Boll Weevil (Coleoptera: Curculionidae) Reproductive Development as a Function of Temperature

Abstract

The effect of temperature on reproductive development in the boll weevil, Anthonomus grandis Boheman, was examined at 12.8, 18.3, 23.9, 29.4, 32.2, and 35.0°C and a 13:11 (L:D) h photoperiod through the use of dissections at specific ages. Logistic functions were used to describe age-frequencies of the presence of eggs, eggs with visible yolk, mature eggs, early reproductive testes (beginning of visible sperm accumulation in the centers of testis lobes), late reproductive testes (visible sperm accumulation in outer areas of testicular follicles), and filled seminal vesicles. Development times for 50 and 90% of the populations to attain these development stages were estimated from logistic functions. Biophysical developmental rate models were fitted to the corresponding development rates. Results indicated a marked temperature dependence of reproductive development, with both low- and high-temperature inhibition at observed temperature extremes. Exposure to lower temperatures did not induce morphological characteristics of diapause. These results suggest a need to reexamine previous studies of diapause induction in which differences in physiological ages of weevils among induction regimes were not considered.