Pest Species Research Articles

Mating dynamics of a sperm-limited drosophilid, Zaprionus indianus.

When males have large sperm, they may become sperm limited and mating dynamics may be affected. One such species is Zaprionus indianus, a drosophilid that is an introduced pest species in the Americas. We examined aspects of mating behavior in Z. indianus to determine the senses necessary for mating and measure female and male remating habits. We found that vision is necessary for successful copulation, but wings, which produce courtship song, are not needed. Males need their foretarsi to successfully copulate and although the foretarsi may be needed for chemoreception, their role in hanging on to the female during copulation may be more important for successful mating. Females that mate once run out of sperm in approximately five days, although mating a second time greatly increases offspring production. Females do not seem to exert pre-mating choice among males with respect to mating with a familiar versus a novel male. Males are not capable of mating continuously and fail to produce offspring in many copulations. Overall, females of this species benefit from polyandry, providing an opportunity to study sexual selection in females. In addition, the dynamics of male competition for fertilizing eggs needs to be studied.

Thrips Species Composition in Ontario Greenhouse Floriculture: Innovative Identification Tools and Implications for Integrated Pest Management.

Proper species identification is the keystone of successful integrated pest management (IPM). However, efforts to identify thrips species in Canadian greenhouses have not been formally made since the 1980s. In response to recent increases in crop damage, we sampled thrips communities from eight commercial floriculture greenhouses in the Niagara region (Ontario, Canada) from May until August 2016. Selected sites were revisited in 2017, 2018, and 2019 to determine changes in species composition over time. Western flower thrips (Frankliniella occidentalis (Pergande)), along with onion thrips (Thrips tabaci Lindeman), constituted the majority of species found. Other pest species (less than 8% of specimens across all sampling years) included poinsettia thrips (Echinothrips americanus Morgan), chrysanthemum thrips (Thrips nigropilosus Uzel), and Frankliniella fusca (Hinds). Further investigations of thrips outbreaks in Ontario from 2016 to 2023 revealed other important species, including Thrips parvispinus (Karny), Hercinothrips femoralis (Reuter), and Scirtothrips dorsalis Hood. The current biocontrol strategies used in Ontario floriculture crops for western flower thrips do not adequately control onion thrips or other thrips pests in ornamental crops, making identification a fundamental step in determining whether biocontrol or chemical control strategies should be implemented. However, traditional taxonomic keys are inaccessible to non-specialists due to their technical difficulty. Using the data gathered in these surveys, we developed a simplified, illustrated identification key for use by growers and IPM consultants.

Dietary metabarcoding reveals the simplification of bird-pest interaction networks across a gradient of agricultural cover.

Agriculture is vital for supporting human populations, but its intensification often leads to landscape homogenization and a decline in non-provisioning ecosystem services. Ecological intensification and multifunctional landscapes are suggested as nature-based alternatives to intensive agriculture, using ecological processes like natural pest regulation to maximize food production. Birds are recognized for their role in increasing crop yields by consuming invertebrate pests in several agroecosystems. However, the understanding of how bird species, their traits and agricultural land cover influence the structure of bird-pest interactions remains limited. We sampled bird-pest interactions monthly for 1 year, at four sites within a multifunctional landscape, following a gradient of increasing agricultural land cover. We analysed 2583 droppings of 55 bird species with DNA metabarcoding and detected 225 pest species in 1139 samples of 42 bird species. As expected, bird-pest interactions were highly variable across bird species. Dietary pest richness was lower in the fully agricultural site, while predation frequency remained consistent across the agricultural land cover gradient. Network analysis revealed a reduction in the complexity of bird-pest interactions as agricultural coverage increased. Bird species abundance affected the bird's contribution to the network structure more than any of the bird traits analysed (weight, phenology, invertebrate frequency in diet and foraging strata), with more common birds being more important to network structure. Overall, our results show that increasing agricultural land cover increases the homogenization of bird-pest interactions. This shows the importance of maintaining natural patches within agricultural landscapes for biodiversity conservation and enhanced biocontrol.

Hybrids of two destructive subterranean termites established in the field, revealing a potential for gene flow between species.

