DIFFERENT SEASONAL REARING CONDITIONS DO NOT AFFECT PHEROMONE-SENSITIVE RECEPTOR NEURONS OF THE ADULT CABBAGE-LOOPER MOTH, TRICHOPLUSIA NI

In southern parts of the United States the cabbage looper moth, Tricho plusia ni (Hubner) (Lepidoptera: Noctuidae), is multivoltine, and ther efore successive generations experience different environmental condit ions during development from larvae to adults. Since environmental con ditions are thought to influence pheromone communication, we tested th e effects of two different temperature and light regimes (selected to mimic those occurring in the spring and summer growing seasons in the south) during rearing on the response characteristics of the adult mal e olfactory receptor neurons responsible for detecting the major compo nent of the female pheromone. The dose-response functions of receptor neurons from the warm- and cold-reared insects were similar in both th eir slopes and thresholds to stimulation with the major component of t he female-emitted pheromone, (Z)-7,dodecen-1-ol acetate and (Z)-7,dode cen-1-ol, a behavioural inhibitor. In double pulse experiments, design ed to emulate the temporal dispersion of pheromone in nature, neurons were stimulated with short pulses (200 ms) of (Z)-7,dodecen-1-ol aceta te separated by varying intervals. Intervals as short as 30 ms reduced the response to a second pulse by over 50%. When the intervals betwee n pulses were longer than 2 s, significant differences were not seen b etween the responses to the first and to the second pulse. These tempo ral response patterns were similar in both warm- and cold-reared anima ls.