Insect Availability Research Articles

Black-throated blue warblers (Setophaga caerulescens) exhibit diet flexibility and track seasonal changes in insect availability.

Changes in leaf phenology from warming spring and autumn temperatures have lengthened the temperate zone growing "green" season and breeding window for migratory birds in North America. However, the fitness benefits of an extended breeding season will depend, in part, on whether species have sufficient dietary flexibility to accommodate seasonal changes in prey availability. We used fecal DNA metabarcoding to test the hypothesis that seasonal changes in the diets of the insectivorous, migratory black-throated blue warbler (Setophaga caerulescens) track changes in the availability of arthropod prey at the Hubbard Brook Experimental Forest, New Hampshire, USA. We examined changes across the breeding season and along an elevation gradient encompassing a 2-week difference in green season length. From 98 fecal samples, we identified 395 taxa from 17 arthropod orders; 242 were identified to species, with Cecrita guttivitta (saddled prominent moth), Theridion frondeum (eastern long-legged cobweaver), and Philodromus rufus (white-striped running crab spider) occurring at the highest frequency. We found significant differences in diet composition between survey periods and weak differences among elevation zones. Variance in diet composition was highest late in the season, and diet richness and diversity were highest early in the season. Diet composition was associated with changes in prey availability surveyed over the green season. However, several taxa occurred in diets more or less than expected relative to their frequency of occurrence from survey data, suggesting that prey selection or avoidance sometimes accompanies opportunistic foraging. This study demonstrates that black-throated blue warblers exhibit diet flexibility and track seasonal changes in prey availability, which has implications for migratory bird responses to climate-induced changes in insect communities with longer green seasons.

The Effect of Cultural Factors on the Consumption of Consumable Insects: Evidence from Rural Southwestern Uganda

Consumable insects are an important part of human food systems and their consumption across diverse cultures dates back into the pre-historical period. This study assessed the effect of cultural factors on the consumption of consumable insects in the Kiruhura district of southwestern Uganda. The study employed a post-positivism research paradigm (mixed methodology) in a cross-sectional survey. The survey was conducted across 134 households in the Kiruhura district of South-western Uganda between January and June 2021 using a self-administered questionnaire and interview guide. Results show that member attitude and perceptions, cultural beliefs, and values were significant drivers of eating insects, particularly grasshoppers in the Kiruhura district. The findings of the study imply that the eating of insects in the area could be enhanced by educating and raising awareness about the importance of utilizing insects as a source of food. More program support that integrates rearing of insects within the household farming system could increase availability and sustainable use of seasonal consumable insects as nutritious food presents great implications for policies targeting dietary interventions.

The Consumption and Diversity Variation Responses of Agricultural Pests and Their Dietary Niche Differentiation in Insectivorous Bats.

Insectivorous bats are generalist predators and can flexibly respond to fluctuations in the distribution and abundance of insect prey. To better understand the effects of bats on arthropod pests, the types of pests eaten by bats and the response of bats to insect prey need to be determined. In this study, we performed DNA metabarcoding to examine prey composition and pest diversity in the diets of four insectivorous species of bats (Hipposideros armiger, Taphozous melanopogon, Aselliscus stoliczkanus, and Miniopterus fuliginosus). We evaluated the correlation between bat activity and insect resources and assessed dietary niche similarity and niche breadth among species and factors that influence prey consumption in bats. We found that the diets of these bats included arthropods from 23 orders and 200 families, dominated by Lepidoptera, Coleoptera, and Diptera. The proportion of agricultural pests in the diet of each of the four species of bats exceeded 40% and comprised 713 agricultural pests, including those that caused severe economic losses. Bats responded to the availability of insects. For example, a higher abundance of insects, especially Lepidoptera, and a higher insect diversity led to an increase in the duration of bat activity. In areas with more abundant insects, the number of bat passes also increased. The dietary composition, diversity, and niches differed among species and were particularly significant between H. armiger and T. melanopogon; the dietary niche width was the greatest in A. stoliczkanus and the narrowest in H. armiger. The diet of bats was correlated with their morphological and echolocation traits. Larger bats preyed more on insects in the order Coleoptera, whereas the proportion of bats consuming insects in the order Lepidoptera increased as the body size decreased. Bats that emitted echolocation calls with a high peak frequency and duration preyed more on insects in the order Mantodea. Our results suggest that dietary niche differentiation promotes the coexistence of different bat species and increases the ability of bats to consume insect prey and agricultural pests. Our findings provide greater insights into the role of bats that prey on agricultural pests and highlight the importance of combining bat conservation with integrated pest management.

