Semi-field Conditions Research Articles

Performance of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) on Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) eggs at laboratory and field conditions.

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is a significant pest threatening crops like maize across Africa, necessitating sustainable pest management alternatives. This study evaluates the efficacy of Trichogramma evanescens as a biological control agent against FAW egg masses in Egypt under laboratory and semi-field conditions. FAW larvae were initially collected from infested maize fields and reared on castor-oil plant leaves. Meanwhile, T. evanescens was propagated using Sitotroga cerealella eggs as hosts. The host eggs, aged 18 to 24h, were sterilized with UV light to prevent host development while maintaining suitability for parasitism. Using custom-designed parasitoid incubators and hemisphere clip-cages, experiments focused on various egg mass configurations, assessing the effects of scales and layering. Laboratory conditions were controlled at 25 ± 2ºC and 55 ± 5% relative humidity, while semi-field trials used large cages in maize fields to approximate natural conditions. The results showed that in laboratory settings, parasitism rates averaged 5.96%, 2.00%, and 1.56% for non-, average-, and dense-scale egg masses, respectively. For egg masses with varying layers, parasitism rates were 5.24% for single-layer, 3.09% for double-layer, and 1.18% for ple-layer, regardless of scale presence. In semi-field conditions, parasitism rates were 1.01% for single-layer, 1.13% for double-layer, and 0.59% for triple-layer egg masses. Correspondingly, parasitism rates for non-, average-, and dense-scale eggs were 1.85%, 0.60% and 0.27%. The study concludes that T. evanescens shows promise for integrated pest management programs; however, its effectiveness is constrained by physical and environmental variables. Optimizing the timing of parasitoid releases and selecting robust strains could enhance the effectiveness of biological control, reducing reliance on chemical pesticides in Egypt.

Effect of microencapsulated/photoresistant extract of Azadirachta indica A. Juss seeds on Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctudae) and its persistence in semi-field

The development of bioinsecticides as an alternative to synthetic insecticides can benefit the economy of exporting and importing countries, family farming, production of high-quality commodities, food security, quality of life, and the natural environment. This study aimed to evaluate the effect of microencapsulated extracts of Azadirachta indica A. Juss on Spodoptera frugiperda J.E. Smith and their persistence in the plant under semi-field conditions. The fresh seeds of A. indica, collected in Brazil, were separated for the preparation of the microencapsulated dry extract (MDE) according to criteria registered in the patent. Lethal concentrations for S. frugiperda were determined using a dose response curve. The treatments were compared: MDE, control and positive control based on azadirachtin, evaluating mortality and growth inhibition. There was a significant difference in mortality between the treatments tested. The lethal concentrations LC50 and LC95, expressed in azadirachtin for the bioinsecticide, were 194.98 and 630.95 ppm, respectively. The growth inhibition of S. frugiperda was above 98 % in the treatments, except for the control. The MDE presented lethal times LT50 and LT90 lower than the other treatments (lethal time LT50 = 2.79 d; lethal time LT90 = 3.97 d). The MDE of A. indica seeds was effective in controlling S. frugiperda up to the fifth instar and is considered as slightly persistent to persistent depending on environmental conditions and irrigation, based on IOBC/WPRS parameters. The MDE has the potential to be a phytosanitary product approved for use in organic agriculture and with greater effectiveness in controlling S. frugiperda compared to similar pesticides.Abbreviations: BOD, Biochemical Oxygen Demand; CPA, commercial product based on azadirachtin; CLE, concentrated liquid extract; DAS, days after spraying; GI, growth inhibition; LC50, lethal concentration for 50% of the population; LC95, lethal concentration for 95% of the population; LT50, lethal time for 50% of the population; LT90, lethal time for 90% of the population; MDE, microencapsulated dry extract.

