Insect Populations Research Articles

A box quadrat for standardised sampling of Orthoptera in open habitats: Design, handling, applications and baseline data

Globally, insects are declining at an alarming rate. Therefore, there is an urgent need for standardised monitoring methods to detect changes in insect populations at an early stage. Box quadrat sampling enables highly precise assessments of Orthoptera community composition within a specific area. However, a detailed design of a box quadrat that guarantees an easy workflow, precise descriptions of its handling and a compilation of baseline data for future comparisons have yet been lacking. Based on thirty years of our own experience in box quadrat sampling, we present here: (i) the detailed design of a box quadrat, (ii) its standardised handling in the field (including a video as a supplement), (iii) its applications and (iv) Orthoptera species richness and abundance baseline data for open habitats. The low construction costs (∼300 €) and simple design allow for a wide distribution of this type of box quadrat in future. Moreover, due to the plug system and the light aluminium construction, the quadrat can easily be transported, assembled, handled and dismantled by one person. For comparisons of Orthoptera species richness, abundance and community composition between habitats, we recommend using a quadrat of 2 m² size and 0.8 m height and a minimum sampling area of 20 m² per plot (10 touchdowns per plot). For long-term monitoring or when species are sampled that generally occur in low density, a sampling area of 30 m² (15 replicates) is suggested. By contrast, for the surveys of tiny species (e.g., groundhoppers) and developmental stages (nymphs), smaller box quadrats can also be used and the sampled area per plot can be below 20 m². Box quadrat sampling is less dependent on favourable weather conditions and vegetation structure than many other insect survey techniques. Overall, it allows rapid and highly precise assessments of Orthoptera community composition.

Horizontal transmission of a rice bacterial pathogen Pantoea ananatis among plants by rice planthoppers.

Pantoea ananatis is a bacterium commonly found in various agronomic crops and agricultural pests. In this study, we present findings on a genome-reduced strain of P. ananatis, known as Lstr, which was initially isolated from Laodelphax striatellus (small brown rice planthopper, SBPH). We identified Lstr as a plant pathogen causing disease in rice using Koch's postulates. The pathogenicity of Lstr on rice is comparable to that of Xanthomonas oryzae pv. oryzae, the main causative agent of rice bacterial blight. Through a series of experiments involving live insects, molecular investigations, and microscopy, we find that Lstr can accumulate within SBPH. Subsequently, Lstr can be transmitted from SBPH to rice plants, resulting in leaf blight, and can also be transmitted to other SBPH individuals. Collectively, our results suggest that SBPH serves as a vector for P. ananatis Lstr in rice plants. P. ananatis may encounter susceptible insect populations and become endemic through horizontal transmission from these insects. This could also be valuable for predicting future occurrences of bacterial leaf blight in rice and other crops caused by P. ananatis.

Insect pest Spodoptera litura (Fabricius) and its resistance against the chemical insecticides: A review

A polyphagous nocturnal pest Spodoptera litura (Fabr.) commonly called armyworm, infests about 150 plant species across 44 families worldwide, with nearly 60 plant species affected just in India. The majority of leaf tissues are consumed by the larvae and only the stem and side shoots will remain in the field. They entirely consume the interior content by boring into them, causing squares and young bolls to shed. This insect can badly affect crops and has a wide range of potential hosts, which can lead to financial losses for farmers and food shortages for consumers. The worldwide distribution of S. litura as a pest results in significant impact on productivity of many crops. They have the capability to invade new places as a wide-ranging species. Armyworm frequently reappears in India every year and causes evident destruction. Different records on the insect population outbreak have been reported from many countries all around the world. The larvae of insect pests enter the fruits and even contaminate it and this causes yield and economic losses. The low temperatures of winter season are the limiting factors that affect species. It migrates mainly to breed during the summer season but is unable to survive in winters. S. litura acquired resistance to several synthetic insecticides, which led to pest outbreaks that were irregular and caused failure of different crops. The resistance and cross-resistance of this pest against insecticide toxin make it more difficult to reduce its population below threshold level. Understanding the mechanisms of resistance is crucial for developing effective resistance management strategies that can restrict or halt the spread of resistance in these pest populations.

