. Detailed examination of brood development throughout the study demonstrated that thiamethoxam had a negative impact on brood development and survivability. Delayed developmental period of two to four days was observed in colonies placed on the thiamethoxam treated mustard field.

Effect of some Amino Acids and Yeast on Root-knot Disease on Tomato Plants

Three amino acids (AAs) viz. glycine, L-proline and L- tryptophan plus yeast fungus, Saccharomyces cerevisiae, were tested against root knot disease, RKD, caused by root-knot nematode, Meloidogyne incognita on tomato cv. Super Strain-B. All AAs and yeast showed significant reduction in the number of galls, developmental stages, egg masses and fecundity of the treated plants associated with corresponding positive response in plant growth characters. tryptophan gave significantly higher response in reducing the final nematode population followed by L-proline and glycine at high concentrations compared with yeast and check plants. In most cases, the soil drench application was more effective than foliar spray in reducing nematode build-up. The inhibitory effect of all treatments on nematode reproduction was positively correlated with increasing the concentration used. Plant growth was also promoted by all treatments used. generally, All AAs gave significant impact in suppressing the development of the nematode pathogen and sequentially reliving the disease severity. Results of this research offered environmentally safe approaches for combating root-knot disease. Further researches are needed to determine the proper doses, and concentrations of tested AAs and yeast under semi-field and field conditions. Investigations must include the impact on plant yield, before recommending them for managing root-knot disease or promoting plant growth on a wide scale.

Predation Efficacy of Chrysoperla carnea (Steph.) on Parlatoria proteus (Curtis) and Fiorinia phoenicis (Balachowsky) under Semi Field Conditions at Giza Governorate

An experiment was conducted to evaluate the efficacy of Chrysoperla carnea (Steph.) against two hard scale insects Parlatoria proteus (Curtis) and Fiorinia phoenicis (Balachowsky); Hemiptera:Diaspididae, in the nursery of El-Orman Botanical Garden Giza Governorate by releasing 5,10 and 15 individuals of 2nd larval instar of C. carnea and counts were taken 15, 30 and 45 days after treatment. Results showed that there were an effective reduction percentage in population of both scale insects. The mean of reduction percentages after 45 days after treatment in case of P. proteus different stages were 52.54, 68.95 and 77.14% for 1st, 2nd and 3rd treatments, respectively. While mean of reduction percentages of different stages of F. phoenicis recorded 58.38, 59.03 and 65.34% for 1st, 2nd and 3rd treatments, respectively.

Toxicity of selected plant-derived pesticides to the citrus spider mites (Acari: Tetranychidae) and their predator, Stethorus gilvifrons, in the semi-field conditions

ABSTRACT To examine selective effectiveness of specific pesticides on the citrus spider mites and their predator, we evaluated the contact toxicity of different plant-derived pesticides including dishwashing liquid, Dayabon, Palizin, Palizin + ­Citrol oil, Tondexir ­+ ­Bartar soap, cpirodiclofen, spiromesifen, pyridaben, chlorpyrifos-ethyl and abamectin and control on the adult of Tetranychus urticae and Panonychus citri, Panonychus ulmi and their predator, Stethorus gilvifrons in the semi-field conditions. The results revealed that at 24, 48 and 72 h after treatment, Tondexir treatment of 3 ml/L + Bartar 1ml/L had the highest mortality rate on the T. urticae, P. citri, and P. ulmi. This value was 98.13, 84.48, and 80.62%, respectively, for 72 h after treatment for these mites. In addition to the mentioned cases, this treatment caused 72.88% mortality in the larvae and 16.13% in the adult predator during 72 h after treatment, while at the same time, the rate of mortality of chlorpyrifos-ethyl and abamectin treatments on ladybirds was 100%. The results of this study showed that herbal treatments have a high efficiency for integrated management programmes of the major harmful citrus mites and have little impact on their natural enemies and can replace the high-risk chemical pesticides.

Competitive Exclusion Prevents Colonization and Compartmentalization Reduces Transmission of ESBL-Producing Escherichia coli in Broilers.

Extended spectrum beta-lactamase (ESBL)-producing bacteria are resistant to extended-spectrum cephalosporins and are common in broilers. Interventions are needed to reduce the prevalence of ESBL-producing bacteria in the broiler production pyramid. This study investigated two different interventions. The effect of a prolonged supply of competitive exclusion (CE) product and compartmentalization on colonization and transmission, after challenge with a low dose of ESBL-producing Escherichia coli, in broilers kept under semi-field conditions, were examined. One-day-old broilers (Ross 308) (n = 400) were housed in four experimental rooms, subdivided in one seeder (S/C1)-pen and eight contact (C2)-pens. In two rooms, CE product was supplied from day 0 to 7. At day 5, seeder-broilers were inoculated with E. coli strain carrying blaCTX–M–1 on plasmid IncI1 (CTX-M-1-E. coli). Presence of CTX-M-1-E. coli was determined using cloacal swabs (day 5–21 daily) and cecal samples (day 21). Time until colonization and cecal excretion (log10 CFU/g) were analyzed using survival analysis and linear regression. Transmission coefficients within and between pens were estimated using maximum likelihood. The microbiota composition was assessed by 16S ribosomal RNA gene amplicon sequencing in cecal content of broilers on days 5 and 21. None of the CE broilers was CTX-M-1-E. coli positive. In contrast, in the untreated rooms 187/200 of the broilers were CTX-M-1-E. coli positive at day 21. Broilers in C2-pens were colonized later than seeder-broilers (Time to event Ratio 3.53, 95% CI 3.14 to 3.93). The transmission coefficient between pens was lower than within pens (3.28 × 10–4 day–2, 95% CI 2.41 × 10–4 to 4.32 × 10–4 vs. 6.12 × 10–2 day–2, 95% CI 4.78 × 10–2 to 7.64 × 10–2). The alpha diversity of the cecal microbiota content was higher in CE broilers than in control broilers at days 5 and 21. The supply of a CE product from day 0 to 7 prevented colonization of CTX-M-1-E. coli after challenge at day 5, likely as a result of CE induced effects on the microbiota composition. Furthermore, compartmentalization reduced transmission rate between broilers. Therefore, a combination of compartmentalization and supply of a CE product may be a useful intervention to reduce transmission and prevent colonization of ESBL/pAmpC-producing bacteria in the broiler production pyramid.