Sublethal fungicide-insecticide co-exposure affects nest recognition and parental investment in a solitary bee

Fungicides may interact synergistically with insecticides. However, our understanding of the impacts of sublethal insecticide-fungicide combinations on solitary bees is mostly restricted to laboratory studies, providing no information about potential consequences on behavior and reproductive success. We analyzed the effects of a fungicide application, alone and in combination with sublethal levels of an insecticide, on the nesting behavior and reproductive output of the solitary bee Osmia cornuta. We released individually-marked females into oilseed rape field cages, and subsequently sprayed the plants with four treatments: control (water), fungicide (tebuconazole), insecticide (acetamiprid at a sublethal concentration), and mixture (fungicide + insecticide). We recorded nesting activity before and after the sprays and assessed post-spray individual reproductive success. Bees of the single pesticide treatments were unaffected by the sprays and did not differ from control bees in any of the parameters measured. The longevity of bees of the mixture treatment was unaffected. However, these bees showed reduced foraging activity, shorter in-nest pollen-nectar deposition times, and increased difficulty recognizing their nesting cavity, leading to a decrease in provisioning rate, parental investment, and offspring production. Our study demonstrates that co-exposure to a fungicide with otherwise harmless levels of an insecticide caused behavioral effects with consequences on reproductive success. Because longevity was unaffected, these effects would not have been easily detected in a chronic laboratory test. Our results have important implications for bee risk assessment, which should account for exposure to multiple compounds and address behavioral effects and reproductive output under semi-field and/or field conditions.

Isolation and identification of native Chilean entomopathogenic fungi and their potential for the control of Drosophila suzukii

Drosophila suzukii is an invasive pest of berries and other soft-skinned fruits, was first detected in Chile in 2017, and has since spread over 2,800 km from north to south. Sustainable control of the spotted-wing drosophila (SWD) is essential due the negative attitude of the consumers toward the excessive use of insecticides. During a survey in Chile for biological control agents, thirty-two isolates of entomopathogenic fungi (EPF) were isolated from mycotized insects and soil samples, identified through sequence analysis, and tested against D. suzukii adults under laboratory conditions. The EPF identified are Akanthomyces muscarius, Beauveria bassiana, Beauveria pseudobassiana, Clonostachys rosea, Metarhizium alvesii, Metarhizium brunneum and Metarhizium robertsii. Six isolates caused 100 % of mortality of D. suzukii adults within ten days after the initial exposition to conidia; these included four B. bassiana isolates (LSB 110, LSB 114, LSB 122 and LSB 125), one M. robertsii isolate (LSB 115) and one M. brunneum isolate (LSB 127). LSB 122 and LSB 125 induced the shortest lethal time (LT50 4 and 4.2 days, respectively), while Akanthomyces and Clonostachys caused ≤ 36 % cumulative mortality of the adults at 10 days of exposure. These results indicate that isolates of B. bassiana, M. robertsii and M. brunneum have significant potential as microbial control agents against D. suzukii adults. This study marks a critical step forward in identifying and validating native entomopathogenic fungi in Chile for sustainable pest management. Future work will focus on further testing these isolates under laboratory, semi-field and field conditions to optimize their application in real-world agricultural settings.

Beauveria bassiana associated with a novel biomimetic hydrogel to control Aedes albopictus through lure and kill ovitraps.

Within the framework of sustainable and effective control methods for Aedes albopictus, two different conidial suspensions, BbCS-1 and BbCS-2 (respectively without and with nutrients), were used as solvents for the biopolymers water-soluble 2-hydroxyethylcellulose (HEC) and sodium alginate (SA). In this way, two different classes of hydrogels were prepared for each polymer (previously shown to attract tiger mosquito oviposition) to produce HEC-based and SA-based Bb/Gel systems with and without nutrients. The aim was to achieve a long-lasting and cost-effective lure-and-kill oviposition substrate useful for lethal ovitraps. Beauveria bassiana (Bb) survival and growth in the different Bb/Gel systems were monitored for 24 days. Following the growth assay, 24-day-old Bb/Gel systems were tested against Ae. albopictus eggs through a hatching test to evaluate their lethal effect. Gel systems enhance Bb's longevity (up to 24 days) more effectively than standard liquid conidial suspensions, proving that tested HEC- and SA-based hydrogels are not toxic for Bb (biocompatibility) and create a microenvironment suitable to sustain prolonged fungal growth. In particular, the results indicate that gel system based on hydroxyethylcellulose is a suitable delivery substrate for supporting the activity of Bb and is simultaneously effective against Ae. albopictus eggs through a combined mechanism of mechanical effect and fungal action (CM > 90%). The efficacy of Bb gel systems was assessed according to its properties in favouring the growth and vitality of Bb as well as in reducing the Ae. albopictus hatching eggs rate. Further studies, in semi-field and field conditions, will be useful to evaluate the efficacy of Bb/Gel systems on adults in terms of attraction, oviposition, mortality, and potential autodissemination to propose a new tool in precision pest management. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Use of Beauveria bassiana and Bacillus amyloliquefaciens Strains as Gossypium hirsutum Seed Coatings: Evaluation of the Bioinsecticidal and Biostimulant Effects in Semi-Field Conditions

