Ecological Entomology

• No evidence was found that transitioning from social to solitary behaviour along a season length gradient generates saw-tooth clines in two socially polymorphic sweat bees.
• Both species exhibited converse Bergman size clines; individuals were smaller where the season was shorter.
• Despite exhibiting broadly similar patterns, size increased with season length linearly in Lasioglossum calceatum but non-linearly in Halictus rubicundus.

• AM fungal inoculation did not have a consistently positive or negative impact on plant growth or herbivore performance.
• Instead, plant lines and larval families responded differently to AM fungal inoculation.
• This indicates that genetic variation in response to AM fungi may play an important role in the ecology and evolution of plant–insect interactions.

• Population differences in physiological responses are examined in an endemic Iberian dung beetle species (Thorectes lusitanicus) using infrared thermography.
• The heating rate between the temperatures of chill coma and the start of activity, a variable associated with land cover characteristics, is the parameter that allows discrimination among populations.
• Thorectes lusitanicus is a species characterised by a high thermotolerance, and its apterism could explain the high diversity of ecophysiological responses found.

• Root feeding by soybean cyst nematodes not only impairs tobacco cutworm development, but also has a negative effect on the development and reproduction of its parasitoid.
• These effects increase in a linear trend yet vary in magnitude across soybean cultivars expressing three different levels of constitutive resistance.
• Soybean constitutive and nematode root feeding-induced defences can have a combined effect to compromise the life-history traits of above-ground leaf-feeding caterpillars.

• In incipient termite colonies, biparental brood care rapidly shifts towards alloparental brood care. This transition may recapitulate the evolutionary trajectory from subsocial wood roach ancestors to eusociality in termites.
• Within 5 months after foundation, brood care duties were fully transferred to workers and the primary reproductives became irreversibly dependent on these workers for survival, reproduction, and colony growth.
• Once brood care has shifted to alloparents, a critical number of workers is necessary to prevent brood loss and initiate colony growth.

• The Asian citrus psyllid (ACP) is the vector of the pathogen that causes citrus greening (HLB), the most destructive disease for citrus worldwide.
• Asian citrus psyllid is attracted to citrus infected with the HLB pathogen under optimal watering conditions. However, under drought stress ACP is not attracted to infected plants, and pathogen-induced volatiles are reduced.
• The parasitoid Tamarixia radiata is attracted to ACP-infested plants under optimal watering conditions but not under drought stress.

• Vanessa cardui shows a strong seasonal migratory strategy in northwest Africa, being practically absent at the end of summer but migrating in huge numbers into the region in October and November.
• Migration was timed to coincide with an increase in resource availability. Upon their arrival, adults concentrated in habitats rich in nectar sources, such as traditional agriculture and ruderal areas, and oueds.
• The main breeding habitats were located in agricultural and ruderal areas in the south of the region, where local populations began to emerge towards the end of the migratory period.

• The influence of plant cover on the cavity-nesting ant Temnothorax crassispinus was analysed.
• Nest sites localised in balsam stands have a lower value for ants, and ant colonies adjust their reproductive effort with respect to the vegetation cover.
• Patches of native and invasive balsams equally affect the ant colonies.

• Koinobiont parasitoids that allow hosts to develop continuously after parasitisation exhibit high flexibility in their development in order to consume host resources efficiently.
• The present study revealed that two koinobiont Drosophila parasitoids adjusted their larval growth rate in response to host conditions, i.e. they retarded their own development when they parasitised young or slowly developing host larvae.
• After host pupariation, one of these parasitoids accelerated development, whereas the other did not. This difference might reflect species-specific strategies of host resource use.

• The number of nest-searching bumblebee queens in early spring was found to predict positively the number of nests subsequently found on transects through woodland and grassland.
• Estimated floral abundance along the transect did not correlate with numbers of nest-searching queens or with the number of nests found, suggesting that queens do not target their searching to areas that are locally high in spring forage.
• Using the distributions of nest-searching queens to target subsequent searches for nests may be a useful technique for increasing the success of researchers in locating bumblebee nests.