Hybridization between invasive pest species may lead to significant genetic and economic impacts that require close monitoring. The two most invasive and destructive termite species worldwide, Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann), have the potential for hybridization in the field. A three-year field survey conducted during the dispersal flight season of Coptotermes in Taiwan identified alates with atypical morphology, which were confirmed as hybrids of the two Coptotermes species using microsatellite and mitochondrial analyses. Out of 27,601 alates collected over three years, 4.4% were confirmed as hybrid alates, and some advanced hybrids (>F1 generations) were identified. The hybrid alates had a dispersal flight season that overlapped with the two parental species 13 out of 15 times. Most of the hybrid alates were females, implying that mating opportunities beyond F1 may primarily be possible through female hybrids. However, the incipient colony growth results from all potential mating combinations suggest that only backcross colonies with hybrid males could sometimes lead to brood development. The observed asymmetrical viability and fertility of hybrid alates may critically reduce the probability of advanced-hybrid colonies being established in the field.

Multi-baiting YATLORf sex pheromone traps to optimize click beetle (Agriotes spp., Coleoptera: Elateridae) monitoring for low-cost IPM of wireworms

Implementation of IPM in arable crops requires affordable monitoring tools. YATLORf traps baited with a synthetic pheromone lure for a target species have proven to be effective for monitoring Europe’s most harmful soil pests: Agriotes spp. After the suitable lure position for each of the main Agriotes species was ascertained, different combinations of lures in the same trap were studied in various European countries. Trials were carried out between 2001 and 2007, with the traps being arranged in blocks. Each block contained one trap per treatment under study (i.e., traps baited with a single species lure and traps baited with combinations of two or more different species lures). Unlike most of the research outputs on sex pheromone lures (e.g., on Lepidoptera species), the results of this research have clearly shown that lures for many Agriotes species can be combined in the same trap without loss of performance against most species. Two clear exceptions were A. sputator and A. rufipalpis, which were sensitive to the presence of the geranyl octanoate in lures for other species. It was possible to multi-bait a trap, i.e., use up to four different lures (A. brevis, A. sordidus, A. litigiosus, and A. ustulatus) with good results, thus demonstrating for the first time that important soil pest species belonging to the same genus can be monitored with multi-baited sex pheromone traps. Multi-baiting the same trap resulted in significantly reduced monitoring costs.

Egg parasitoid assemblages and their effectiveness against the Lepidoptera soybean defoliators in Argentina's subtropical production region

AbstractSoybean, Glycine max (L.) Merr. (Fabaceae), is one of the most important crops worldwide, but caterpillars of various species (Lepidoptera) may greatly reduce its annual yield. Nowadays, the main method of controlling these pest species is based on the use of broad‐spectrum insecticides, which are harmful to human health and increase environmental contamination. Therefore, other sustainable methods of control, such as biological control, are in increasing demand. The present study aimed to identify the egg parasitoid species that attack lepidopterans defoliating soybeans in South America's subtropical regions, as well as evaluate their effectiveness at various stages of soybean development. The research was conducted in a commercial soybean field (80 ha) located in Tucumán, Argentina, which was surrounded by wild vegetation as a way to promote biological control. Every week, throughout three consecutive soybean seasons, 20 soybean plants were randomly selected and brought to the laboratory in search of lepidopteran eggs. Over the course of the three crop seasons, the soybean plants were attacked by Anticarsia gemmatalis Hübner (Erebidae), Rachiplusia nu (Guenée), and Chrysodeixis includens (Walker) (both Noctuidae). Six egg parasitoid species were identified, but only three of them were frequently found during the current study. Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) was the most predominant species attacking all lepidopteran pests across all soybean phenological stages. Encarsia porteri (Mercet) (Hymenoptera: Aphelinidae) preferred to attack R. nu eggs, whereas Telenomus cyamophylax Polaszek (Hymenoptera: Scelionidae) parasitized only A. gemmatalis and R. nu eggs. Despite the use of insecticides in the soybean field, the parasitism rates recorded were high. This suggests that using conservation tactics such as native vegetation patches and surrounding alternative crops may result in higher rates of natural control.

