Effect of Elevated Temperature on the Bionomics of Aenasius arizonensis Girault

An experiment was conducted to know the effect of thermal stress on the biological attributes of the parasitoid Aenasius arizonensis Girault of the cotton mealybug Phenacoccus solenopsis Tinsley. The results revealed that temperature showed a significant effect on the biological fitness traits of the A. arizonensis; when exposed to 32°C, parasitisation, fecundity, female sex ratio and adult longevity. At 32°C these viz., parasitisation (77%), sex ratio (63.46) and days taken from oviposition to mummy formation (6.4) were found to be the highest. Other fitness traits like fecundity (142.8) and developmental duration (11.2 - males, 12.6 - females) were found to be the highest at 27°C. These parameters gradually decreased with increasing temperature, indicating a negative relationship. Morphometrics of adults revealed that mean length and breadth of mummies, total length and breadth of adult male and females, total width of head, total length of antenna and total hind tibial length were maximum at 27°C as compared to those observed with high temperature treatments. Thus high temperature was observed to have an adverse effect on the growth and development of the parasitoid.