Ecological Entomology

doi: 10.1111/een.13167pmid: N/A

Lewis, Megan J.; Berson, Jacob D.; Didham, Raphael K.; Evans, Theodore A.

doi: 10.1111/een.13277pmid: N/A

Current methods for identifying resource preferences in dung beetles are based on above‐ground trials. Although useful, these methods do not directly investigate resource provisioning of offspring below ground, missing an important part of dung beetle ecology. We tested the potential for UV‐fluorescent and non‐fluorescent coloured glitters to be used as markers for tracing the origin of dung incorporated into brood balls (dung shaped by parental beetles enclosing an egg), and so aid in a more complete understanding of resource use in dung beetles. We tested the effect of glitter addition on brood ball production in two species of tunnelling dung beetles, Onthophagus taurus and Euoniticellus fulvus. There was no effect of glitter addition on brood ball production during no‐choice tests for each species: both species made a similar number of brood balls, regardless of glitter presence or glitter colour. In a separate choice trial, O. taurus showed no preference for dung when presented with four dung pats containing four unique glitter colours. Here we show that glitter can be used as an effective marker of individual brood ball origin in tunnelling dung beetles. This method provides a useful tool for tracking below ground resource use and larval provisioning experiments in dung beetles.

Dozier, Amy Elizabeth; Straw, Edward Alexander; Stanley, Dara Anne

doi: 10.1111/een.13260pmid: N/A

Cuckoo bumblebees (Bombus subgenus Psithyrus) are social parasites that have lost the ability to establish their own nests, and instead usurp the nest of a bumblebee host to reproduce. Accordingly, they are entirely dependent upon a host species to complete their life cycle, and are therefore vulnerable to co–extinction. Despite this, the current consensus is that there remains much we do not know about the fundamental ecology of many cuckoo bumblebee species, which is crucial for conservation. To investigate data gaps for cuckoo bumblebees, we conducted a systematic review to quantify the peer‐reviewed literature that has been produced, including which species have been most studied and which disciplines have been explored. Over half of all Psithyrus species were represented in fewer than 10 publications each, including 2 species listed as Critically Endangered by the IUCN. Research on cuckoo bumblebees is heavily weighted towards Europe and European species, while Asian species were under‐represented. Key research areas such as ecology and behaviour have received little attention for the majority of cuckoo bumblebees, which may hamper conservation efforts Our results quantitatively support observations made in other publications on the scarcity of data on cuckoo bumblebees, and highlight the need for further research on many species for whom fundamental knowledge is missing—particularly in light of the vulnerability of this subgenus to extinction.

Nagano, Yuta

doi: 10.1111/een.13262pmid: N/A

Plant‐pollinator interactions are essential to sustaining biodiversity and ecosystem functioning in terrestrial ecosystems and are variable on several spatiotemporal scales. On a fine temporal scale, the responses of pollinators to temperature and floral resource dynamics are likely to be related to the temporal turnover of plant‐pollinator interactions. However, the temporal dynamics of plant‐pollinator interactions on a fine scale are largely unknown. The present study aims to reveal the temporal turnover of plant‐pollinator interactions over a single day and investigates these interactions in semi‐natural grasslands in a Japanese agricultural landscape from the early morning to the evening. The interaction turnover was evaluated as temporal β‐diversity and divided into two components: interaction rewiring and species turnover. Insect species richness and the number of interactions showed hump‐shaped responses to the time of the day, and these responses differed for the different insect groups. Furthermore, the peak time of insect visitation frequency differed among 11 plant species. Interaction turnover (total β‐diversity) in the same day was higher than that in different days. Although interaction rewiring in different days was higher than that in the same day, species turnover had an opposite pattern. Over a single day, the relative importance of interaction rewiring was higher in the morning, while species turnover was higher in the evening. Around noon, interaction rewiring and species turnover were equally important. Therefore, the daily rhythm of pollinator activities and changes in the main floral resources drive the temporal turnover of plant‐pollinator interactions over a single day.

Pimentel, Carla S.; Firmino, Paulo N.; Almeida, Raquel P.; Lombardero, Maria J.; Ayres, Matthew P.; Calvão, Teresa

doi: 10.1111/een.13263pmid: N/A

1. Niche theory, neutral theory, and more recently the unifying theory of biodiversity offer alternative views of the structure (or not) of ecological communities. The relative importance of these theories has not been so thoroughly used to explain community assembly processes in phytophagous insects.

Oliveira, Tamires Camila Talamonte; Brandão‐Dias, Pedro Ferreira Pinto; Egan, Scott Patrick; Morales‐Silva, Tiago; Zaldívar‐Riverón, Alejandro; Silva, Victor Hugo Duarte; Oliveira, Gabriella Melo; Faria, Lucas Del Bianco

doi: 10.1111/een.13261pmid:

Fagundes, Marcilio; Fernandes, Zaura Couto; Neves, Frederico Siqueira; Fernandes, Geraldo Wilson; Cuevas‐Reyes, Pablo; Cornelissen, Tatiana

