Alfonso Agro

Behavioral response of the egg parasitoid Ooencyrtus telenomicida to host-related chemical cues in a tritrophic perspective

The response of the generalist egg parasitoid Ooencyrtustelenomicida (Vassiliev) (Hymenoptera: Encyrtidae) to host-related chemical cues from tomato plants, Solanum lycopersicum L., and adults of Nezara viridula (L.) (Heteroptera: Pentatomidae) was investigated in laboratory-based no-choice and paired-choice tests. In Y-tube olfactometer experiments, when female wasps were exposed to volatiles from plants in different conditions, they were attracted only to volatiles produced by N. viridula adult-infested tomato plants. When female wasps were exposed to adults of N. viridula, they were attracted to volatiles from virgin males, and, at a lower level, to volatiles from mated females in preoviposition state. Finally, studies in open arena showed that chemical footprints left by adults of N. viridula did not induce arrestment responses in wasp females. These results are discussed in terms of extrinsic competition with other beneficial egg parasitoids that in field can compete for the same egg mass, since intraguild interactions may affect the success of a biological control program.

Temporal variations in symbiotic hindgut protist community of the subterranean termite Reticulitermes lucifugus Rossi in Sicily.

The dynamics of symbiotic protist communities of Reticulitermes lucifugus “Sicily” were investigated to assess the effects of seasonal environmental conditions and the termite’s feeding activity. In worker and soldier castes, the total protist population (total abundance), individual species abundances, and species proportions in their hindguts were examined monthly from December 2012 to February 2014. The main protist species taken into account were Dinenympha fimbriata Kirby, D. gracilis Leidy, Pyrsonympha flagellata Gras., Spirotrichonympha flagellata Grassi u. Fòa, Holomastigotes elongatum Grassi u. Fòa, and Trichonympha agilis Leidy, while others were not specifically identified, but were counted together. Seasonal comparisons between worker and soldier castes were made. Further, monthly data of workers were examined. We always found the presence of symbiontic protists in worker and soldier hindguts, therefore we hypothesize that termites fed without periods of interruption. In both castes the total protist population and species abundance showed variable trends with the highest values in summer. Workers were found to have significantly larger populations of protists and abundances of individual species than soldiers. Similar protist species were observed in both castes and in all periods, except for H. elongatum which was sometimes absent in soldiers. In hindguts of workers and soldiers the proportions of the protist species often showed a significant variation across seasons except for S. flagellata and T. agilis. In both castes we always detected the highest percentage of Dinenympha spp. with respect to the other species. Elements that might influence these aspects are discussed.