On the home-visiting dragons: a year-round observation of dragonflies (Insecta: Odonata) entering an urban residence

Wildlife intrusion into human settlement and residency has long been viewed as a disturbance rather than regarded from other perspectives, such as wildlife welfare or conservation. Insects were part of that wildlife that were considered as pests or nuisances whenever their existence intersected with human livelihood. In this study, we documented a year-round (August 2019 to August 2020) observation of dragonflies intruding into a residence in the densely populated urban area in Padang City, West Sumatra, Indonesia. The study used the descriptive method, where the data was recorded from any occasion an individual or more dragonflies entered the house. The observation recorded the date and time of entry, species identification, and sex which was later analyzed. During the observation, we recorded 41 individuals entering the residence. They were classified into two damselfly species (Zygoptera) and ten valid dragonfly species (Anisoptera). Orthetrum sabina, Tholymis tillarga and Gynacantha dorhni became the most recorded species with 8, 7, and 7 total individuals, respectively. With 12 individuals recorded in a month, February 2020 was the most dragonfly-intruded period, much higher than the intrusion rate of 2.8 individuals per month. Dragonflies were observed entering the residence at midday (10 individuals), afternoon (12 individuals), evening (11 individuals) or night (8 individuals); this might suggest that night lighting might be what caused them to get into the residence. Both sexes were equal (18 females, 20 males, and three unsexed). The availability of tiny prey insects within the settlement area is another causative factor in this phenomenon. This intrusion should be alarming that the urbanization processes need to be reconsidered to be more ecological-friendly.

When can we expect natural habitats to enhance pest control by generalist predators? Insights from a simple, simulated agricultural landscape

Many field studies have reported that natural habitats in the agricultural landscape are associated with increased predator abundance and/or decreased crop pest load. However, recently published meta-analyses have found mixed results, with natural habitats being associated with increased pest loads as often as decreased loads. We investigate possible reasons for these conflicting results using a mechanistic model that simulates the dynamics of a generalist, omnivorous predatory bug and a plant bug pest in a landscape consisting of a 1 km2 annual field crop monoculture bisected by a 60 m wide natural habitat strip. The model simulates the movement of adult predators in the landscape via both trivial movement and long-distance dispersal, along with the movement of energy and egg reserves carried by those predators. We simulate multiple scenarios varying the presence or absence of floral resources and alternate prey in the natural habitat and crop, and the presence or absence of overwintering refuges for the predator and pest insect in the natural habitat. Food resources provided to the predator by the natural habitat did not enhance natural control in adjacent crops. When the natural habitat served as an overwintering refuge for predators, natural control of pests was enhanced if food resources were available in the crop for those predators. Availability of alternate prey was more important to the predator than floral resources. Early-season crop pest loads were always increased when pest insects overwintered in the natural habitat, however early-season availability of pest insects enhanced natural control across the whole-season. Overall, crop pest loads were highly variable across simulation scenarios, reproducing the conflicting results from field research.

The Potential of Edible Insects as a Safe, Palatable, and Sustainable Food Source in the European Union

Entomophagy describes the practice of eating insects. Insects are considered extremely nutritious in many countries worldwide. However, there is a lethargic uptake of this practice in Europe where consuming insects and insect-based foodstuffs is often regarded with disgust. Such perceptions and concerns are often due to a lack of exposure to and availability of food-grade insects as a food source and are often driven by neophobia and cultural norms. In recent years, due to accelerating climate change, an urgency to develop alternate safe and sustainable food-sources has emerged. There are currently over 2000 species of insects approved by the World Health Organization as safe to eat and suitable for human consumption. This review article provides an updated overview of the potential of edible insects as a safe, palatable, and sustainable food source. Furthermore, legislation, food safety issues, and the nutritional composition of invertebrates including, but not limited, to crickets (Orthoptera) and mealworms (Coleoptera) are also explored within this review. This article also discusses insect farming methods and the potential upscaling of the industry with regard to future prospects for insects as a sustainable food source. Finally, the topics addressed in this article are areas of potential concern to current and future consumers of edible insects.

