Migration of Pseudaletia separata WALKER (Lepidoptera : Noctuidae) : Considerations of Factors Affecting Time of Taking-Off and Flight Period

Abstract

Taking-off and flight period in the migration of P. separata were discussed based upon the laboratory observations. Adult emergence showed its peak within 2 hr after sunset, which suggests that most newly emerged moths are unable to fly until sunset of the next day because of the teneral period. Adults lived for over six days without feeding honey solution, suggesting that they could transmigrate for more than two days by subtracting the preflight and preovipositional periods. Ovary of P. separata was immature at emergenece. Once females fed honey solution, their ovary grew as age passed. Females assumed calling and mated when they had matured eggs on and after day 3. In starvation tests, the copulation day was delayed by starvation from days 1 and 2, but no significant difference in fecundity was found between control and groups starved. Given these results, the incipient incentive to migration of this species would be flight for feeding. Moths taking off on day 1 could migrate farther distance than on the later days, assuming that the females could fly for long periods before copulation.