Effect of temperature on life history of Aprostocetus vaquitarum (Hymenoptera: Eulophidae), an egg parasitoid of Diaprepes abbreviatus (Coleoptera: Curculionidae)

The effect of temperatures ranging from 5 to 40 °C on Aprostocetus vaquitarum Wolcott (Hymenoptera: Eulophidae) oviposition and development were investigated. There were significant differences in the rate of development among the temperatures for all life stages. The egg stage lasted approximately 7 times longer at 15 than at 25 or 30 °C and the larval stage, consisting of 4 instars, took significantly less time at each increasing temperature from 15 to 30 °C. A. vaquitarum development from egg to adult took 16.3 days at 30 °C, significantly faster than the other temperatures tested. At 15 °C A. vaquitarum reached the pupal stage after a mean of 41.6 days but did not successfully complete pupation. A. vaquitarum eggs hatched on 66% of the parasitized egg masses at 35 °C but did not survive past the first instar. A. vaquitarum did not develop past the egg stage at 5 or 40 °C. Host Diaprepes abbreviatus L. (Coleoptera: Curculionidae) eggs also did not survive at temperatures of 35 and 40 °C on live plants. Upper and lower temperature thresholds for A. vaquitarum development were calculated to be 33.0 and 16.0 °C, respectively. Maximum development rate occurred at 30.9 °C and a thermal constant of 494.2 DD was calculated. Photoperiods ranging from 10L:14D to 16L:8D did not significantly affect development time from egg to adult at 25 °C. Oviposition was significantly higher at 30 °C than at the other temperatures tested; oviposition was also relatively high at 25 and 35 °C and several eggs were laid at 20 °C. Relatively cool winter temperatures in central Florida may be contributing to the limited range of A. vaquitarum in the state.