Courtship Behavior in <I>Choristoneura rosaceana</I> and <I>Pandemis pyrusana</I> (Lepidoptera: Tortricidae)

Abstract

Abstract The characterization of courtship behavior in two sympatric and synchronic leafroller species, Choristoneura rosaceana (Harris) and Pandemis pyrusana Kearfott, indicated that only pheromone permeated airflow was needed as a releaser to initiate the male mating sequence. Mating ethograms demonstrate that males of both species perform six observable, discrete, and homogeneous steps: 1) wing fanning; 2) first contact; 3) male next to female (mostly in C. rosaceana), head-to-head (only P. pyrusana); 4) curled abdomen; 5) genitalia engagement; and 6) end-to-end position (mating). The sequences were highly stereotypic, suggesting that once a male starts the mating sequence, the rest of the steps will most likely follow. First contact with the female was a preprogrammed response, not requiring further cues. Copulation was more likely when the female remained stationary after first contact. Unsuccessful mating sequences were frequent during the study because females escaped by walking away, turning around, or jumping away. Because courtship behavior is a mechanism to select sexual partners, it is possible to hypothesize that responses resulting in an unsuccessful mating (assumed to be rejection) validate this mechanism. The mating sequence of C. rosaceana best matches the simple courtship behavior model, whereas the sequence in P. pyrusana resembles an interactive courtship. Overall results indicate that courtship behavior in both species would be compatible with attracticide (i.e., sex pheromone + insecticide) technology that requires direct contact between males and the pheromone source.