Seasonal Variation in Adult Longevity of <I>Aleoides percurrens</I> Lyle (Hymenoptera: Braconidae), a Larval Parasitoid of Poplar Defoliator <I>Clostera cupreata</I> Butler

Abstract

Seasonal variation in adult longevity of Aleoides percurrens Lyle was studied with respect to ambient temperature and relative humidity from April to early December for 2 years (1991- 1992) at Forest Research Institute, Dehra Dun (78°01' N latitude 77° 59' E longitude), India. Longevity was studied in presence of food (honey-sugar solution) and in the absence of host .larvae. Parasitoid longevity peaked in September (12.8 ± 2.8 days) when mean relative humidity was 81.0 ± 2.1% (69-93%) and mean temperature was 24.2 ± 2.7°C (19.2-31.3°C). Longevity was shortest in April (3.0±1.0days) when the mean relative humidity was 54.5±5.1% (36-75%) and mean temperature was 21.3±2.3°C (10.7-32.0°C). A high significant and positive correlation (r = 0.6604) was established between relative humidity and adult longevity. The linear and square relationships established are given by the expressions [Longevity = -7.9127 + 0.22049 (RH), R² = 0.4361, P2), R² = 0.4607, P < 0.001, respectively]. However the correlation between ambient temperature and adult longevity was non-significant (r = 0.0174).