STRAINS SELECTION OF AGROTIS-IPSILON HFN (LEP, NOCTUIDAE) WITH LONG OR SHORT DELAY FOR OVIPOSITION - COMPARISON OF REPRODUCTIVE ACTIVITY

Two strains of A. ipsilon were obtained through a 20 generation selection based upon the delay for oviposition. The two strains (late oviposition: 12-18 days and early oviposition: 4-5 days) did not differ regarding the consecutive events of reproduction (oocyte maturation, calling, mating and oviposition). Adults showing a late oviposition exhibit a progressive lengthening of the precited events rather than a true arrest at a given moment. Reciprocal crossing of these 2 strains show that preoviposition time essentially depends upon the original strain of the female, whereas mating rate partially depends on that of the male. The results issued from the long preoviposition strain elicit that calling starts at the sculptured-eggs stage of ovarian development. On the other hand, when preoviposition is short, calling can occur for females which oocytes are not yet apparently developed. Considering the important spacing of preoviposition times in natural population, (3 to 25 days), the 2 types of insects, corresponding to the 2 selected strains including all the intermidiates, are supposed to coexist within a single population. This individual variability might, along with other abiotic factors (photoperiod), originate the aptitude of A. ipsilon adults for migration.