Multigenerational hormetic effects of different insecticides on Spodoptera frugiperda (J.E. smith) (Lepidoptera: Noctuidae)

To protect crops from pest insects, farmers continuously use insecticides, which eventually degrade into residue due to abiotic or biotic factors. These residual effects of pesticides may cause low lethal and/or sublethal impacts on the exposed pest insect populations, leading to the induction of pest resurgence through hormesis and ultimately the development of resistance. Hormesis is a beneficial bi-phasic effect generally characterized by low-dose reproductive stimulation and high-dose inhibition. In the present study, we investigated the impact of low lethal and sublethal concentrations (LC10, LC20, and LC30) of spinetoram, chlorantraniliprole, and thiodicarb on the F0 generation as well as their multigenerational hormesis effects on the F1 and F2 generations of Fall Armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). The study focused on reproductive parameters, fecundity, fertility, and life index parameters such as net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), mean length of generation (Tc), and gross reproductive rate (GRR). Fecundity of S. frugiperda increased by 4.82%, 4.63% and 4.58%, while eggs fertility improved by 7.77%, 6.78% and 6.52% at LC10 of thiodicarb, chlorantraniliprole and spinetoram, respectively, from the F1 to F2 generation. Further, interaction analysis (Concentration × Insecticidal treatments) revealed that important vital parameters like pre-oviposition period (POP), oviposition period (OP), post-oviposition period (PtOP), R0,rm,λ, Tc and GRR of F0 were negatively impacted by LC30 of all the tested insecticides and LC20 of only spinetoram. However, LC10 of any of the tested insecticides did not affect these parameters when compared with control. Furthermore, interactive analysis in multigenerational exposure experiments (Concentration × Insecticidal treatments × Generation(s)) showed hermetic effects of LC10 of all tested insecticides which is more positive in F2 as compared to F1 generation. These unwanted positive hermetic effects of low lethal concentrations (LC10) of tested insecticides in offspring of exposed parental population of S. frugiperda indicated its resistance and/or resurgence. Furthernore, present study emphasizes the necessity for additional research to elucidate the underlying mechanisms responsible for these effects.

Downregulation of APN1 and ABCC2 mutation in Bt Cry1Ac-resistant Trichoplusia ni are genetically independent.

The resistance to the insecticidal protein Cry1Ac from the bacterium Bacillus thuringiensis (Bt) in the cabbage looper, Trichoplusia ni, has previously been identified to be associated with a frameshift mutation in the ABC transporter ABCC2 gene and with altered expression of the aminopeptidase N (APN) genes APN1 and APN6, shown as missing of the 110-kDa APN1 (phenotype APN1¯) in larval midgut brush border membrane vesicles (BBMV). In this study, genetic linkage analysis identified that the APN1¯ phenotype and the ABCC2 mutation in Cry1Ac-resistant T. ni segregated independently, although they were always associated under Cry1Ac selection. The ABCC2 mutation and APN1¯ phenotype were separated into two T. ni strains respectively. Bioassays of the T. ni strains with Cry1Ac determined that the T. ni with the APN1¯ phenotype showed a low level resistance to Cry1Ac (3.5-fold), and the associated resistance is incompletely dominant in the background of the ABCC2 mutation. Whereas the ABCC2 mutation-associated resistance to Cry1Ac is at a moderate level, and the resistance is incompletely recessive in the genetic background of downregulated APN1. Analysis of Cry1Ac binding to larval midgut BBMV indicated that the midgut in larvae with the APN1¯ phenotype had reduced binding affinity for Cry1Ac, but the number of binding sites remained unchanged, and the midgut in larvae with the ABCC2 mutation had both reduced binding affinity and reduced number of binding sites for Cry1Ac. The reduced Cry1Ac binding to BBMV from larvae with the ABCC2 mutation or APN1¯ phenotype correlated with the lower levels of resistance.IMPORTANCEThe soil bacterium Bacillus thuringiensis (Bt) is an important insect pathogen used as a bioinsecticide for pest control. Bt genes coding for insecticidal proteins are the primary transgenes engineered into transgenic crops (Bt crops) to confer insect resistance. However, the evolution of resistance to Bt proteins in insect populations in response to exposure to Bt threatens the sustainable application of Bt biotechnology. Cry1Ac is a major insecticidal toxin utilized for insect control. Genetic mechanisms of insect resistance to Cry1Ac are complex and require to be better understood. The resistance to Cry1Ac in Trichoplusia ni is associated with a mutation in the ABCC2 gene and also associated with the APN expression phenotype APN1¯. This study identified the genetic independence of the APN1¯ phenotype from the ABCC2 mutation and isolated and analyzed the ABCC2 mutation-associated and APN1¯ phenotype-associated resistance traits in T. ni to provide new insights into the genetic mechanisms of Cry1Ac resistance in insects.

