Biology and seasonal incidence of Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae) on Ashwagandha [Withania somnifera (L.) Dunal] in charotur region of Gujarat

Spotted beetle, Henosepilachna vigintioctopunctata (F.) (Coleoptera: Coccinellidae) is one of the major pest of ashwagandha in charotur region of Gujarat. Its seasonal incidence in cultivated ashwagandha during 2008–09 & 2009–10 along with biology was studied. Spotted beetle was active from last week of September to mid of December with a peak population of grubs (7.8 nos/plant) and adults (1.73 nos/plant) in 2^nd week of October (41 SMW) during both the years of observation. Population of spotted beetle showed significant positive correlation with atmospheric temperature (Maximum, Minimum & Mean), however, relative humidity had no effect on development of various stages of the pest beetle. The pest completed its life cycle in 20.08±0.24 days on ashwagandha after passing through four larval instars. The longevity of male and female adults of the pest was 67.79±3.96 and 67.20±3.85 days, respectively. The gravid females laid 562.54±76.16 eggs in several batches during the ovipositional period of 45.67±5.19 days.