Factors affecting egg production and oviposition in populations ofColias philodice eurythemeBoisduval (Lepidoptera: Pieridae)

Abstract

Populations of the alfalfa caterpillar, Colias philodice eurytheme Boisduval, reach very high numbers during the more favorable summer months in California. This study was conducted to determine the important factors affecting egg production and oviposition, and their corresponding effects on population trends of this insect. The reproductive system of the female does not differ greatly from those of other Lepidoptera with two genital apertures. Mating usually occurs a few hours after emergence, and involves the passage of a spermatophore which is formed in the female from the glandular secretions of the male.Oogenesis is largely controlled by temperature although some sugar is also required for the maturation of a large number of eggs. Adult food is more important in its effect on oogenesis than on oviposition. Temperature is generally more critical than humidity, light intensity, or food in controlling the oviposition rates of Colias philodice eurysbeme, The optimum body temperature for high rates of oviposition appears to be 32°C. The upper and lower thermal limits of body temperature for oviposition are 46°C and 21°C, respectively. The optimum humidity for a high oviposition rate ranges from 26 to 45 per cent. At the higher and lower temperatures, any effect that humidity may have on oviposition is masked by the effects' of temperature.A female may lay as many as 1,172 eggs, but the average is about 715. Under field conditions, these numbers are probably seldom realized. The sex ratio usually favors the male.' In order to determine the reproductive potential of a population, the age, fat body content, and number of matings of various classes of the population must be determined by dissection.

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“…Much of the following has been reported by Stern and Smith (1960), whose results are confirmed and in some ways extended by unpublished observations of the present writer. Mating by Colias occurs following active search by mature males for newly emerging females, which rest among the plant cover.…”

Reproductive Biology of the Grape Vine Moth, Phalaenoides Glycine Lewin (Lepidoptera: Agaristidae)

“…In mature females eggs also are found in the common oviduct. Very occasionally mature eggs were found in the ductus seminalis-a phenomenon also observed in Colias philodice Boisduval (Stern and Smith 1960).…”

“…1. The terminology used has been adapted from Callahan and Chapin (1 960), Holt and North (1970) and Stern and Smith (1960).…”

Ejaculate production schedule and the degree of protandry in fishflies (Megaloptera: Corydalidae)

“…The degree of protandry is also predicted theoretically or known empirically to be reduced by the following factors: the remating of females (Parker & Courtney 1983;Zonneveld 1992Zonneveld , 1996a; decreasing sexual dimorphism in male to female body size if the growth rate does not differ between males and females (Lederhouse, Finke & Scriber 1982;Singer 1982;; a decrease in population density (Zonneveld & Metz 1991;Kleckner et al 1995;Bradshaw et al 1997); an increase in food availability during larval growth (Kleckner et al 1995); and higher temperatures (Stern & Smith 1960;Baughman, Murphy & Ehrlich 1988).…”