Use of Beauveria bassiana and Bacillus amyloliquefaciens Strains as Gossypium hirsutum Seed Coatings: Evaluation of the Bioinsecticidal and Biostimulant Effects in Semi-Field Conditions

Evaluation of the In2care Mosquito Station against Culex quinquefasciatus mosquitoes (Diptera: Culicidae)under semifield conditions.

Culex quinquefasciatus is an important mosquito vector responsible for the transmission of filarial worms, arthropod-borne viruses like Oropouche, St. Louis encephalitis, andWest Nile and protozoans that cause avian malaria. Due to insecticide resistance documented in Cx. quinquefasciatus populations worldwide, integrated vector management programs can benefit from new strategies to control this species. The In2Care Mosquito Station (In2Care station), a commercially available dissemination station containing pyriproxyfen (PPF) and Beauveria bassiana spores, has been shown to be effective against skip-ovipositing Aedes aegypti and Aedes albopictus in previously conducted semifield and field trials. To determine the potential of Cx. quinquefasciatus adult females to autodisseminate PPF and if the In2Care station could be used for Cx. quinquefasciatus control, we assessed its efficacy in a semifield setting against wild Cx. quinquefasciatus. We found that the In2Care station was attractive to gravid Cx. quinquefasciatus females, with a significantly higher percentage of egg rafts laid in the In2Care station compared to alternative ovipots. Adult females successfully autodisseminated PPF from the In2Care station to surrounding ovipots, leading to a significant increase in mosquito emergence inhibition. Additionally, adult Cx. quinquefasciatus exposure to B. bassiana spores significantly reduced mosquito survivorship. These results suggest that the In2Care station may be effective against Cx. quinquefasciatus in addition to Ae. aegypti and Ae. albopictus. Additional field evaluations are needed to assess impacts at the population level.

Toxicity and efficacy of azadirachtin, and oxymatrine-based biopesticides against cabbage aphid and their impacts on predator insects

The aphidicidal activity and efficacy of azadirachtin- and oxymatrine-based biopesticides on the cabbage aphid Brevicoryne brassicae (Linnaeus, 1758) (Hemiptera: Aphididae), and their impacts on the main insect predators of this aphid were assessed under laboratory, semi-field, or field conditions. Laboratory results showed that azadirachtin- and oxymatrine-based biopesticides provided high acute toxicity against B. brassicae nymphs and adult females, in a manner dependent on the concentration, developmental stage, and exposure time of insects to residues. Among the insect's developmental stages, B. brassicae nymphs were more susceptible to biopesticides than adult females. In addition to acute toxicity, the biopesticides reduced the number of offspring and the amount of honeydew excreted by B. brassicae adult females. Furthermore, the biopesticides induced a repellent effect on B. brassicae adult females. Despite their high toxicity, in semi-field conditions, the azadirachtin- and oxymatrine-based biopesticides showed low biological persistence [mortality >80% up to 3 and 1 day after spraying (DAS), respectively] in comparison to the synthetic insecticide flupyradifurone (mortality >80% up to 7 DAS), which was used as a positive control. However, in the field, the biopesticides demonstrated high efficacy in controlling the B. brassicae population, with no significant impact on the population levels of different species of lacewings, ladybugs, and syrphids, which are considered the main insect predators of the cabbage aphid in agroecosystems. Therefore, azadirachtin- and oxymatrine-based biopesticides constitute an important management measure for B. brassicae in agroecosystems, including those with an ecological basis where management tools are limited, and effective control tactics must be incorporated.