Efficacy of an inflatable deterrent for reducing New World vulture human-wildlife conflict

Increasing urbanization coupled with spatial expansion and numerical increase of New World vulture populations has engendered a rise in human-vulture conflict, creating a need for effective tools to mitigate vulture-related damage. Visual frightening devices that mimic the presence of human or other predators can be employed in human-vulture conflict scenarios to increase perceived risk by the pest species, thereby eliciting an antipredator behavioral response, such as fleeing. One visual frightening device, inflatable scarecrows, recently proved effective at reducing passerine attendance at feral swine feeders, but their effectiveness when directed at other species and conflict scenarios has varied. Our primary objective was to evaluate an inflatable deterrent for reducing the number of black (Coragyps atratus) and turkey vultures (Cathartes aura) present (hereafter abundance) at 13 human-vulture conflict sites throughout the southeastern United States. We predicted that vulture abundance would be substantially reduced when inflatable deterrents were deployed. Because we suspected other factors might also influence vulture site abundance, we also examined the exploratory variables of weather, site size (area), and vulture tolerance to human approach in relation to vulture site abundance using a model selection approach. Black vulture site abundance was more pervasive than turkey vultures, occurring at all sites and accounting for 85% of daily vulture counts (10.78 ± 0.52 vultures/site/day) whereas turkey vultures were only present at 62% of sites (2.12 ± 0.21). Across all sites, inflatable scarecrows were effective at reducing vulture abundance by 82% during the seventeen-day treatment period when deterrents were deployed (3.50 ± 0.20), but only a 48% reduction during the twenty-one-day post-treatment phase (15.34 ± 1.39) was observed. Site size and weather did not influence tool effectiveness. Human tolerance at sites, as determined by vulture flight initiation distance, was influential, with tool effectiveness being reduced at sites where local human tolerance was high. We recommend inflatable scarecrows as a tool to reduce vulture-wildlife conflict to private property and recreation at sites where the conflict is spatially restricted (e.g., parking lot or recreation area), conducive to scarecrow deployment (e.g., flat stable surfaces), and where vulture site human tolerance is low to moderate.

Endosymbiont and gut bacterial communities of the brown-banded cockroach, Supella longipalpa.

The brown-banded cockroach (Supella longipalpa) is a widespread nuisance and public health pest. Like the German cockroach (Blattella germanica), this species is adapted to the indoor biome and completes the entirety of its life cycle in human-built structures. Recently, understanding the contributions of commensal and symbiotic microbes to the biology of cockroach pests, as well as the applications of targeting these microbes for pest control, have garnered significant scientific interest. However, relative to B. germanica, the biology of S. longipalpa, including its microbial associations, is understudied. Therefore, the goal of the present study was to quantitatively examine and characterize both the endosymbiont and gut bacterial communities of S. longipalpa for the first time. To do so, bacterial 16S rRNA gene amplicon sequencing was conducted on DNA extracts from whole adult females and males, early instar nymphs, and late instar nymphs. The results demonstrate that the gut microbiome is dominated by two genera of bacteria known to have beneficial probiotic effects in other organisms, namely Lactobacillus and Akkermansia. Furthermore, our data show a significant effect of nymphal development on diversity and variation in the gut microbiome. Lastly, we reveal significant negative correlations between the two intracellular endosymbionts, Blattabacterium and Wolbachia, as well as between Blattabacterium and the gut microbiome, suggesting that Blattabacterium endosymbionts could directly or indirectly influence the composition of other bacterial populations. These findings have implications for understanding the adaptation of S. longipalpa to the indoor biome, its divergence from other indoor cockroach pest species such as B. germanica, the development of novel control approaches that target the microbiome, and fundamental insect-microbe interactions more broadly.

A new biocontrol agent against old enemies: The potential of Trichogramma foersteri for the control of Spodoptera frugiperda and Spodoptera eridania

