Effect of temperature on the chemical profiles of nest materials of social wasps

Social insects depend on their nests for protection against predation and abiotic threats. Accordingly, the chemical compounds present in the material wasps use to build their nests can both facilitate communication and repel predators. It is herein hypothesized that different wasp species build their nests with different structure and substrate materials and that such materials consist of chemical compounds related to unique wasp behavior and outside temperature variation. To test this hypothesis, nests were collected from three species of social wasps, the samples of which were subjected to temperature variation under laboratory conditions. The compounds present in the substrate were analyzed by gas chromatography coupled to mass spectrometry. Chemical compounds identified in the nest material of the three species responded differently to temperature variation. Chemical compounds from Polybia nests were altered significantly when subjected to temperature variation, whereas the nests of Polistes versicolor did not significantly change in relation to the control. The differences found between Polistes and Polybia nests may be related to genetic factors, but also to the type of nest they construct. It is possible that divergent evolutionary strategies for maintaining colony temperature, as a function of the chemical composition of the nests, may have appeared between wasps that have open and closed nests. In relatively small colonies, nest substrate is more resistant to temperature variation because it is composed of a greater diversity of elements and thus capable of holding heavier, longer carbon chains. Our results suggest that chemical compounds in the nest material of the three wasp species analysed responded differently to fluctuating ambient temperatures and that such variation could result from the biochemical differences of unique wasp species or from thermoregulation strategies of colonies.

Chemical signals might mediate interactions between females and juveniles of Latrodectus geometricus (Araneae: Theridiidae)

Studies related to communication on spiders show that, as in other invertebrates, the interactions between conspecifics are also made through chemical signals. Therefore, in order to assess whether the composition of cuticular compounds might be involved in interactions that occur during the days after the emergence of juveniles in Latrodectus geometricus, we conducted behavioral and cuticular chemical profiles analysis of females and juveniles of different ages. The results show that females, regardless of their reproductive state, tolerate juveniles of other females with up to 40 days post-emergence and attack juveniles of 80 days post-emergence. Cuticlar chemical analysis shows that while the profile of juveniles is similar to adult's profile, they can remain in the web without being confused with threat or prey. Also, cuticular chemical profiles vary between different populations probably due to genetic and environmental differences or similarities between them. Finally, females in incubation period are able to detect the presence of eggs within any egg sac, but cannot distinguish egg sacs produced by conspecifics from the ones they had produced.