Toxicological Impact Of Lambda-Cyhalothrin On Apis Mellifera: Comparative Analysis Under Semi-Field And Field Conditions

Abstract Lambda-cyhalothrin is the most widely used insecticide worldwide. This study investigates the impact of lambda-cyhalothrin on honeybees (Apis mellifera) colonies under semi-field and field conditions utilizing the formulated product (Karate 5% at a concentration of 0.85 ml/l). Considering the application of lambda-cyhalothrin in onion fields, the foraging activities reduced by 27.89 and 29.28% under semi-field and field conditions, respectively. The number of dead workers in the comparison group was three-fold higher than that in the control group under both semi-field and field conditions. Under semi-field and field conditions, reductions were observed in the brood (22.6 and 24.01%), pollen (94.46 and 41.51%), and nectar (69.27 and 44.50%) areas. The effect of lambda-cyhalothrin on the strength of A. mellifera under semi-field conditions resulted in a significant decrease until the 14th day (2.20 bee frames/hive) and in field condition it was on the 7th day (4.79 bee frames/hive). This highlights the non-bee-safe nature of lambda-cyhalothrin when applied during flowering, and spraying should be avoided to reduce its contamination of nectar and pollen. Overall, our results show the significance of conducting field trials to accurately assess the risk of pesticides, depicting a more realistic exposure scenario under actual colony conditions.

Modelling passive sampling of hydrophilic compounds under time-variable aqueous concentrations

Passive sampling is a crucial method for evaluating concentrations of hydrophilic organic compounds in the aquatic environment, but it is insufficiently understood to what extent passive samplers capture the intermittent emissions that frequently occur for this group of compounds. In the present study, silicone sheets and styrene-divinyl benzene-reversed phase sulfonated extraction disks with and without a polyethersulfone membrane were exposed under semi-field conditions in a 31 m3 flume at three different flow velocities. Natural processes and spiking/dilution measures caused aqueous concentrations to vary strongly with time. The data were analyzed using two analytical models that account for these time-variable concentrations: a sampling rate model and a diffusion model. The diffusion model generally gave a better fit of the data than the sampling rate model, but the difference in residual errors was quite small (median errors of 19 vs. 25% for silicone and 22 vs. 25% for SDB-RPS samplers). The sampling rate model was therefore adequate enough to evaluate the time-integrative capabilities of the samplers. Sampler performance was best for SDB-RPS samplers with a polyethersulfone membrane, despite the occurrence of lag times for some compounds (0.1 to 0.4 days). Sampling rates for this design also spanned a narrower range (80 to 110 mL/day) than SDB-RPS samplers without a membrane (100 to 660 mL/day). The effect of biofouling was similar for all compounds and was consistent with a biofouling layer thickness of 150 µm.

Impact of Trichoderma afroharzianum infection on fresh matter content and grain quality in maize.

Trichoderma afroharzianum, a ubiquitous soil-borne fungus found on plant roots and decaying residues, displays competitive traits and mycoparasitic behavior against diverse microorganisms. Selected strains of this fungus are known in agriculture for their beneficial effects on plant growth and as bio-fungicides. However, recent findings have pinpointed Trichoderma afroharzianum as the causal agent behind maize ear rot disease in Europe since 2018, notably impacting maize cobs in Germany, France, and Italy. This study aims to evaluate the severity of Trichoderma ear rot disease on maize fresh matter content and specific quality parameters under semi-field conditions. Two distinct maize varieties were artificially inoculated with a pathogenic Trichoderma isolate at the flowering stage using needle pin or silk channel methods. Disease severity was assessed visually at the time of harvest based on the percentage of infected kernels according to EPPO Guidelines (PP 1/285). Fresh matter content and quality parameters such as alpha-amylase activity, C/N ratio, water, and sugar content were analyzed. Results showed that needle pin inoculation led to higher disease severity (60%) compared to silk channel inoculation (39%). Cob weight decreased significantly at the highest disease severity level by up to 50% compared to control plants. In both varieties, alpha-amylase activity increased significantly with higher Trichoderma disease severity, resulting in starch degradation and increased glucose release. The germination rate was severely affected by the infection, with only 22% of grains germinating, and the seedlings showed shortened and deformed growth. This is the first report on Trichoderma ear rot infection and its effect on fresh matter content and quality parameters in maize after artificial inoculation under field conditions. The results address an important knowledge gap and provide valuable insights into the infection pathway and impact on maize quality.

