Influence of Temperature on Oviposition and Adult Longevity of Bracon mellitor 1 Reared on Boll Weevils 23

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Abstract
Adults of the parasite Bracon mellitor Say were held under constant temperatures (15.6, 21.1, 26.7, 32.2 and 37.8°C), day/night temperature extremes (37.8/15.6°C and 32.2/21.1°C) and 2 regimes simulating field temperatures. Daily oviposition and mortality data were collected and used to calculate “capacity for increase” (r c ), net reproductive rate (R o ), mean generation time (T c ) and finite rate of natural increase (λ). Values of r c increased with temperatures from 15.6–32.2°C, then rapidly fell to zero as no adults survived to oviposit at 37.8°C. The large increase observed between 15.6 and 21.1°C was evidence for a minimum threshold effect. Generally, r c was not significantly higher at variable temperatures, and a maximum r c value of 0.26 occurred at a constant temperature of 32.2°C and under one of the field simulations. Adult longevity decreased with increasing temperature from a mean of 99.2 days at 15.6°C to a mean of 7 days at 37.8°C. Females lived shorter lives under the variable temperature regimes.

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