Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/1998
Publication Date: N/A
Citation: N/A Interpretive Summary: The boll weevil is a key pest of cotton in parts of the United States. Catolaccus grandis, a parasitic wasp from southern Mexico, is highly effective as a biological control agent when use in augmentative releases against the boll weevil. However, the practical use of this parasite in augmentative release programs depends on our ability to economically produce it in sufficient numbers. We found that different photoperiods influence on the circadian rhythms of oviposition and emergence, progeny sex ratio and reproductive potential of this parasitoid. These findings are important to correctly select the optimal photoperiod for C. grandis maintenance and will be used in the development of highly efficient mass rearing procedures for C. grandis. Such a rearing system will make augmentative releases of the parasite for management of the boll weevil practical.
Technical Abstract: 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 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 32.2-7.0% 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 regime.