Dynamics of nest occupation and homing of solitary bees in painted trap nests

1. The oil‐collecting bee Centris analis (Fabricius, 1804) is an important pollinator for the Neotropical region. The species can be attracted to nest in human‐made cavities. Such trap nests or insect hotels offer the opportunity to study the behaviour of populations in semifield conditions.2. We studied a newly established trap nest aggregation of C. analis in Mato Grosso do Sul, Brazil and tested the effect that differentially painted nesting options have on the rate of nest foundation, and on the ability of relocating the nest when returning from a foraging trip (homing behaviour). Moreover, we tested if the duration of foraging trips decreased with time.3. We found that females preferred to nest in painted nests compared to unpainted nests, with blue nests being the most occupied ones, followed by purple, yellow, white, and green. Furthermore, bees improved their homing behaviour with time, however, nest colour did not seem to have an effect on this process. Moreover, we found that bees reduce the duration of their foraging trips with time. This could be an indicator of improved foraging efficiency through learning.4. These findings could inform a new and fruitful line of research on the behaviour and ecology of trap nesting solitary bees.

Field Evaluation of a Spatial Repellent Emanation Vest for Personal Protection Against Outdoor Biting Mosquitoes.

Exophilic vectors are an important contributor to residual malaria transmission. Wearable spatial repellents (SR) can potentially provide personal protection in early evening hours before people retire indoors. An SR prototype for passive delivery of transfluthrin (TFT) for protecting humans against nocturnal mosquitoes in Kanchanaburi, western Thailand, is evaluated. A plastic polyethylene terephthalate (PET) sheet (676 cm2) treated with 55-mg TFT (TFT-PET), attached to the back of short-sleeve vest worn by human collector, was evaluated under semifield and outdoor conditions. Field-caught, nonblood-fed female Anopheles minimus s.l. were released in a 40 m length, semifield screened enclosure. Two collectors positioned at opposite ends conducted 12-h human-landing collections (HLC). The outdoor experiment was conducted between treatments among four collectors at four equidistant positions who performed HLC. Both trials were conducted for 30 consecutive nights. TFT-PET provided 67% greater protection (P < 0.001) for 12 h compared with unprotected control, a threefold reduction in the attack. In outdoor trials, TFT-PET provided only 16% protection against An. harrisoni Harbach & Manguin (Diptera: Culicidae) compared with unprotected collector (P = 0.0213). The TFT-PET vest reduced nonanophelines landing by 1.4-fold compared with the PET control with a 29% protective efficacy. These findings suggest that TFT-PET had diminished protective efficacy in an open field environment. Nonetheless, the concept of a wearable TFT emanatory device has the potential for protecting against outdoor biting mosquitoes. Further development of portable SR tools is required, active ingredient selection and dose optimization, and more suitable device design and materials for advancing product feasibility.

Yes, Irradiated Sterile Male Mosquitoes Can Be Sexually Competitive!

Adequate sexual competitiveness of sterile males is a prerequisite for genetic control methods, including the sterile insect technique. During the past decade several semi-field and open-field trials demonstrated that irradiated male mosquitoes can be competitive.

Impact of visual features on capture of Aedes aegypti with host decoy traps (HDT).

The host decoy trap (HDT) is a surveillance trap that presents a combination of heat, visual and odour stimuli to attract bloodmeal-seeking mosquitoes. Here we employed a semi-field study to demonstrate the role of the visual attributes present on the HDT on the effectiveness of Aedes aegypti capture. Our results show that the HDT is an effective means of capturing Ae. aegypti mosquitoes in semi-field conditions, with a per trial capture rate of up to 69% across four visually distinct HDTs. The solid black coloured HDT captured more mosquitoes than HDTs with black-white stripes, black-white checkerboard patches or solid white colour by a factor of 1.9, 1.7 and 1.5, respectively. In all cases, mosquito capture was not evenly distributed on the HDT surface, with captures on the HDT's outer downwind half, away from the odour delivery, exceeding captures on the inner upwind half. We conclude that the solid black surface of the original HDT design is more effective than the other surfaces (white or black/white patterns) for the capture of Ae. aegypti. Our results demonstrate that mosquito attraction to the thermal and odorant cues of the HDT is modulated by visual information.