The Response of Insects and Weeds within the Crop to Variation in Sowing Density of Canola

The relationships between weeds and insects in canola stands with different seeding rates are not fully understood. Varying seeding rates in canola crops can create different conditions that affect both weed and insect populations and their interactions. The aim of this work was to determine the response of weeds and insects of selected taxa to different densities of canola stand densities and to clarify the interactions between weeds and insects in canola stands. The field experiment was conducted on a plot located in the cadastral area of the municipality of Pěnčín (Moravia, Czech Republic). The results show that a reduced canola sowing rate of oilseed rape leads to increased weed infestation, which is dominated by one taxon (Papaver rhoeas L.). The increase in weed infestation of canola stands is not reflected in an increase in the diversity of captured insects. Increased canola seeding rate improves weed suppression but increases the number of canola pest insects. A higher number of plants and more canola biomass increase the food supply and, thus, make the stand more attractive to canola pests. The taxon Brassicogethes aeneus dominated the pests species spectrum. Changing the seeding rate of canola results in a response in weed and insect populations. The standard recommended seeding rate is optimal in terms of competitive suppression of weeds and the occurrence of pests and trapped insects. Increasing or decreasing the seeding rate of rapeseed does not bring any benefits in terms of pest regulation or biodiversity. However, the results obtained indicate an interesting weed–insect interaction in the conditions of canola stands.

Microsporidia-cypovirus interactions during simultaneous infection of the tree defoliator Dendrolimus sibiricus (Lepidoptera: Lasiocampidae)

The Siberian moth, Dendrolimus sibiricus is a dangerous forest defoliator, the number one pest of boreal forests in Asia. Search for effective and ecologically friendly control measures drives attention to microbial pathogens. Viruses and microsporidia are obligate intracellular parasites widespread in insect populations causing either chronic or acute infections. Interactions of these pathogens vary from antagonistic to synergistic. The goal of the work was to test a recently discovered cytoplasmatic polyhedrosis virus (cypovirus) strain DsCPV-1 isolated from D.sibiricus, combined with a microsporidium, against D. sibiricus, by feeding the inoculum (viral polyhedral and microsporidian spores). Three different microsporidian parasites of lepidopterans were tested against D. sibiricus as monoinfection: Nosema bombycis from silkworm, N. pyrausta from corn borer, and Tubulinosema loxostegi from beet webworm. Nosema bombycis was the most virulent, with a median lethal time of 7 days in the first and second instars treated with 100,000 and 1 million spores/larva, respectively. Nosema bombycis (dose 100,000 spores/larva) was chosen to test it as mixed infection in combination with an extremely low dose of DsCPV-1 (1 polyhedron/larva) against two races of D. sibiricus second instar larvae (the fir-feeding race and the larch-feeding race). The mixed infection demonstrated the most prominent negative effect on larval lethal time and weight for the both tested races. Mixed infections showed a synergistic effect for the fir-feeding larvae but additive effect only for the larch feeding larvae. Both pathogens co-developed successfully in the larvae with equal ratio of producing inoculum. The combination of these entomopathogens is therefore promising for forest protection against the Siberian moth and could be the way to significantly decrease the amount of pathogens applied in field.