Synthesis and evaluation of chitosan-based phosphatic nanofertilizer on morpho-physiological characteristics in maize under semi-field conditions

Synthesis and evaluation of chitosan-based phosphatic nanofertilizer on morpho-physiological characteristics in maize under semi-field conditions

Response of cotton mealybug, Phenacoccus Solenopsis Tinsley (Sternorrhyncha: Pseudococcidae) to predators, neem oil, and synthetic insecticide under semi-field and field conditions

Response of cotton mealybug, Phenacoccus Solenopsis Tinsley (Sternorrhyncha: Pseudococcidae) to predators, neem oil, and synthetic insecticide under semi-field and field conditions

Incompatible insect technique: insights on potential outcomes of releasing contaminant females: a proof of concept under semi-field conditions.

Releasing large numbers of Aedes albopictus males, carrying the artificially introduced Wolbachia 'wPip' strain, results in a decrease in the reproductive capacity of wild females due to a phenomenon known as cytoplasmic incompatibility (CI). This vector control strategy is referred to as the incompatible insect technique (IIT). However, its widespread implementation faces various challenges, including the complexity of removing fertile females from the males intended for release. Here, we present the results of semi-field experiments comparing the impact of minimal female co-release on two IIT modes: unidirectional CI-based (UnCI IIT) and bidirectional CI-based (BiCI IIT), specifically targeting Ae. albopictus. The contamination of 'wPip' infected females (2%) during male releases significantly weakened the overall effectiveness of IIT, emphasizing the need for thorough sex separation. Specifically, with UnCI IIT, despite the low rate of co-released females, there was a gradual rise in 'wPip' infection frequency, resulting in more compatible mating and subsequently higher rates of egg hatching. Conversely, this pattern was effectively mitigated in BiCI IIT owing to the reciprocal sterility between the wild-type and the 'wPip' infected populations. Through an experimental approach, conducted in a semi-field setting, we have contributed to advancing scientific understanding regarding the potential outcomes of implementing the IIT strategy in the absence of a complete sexing system. The results suggest that safety measures for mitigating the potential impacts of co-released females can be tailored according to the specific type of IIT being utilized. © 2024 Society of Chemical Industry.

Entomopathogenic fungi against the dengue vector Aedes aegypti: laboratory and semifield assessment

Aedes aegypti, in addition to its association with arboviruses of significant public health concern, poses a considerable challenge to the scientific community, which is actively working to devise innovative strategies to address this threat. Entomopathogenic fungi (EPF) are important bioagents for insect pest control. This study aimed to evaluate the virulence of EPF against Ae. aegypti larvae and adults under laboratory and semifield conditions. Conidia powder from M. anisopliae CG 153 or B. bassiana CG 479, at concentrations ranging from 1×105 to 1×108 conidia/mL, was tested against larvae (N=30) under laboratory conditions, while conidia suspension was used against adults (N=30) via the impregnated filter paper method. Survival curves were compared using the Log-rank test. Both isolates exhibited virulence against larvae and adults, with survival rates ranging from 0% to 64% and 20% to 76%, respectively. Subsequently, both fungi, at a concentration of 107 conidia/mL, were tested against larvae (N=60) and adults (N=60) under laboratory and semifield conditions. Under semifield conditions, larvae and adults showed survival rates ranging from 12% to 35% and 5% to 20%, respectively. The semifield tests produced promising results in decreasing mosquito survival rates. Consequently, this study concludes that the isolates M. anisopliae CG153 and B. bassiana CG 479 have the potential to serve as eco-friendly insecticides against mosquitoes, thus warranting further exploration in the bioprospecting of EPF-based products.