Wind energy development can lead to guild‐specific habitat loss in boreal forest bats

Forest management rarely considers protecting bats in Fennoscandian regions although all species rely on forest habitat at some point in their annual cycle. This issue is especially evident as wind parks have increasingly been developed inside Fennoscandian forests, against the advice of international bat conservation guidelines. In this study, we aimed to describe and explain bat community dynamics at a Norwegian wind park located in a boreal forest, especially to understand potential avoidance or attraction effects. The bat community was sampled acoustically and described using foraging guilds (short, medium, and long‐range echolocators; SRE, MRE, LRE) as well as behavior (commuting, feeding and social calls). Sampling was undertaken at two locations per turbine: 1) the turbine pad and 2) a paired natural habitat at ground level, as well as from a meteorological tower. We used a recently developed method for camera trapping nocturnal flying insects synchronously with bat acoustic activity. Our results reveal trends in feeding and general bat activity across foraging guilds in relation to insect availability, habitat type, wind, temperature, and seasonality. We show how seasonal patterns in behavior across guilds were affected by habitat type, temperature, and wind. We found that SRE commuting and especially feeding activity was highest in natural habitats, whereas LRE overall activity at habitats more season dependent. We found that nocturnal insect availability was positively correlated with total bat feeding activity throughout the night. Our results provide evidence for both direct and indirect risks to bat communities by wind parks: SRE bat habitat is lost to wind energy infrastructure and LRE bat may have an increased risk of fatality. Our findings provide important insights on seasonal and spatial variability in bat activity, which can inform standardizing monitoring of bats acoustically in boreal forests, at wind parks, and in combination with non‐invasive insect monitoring.

Entomophagy practices, use patterns, and factors influencing perception and consumption frequency of edible insects in the Republic of Benin

BackgroundEdible insects are important sources of essential nutrients and have the potential to contribute to malnutrition reduction and food security in the Republic of Benin. However, their consumption is always restricted to a limited number of sociocultural groups. To determine how the consumption of insects could be promoted as an alternative food source, this study documents the endogenous knowledge associated with edible insects and, the main factors that govern their perception and frequency consumption.MethodsA survey was conducted towards 479 rural households consuming edible insects through 91 villages of Atacora, Alibori, Zou, and Plateau departments using individual interviews with a semi-structured questionnaire. The survey was focused on the inventory of edible insects and the documentation of consumers’ acceptance, frequencies and motive reason of consumption, local uses, and accessibility to edible insects. Samples of edible insects were collected and preserved in 70% alcohol for taxonomic identification.ResultsThe majority of surveyed people (79.1%) were consumers of edible insects since many years ago (29.1 ± 17.2 years). Insect species belonging to 17 genera of 7 families and 3 orders of insects were used as food, with Brachytrupes membranaceus Drury being the most widespread and consumed. Six factors affecting edible insect availability were identified with the chemical pollution as the most important. Besides their food use (63.2%), edible insects in the study area were used for several purposes. We find that ethnicity, religion, age, education level, and monthly frequency of insect consumption are the main factors influencing the local perception of edible insects. Indeed ethnic group, religion ethnicity, and market accessibility have a positive influence on edible insect consumption frequency. The Hierarchical Clustering of Principal Components has allowed us to classify the interviewees into 3 groups with different perceptions of entomophagy and their characteristics will make it possible to better orient the strategies for promoting entomophagy in the Republic of Benin.ConclusionsReligion and tradition are among the main factors that influence entomophagy in Benin Republic. The development of a national strategy to promote entomophagy should take into account the recorded insect consumption motivations, and their different uses by each ethnic group, and mainly target young people.