Population suppression with dominant female-lethal alleles is boosted by homing gene drive

BackgroundMethods to suppress pest insect populations using genetic constructs and repeated releases of male homozygotes have recently been shown to be an attractive alternative to older sterile insect techniques based on radiation. Female-specific lethal alleles have substantially increased power, but still require large, sustained transgenic insect releases. Gene drive alleles bias their own inheritance to spread throughout populations, potentially allowing population suppression with a single, small-size release. However, suppression drives often suffer from efficiency issues, and the most well-studied type, homing drives, tend to spread without limit.ResultsIn this study, we show that coupling female-specific lethal alleles with homing gene drive allowed substantial improvement in efficiency while still retaining the self-limiting nature (and thus confinement) of a lethal allele strategy. Using a mosquito model, we show the required release sizes for population elimination in a variety of scenarios, including different density growth curves, with comparisons to other systems. Resistance alleles reduced the power of this method, but these could be overcome by targeting an essential gene with the drive while also providing rescue. A proof-of-principle demonstration of this system in Drosophila melanogaster was effective in both biasing its inheritance and achieving high lethality among females that inherit the construct in the absence of antibiotic.ConclusionsOverall, our study shows that substantial improvements can be achieved in female-specific lethal systems for population suppression by combining them with various types of gene drive.

Have native insect pests associated with a native crop in Maine declined over the past three to five decades?

Abstract Lowbush blueberry is an important berry crop in Maine (USA), Quebec and the Maritime provinces of Canada. The other economically important crops in Maine are potato, dairy and organic mixed vegetable produce. Lowbush blueberry is a complex of 1–4 Vaccinium species, primarily dominated by Vaccinium angustifolium Aiton. All but one of the insect pest species in this crop system are native to the regions where it is managed in North America. Insect decline has been shown to be a recent global phenomenon although it has rarely been studied in agricultural ecosystems. Long‐term datasets of insect species abundances are a powerful tool for insect population trends. To determine if native insect pests have declined over the past several decades in Maine lowbush blueberry, we surveyed three native species. All surveys were conducted in commercial blueberry fields; although, none of the sample sites were sprayed with insecticides. Insect pest sampling comprised two surveys (1961–2014 and 1998–2017) conducted on the larval stage of the blueberry maggot fly (Rhagoletis mendax Curran), one survey (1981–2016) on the larval stage of the blueberry spanworm (Itame argillacearia (Packard)), and one survey (1983–2019) on the larval stage of the blueberry flea beetle (Altica sylvia Malloch). Based upon the analysis of our long‐term population‐level datasets, we found no evidence that insect decline has occurred in this native blueberry insect pest complex intimately associated with the lowbush blueberry, a native crop plant in North America, despite recent documentation of rapid climate change occurring in the lowbush blueberry production areas.

