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Circadian Rhythms of Oviposition and Emergence of the Ectoparasitoid Catolaccus Grandis (Hymenoptera: Pteromolidae)

S.M. Greenberg, J.A. Morales-Ramos, E.G. King


Catolaccus grandis (Burks) females oviposited 48.5-78.0% of their eggs between 0700 to 1300 h during a 24-h period. Moreover, 22.0-30.7% of their eggs were oviposited between 1300 to 1900 h. Only 3.9-20.8% of their eggs were oviposited between 1900 to 0700 h. The fecundity of parasitoid females held under the 14 h photophase regime (16.8 eggs per female per day) was significantly higher than fecundity of females held under the 10 h photophase (10.9 eggs per female per day). More female eggs were oviposited between 0700 to 1300 h (58.4-71.7%) in all photoperiods tested. During the 0700 to 1300 h period 30.0-50.0% of the adults emerged, and 32.2-70.0% of the adults emerged between 1900 to 0700 h compared with 0.0-17.8% emergence between 1300 to 1900 h.

Under constant light or dark conditions the pattern of circadian rhythms tended to disappear and the oviposition rates were constant throughout the day. The length of the photophase inversely affected developmental time of female and male parasitoids. The duration (days) of emergence by C. grandis was positively correlated with the length of the photophase, ranging from 2 d for the 14 h or 24 h photophase regimes to 5 d for the 10 h or 0 h photophase regimes.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1095 - 1099
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998