Predicting consumers’ intention towards entomophagy using an extended theory of planned behavior: evidence from Myanmar

The concept of entomophagy—consuming insects as food—has become particularly important from the perspective of food security. Myanmar is an entomophagous country, but where chronic malnutrition problems persist. A lack of research into the topic of entomophagy in Myanmar makes it difficult to understand people's behavior regarding edible insects as food, as well as their motives and aversions. As this knowledge gap emphasizes the need for consumer studies of edible insects in Myanmar, this study examines the factors affecting consumers’ intention to eat insects. The model used is based on the theory of planned behavior, extended by the variable environmental concern. Data collection was conducted through telephone interviews, acquiring 872 respondents. Structural equation modelling analysis was performed to predict the influence factors on consumption intention towards edible insects. Results revealed that participants’ consumption intention was low and primarily influenced by attitude, subjective norm, perceived behavioral control, and environmental concern. Only four out of ten factors had moderating effects on consumption intention, mainly the administrative division, urban or rural location, educational level and ethnic groups. These results are useful for further developing the insect sector in Myanmar, and especially for creating more public awareness of the benefits of eating insects as well as promoting a more positive attitude and possibly leading to an increase in consumption intention. A gradual shift from mere collection to insect farming would improve all year availability of edible insects and reduce the difficulties of consumers accessing edible insects. Consequently, edible insects can assist in achieving the nutrition policy's objective of reducing all types of malnutrition by making it easier for all people, at all times of the year, to acquire nutritious food at an affordable price.

Influence of ambient temperature on the phenology of the greater mouse-eared bat (Myotis myotis).

In order to assess the consequences of climate change and evaluate its impacts on wildlife, it is essential to do so on a species-specific level. It is assumed that changes in the ambient temperature influence energy consumption as well as food availability and thus foraging behavior, reproduction, survival, and therefore population dynamics in bats. Based on this assumption, the present study aims to gain insights into the roosting and breeding behavior of the greater mouse-eared bat (Myotis myotis) in relation to changes of the ambient temperature. For this purpose, we investigated the effect of ambient temperature on the phenology of the greater mouse-eared bat by using activity data of the bats collected using light barriers at the maternity roosts. The light barrier used in this study is a system that detects the interruption of two light beams, for example, by a flying bat, and displays it as an electrical signal. The investigations have shown that the higher the winter temperatures, the earlier the greater mouse-eared bats returned to the roosts to form the maternity colony; however, this was only true for ambient temperatures below 0.5°C,birth season started earlier at higher spring temperatures,the dissolution of maternity roosts occurred earlier with earlier birth season and at higher ambient temperatures during lactation. The results revealed that ambient temperature has an influence on the phenology of the greater mouse-eared bat. Depending on the respective life history stage, an increase in ambient temperature can have a positive or negative effect on the fitness of the animals. In recent years, mild winters have been recorded more frequently, which can have an influence on the behavior of bats. Warm winters within certain limits seem to lead to an earlier formation of the maternity colony, which can be positive or negative for the bats depending on persistent weather conditions and thus insect availability. In the course of climate change, we can also expect earlier spring events and an increase in spring temperature, as well as hot spells in summer. These warm springs and summers seem to lead to an earlier beginning of births, a faster development of the juveniles and an earlier dissolution of the maternity roost. An advance of reproductive activities can be assumed to increase the chance to survive the following winter in both mothers and their young, as they have more time to build up sufficient energy reserves for hibernation before winter starts. Due to the climatic changes, phenological changes of the bats be expected. This study highlights that in order to understand the impact of climate change on biodiversity, it is necessary to investigate in detail effects on a species-specific level and also to consider direct and indirect effects of ambient temperature on different life history stages.