The German insect monitoring scheme: Establishment of a nationwide long-term recording of arthropods

A standardised monitoring is indispensable to identify trends of insect populations. However, until recently, a systematic monitoring of insects in Germany was missing. Therefore, the German federal ministry for the environment funded the conceptualisation of an insect monitoring scheme.Here, we inform about the general concept and structure of the German insect monitoring scheme (GIMS) and the steps taken and still to be taken for the implementation of the scheme. A first step was the development of the objectives, general concept und structure of the GIMS in close collaboration with the nature conservation authorities at the national and federal state levels, as the latter are responsible for the implementation of nature conservation-related monitoring schemes. The GIMS is structured into two sections: section 1 ‘Monitoring of common insects’ and section 2 ‘Monitoring of rare insects’. Both sections contain modules that focus on selected aspects of insect diversity. In section 1, insect communities of the wider countryside will be monitored. Section 2 focuses on insect communities in rare habitats and species of high conservation value (e.g. threatened species). The next step was to develop standardised sampling methods for the modules in collaboration with experts and the nature conservation authorities. Wherever appropriate, synergies with other monitoring schemes were created, e.g. for combined analyses with environmental variables.Parallel to the development of the concept, several federal states have already implemented selected modules of the GIMS. Furthermore, the module ‘Grasshoppers in grasslands’ was tested during a pilot phase. By using the data from the pilot phase and the High Nature Value Farmland Monitoring scheme the relationship between high nature value farmland and grasshopper diversity was evaluated. This indicated the great potential of using synergies among monitoring schemes for joint data analyses and showed that it is worth exploring such approaches in greater depth.

Role of Entomology in the Era of Precision Agriculture: A Review

Precision agriculture (PA) represents a transformative approach to farming by utilizing advanced technologies like GPS remote sensing, and data analytics to optimize crop production and minimize environmental impacts. While technological advancements in PA are well-documented, the role of entomology is often overlooked. This review highlights the critical intersection between entomology and PA, demonstrating how understanding insect behavior, population dynamics, and ecological interactions enhances PA practices. Insects play pivotal roles in pest management, pollination, and ecosystem health, making their study essential for developing effective PA strategies. The review examines how entomological research has informed precision pest management, integrated pest management (IPM) systems, and the use of biological control agents within the PA framework. It discusses how integrating entomological insights with PA technologies, such as remote sensing and sensor networks, enables real-time monitoring and targeted pest control, thus improving crop yields and reducing pesticide use. Additionally, the review addresses challenges such as data integration, technology accessibility, resistance management, and environmental concerns, and highlights prospects including advancements in technology, innovation in monitoring techniques, and the integration of biological control methods. By emphasizing the need for interdisciplinary collaboration, this review underscores the importance of combining entomological knowledge with PA tools to develop more sustainable and efficient agricultural practices. The integration of entomology into PA not only enhances pest management but also contributes to broader goals of environmental sustainability and agricultural resilience. Overall, this review offers a comprehensive overview of how entomology can advance precision agriculture and foster sustainable food production systems.

Seasonal Incidence of Scirtothrips dorsalis and Bemisia tabaci on Chilli with Studies on Comparative Efficacy of Insecticides and Botanical Oils

The study conducted at Sam Higginbottom University of Technology and Sciences in Prayagraj during the 2019 and 2020 kharif seasons provided comprehensive insights into insect population dynamics and insecticide efficacy against thrips and whiteflies in chilli cultivation. Key findings revealed significant pest population fluctuations, with thrips peaking at 16 per plant during the 43rd Standard Meteorological Week (SMW) in late October for both years. Whitefly populations reached up to 17.6 per plant, peaking during the 44th week in 2019 and the 43rd week in 2020, both in late October. Correlation analyses showed significant negative relationships between insect populations and temperature, wind velocity, and rainfall, while a positive correlation was observed with sunshine duration. Multiple linear regression models demonstrated that weather parameters collectively explained 69.8% and 70.4% of thrips population variability in 2019 and 2020, respectively, and 87.7% and 17.2% of whitefly population variability. Stepwise regression models revealed that in 2019, maximum temperature and rainfall jointly accounted for 46% of pest population variability. In 2020, the addition of wind velocity to these factors explained 83% and 56% of variability in thrips and whitefly populations, respectively. Insecticide efficacy evaluation showed acetamiprid as most effective against thrips (92.14% reduction) and imidacloprid against whiteflies (88.89% reduction). Thiamethoxam and imidacloprid demonstrated comparable effectiveness. Economic analysis highlighted imidacloprid's superiority, providing effective pest control, the highest chili yield, and the best cost-benefit ratios (1:8.30 in 2019 and 1:5.38 in 2020).