Species of the genus Trichogramma Westwood (Hymenoptera: Trichogrammatidae) are widely used for pest control, highlighting the importance of exploring new species for the advancement of biological control programs. The study aimed to evaluate the efficacy of Trichogramma foersteri Takahashi, a recently discovered species, in controlling Spodoptera frugiperda (JE Smith) and S. eridania (Stoll), two significant pests of numerous cash crops. Over three days, the research examined parasitism, non-reproductive mortality, and emergence rates for both pest species. Trichogramma foersteri demonstrated effective parasitism, reducing 144.1 ± 6.0 eggs (one layer) and 55.4 ± 4.0 eggs (two layers) of S. frugiperda, as well as controlling 150.7 ± 5.6 eggs of S. eridania. Non-reproductive effects contributed significantly to mortality, causing the demise of 192.6 ± 4.7 and 118.6 ± 3.8 eggs in one and two layers of S. frugiperda, and 294.7 ± 7.0 eggs in S. eridania. Within three days, T. foersteri controlled approximately 334.2 ± 7.6 and 174.0 ± 4.0 eggs of S. frugiperda in one and two layers, respectively, and 445.4 ± 7.2 eggs of S. eridania. The highest emergence of T. foersteri occurred on the first day of evaluation, with 80.4 % for S. frugiperda and 23.0 % for S. eridania. These findings underscore the potential of T. foersteri as an effective control agent for both pests and provide valuable insights for the development of sustainable pest control strategies.

Polygenic adaptation of a cosmopolitan pest to a novel thermal environment.

The fluctuation in temperature poses a significant challenge for poikilothermic organisms, notably insects, particularly in the context of changing climatic conditions. In insects, temperature adaptation has been driven by polygenes. In addition to genes that directly affect traits (core genes), other genes (peripheral genes) may also play a role in insect temperature adaptation. This study focuses on two peripheral genes, the GRIP and coiled-coil domain containing 2 (GCC2) and karyopherin subunit beta 1 (KPNB1). These genes are differentially expressed at different temperatures in the cosmopolitan pest, Plutella xylostella. GCC2 and KPNB1 in P. xylostella were cloned, and their relative expression patterns were identified. Reduced capacity for thermal adaptation (development, reproduction and response to temperature extremes) in the GCC2-deficient and KPNB1-deficient P. xylostella strains, which were constructed by CRISPR/Cas9 technique. Deletion of the PxGCC2 or PxKPNB1 genes in P. xylostella also had a differential effect on gene expression for many traits including stress resistance, resistance to pesticides, involved in immunity, trehalose metabolism, fatty acid metabolism and so forth. The ability of the moth to adapt to temperature via different pathways is likely to be key to its ability to remain an important pest species under predicted climate change conditions.

Estimation of kairomone substances on the behavior of entomophages Trichogramma evanescens Westw. and Bracon hebetor Say.

The aim of the given paper was to estimate the effectiveness of biologically active substances with kairomone properties on the behavior of the entomophagy’s Trichogramma evanescens and Bracon hebetor in the vision of increasing the parasitism potential of different ontogenetic stages of pest development. Biologically active substances with kairomone properties were obtained and tested for increasing the biological indices of the entomophagy’s Trichogramma evanescens and Bracon hebetor. The alcohol-based extract and eggs of the laboratory host Sitotroga cerealella — as a source with kairomone properties for the entomophagy Trichogramma evanescens, and the alcohol-based extract from the larvae and excrement of the laboratory host Galleria melonella — as a source with kairomone properties for the entomophagy were used Bracon hebetor. It was found that due to the influence of kairomone substances, the female entomophagy’s Trichogramma evanescens and Bracon hebetor become more active in searching for eggs and larvae for parasitism, compared to the control variant. It has been demonstrated that biologically active substances, emitted by pest species for the purpose of communication between individuals of the same species, can also be used as kairomone substances by different species of entomophagy’s. The given factor can be further developed with the aim of application in plant protection as a means of activating and increasing the effectiveness of both released and natural entomophagy’s.

Presence of Multiple Genetic Mutations Related to Insecticide Resistance in Chinese Field Samples of Two Phthorimaea Pest Species.