Bats increased foraging activity at experimental prey patches near hibernacula

Abstract Emerging infectious diseases in wildlife can threaten vulnerable host populations. Actions targeting habitat improvements to aid population resilience and recovery may be beneficial long‐term strategies, yet testing the efficacy of such strategies before major conservation investments are made can be challenging. The disease white‐nose syndrome (WNS) has caused severe declines in several species of North American hibernating bats. We tested a novel conservation approach targeted at improving foraging conditions near bat hibernacula by experimentally manipulating insect density in the pre‐hibernation fattening period and spring emergence recovery period. We measured foraging (feeding buzzes) and echolocation activity of little brown bats Myotis lucifugus at ultraviolet (UV) light lures to determine behavioural response to augmented foraging conditions and characterized insect availability at UV light lures. In the fall, bat foraging activity was three times greater (95% CI: 1.5–5.8; p = 0.002) when UV lights were on, but there was no statistical support for differences in echolocation activity response when our experimental design alternated between nights with lights on and off. In the spring, we allowed UV light lures to run consistently each night and compared with a control location in similar habitat. Bat foraging activity was 8.5 times greater (95% CI: 4.5–16.0; p < 0.0001) and echolocation activity was 4.4 times higher (95% CI: 3.0–6.5; p < 0.0001) at UV light lures in the spring experiment. In both the fall and spring, UV light lures resulted in concentrated insect availability, attracting primarily moths (Order: Lepidoptera). In both seasons, nightly temperature had a strong influence on bat foraging, echolocation and insect activity. We show that a bat species threatened by WNS used enhanced foraging habitats near hibernacula during the critical pre‐ and post‐hibernation phases of their annual cycle. While light lures are unlikely to be a long‐term management strategy, our experiment provides initial evidence that bats behaviourally respond with increased foraging activity in areas with augmented insect prey availability. Our experimental results support developing management strategies focused on habitat protection, including restoration and enhancement of foraging habitats, in the immediate vicinity of bat hibernacula.

Effects of enhanced insect feeding on the faecal microbiota and transcriptome of a family of captive common marmosets (Callithrix jacchus).

Common marmosets have been widely used in biomedical research for years. Nutritional control is an important factor in managing their health, and insect intake would be beneficial for that purpose because common marmosets frequently feed on insects in natural habitats. Here, we examined the effect of enhanced insect feeding on the gut by analysing the faecal microbiota and transcripts of captive marmosets. A family consisting of six marmosets was divided into two groups. During the seven-day intervention period, one group (the insect feeding group, or Group IF) was fed one cricket and one giant mealworm per marmoset per day, while the other (the control group, or Group C) was not fed these insects. RNA was extracted from faecal samples to evaluate the ecology and transcripts of the microbiota, which were then compared among time points before (Pre), immediately after (Post), and two weeks after the intervention (Follow_up) using total RNA sequencing. The gut microbiota of marmosets showed Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria as dominant phyla. Linear discriminant analysis showed differential characteristics of microbiota with and without insect feeding treatment. Further analysis of differentially expressed genes revealed increases and decreases in Bacteroidetes and Firmicutes, respectively, corresponding to the availability of insects under both Post and Follow_up conditions. Significant changes specific to insect feeding were also detected within the transcriptome, some of which were synchronized with the fluctuations in the microbiota, suggesting a functional correlation or interaction between the two. The rapid changes in the microbiota and transcripts may be achieved by the microbiota community originally developed in the wild through marmosets' feeding ecology. The results were informative for identifying the physiological impact of insect feeding to produce a better food regimen and for detecting transcripts that are currently unidentifiable.

Comparing the Performance of Hyphantria cunea (Lepidoptera: Arctiidae) on Artificial and Natural Diets: Feasibility of Mass-Rearing on Artificial Diets.

In China, Hyphantria cunea (Drury) is an invasive phytophagous pest; it attacks nearly all species of defoliated trees. To develop integrated pest management programs (IPM) for H. cunea, we need to ensure the availability of insects by mass-rearing them on artificial diets under laboratory conditions. This study compared the growth characteristics, nutritional indices, growth indices, and digestive enzyme activity of insects reared on Pterocarya stenoptera C.DC (Fagales: Juglandaceae), the Chinese wingnut, and an artificial diet. We also investigated the correlation between diet components and growth indices using principal components analysis and Pearson correlation analysis. We found that mass-rearing of H. cunea on an artificial diet was feasible. It led to a shorter developmental period, with heavier larvae and pupae than natural diets. The principal components analysis indicated that the growth indices and α-Amylase were significantly positively associated with PC1, which explained 82.45% of the total data variability. Pearson correlation analysis showed a significant correlation between digestion, absorption parameters, and growth. Developing a mass-rearing program to produce H. cunea on an artificial diet will be valuable for improving IPM strategies. Understanding the mechanism of the responses of phytophagous insect populations to anthropogenic diet regulation can provide new ideas and methods for pest control.