Who is afraid of modelling time as a continuous variable?

Abstract Most models of ecological and eco‐evolutionary processes involve creating trajectories of something, be it population densities, average trait values, or environmental states, over time. This requires decision‐making regarding how to represent the flow of time in models. Most ecologists are exposed to continuous‐time models (typically in the form of ordinary differential equations) as part of their training, especially since the famous Lotka‐Volterra predator–prey dynamics are formulated this way. However, few appear sufficiently well trained to produce their own work with continuous‐time models and may lack exposure to the true versatility of available methods. Specifically, knowledge that discrete individuals can be modelled in continuous time using the Gillespie algorithm is not as widespread as it should be. I will illustrate the flexibility of continous‐time modelling methods such that researchers can make informed choices, and not resort to discretizing time as a ‘default’ without a clear biological motivation to do so. I provide three example‐based tutorials: (1) a comparison of deterministic and stochastic dynamics of the Lotka‐Volterra predator–prey model, (2) an evaluation of matelessness in a hypothetical insect population (and of selection to mate more often by either searching more efficiently or by shortening the ‘time out’ after each mating) and (3) within‐season density dependence followed by a birth pulse leading to Beverton‐Holt or Ricker dynamics depending on whether the deaths of conspecifics help reduce the mortality of others or not (compensatory mortality). I highlight properties of the exponential distribution that, while counter‐intuitive, are good to know when deriving expected lifetime reproductive success or other similar quantities. I also give guidance on how to proceed if the so‐called memorylessness assumption does not hold in a given situation, and show how continuous and discrete times can be freely mixed if the biological situation dictates this to be the preferred option. Continuous‐time models can also be empirically fitted to data, and I review briefly the insight this gives into the so‐called ‘do hares eat lynx?’ paradox that has been plaguing the interpretation of the Hudson Bay hare and lynx dataset.

You are what you eat - The influence of polyphagic and monophagic diet on the flight performance of bees.

Movement performance of insects is an important measure of physiological fitness and is likely affected by novel stressors associated with global change. Reduced fitness can lead to smaller foraging areas and thus to decreasing abundance, diversity and nutritional quality, which could weaken insect populations and contribute to global insect decline. Here, we combined two different methods: An experimental semi-field design applying treatments in outdoor flight cages and a follow-up experiment conducted in the laboratory, in which different parameters of movement performance, such as (a) velocity, (b) duration and (c) distance of an insect's flight can be quantified. We kept colonies of the bumblebee Bombus terrestris under contrasting nutritional conditions and measured treatment effects on the movement performance of individuals. Monophagously fed bumblebees showed reduced movement performance than polyphagously fed bumblebees. In particular, they stopped more frequently during flight, flew shorter distances and showed less often flight duration of 20 min. Our results suggest that nutritional deficiency due to a monophagic diet leads to reduced flight performance, which can have dramatic negative consequences for bees. Reduced flight performance may result in decreased availability of host plants, which may negatively affect stress resistance of bees and brood provisioning, facilitating extinction of insects. Although food of great nutritional value is an important compensator for the negative effects of different novel stressor, such as pesticides, it is not much known how to compensate for the effects of nutritional stress, especially in landscapes dominated by monocultures. However, our experimental approach with semi-field and laboratory components has high potential for further studies investigating the impact of different stressors on the physiological fitness of insects but also body mass, or reproductive success and to find factors that may mitigate or even overcome the negative effect of stressors on insects.