Potatoes hold the distinction of being the largest non-cereal food crop globally. The application of insecticides has been the most common technology for pest control. The repeated use of synthetic insecticides of the same chemical class and frequent applications have resulted in the emergence of insecticide resistance. Two closely related pests that feed on potato crops are the potato tuber moth, Phthorimaea operculella, and the tomato leafminer, Phthorimaea absoluta (syn. Tuta absoluta). Previous studies indicated the existence of insecticide resistance to various classes of insecticides including organophosphates, carbamates, and pyrethroids in field populations of P. operculella and P. absoluta. However, the exact mechanisms of insecticide resistance in P. operculella and to a lesser extent P. absoluta remain still poorly understood. Detecting resistance genotypes is crucial for the prediction and management of insecticide resistance. In this study, we identified multiple genetic mutations related to insecticide resistance in two species of Phthorimaea. An unexpected genetic divergence on target-site mutations was observed between P. operculella and P. absoluta. Three mutations (A201S, L231V, and F290V) in Ace1 (acetylcholinesterase), four mutations (M918T, L925M, T928I, and L1014F) in VGSC (voltage-gated sodium channel), and one mutation (A301S) in RDL (GABA-gated chloride channel) have been detected with varying frequencies in Chinese P. absoluta field populations. In contrast, P. operculella field populations showed three mutations (F158Y, A201S, and L231V) in Ace1, one mutation (L1014F) in VGSC at a lower frequency, and no mutation in RDL. These findings suggest that pyrethroids, organophosphates, and carbamates are likely to be ineffective in controlling P. absoluta, but not P. operculella. These findings contributed to a deeper understanding of the presence of target-site mutations conferring resistance to commonly used (and cheap) classes of insecticides in two closely related potato pests. It is recommended to consider the resistance status of both pests for the implementation of resistance management strategies in potatoes.

Efficacy of pesticides against Nesidiocoris tenuis Reuter (Hemiptera: Miridae), an emerging threat in the cultivation of tomato in Northwest Europe

As non-chemical methods are not always effective to manage pests, the search for chemical solutions that efficiently combat pest species, while safeguarding the environment and beneficial organisms, is essential for advancing effective Integrated Pest Management (IPM) programs. Here, we investigated the efficacy of commercially available pesticides in managing Nesidiocoris tenuis, an emerging threat in the cultivation of tomato in Northwest Europe, while preserving the biocontrol agent Macrolophus pygmaeus. Fourteen pesticides were assessed for their residual toxicity on adults and nymphs in laboratory experiments, after which the most promising candidate was evaluated in cages and semi-commercial greenhouse conditions. Among the pesticides tested, chlorantraniliprole, hexythiazox, tebufenozide and azadirachtin had minimal impact on both insect species, with less than 37.5% corrected mortality. Pirimicarb, sulfoxaflor, acetamiprid, flupyradifurone, thiacloprid, tebufenpyrad, spinosad, indoxacarb, and a mixture of pyrethrins and piperonyl butoxide were harmful to N. tenuis, but also affected M. pygmaeus (up to 100% mortality). Emamectin benzoate was moderately effective to N. tenuis adults (87%) and nymphs (80%), but had limited effects on M. pygmaeus. Application of emamectin benzoate at the maximum recommended concentration resulted in a significantly higher mortality of N. tenuis adults (85%) compared to M. pygmaeus (53%) in cage experiments, while it significantly reduced N. tenuis nymphs and the number of necrotic rings in a greenhouse experiment. Emamectin benzoate emerges as a promising candidate for inclusion in IPM programs. However, further research is necessary to determine its compatibility with other management strategies for controlling N. tenuis and other tomato pests.

Thripidae pest species community identification and population genetic diversity analyses of 2 dominant thrips in cotton fields of China.

Thrips are devastating pests for various crops, and they can rasp tender leaves, terminal buds, and flowers, which specifically causing huge economic losses to cotton production. However, there is very little knowledge about the species composition of thrips in mainland China, as well as the genetic structure of the thrips populations, particularly in the cotton-producing regions. In this study, thrips were collected from 40 geographical locations at 8 different provinces which representing majority cotton-producing belts in China, and mitochondrial cytochrome oxidase subunit I sequence was used to identify species composition and evaluate the genetic diversity of collected thrips individuals. Based on experimental results proven that overall, 10 and 8 species of thrips were identified in seedling and flowering stage respectively, which is corresponding dominant species are Thrip tabaci (Lindeman) and Frankliniella intonsa (Trybom). Genetically, 24 haplotypes were identified in 310 T. tabaci individuals from 10 locations, and 263 haplotypes were detected in 1,861 F. intonsa individuals from 40 locations. Hap1 (T. tabaci) is the most widely distributed haplotype among all the T. tabaci samples. Likewise, Hap 2 is the most widely distributed and abundant haplotype among all samples of F. intonsa. The genetic differentiation degrees of T. tabaci between SXYC population and other 9 populations were high, but its gene flow in these 10 regions was relatively low, which might be due to geographical barriers. The Mantel tests showed no correlation between genetic distance and geographic distance of the 2 thrip species. Demographic analysis results showed that both T. tabaci and F. intonsa experienced population expansion in China. Taken together, this study identifies the species composition of thrips in major cotton-producing regions at different growth periods and evaluates effects of geomorphology on the geographical distribution of haplotypes of dominant thrips T. tabaci and F. intonsa.

