Quiescence Behaviour in Ceuthorhynchus portulacae Marshall, a Potential Biocontrol Agent of the Purslane Weed, Portulaca oleracea L.

Portulaca oleracea L. is considered as a serious problematic weed of vegetables, vineyards and banana orchards in many parts of India. Ceutorhynchus portulacae Marshall (Coleoptera: Curculionidae) was identified as a potential indigenous biocontrol agent, which could be utilised for the effective suppression of the purslane weed. Field and laboratory studies in Bangalore revealed that the adults cease to feed and multiply during the cold winter months of November-January, indicating the possibility of diapause in the adult stage. A study was carried out to determine whether adults undergo diapause and the factors governing it. Behavioural and physiological observations showed that the adults were not capable of undergoing any diapause. But, they remain inactive during the cold winter period and become active with the advent of favourable environmental conditions.