Search results for " insects"
showing 10 items of 50 documents
Cuticular hydrocarbon profiles differ between ant body parts: implications for communication and our understanding of CHC diffusion.
2020
Abstract Insect cuticular hydrocarbons (CHCs) serve as communication signals and protect against desiccation. They form complex blends of up to 150 different compounds. Due to differences in molecular packing, CHC classes differ in melting point. Communication is especially important in social insects like ants, which use CHCs to communicate within the colony and to recognize nestmates. Nestmate recognition models often assume a homogenous colony odor, where CHCs are collected, mixed, and redistributed in the postpharyngeal gland (PPG). Via diffusion, recognition cues should evenly spread over the body surface. Hence, CHC composition should be similar across body parts and in the PPG. To te…
Sex-allocation conflict and sexual selection throughout the lifespan of eusocial colonies.
2018
AbstractModels of sex allocation conflict are central to evolutionary biology but have mostly assumed static decisions, where resource allocation strategies are constant over colony lifespan. Here, we develop a model to study how the evolution of dynamic resource allocation strategies is affected by the queen-worker conflict in annual eusocial insects. We demonstrate that the time of dispersal of sexuals affects the sex allocation ratio through sexual selection on males. Furthermore, our model provides three predictions that depart from established results of classic static allocation models. First, we find that the queen wins the sex allocation conflict, while the workers determine the max…
Oxidative stress and senescence in social insects: A significant but inconsistent link?
2021
The life-prolonging effects of antioxidants have long entered popular culture, but the scientific community still debates whether free radicals and the resulting oxidative stress negatively affect longevity. Social insects are intriguing models for analysing the relationship between oxidative stress and senescence because life histories differ vastly between long-lived reproductives and the genetically similar but short-lived workers. Here, we present the results of an experiment on the accumulation of oxidative damage to proteins, and a comparative analysis of the expression of 20 selected genes commonly involved in managing oxidative damage, across four species of social insects: a termit…
Nanda-Hamner Curves Show Huge Latitudinal Variation but No Circadian Components in Drosophila Montana Photoperiodism
2021
Insect species with a wide distribution offer a great opportunity to trace latitudinal variation in the photoperiodic regulation of traits important in reproduction and stress tolerances. We measured this variation in the photoperiodic time-measuring system underlying reproductive diapause in Drosophila montana, using a Nanda-Hamner (NH) protocol. None of the study strains showed diel rhythmicity in female diapause proportions under a constant day length (12 h) and varying night lengths in photoperiods ranging from 16 to 84 h at 16°C. In the northernmost strains (above 55°N), nearly all females entered diapause under all photoperiods and about half of them even in continuous darkness, whil…
Comparative transcriptomic analysis of the mechanisms underpinning ageing and fecundity in social insects.
2021
The exceptional longevity of social insect queens despite their lifelong high fecundity remains poorly understood in ageing biology. To gain insights into the mechanisms that might underlie ageing in social insects, we compared gene expression patterns between young and old castes (both queens and workers) across different lineages of social insects (two termite, two bee and two ant species). After global analyses, we paid particular attention to genes of the insulin/insulin-like growth factor 1 signalling (IIS)/target of rapamycin (TOR)/juvenile hormone (JH) network, which is well known to regulate lifespan and the trade-off between reproduction and somatic maintenance in solitary insects…
Beta diversity of stream insects differs between boreal and subtropical regions, but land use does not generally cause biotic homogenization
2021
Made available in DSpace on 2021-06-25T10:17:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 Previous studies have found mixed results regarding the relationship between beta diversity and latitude. In addition, by influencing local environmental heterogeneity, land use maymodify spatial taxonomic and functional variability among communities causing biotic differentiation or homogenization. We tested 1) whether taxonomic and functional beta diversities among streams within watersheds differ between subtropical and boreal regions and 2) whether land use is related to taxonomic and functional beta diversities in both regions.Wesampled aquatic insects in 100 subtropical (Brazil…
Emergence, dispersal, and mate finding via a substrate-borne sex pheromone in the parasitoidMetaphycus luteolus
2013
Metaphycus luteolus Timberlake (Hymenoptera: Encyrtidae) is a facultatively gregarious parasitoid of soft scale insects. We conducted behavioral experiments to better understand the mating structure of this species. Emergence of male and female offspring is synchronized, beginning at the onset of photoperiod. Both sexes are able to disperse, although dispersal of males from natal patches appears to take longer than dispersal of females. We demonstrated the presence of a female-produced contact pheromone using open arena bioassays and motion tracking software, testing residues deposited by walking females, and extracts of females. Males responded to the females' chemical footprints' and to a…
Influence of brood temperature and hygrometry variations on the development of the honey bee ectoparasite Varroa jacobsoni (Mesostigmata : Varroidae)
1990
The influence of different temperatures (from 26 to 39.5°C) and relative humidities (40 and 70%) on the development of Varma jacobsoni (Oudemans) was studied by placing newly capped and parasitized worker bee broods into thermostatically controlled chambers. In one set of experiments the temperature was kept constant, and in the second set, the parasitized worker broods were placed at a temperature of 40,41, or 42°C for a time varying from 0 to 24 h and then returned to 32.5°C. The optimal temperature for development of the mites was between 32.5 and 33.4°C, which corresponds to the brood temperature of Apis mellifera L. Above 36.5°C, reproduction of varroa females was significantly reduced…
Temperature differences associated with colour do not determine where the acorn ant Temnothorax crassispinus (Hymenoptera: Formicidae) chooses to nest
2021
Temperature is an important factor for invertebrates. Social insects build nests, which along with their ability to thermoregulate, provide shelter from extreme temperatures. However, for many species of ants the most common method of controlling the temperature inside a nest is to choose a suitable nest site. During a fi eld experiment, the choice of nest site by the acorn ant Temnothorax crassispinus, a species which lives in coniferous and mixed forests, was studied. It typically occupies ephemeral nest sites and can move to a new nest site several times in one season. It was predicted that in early spring, dark coloured nest sites would be warmer and thus more frequently occupied by ant…
A review on introduced alien insect pests and their associated parasitoids on eucalyptus trees in Sicily
2018
A review is reported in the present paper on invasive alien insects introduced in Sicily on Eucalyptus trees, together with unpublished results from recent surveys. As to the latter ones, observations were conducted especially on Thaumastocoris peregrinus (Carpintero & Dellapé) (Hemiptera, Thaumastocoridae), the most recently introduced species. Overall, eight alien insect pests have been accidentally introduced in the island on Eucalyptus, belonging to the orders Hemiptera (Aphalaridae, 2 spp.; Thaumastocoridae, 1 sp.), Coleoptera (Cerambycidae, 2 spp.; Curculionidae, 1 sp.) and Hymenoptera (Eulophidae, 2 spp.). Two encyrtid parasitoids, Avetianella longoi Siscaro and Psyllaephagus bliteus…