Studies on Insect Pest Succession and their Natural Enemies in Brinjal

The Present investigation was carried out at College of Agriculture, Vijayapura, Karnataka to study insect - pests succession and their natural enemies on brinjal during 2021-22. Studies revealed that, four species of insect pests and one coccinellid predatorwere observed at different crop growth stages. The first attack on the crop appeared at one week after transplantation and continued up to till crop reached fruiting and maturity stage. Pests that found attacking on the crop were leaf hopper (Amrasca biguttulabiguttula Ishida), aphids (Aphis gossypii Glover), whitefly (Bemisia tabaci Gennadius), shoot and fruit borer (Leucinodes orbonalis Guenee) and coccinellid predator, Cheliomenes sexmaculata (Fabricius). Brinjal shoot and fruit borer (L. orbonalis) was identified as amajor pest among them.From the seedling stage to fruiting and maturity stage, the populations of Jassids, aphids, coccinellids were observed, white flies were observed from vegetative stage to fruiting and maturity stage, while the population of shoot and fruit borer were observed and recorded during the vegetative stage to fruiting and maturity stage of the crop. Leaf hoppers, aphids and whitefly were found to damage the crop moderatelyand extent of damage caused by L. orbonalis was created much economic loss.

The ancestral karyotype of the Heliantheae Alliance, herbicide resistance, and human allergens: Insights from the genomes of common and giant ragweed.

Ambrosia artemisiifolia and Ambrosia trifida (Asteraceae) are important pest species and the two greatest sources of aeroallergens globally. Here, we took advantage of a hybrid to simplify genome assembly and present chromosome-level assemblies for both species. These assemblies show high levels of completeness with Benchmarking Universal Single-Copy Ortholog (BUSCO) scores of 94.5% for A. artemisiifolia and 96.1% for A. trifida and long terminal repeat (LTR) Assembly Index values of 26.6 and 23.6, respectively. The genomes were annotated using RNA data identifying 41,642 genes in A. artemisiifolia and 50,203 in A. trifida. More than half of the genome is composed of repetitive elements, with 62% in A. artemisiifolia and 69% in A. trifida. Single copies of herbicide resistance-associated genes PPX2L, HPPD, and ALS were found, while two copies of the EPSPS gene were identified; this latter observation may reveal a possible mechanism of resistance to the herbicide glyphosate. Ten of the 12 main allergenicity genes were also localized, some forming clusters with several copies, especially in A. artemisiifolia. The evolution of genome structure has differed among these two species. The genome of A. trifida has undergone greater rearrangement, possibly the result of chromoplexy. In contrast, the genome of A. artemisiifolia retains a structure that makes the allotetraploidization of the most recent common ancestor of the Heliantheae Alliance the clearest feature of its genome. When compared to other Heliantheae Alliance species, this allowed us to reconstruct the common ancestor's karyotype-a key step for furthering of our understanding of the evolution and diversification of this economically and allergenically important group.

Antagonistic and additive effect when combining biopesticides against the fall armyworm, Spodoptera frugiperda

Fall armyworm, Spodoptera frugiperda (FAW) is a cosmopolitan crop pest species that has recently become established in sub-Saharan Africa and Southeast Asia. Current FAW control is almost entirely dependent on synthetic pesticides. Biopesticides offer a more sustainable alternative but have limitations. For example, pyrethrum is an effective botanical insecticide with low mammalian toxicity but is highly UV labile, resulting in a rapid loss of efficacy in the field. Beauveria bassiana is an entomopathogenic fungus that is more persistent, but there is a time lag of several days before it causes insect mortality and leads to effective control. The combination of these biopesticides could mitigate their drawbacks for FAW control. Here we evaluated the efficacy of pyrethrum and B. bassiana as individual treatments and in combination against 3rd instar FAW. Four different combinations of these two biopesticides were tested, resulting in an antagonistic relationship at the lowest concentrations of B. bassiana and pyrethrum (1 × 104 conidia mL−1 with 25 ppm) and an additive effect for the other 3 combined treatments (1 × 104 conidia mL−1 with 100 ppm and 1 × 105 conidia mL−1 with 25 ppm and 100 ppm pyrethrum). Additionally, a delay in efficacy from B. bassiana was observed when combined with pyrethrum as well as a general inhibition of growth on agar plates. These results appear to show that this particular combination of biopesticides is not universally beneficial or detrimental to pest control strategies and is dependent on the doses of each biopesticide applied. However, the additive effect shown here at specific concentrations does indicate that combining biopesticides could help overcome the challenges of persistence seen in botanical pesticides and the slow establishment of EPF, with the potential to improve effectiveness of biopesticides for IPM.