Entomological assessment of hessian fabric transfluthrin vapour emanators for protecting against outdoor-biting Aedes aegypti in coastal Tanzania.

A low technology emanator device for slowly releasing vapour of the volatile pyrethroid transfluthrin was recently developed in Tanzania that provides robust protection against night biting Anopheles and Culex vectors of malaria and filariasis for several months. Here these same emanator devices were assessed in Dar es Salaam city, as a means of protection against outdoor-biting Aedes (Stegomia) aegypti, the most important vector of human arboviruses worldwide, in parallel with similar studies in Haiti and Brazil. A series of entomological experiments were conducted under field and semi-field conditions, to evaluate whether transfluthrin emanators protect against wild Ae. aegypti, and also compare the transfluthrin responsiveness of Ae. aegypti originating from wild-caught eggs to established pyrethroid-susceptible Ae. aegypti and Anopheles gambiae colonies. Preliminary measurements of transfluthrin vapour concentration in air samples collected near treated emanators were conducted by gas chromatography-mass spectrometry. Two full field experiments with four different emanator designs and three different transfluthrin formulations consistently indicated negligible reduction of human landing rates by wild Ae. aegypti. Under semi-field conditions in large cages, 50 to 60% reductions of landing rates were observed, regardless of which transfluthrin dose, capture method, emanator placement position, or source of mosquitoes (mildly pyrethroid resistant wild caught Ae. aegypti or pyrethroid-susceptible colonies of Ae. aegypti and An. gambiae) was used. Air samples collected immediately downwind from an emanator treated with the highest transfluthrin dose (15g), contained 12 to 19 μg/m3 transfluthrin vapour. It appears unlikely that the moderate levels of pyrethroid resistance observed in wild Ae. aegypti can explain the modest-to-undetectable levels of protection exhibited. While potential inhalation exposure could be of concern for the highest (15g) dose evaluated, 3g of transfluthrin appears sufficient to achieve the modest levels of protection that were demonstrated entomologically. While the generally low levels of protection against Aedes reported here from Tanzania, and from similar entomological studies in Haiti and Brazil, are discouraging, complementary social science studies in Haiti and Brazil suggest end-users perceive valuable levels of protection against mosquitoes. It therefore remains unclear whether transfluthrin emanators have potential for protecting against Aedes vectors of important human arboviruses.

Comparison of two different experimental environments for resistance screenings for the leafhopper-transmitted wheat dwarf virus in wheat

Wheat dwarf virus (WDV) causes high yield losses in wheat and other cereals and is therefore an important pathogen transmitted by the leafhopper Psammotettix alienus. Climate change will increase infections by insect-transmitted viruses due to the increasing spread of vectors. In the context of integrated pest management, the cultivation of WDV-resistant/tolerant varieties is an effective way of controlling WDV. Evaluation of tolerant/resistant genotypes is based on inoculation with viruliferous leafhoppers and subsequent phenotyping in gauze houses under semi-field conditions. For successful screening, it is important to ensure the uniform and reproducible inoculation of plants. Abiotic conditions, particularly temperature, have a critical influence on inoculation success, and thus, variations in infection rates were observed within and between previous replicates in the field. Furthermore, the leafhopper population reared in the greenhouse has to be reestablished after each infection, which delays the screening process. We addressed these issues by developing an improved inoculation assay in which plants are inoculated in small infection hoods in the greenhouse before being planted out in gauze houses. This procedure allows optimal environmental conditions for WDV infection of test plants and allows the plants with WDV infection to develop under natural environmental conditions for symptom scoring. In addition, the viruliferous leafhoppers were recollected from the test plants after infection, allowing a sustainable use of the insects. The method thus enables more reliable phenotyping by increasing infection success and testing a greater number of genotypes in a shorter time.

Adhesion Peptide-Functionalized Biobased Microgels for Controlled Delivery of Pesticides.