Combining bulk stable H isotope (δ2H) measurements with fatty acid profiles to examine differential use of aquatic vs. terrestrial prey by three sympatric species of aerial insectivorous birds

Aerial insectivorous songbirds such as swallows and martins have declined substantially in North America in recent decades. Aquatic-emergent insects provide more beneficial omega-3 fatty acids than terrestrial insects, and thus, diet quality is expected to vary among aerial insectivores with differential access to aquatic-emergent insects. We compared the stable hydrogen isotope (δ2H) values of feathers and bulk blood plasma fatty acids of nestling purple martins (Progne subis), tree swallows (Tachycineta bicolor), and barn swallows (Hirundo rustica), at lakeshore and inland sites near Lake Erie, Ontario, Canada. We found that diet quality differed between inland and lakeshore nesting habitats, but differences depended on species. Overall, purple martin and tree swallow nestlings had lower feather δ2H values, indicating a more aquatic-emergent diet, and lakeshore populations of both species had higher omega-3 fatty acid levels in their blood plasma compared to inland populations. Conversely, higher plasma levels of omega-6 fatty acids were found in inland birds. Tree swallows have a low omega-3 conversion efficiency from precursor substrates and so depend on aquatic subsidies to fulfill their nutritional needs. We suggest this may also be the case with purple martins. Barn swallows had the most positive feather δ2H values, regardless of proximity to the lakeshore, indicating a more terrestrial diet. However, barn swallow nestlings had consistently higher plasma omega-3 docosahexaenoic acid (DHA) regardless of nesting location, suggesting that barn swallows can efficiently convert omega-3 precursors into their beneficial elongated fatty acid chains. Our study indicates the benefit of combining plasma fatty acid compositional analyses with bulk feather δ2H values to decipher interspecific differences in adaptations to availability of aquatic-emergent insects.

Survey, Consumption Methods and Uses of Edible Forest Insects in Selected Local Government Areas, Cross River State, Nigeria

The survey and consumption methods of edible forest insects was investigated within a period of eight months. Information on respondents’ demography, availability, harvesting methods and uses was collected using questionnaire and field survey. Data generated was analysed using frequency tables, charts and bar diagrams. Females (51%) were higher in number than males (49%) in the collection of edible forest insects, with over 70 percent of the collectors haven’t completed their secondary (46%) and tertiary (32%) education. The main preservation and consumption methods were roasting and frying, with majority of the people utilizing the insects majorly as food ingredients and sweetener. Most of the insects identified were consumed at adult stage, with exception of caterpillar that was consumed at larval stage. In all the locations and with the exception of termites and crickets which were available during the rainy and dry seasons, respectively, all other insects identified were available all year round. There was a strong positive relationship interms of insect availability, collection methods and uses between Akamkpa and Obubra (rs = 0.089), Obubra and Ogoja (rs – 0.689). The was not the same for Ogoja and Akamkpa (rs = 0.352), as well as ogoja and Obubra (rs = 0.102), respectively.

Weather and nest cavity characteristics influence fecundity in mountain chickadees.