Assessing the Impact of Elevated Temperature on Reproductive Success in Fall Armyworm

Climate change poses a significant threat to insect populations, with rising temperatures potentially affecting their survival, fecundity, and overall reproductive success. This study investigates the impact of elevated temperature on the reproductive success of Spodoptera frugiperda (fall armyworm), a highly destructive and invasive pest. Newly emerged adult moths were exposed to a single heat stress event at 42°C for 2 or 6 hours, simulating extreme summer conditions. Fecundity and hatching percentage were measured to assess reproductive performance under thermal stress. The results revealed a significant impact of temperature on both fecundity and hatching percentage. Fecundity was significantly reduced to 1159.5 ± 35.6 eggs when adults were exposed to 42°C for 2 hours, compared to the control group at 27°C, which exhibited a fecundity of 1376.8 ± 30.9 eggs. Interestingly, a recovery was observed in the 6-hour exposure group, where fecundity increased to 1448.7 ± 25.5 eggs, comparable to the control. In contrast, hatching percentage showed a decline under prolonged heat exposure. While the control group and 2-hour exposure group had hatching percentages of 93 ± 1.2% and 90.5 ± 0.9%, respectively, a significant reduction to 78.2 ± 0.9% was observed after 6 hours at 42°C. These findings highlight the potential for heat stress to impair reproductive output in S. frugiperda, with implications for population dynamics under climate change. The study provides critical insights into how brief periods of extreme temperatures can affect pest populations, informing pest management strategies in the context of global warming.

Application of the solitary red mason bee, Osmia rufa L. (syn. O. bicornis), in forest monocultures in Poland

Seed orchards are utilised in forestry to avoid monoculture cultivation in forest areas and also constitute a gene bank for various tree species. In order to meet seed needs, preserve species diversity and genetic resources of forest management of the country, several hundred seed orchards served the purposes in Poland today. The paper presents an innovative solution to increase tree yield by introducing nests of solitary bees Osmia rufa L. (syn. O. bicornis) into monocultures. These insects are a natural solution that allows increasing the yield of selected tree and shrub species, especially fruit trees and shrubs and selected forest species. In order to determine the suitability of Osmia rufa L. to support the seed production process, a several-year research project was pursued consisting in assessing the quality of seeds, bee reproduction and identifying natural populations of insects in forest areas that were already present there before the introduction of bees. The research clearly shows that red mason bee, Osmia rufa L., can be employed with great success in forest areas to increase the productivity of selected forest tree species. Additionally, the work presents the results of study of red mason bee reproduction, showing that these bees in forest areas can also develop properly. Keywords: seed orchards; Tilia cordata; Quercus petraea; Prunus avium; insects; rearing of bees

Toxicity and Sublethal Effects of Piper hispidinervum Essential Oil on Behavioral and Physiological Responses of Sitophilus zeamais Populations.

This study aimed to evaluate the toxicity of Piper hispidinervum essential oil (PHEO) against 11 Brazilian populations of Sitophilus zeamais (Coleoptera: Curculionidae). The effects of sublethal doses of PHEO on the behavior (walking and flying), respiration, and population growth (ri) of the insect populations were investigated. PHEO toxicity was determined through concentration-mortality bioassays, with mortality curves established using increasing PHEO concentrations ranging from 140.00 to 1000.00 μL kg-1. Behavior was evaluated based on walking distance, walking time, walking speed, walking time proportion, flight height, and flight takeoff success. Respiration was measured via the respiratory rate, while population growth (ri) was assessed through the instantaneous growth rate. All 11 populations of S. zeamais were susceptible to PHEO, showing no signs of resistance. The populations exhibited varying behavioral and physiological responses to sublethal exposure to PHEO, indicating different mitigation strategies. The results confirm that PHEO possesses insecticidal potential for controlling S. zeamais populations. However, the observed behavioral and physiological responses should be considered when establishing control measures in pest management programs for stored products.

Landscape change and alien invasions drive shifts in native lady beetle communities over a century.