• Aquatic container habitats vary greatly in age and their history of use by prior non-overlapping cohorts of detritivorous mosquito larvae. In this study habitat age and prior use by larvae were manipulated.
• It was found that more larvae survived, they developed faster, and the resulting adults lived longer when reared in older habitats. It was also found that prior utilisation delayed development in the younger habitats.
• It is hypothesised that extended conditioning of leaf detritus increased the availability of recalcitrant nutrients, making older habitats of higher quality. Prior utilisation probably only has strong effects in poor-quality habitats.

• Distinct rhythmic cycles of harvesting two different resources, leaves and fruit, can be maintained by a single leaf-cutting ant colony.
• These rhythms may be controlled by backlogs of unprocessed leaf and fruit material that accumulate and diminish in the nest at different speeds.
• The role material caches play in the productive activity of leaf-cutting ant colonies may have parallels to the role of warehouses in supply chains in the human economy.

• A classic olfactory conditioning protocol for Drosophila is modified to examine the role of environmental diversity on learning in Drosophila melanogaster.
• Flies presented with a variety of odour–taste associations over a few minutes subsequently learn a standard olfactory–gustatory associative learning task poorly, relative to those exposed to a low diversity of associations.
• Such an effect could help to explain the relationship between biodiversity and ecosystem functioning, the evolution of floral constancy in pollinators, and the pest-protective effects of mixed species crops.

• In this study, the role of ants as biotic defence in individuals of a tropical ant-plant was investigated experimentally with a simultaneous manipulation of plant quality and ant defence.
• Fertilisation increased the availability of foliar nitrogen, and herbivory rates were significantly higher in fertilised plants (F) with ants excluded (AE).
• Although top-down factors were important in determining herbivory, the study reinforced the crucial role of leaf nutritional quality for herbivory levels experienced by plants and the conditionality of ant defence.

• Yponomeuta evonymellus females preferentially chose to oviposit on the host plant species on which they had fed as larvae.
• Potential fecundity of females and the survival of their offspring were significantly higher on native to Europe Prunus padus than on non-native P. serotina.
• The reduced survival of Y. evonymellus offspring on P. serotina was correlated with a smaller bud mass and volume, lower leaf mass and surface area, and difficulty in constructing a protective tent against unfavourable weather conditions.

Mean leaf N and P contents consumed by 23 grasshopper species choosing among 24 plant species are highly correlated, defining a unique nutritional axis.

The grasshopper body P content (but not body N content) is correlated with the mean N and P content of the consumed leaves.

If differences in body P content across grasshopper species reflect different growth rates, contrasting plant preferences for P and N may fulfil their nutritional requirements.

The leaf miner Micrurapteryx salicifoliella has specialised morphology requiring direct egg–leaf contact for successful hatching. Trichome density across 10 Salix species was negatively associated with oviposition by this lepidopteran species.

However, trichomes were positively associated with larval survival, possibly due to trade-offs between physical and chemical defence.

Overall, trichome density was negatively related to leaf-mining damage among Salix species, suggesting that foliar trichomes can function as an effective defence by deterring herbivore oviposition.

In a soybean aphid (Aphis glycines Matsumura) population under predation, predator-free space colonisation by alate individuals increased population size and aphid prevalence (i.e. proportion of plants colonised).

Despite lower fecundity by alate individuals, the initial presence of this morph in an A. glycines population under predation increased aphid prevalence, with only a temporary decrease in population size.

We conclude that increased prevalence might provide an ecological advantage important enough to warrant the production of alate morphs by an aphid population under predation.

Bacterial symbionts can protect their aphid hosts against parasitoids.

We investigated whether protective symbionts affect hyperparasitoids at the trophic level above aphid parasitoids.

We found that protective symbionts significantly reduce numbers of hatching hyperparasitoids by reducing the number of available parasitoid hosts, but there is no evidence of more complex interactions between symbionts and hyperparasitoids.