Efficacy of Entomopathogens, Botanical and New Generation Insecticides Against Papaya Mealybug

The papaya mealybug is an invasive polyphagus pest species causing several economic damages to a wide range of agricultural crop. Five new generation insecticides of different groups, one botanical and one entomopathogenic fungus (Beauveria bassiana) were evaluated in laboratory for their effectiveness in reducing mealybug incidence on papaya. The present study was conducted to evaluate the toxic effect of different insecticides at different concentration against P.marginatus. Among the 7 insecticides, Imixam 70 WDG (Imidacloprid+Thiamethoxam) was the most effective insecticide followed by Ravjum 14.5 SC (Indoxacarb), Saka 25 SC (Abamectin 5% +Spirodiclofen 20%), Imixan and Biotrin 0.5% (Matrin), Tundra 20 SP (Acetameprid), Antario (Bacillus thuringiensis+Abamectin) and Beauveria bassiana, respectively.All the selected insecticides provided their highest efficacy at their maximum doses as well as within 7-9 DAT, among them two new generation insecticides e.g. Saka 25 SC (Abamectin 5% +Spirodiclofen 20%) @ 1.0 ml/L, Ravjum 14.5 SC (Indoxacarb) @ 1.0 ml/L and the botanical insecticide Biotrin 0.5% upto 7 DAT would be effective in controlling papaya mealybug considering the efficacy. To confirmation of the results, need to be tested under field condition. Bangladesh J. Nuclear Agric, 37(2): 81-88, 2023

Spatial variation in cocoa insect pest populations and its implication for pest management

ABSTRACT Currently, mirids, stink bugs and coreid bugs are the most important insect pests of cocoa in Ghana. The populations of these insect pests are known to be influenced by the availability of food and breeding sites, as well as the macro and micro climates in cocoa farms. The study investigated variations in the population dynamics of these pests and their damage trends within a square mile (259 hectares). Pest numbers and damage were assessed monthly on 100 trees per plot from 2015 to 2020, each plot measuring one acre (0.4 hectare). Significant differences (p < 0.05) were observed in pest numbers and damage symptoms of the different pest species for the various months of assessment. Populations of each pest species (mirids, stink bugs and the coreid bugs) and their associated damage in the various cocoa plots were significantly different (p < 0.05). The study showed that relying on the pest activity in one cocoa plantation to determine pest management activities in a nearby cocoa plot may not always lead to accurate and effective pest control. The need for pest surveillance and monitoring at the farm level as a basis to design effective Integrated Pest Management in cocoa production is discussed.

Mating harassment may boost the effectiveness of the sterile insect technique for Aedes mosquitoes

The sterile insect technique is based on the overflooding of a target population with released sterile males inducing sterility in the wild female population. It has proven to be effective against several insect pest species of agricultural and veterinary importance and is under development for Aedes mosquitoes. Here, we show that the release of sterile males at high sterile male to wild female ratios may also impact the target female population through mating harassment. Under laboratory conditions, male to female ratios above 50 to 1 reduce the longevity of female Aedes mosquitoes by reducing their feeding success. Under controlled conditions, blood uptake of females from an artificial host or from a mouse and biting rates on humans are also reduced. Finally, in a field trial conducted in a 1.17 ha area in China, the female biting rate is reduced by 80%, concurrent to a reduction of female mosquito density of 40% due to the swarming of males around humans attempting to mate with the female mosquitoes. This suggests that the sterile insect technique does not only suppress mosquito vector populations through the induction of sterility, but may also reduce disease transmission due to increased female mortality and lower host contact.