Understanding causes of insect population declines is essential for the development of successful conservation plans, but data limitations restrict assessment across spatial and temporal scales. Museum records represent a source of historical data that can be leveraged to investigate temporal trends in insect communities. Native lady beetle decline has been attributed to competition with established alien species and landscape change, but the relative importance of these drivers is difficult to measure with short-term field-based studies. We assessed distribution patterns for native lady beetles over 12 decades using museum records, and evaluated the relative importance of alien species and landscape change as factors contributing to changes in communities. We compiled occurrence records for 28 lady beetle species collected in Ohio, USA, from 1900 to 2018. Taxonomic beta-diversity was used to evaluate changes in lady beetle community composition over time. To evaluate the relative influence of temporal, spatial, landscape, and community factors on the captures of native species, we constructed negative binomial generalized additive models. We report evidence of declines in captures for several native species. Importantly, the timing, severity, and drivers of these documented declines were species-specific. Land cover change was associated with declines in captures, particularly for Coccinella novemnotata which declined prior to the arrival of alien species. Following the establishment and spread of alien lady beetles, processes of species loss/gain and turnover shifted communities toward the dominance of a few alien species beginning in the 1980s. Because factors associated with declines in captures were highly species-specific, this emphasizes that mechanisms driving population losses cannot be generalized even among closely related native species. These findings also indicate the importance of museum holdings and the analysis of species-level data when studying temporal trends in insect populations.

The smell of infection: Disease surveillance in insects using volatile organic compounds

Abstract Insects play crucial roles in nearly every ecosystem and provide a wide array of ecosystem services. However, both managed and wild insect populations face threats from parasites and pathogens, which require surveillance to mitigate. Current infectious disease surveillance methods for insects often involve invasive, time‐consuming and occasionally destructive techniques, such as manual inspections and molecular detection. Volatile organic compound (VOC) surveillance provides a real‐time, accurate and non‐invasive alternative for disease detection and has been well‐established in humans and livestock. Recent advances in sensor technology now allow for the development of in‐field VOC surveillance devices. This review explores the need for disease surveillance in insects and highlights recent advances of using VOCs for this purpose, focusing on honey bees as an example. We outline potential applications, challenges and future prospects of using VOCs for insect disease surveillance, providing examples of how this technology could be globally applied to mitigate the impacts of disease in a range of insect systems.

A tiny sample rapid visual detection technology for imidacloprid resistance in Aphis gossypii by CRISPR/Cas12a

Insecticide resistance monitoring is essential for guiding chemical pest control and resistance management policies. Currently, rapid and effective technology for monitoring the resistance of tiny insects in the field is absent. Aphis gossypii Glover is a typical tiny insect, and one of the most frequently reported insecticide-resistant pests. In this study, we established a novel CRISPR/Cas12a-based rapid visual detection approach for detecting the V62I and R81T mutations in the β1 subunit of the nAChR in A. gossypii, to reflect target-site resistance to imidacloprid. Based on the nAChR β1 subunit gene in A. gossypii, the V62I/R81T-specific RPA primers and crRNAs were designed, and the ratio of 10 μM/2 μM/10 μM for ssDNA/Cas12a/crRNA was selected as the optimal dosage for the CRISPR reaction, ensuring that Cas12a only accurately recognizes imidacloprid-resistance templates. Our data show that the field populations of resistant insects possessing V62I and R81T mutations to imidacloprid can be accurately identified within one hour using the RPA-CRISPR/Cas12a detection approach under visible blue light at 440–460 nm. The protocol for RPA-CRISPR detection necessitates a single less than 2 mm specimen of A. gossypii tissues to perform RPA-CRISPR detection, and the process only requires a container at 37 °C and a portable blue light at 440–460 nm. Our research represents the first application of RPA-CRISPR technology in insecticide resistance detection, offers a new method for the resistance monitoring of A. gossypii or other tiny insects, helps delay the development of resistance to imidacloprid, improves the sustainability of chemical control, and provides theoretical guidance for managing pest resistance.