Food availability plays a major role in the seasonal polyphenism for pupal colour of specialist butterflies inhabiting arid environments with winter rains where day length does not positively covary with host productivity.

Food availability determines pupal coloration. An ad libitum food regime results in green pupae, while restrictions in food regimen yield brown pupae. By contrast, photoperiod does not influence pupal colour.

Survival probability of pupae placed on cacti is higher than those placed on rocks and shrubs, with green pupae on cacti exhibiting the lowest predation risk across habitats.

Initial egg loads in the polyembryonic parasitoid, Copidosoma koehleri (Hymenoptera: Encyrtidae), vary among females. The variation is lowest among clone-mates, intermediate among non-clone sisters and highest among non-sister females.

The females' initial egg loads increased with body size. Body size and initial egg loads did not correlate with longevity and fecundity. Host deprivation prolonged the wasps' life span.

These results suggest that pre-adult egg production is not traded off with longevity, but that egg maturation and oviposition at the adult stage carry a survival cost.

Several mosquito species avoid ovipositing in pools containing fish.

We show that ovipositing Culex distinguish among fish species.

This response cannot be explained by predator efficiency differences.

We found that the growth rate of five pea aphid genotypes changed when competing with a vetch aphid clone across three faba bean cultivars, where the different genotypes responded differently.

We also found that the aggregation of the pea aphid genotypes on the plant varied as a function of competition and the plant cultivar on which the interaction took place.

The vetch aphid also adapted its strategy (performance and aggregation) with regard to competing pea aphids. The context and identity G × E versus G × G × E matter in aphid competition.

Dung beetles are a species-rich insect group that support pasture production by feeding on and burying the dung of livestock.

We tested whether dung beetle species richness influenced four ecosystem functions, individually and in combination, and whether this relationship was affected by exposure to residues of ivermectin, a veterinary anthelmintic.

Effects of experimental manipulations were weak, but there was evidence that species-rich dung beetle assemblages increase functioning when multiple ecosystem functions were considered simultaneously and in the absence of ivermectin.

Among Aphis craccivora in a central Kentucky alfalfa field, we demonstrate experimentally that Hamiltonella infection did not lower successful parasitism by naturally occurring parasitoid wasps.

Hamiltonella was also ineffective against the most common parasitoid wasp species in a controlled laboratory assay.

Our work emphasises the fact that defensive symbionts sometimes provide no tangible defensive benefits under field conditions, depending on parasitoid community composition.

We studied gall abundance and richness on willows to illustrate the processes maintaining one of the richest assemblages of gall formers associated with a single genus of host plants.

Integrated information on willow defences, nutrient content and phylogeny shows that the abundance of gallers on willows is affected mainly by leaf nutrient content.

On the other hand, the richness of gallers was affected mainly by willow phylogeny, suggesting that it is probably willow radiation driving galler speciation.

Recent observations of actuarial senescence – an increase in mortality rate with age – have challenged the assertion that the brevity of adult insect life spans precludes ageing.

Here we quantified the rate of senescence in 22 species of Lepidoptera by fitting demographic models to adult survivorship data drawn from a range of field and laboratory studies.

Senescence was evident in all 22 species investigated, with a model of age-related mortality consistently fitting the survivorship curves significantly better than an alternative model that assumes constant mortality.

We investigate whether caterpillars with morphological or behavioural defences have decreased risk of falling prey to ants, and if defence traits mediate host plant use in ant-rich cerrado savanna.

Caterpillars without morphological defences or inside open shelters were found on plants with fewer ants. Caterpillars using ant-visited plants (with extrafloral nectaries) lived in closed shelters or presented morphological defences.

Efficient defence against ants is crucial for caterpillar survival and mediates host plant use by lepidopterans in cerrado. Our study highlights the importance of a tritrophic viewpoint in risky environments.

The present results indicated that increase in floral-resource density generally led to lower efficiency and attentiveness in the foraging floriphilic katydids.

The first evidence of the neural constraint hypothesis in the context of resource density is provided.

The applicability of the neural constraint hypothesis in florivory is also corroborated.