doi: 10.1111/een.13264pmid: N/A

Characterising host selection mechanisms and the performance of seed‐predating insects on different hosts has broad implications for ecology and applied entomology. We assessed host selection and performance of endophagous seed‐predating insects on three species of Copaifera, testing two hypotheses: (i) large‐sized trees produce larger seeds and have higher levels of seed predation than their smaller congeneric relatives, and (ii) endophagous seed‐predating insects that develop in larger‐seeded trees exhibit higher body mass, lipid content, and muscle mass as they obtain higher amount of food resources. Unpredated seeds of the large‐sized Copaifera langsdorffii showed greater mass than their smaller congeneric relatives C. arenicola and C. oblongifolia. Two species of endophagous seed‐predating beetles (Rhinochenus brevicollis and Apion sp.) were found attacking seeds of the three Copaifera species. Rhinochenus brevicollis preyed on a higher percentage of seeds than Apion sp. The shrub C. oblongifolia had the highest percentage of seed predation, contradicting our original hypothesis that larger species have a higher percentage of seed predation. Rhinochenus brevicollis preyed on a higher percentage of seeds of larger‐sized species than Apion sp. The higher dispersal ability of R. brevicollis associated with different patterns of plant species distribution may be the mechanism driving differential seed predation among Copaifera species. Adult insects that emerged from C. langsdorffii seeds showed higher body mass and lipidic content. It is likely that insects developing in larger seeds obtain a higher amount of food resources during their development. Finally, we observed a positive relationship between body weight and lipidic content in adults of R. brevicollis. We suggest that studies shedding light onto insect performance in different host‐sized seeds are necessary to understand host selection by beetles.

Deans, Carrie A.; Hutchison, William D.

doi: 10.1111/een.13265pmid: N/A

Nutrition provides the resources necessary to carry out all the physiological functions organisms require. This has important implications for insect pest management, as polyphagous species can experience considerable nutritional variability, which may impact their response to management tactics. Many studies have shown that dietary protein and carbohydrates play a primary role in insect fitness and that insects regulate their intake of these macronutrients to reach an optimal balance or intake target. Importantly, this intake target can vary across developmental stages, gender, and environmental conditions as physiological requirements change. In this study, we determined the intake target for adult spotted‐wing Drosophila, Drosophila suzukii, an invasive polyphagous fruit pest. We found that adult D. suzukii regulate their intake to meet a 1:4–1:5 protein‐to‐carbohydrate ratio, which is slightly more carbohydrate‐biased than the larval intake target. We also examined the effect of nutritional state on susceptibility to three commonly‐used insecticides by rearing flies on diets with different field‐relevant protein‐to‐carbohydrate ratios and exposing adults to an LC50 dose of zeta‐cypermethrin, spinetoram, or pyrethrin. Overall, female flies had higher survivorship than males, and diet effects varied across insecticides. Diet had no impact in the spinetoram treatments, while the extreme carbohydrate‐ and protein‐biased diets produced the lowest survivorship and reproductive performance in the zeta‐cypermethrin treatments. Survivorship increased with dietary protein in the pyrethrin treatments but reproductive performance did not differ across diets. Our results suggest that tactics, which reduce fly access to dietary protein sources, such as sterilisation, could increase fly susceptibility to insecticides.

Randall, Brendan A.; Cinto Mejía, Elizeth; Hauri, Kayleigh C.; Wetzel, William C.

doi: 10.1111/een.13266pmid: N/A

Discretional cannibalism is a widespread phenomenon among lepidopteran herbivores. Herbivores encounter variation in dietary nutrient quality when foraging, which alters feeding behaviour, as well as population‐ and trophic‐level dynamics. For example, plant resistance traits directly influence feeding patterns in insect herbivores through reduced consumption of plant tissue and increased rates of cannibalism. However, the effects of dietary composition, in particular unbalanced macronutrient ratios, on driving cannibalism remain unknown. We examined the effects of unbalanced macronutrient ratios on cannibalism in the generalist caterpillar Trichoplusia ni using an artificial diet experiment with varied ratios of two important macronutrients: protein and carbohydrates. We quantified cannibalistic behaviour from the second instar to pupation and measured survival among cannibals and non‐cannibals to understand the long‐term and short‐term costs and benefits of cannibalism. Caterpillars in high carbohydrate, low protein treatments cannibalised 20% more than the optimum control diet treatment, whereas herbivores in high protein, low carbohydrate treatments cannibalised 33% more than herbivores reared on the optimum macronutrient diet treatment. Survival of cannibals in macronutrient‐deficient diet treatments was 10.4%, compared with 76.9% for cannibals in the optimal macronutrient diet treatment. While previous work demonstrates the importance of induced chemical defence in promoting shifts to cannibalism, our results indicate that unbalanced macronutrient ratios can also promote cannibalism in insect herbivores. We propose that understanding how unbalanced macronutrient ratios drive cannibalism yields insight into how dietary quality, including both plant resistance traits and plant nutrients, influences behavioural plasticity and mediates plant–herbivore interactions.

Schulz, Nora K. E.; Stewart, Carly M.; Tate, Ann T.

doi: 10.1111/een.13268pmid: N/A

Immune responses are energetically costly to produce and often trade off with investment in reproduction and offspring provisioning. We predicted that hosts can interpret the magnitude of the infection threat from cues like initial bacterial load to adjust reproductive investment into offspring quantity and quality. To test this prediction, we exposed female flour beetles (Tribolium castaneum) to naïve or sterile media controls or one of three increasing doses of heat‐killed Bacillus thuringiensis (Bt). To estimate offspring quantity, we measured the number of eggs and hatched larvae from each maternal treatment group. To estimate offspring quality, we measured egg protein content, development to pupation, pupal weight and offspring survival against Bt infection. Compared to naïve controls, low and intermediate bacterial doses resulted in lower female fecundity, suggesting a shift to a somatic maintenance strategy. Meanwhile, in the highest‐dose group, fecundity was negatively correlated with egg protein content. This may reflect a trade‐off between offspring quality and quantity that could mask terminal investment based on metrics of quantity alone. Our results underscore the need to account for the magnitude of environmental cues when quantifying plasticity and trade‐offs among life history traits, and provide new insight into the transgenerational effects of immune responses.