Perching mate-locating strategy in Paysandisia archon (Lepidoptera: Castniidae): behavioral and morpho-physiological investigations.

We studied Paysandisia archon (Burmeister) (Lepidoptera: Castniidae: Castniinae) courtship behavior to provide a detailed qualitative and quantitative description of male and female behaviors. Moreover, to investigate the role of antennal olfaction and visual stimuli in mate-recognition, bioassays with antennectomized adults and dummies were performed. To assess the presence of a pheromone gland in the ovipositor, morphological (using light and scanning electron microscopic techniques), electrophysiological, and chemical investigations were carried out. We observed perching mate-locating behavior of P. archon males, with the female triggering the courtship sequence by approaching the perching male first. The stereotyped courtship sequence is made up of five main steps: female flight, pair flight, alighting close, copulation attempt, and clasping. Our findings suggest that visual cues are important in P. archon courtship behavior, and the role of chemical cues is also discussed. Moreover, we observed a higher antenna cleaning frequency in females than in males. Ovipositor extrusions during courtship appeared not to be related to calling behavior, and histological investigations showed no evidence of glandular tissues involved in sex pheromone production. The P. archon ovipositor consists of the eighth uromere, which forms the ovipositor base, and the 9th and 10th uromeres are fused together and connected to the base by an intersegmental membrane. Overall, 24 compounds were identified from extracts obtained from ovipositors: 9 compounds were detected only in extracts from the ovipositors of 24-h-old virgin females, and not from those of 1-h-old females. None of these compounds elicited any significant electrophysiological responses from male antennae.

Sex-dispersal differences of four phloem-feeding vectors and their relationship to wild-plant abundance in vineyard agroecosystems.

Sex-dispersal differences of four phloem-feeding vectors and their relationship to wild-plant abundance were analyzed over 2 yr in two vineyard agroecosystems. Adults of Euscelis lineolatus Brullè, Neoaliturus fenestratus (Herrich-Schäffer), Psammotettix alienus (Dahlbom), and Hyalesthes obsoletus Signoret were sampled by using yellow sticky traps at two heights (20 and 150 cm) above the ground in a regular geo-referenced grid. Wild vegetation was surveyed around each sampling point. The most abundant species collected was N. fenestratus, followed by P. alienus, H. obsoletus, and E. lineolatus. Low traps were more effective in capturing the females of N. fenestratus and P. alienus and the males of all of the species, except N. fenestratus at one site. Sex ratio was male-biased for N. fenestratus in both agroecosystems at both trap heights, and only in low traps for H. obsoletus and P. alienus at one site. Insect abundance, temporal population dynamics, and dispersal patterns showed considerable fluctuations according to vineyard agroecosystems and years. In the current study, all of the four phloem-feeding vectors were not found homogeneously in the vineyards, and they were aggregated in correspondence with their herbaceous wild-plant hosts. Insects tended to disperse from the borders toward the vineyard, or vice versa Colonizing pattern was strongly affected by border vegetation, fallow fields, and vineyard ground-cover vegetation. Different plant communities were identified inside the agroecosystems, and significant correlations among insect and plant-species abundances were recorded. Data highlight the importance of understanding the dispersal patterns of vector species for the application of correct integrated pest-management strategies.