Examining direct and indirect effects on reproduction at multiple scales allows for a broad understanding of species' resilience to environmental change. We examine how the fecundity of the mountain chickadee (Poecile gambeli), a secondary cavity-nesting, insectivorous bird, varied in relation to factors at three scales: regional weather conditions, regional- and site-level food availability, site-level community dynamics, and nest-level cavity characteristics. We hypothesized that earlier laying dates and higher fecundity (clutch size, nest survival, brood size) would be associated with milder climatic conditions, increased food from insect outbreaks, lower densities of conspecifics and nest predators (red squirrel; Tamiasciurus hudsonicus), and safer (smaller, higher) cavities. We collected data on laying date, clutch size, brood size, nest fate (success/failure), and cavity characteristics from 513 mountain chickadee nests in tree cavities in temperate mixed coniferous-broadleaf forest in interior British Columbia, Canada, from 2000 to 2011. We surveyed annual abundances of mountain chickadees and squirrels using repeated point counts, and mountain pine beetle (Dendroctonus ponderosae) and lepidopteran defoliators by monitoring host trees and by using regional-scale aerial overview forest insect survey data. We used weather data (temperature, rain, snow) from a local Environment and Climate Change Canada weather station. We modeled laying date, clutch size, daily nest survival, and brood size as a function of predictors at regional-, site-, and nest-scales. Measures of fecundity varied dramatically across years and spatial scales. At the regional (study-wide) scale, chickadees laid earlier and larger first clutches in warmer springs with minimal storms, and daily nest survival (DSR) increased with a 2-year lag in growing season temperature. Despite a doubling of mountain chickadee density that roughly accompanied the outbreaks of mountain pine beetle and lepidopteran defoliators, we found little evidence at the site scale that fecundity was influenced by insect availability, conspecific density, or predator density. At the nest scale, DSR and brood size increased with clutch size but DSR declined with nest cavity size indicating a positive reproductive effect of small-bodied cavity excavators. Double-brooding, rare in chickadees, occurred frequently in 2005 and 2007, coinciding with early breeding, high food availability from insect outbreaks, and warm spring temperatures with 0-1 spring storms. Our results support the idea that fecundity in secondary cavity-nesting species is impacted directly and indirectly by weather, and indirectly through changes in community dynamics (via cavity resource supply). We stress the importance of adopting holistic, community-level study frameworks to refine our understanding of fecundity in opportunistic and climate-sensitive species in future.

The modulating effect of food composition on the immune system in growing ring-necked pheasants (Phasianus colchicus).

The decline in the population of ring-necked pheasants (Phasianus colchicus) in northwestern Germany since 2007 raises questions about the underlying causes. We therefore studied the growth and immune status of ring-necked pheasant chicks dependent on different feed composition. Here, 490 ring-necked pheasant chicks were raised in five groups up to nine weeks. While control groups C1 and C2 received sufficient crude protein (28%) and energy (12.5 MJ/Kg feed) according to current standards, group C2 was treated with cyclosporine eight hours prior to phythemagglutination (PHA) testing, serving as a positive immune suppressed control. Group V1 was fed with reduced protein (20%) but optimal energy content (12.5 MJ/Kg feed), group V2 was fed with sufficient protein (28%) and reduced energy content (10 MJ/kg feed) whereas group V3 was fed reduced crude protein (20%) and reduced energy content (10MJ/kg feed). On all chicks, health status was checked each week, and 20 birds of each group were weighed randomly per week. PHA-testing was performed on 12 birds of each group to study the in vivo non-specific activation of lymphocytes at week 2, 4, 6, 7, 8 and 9. In addition, hemolysis-hemagglutination-assay (HHA) was performed on each of the PHA-tested chicks, which were subsequently euthanized and dissected. Histopathologic examinations of 5 birds that were randomly chosen were performed. The PHA-test results demonstrate significant differences between control (C1, C2) and experimental groups (V1-V3) in several developmental stages. According to the HHA results, weekly testing detected a significant increase of titres per week in all groups without significant differences. Here, only hemagglutination and no lysis of samples was observed. It seems appropriate to conclude that during their first weeks of life, protein content is of higher importance in ring-necked pheasant chicks than energy intake. In particular T-cell response is significantly reduced, which indicate a weaker immune system resulting in a higher risk for clinical diseases. Therefore, we assume that protein i.e. insect availability is a highly important co-factor in the free-ranging population dynamics, and is linked to declines of the northwestern German population.

Life history traits and a method for continuous mass rearing of the planthopper Pentastiridius leporinus, a vector of the causal agent of syndrome 'basses richesses' in sugar beet.

The planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) is the main vector of the γ-3 proteobacterium 'Candidatus Arsenophonus phytopathogenicus' which causes the syndrome 'basses richesses' (SBR) in sugar beet. SBR is a new and fast-spreading disease in Central Europe that leads to high yield losses. To date, the development of management strategies has been hampered by insufficient knowledge about general life history traits of the planthopper and, most importantly, the year-round availability of insects reared under controlled conditions. Rearing of P. leporinus has been considered challenging and to date no protocol exists. Here we describe a method for mass rearing P. leporinus on sugar beet from egg to adult that has produced five generations and over 20 000 individuals between June 2020 and March 2022. An alternative host such as wheat is not necessary for completing the life cycle. No-choice experiments showed that P. leporinus lays 139.1 ± 132.9 eggs on sugar beet, whereas no oviposition was observed on its nymphal host wheat. Head capsule width was identified as a trait that unequivocally distinguished the five nymphal instars. Developmental time from first instar to adult was 193.6 ± 35.8 days for males and 193.5 ± 59.2 days for females. Infection rates of adults were tested with a nested polymerase chain reaction. The results demonstrated that 70%-80% of reared planthoppers across all generations carried the SBR proteobacterium. The mass-rearing protocol and life history data will help overcome an important bottleneck in SBR research and enhance efforts in developing integrated pest management tools. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Annual adult survival rates for four sympatric breeding swallow species: effects of environmental factors and density-dependence

Swallow (Family: Hirundinidae) populations in the Canadian Maritimes have declined since the 1980s. Using mark–recapture data from 2012 to 2019, we determined apparent annual adult survival rates for Barn ( Hirundo rustica Linnaeus, 1758), Tree ( Tachycineta bicolor (Vieillot, 1808)), Bank ( Riparia riparia (Linnaeus, 1758)), and Cliff ( Petrochelidon pyrrhonota (Vieillot, 1817)) swallows. For two data-rich species (Barn and Tree swallows), we modelled the relationships between survival and weather (cold snaps, precipitation, temperature, and wind speed), climate (El Niño–Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO)), Enhanced Vegetation Index (EVI) as a measure of primary productivity during the winter, number of active nests as a measure of site quality, and the Breeding Bird Survey (BBS) annual population index as density-dependent processes. Survival rates for all four species were typically higher (Barn and Tree) or similar to (Cliff and Bank) of estimates from populations that have not undergone severe, long-term declines. Across weather and climate variables, conditions that are typically favourable for high insect availability (e.g., higher precipitation, warmer temperatures, and lower wind speeds) resulted in higher survival. For female Barn and Tree swallows, survival was higher when EVI was lower, and for Barn Swallows, survival was also higher when the BBS index was higher. Collectively our results demonstrate that conditions throughout the annual cycle affect survival, and the relationships with weather and climate variables support the importance of high insect availability.

Combined influence of food availability and agricultural intensification on a declining aerial insectivore

AbstractAerial insectivores show worldwide population declines coinciding with shifts in agricultural practices. Increasing reliance on certain agricultural practices is thought to have led to an overall reduction in insect abundance that negatively affects aerial insectivore fitness. The relationship between prey availability and the fitness of insectivores may thus vary with the extent of agricultural intensity. It is therefore imperative to quantify the strength and direction of these associations. Here we used data from an 11‐year study monitoring the breeding of Tree Swallows (Tachycineta bicolor) and the availability of Diptera (their main prey) across a gradient of agricultural intensification in southern Québec, Canada. This gradient was characterized by a shift in agricultural production, whereby landscapes composed of forage and pastures represented less agro‐intensive landscapes and those focusing on large‐scale arable row crop monocultures, such as corn (Zea mays) or soybean (Glycine max) that are innately associated with significant mechanization and agro‐chemical inputs, represented more agro‐intensive landscapes. We evaluated the landscape characteristics affecting prey availability and how this relationship influences the fledging success, duration of the nestling period, fledgling body mass, and wing length as these variables are known to influence the population dynamics of this species. Diptera availability was greatest within predominately forested landscapes, while within landscapes dominated by agriculture, it was marginally greater in less agro‐intensive areas. Of the measured fitness and body condition proxies, both fledging success and nestling body mass were positively related to prey availability. The impact of prey availability varied across the agricultural gradient as fledging success improved with increasing prey levels within forage landscapes yet declined in more agro‐intensive landscapes. Finally, after accounting for prey availability, fledging success was lowest, nestling periods were the longest, and wing length of fledglings were shortest within more agro‐intensive landscapes. Our results highlight the interacting roles that aerial insect availability and agricultural intensification have on the fitness of aerial insectivores, and by extension how food availability may interact with other aspects of breeding habitats to influence the population dynamics of predators.