Performance of the parasitoid Praon volucre in Aulacorthum solani at five temperatures

This study aimed to evaluate the effect of temperature on biological parameters of Praon volucre (Haliday) (Hymenoptera Braconidae) and to determine its thermal requirements with the aphid Aulacorthum solani (Kaltenbach) (Rhynchota Aphididae) as host. Tests were carried out at 18, 20, 22, 24, and 26 ± 1 °C, RH 70 ± 10% and 12h photophase. 24h-old mated P. volucre females without previous experience of oviposition were released into a Petri dish containing a leaf disc of lettuce on a water/agar layer (1%) and 20 second- and third-instar nymphs of A. solani. Percentages of mummification were highest at 18 °C (64%) and 20 °C (66%). Developmental time decreased as the temperature increased, ranging from 19.8 days at 18 °C to 12.3 days at 26 °C. Emergence rate was not affected by temperature and was between 79.6% and 93.4%. Sex ratios varied between 32% and 51% females, but did not differ significantly at the 5 temperatures. Adult longevity strongly decreased with increasing temperature in the range from 18 °C to 22 °C, but was similar in the range from 22 to 26 °C. A. solani had an average tibia length of 0.52 mm when oviposition by P. volucre took place, and 1.17 mm at mummification. Even though host size at mummification was not influenced by temperature, parasitoid size was negatively affected by higher temperatures. The threshold temperature for development was 4.5°C and the thermal constant was 270 DD. Our findings indicate that P. volucre performs best at temperatures from 22 °C to 24 °C, and that a mixture of 2nd and 3rd instar nymphs of A. solani is adequate for rearing this parasitoid. This information helps optimization of parasitoid mass-rearing, and with timing of parasitoid releases to obtain establishment and synchronization with the host under greenhouse conditions