Widespread use of plant protection agents in agriculture is a major cause of pollution. Apart from active ingredients, the environmental impact of auxiliary synthetic polymers should be minimized if they are highly persistent. An alternative to synthetic polymers is the use of natural polysaccharides, which are abundant and biodegradable. In this study, we explore pectin microgels functionalized with anchor peptides (P-MAPs) to be used as an alternative biobased pesticide delivery system. Using copper as the active ingredient, P-MAPs effectively prevented infection of grapevine plants with downy mildew under semi-field conditions on par with commercial copper pesticides. By using anchor peptides, the microgels tightly bind to the leaf surface, exhibiting excellent rain fastness and prolonged fungicidal activity. Finally, P-MAPs are shown to be easily degradable by enzymes found in nature, demonstrating their negligible long-term impact on the environment.

Efficacy of Pirikool® 300 CS used for indoor residual spraying on three different substrates in semi-field experimental conditions

BackgroundVector control using insecticides is a key prevention strategy against malaria. Unfortunately, insecticide resistance in mosquitoes threatens all progress in malaria control. In the perspective of managing this resistance, new insecticide formulations are being tested to improve the effectiveness of vector control tools.MethodsThe efficacy and residual activity of Pirikool® 300 CS was evaluated in comparison with Actellic® 300 CS in experimental huts at the Tiassalé experimental station on three substrates including cement, wood and mud. The mortality, blood-feeding inhibition, exiting behaviour and deterrency of free-flying wild mosquitoes was evaluated. Cone bioassay tests with susceptible and resistant mosquito strains were conducted in the huts to determine residual efficacy.ResultsA total of 20,505 mosquitoes of which 10,979 (53%) wild female Anopheles gambiae were collected for 112 nights. Residual efficacy obtained from monthly cone bioassay was higher than 80% with the susceptible, laboratory-maintained An. gambiae Kisumu strain, from the first to the tenth study period on all three types of treated substrate for both Actellic® 300CS and Pirikool® 300CS. This residual efficacy on the wild Tiassalé strain was over 80% until the 4th month of study on Pirikool® 300CS S treated substrates. Overall 24-h mortalities of wild free-flying An. gambiae sensu lato which entered in the experimental huts over the 8-months trial on Pirikool® 300CS treatment was 50.5%, 75.9% and 52.7%, respectively, on cement wall, wood wall and mud wall. The positive reference product Actellic® 300CS treatment induced mortalities of 42.0%, 51.8% and 41.8% on cement wall, wood wall and mud wall.ConclusionPirikool® 300CS has performed really well against resistant strains of An. gambiae using indoor residual spraying method in experimental huts. It could be an alternative product for indoor residual spraying in response to the vectors' resistance to insecticides.

Development of underground detection system using a metal detector and aluminum tag for, Copris ochus (Coleoptera: Scarabaeidae).

Tracking of soil-dwelling insects poses greater challenges compared to aboveground-dwelling animals in terrestrial systems. A metal detector system consisting of a commercially available detector and aluminum tags was developed for detecting dung beetle, Copris ochus Motschulsky(Coleoptera: Scarabaeidae). First, detection efficacy of the system was evaluated by varying volumes of aluminum tags attached on a plastic model of the insect and also by varying angles. Then, detection efficacy was evaluated by varying depths of aluminum-tagged models under soil in 2 vegetation types. Finally, the effects of tag attachment on C. ochus adults were assessed for survivorship, burrowing depth, and horizontal movement. Generally, an increase in tag volume resulted in greater detection distance in semi-field conditions. Maximum detection distance of aluminum tag increased up to 17cm below soil surface as the tag size (0.5 × 1.0cm [width × length]) and thickness (16 layers) were maximized, resulting in a tag weight of 31.4mg, comprising ca. 9% of average weight of C. ochus adult. Furthermore, the detection efficacy did not vary among angles except for 90°. In the field, metal detectors successfully detected 5 aluminum-tagged models in 20 × 10 m (W × L) arena within 10min with detection rates ≥85% for up to depth of 10cm and 45%-60% at depth of 20cm. Finally, aluminum tagging did not significantly affect survivorship and behaviors of C. ochus. Our study indicates the potential of metal detector system for tracking C. ochus under soil.