THE BERTHA ARMYWORM, MAMESTRA CONFIGURATA (LEPIDOPTERA: NOCTUIDAE). STERILIZATION OF ADULTS BY EXPOSURE OF PREPUPAL–PUPAL STAGES TO 25°C

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Abstract
Exposure of the prepupal and pupal stages of the bertha arrnyworm to 25°C during development had no obvious effect on pupal or adult survival, but reduced the incidence both of attempted mating and of spermatophore transfer and caused mated females with spermatophores to lay only a small number of eggs, all of which were sterile. Pupae are formed in the soil of rape fields during the latter part of August at depths up to 15 cm, and the frequency of their exposure to 25°C may influence population density the following year. Temperature profiles in the soil of rape fields are unknown, but an analysis of soil temperature records under sod from nine meteorological stations in the rape growing area indicated that they frequently reached 25°C. Thus there is sufficient probability that soil temperatures in rape reach a sterilizing temperature to warrant specific studies on temperature profiles in rape and their correlation with published meteorological data and with the fecundity of natural populations of the insect.