International Ethological Conference, 25th (1997), Vienna
Laboratory of Ethology, Department of Veterinary Medicine, Tokyo University of Agriculture and Technology
ABSTRACT. Female cabbage white butterfly, Pieris rapae crucivora (Lepidoptera: Pieridae), would mate shortly after eclosion and remain unreceptive for several days after then. Males, on the other hand, are potential to mate more frequently than female and will engage in searching female everyday. It follows that the operational sex ratio is biased toward the male, and males compete for the access to females. We observed the female searching behavior of male butterflies in terms of how they maximize their reproductive success. Each male was marked to be identified individually, observed in a 12 x 24 x 2 m netted cage and its behavior was recorded every five minutes from 5:00 to 17:00 in July to September. The result showed that there were large variance in female searching behavior. Some males began searching behavior around seven o'clock, and others did so around ten o`clock. Some males engaged in searching behavior three hours a day, others did an hour. Those variance were partly accounted for by meteorological factors, male age and copulation career. Besides those environmental and physiological factors, the variance was shown to be accounted for in part by some factor intrinsic to each individual. The intrinsic variance might be genetic, since the observed males were raised under the similar condition. If the genetic variance is correlated with the reproductive success, it should be incompatible with the presupposition assumed in the most of models of reproductive behavior.