Insecticidal potential of some indigenous weeds extracts of Bahawalpur Pakistan againstdusky cotton bug (Oxycarenus hyalinipennis) (Costa) (Hemiptera: Lygaidae) under laboratory conditions

Abstract

Owing to large scale use of chemical insecticides there is always need to find new alternatives to chemical insecticides. This study evaluated the aqueous extracts of three weeds namely Datura alba (Nees), Withania somnifera (Linnaeus) and Chenopodium album (Linnaeus) for insecticidal potential against Oxycarenus hyalinipennis (Costa) (Hemiptera: Lygaeidae) under laboratory conditions. Extracts were prepared from three plant parts e.g., leaves, stems and roots and applied at five concentrations ranging from 1 to 20 %. To check the mortality not because of weed extracts control treatment (water only) was also included as sixth treatment. Mortality of pest insects was assessed after three exposure periods e.g., 24h, 48 hand 72 h. Among the three weeds tested, mortality was more due to extract of D. alba weed which thus proved more toxic compared to other two weeds. Among plant parts, root extracts were more potent than leaves and stem extracts and the more concentration of 20 per cent usually resulted in maximum mortality. Maximum mortality of insects was after 72 h period followed by 48 h and minimum was after 24 h period. However maximum mortality of 60 % in case of D. alba warrants attention towards the options of either increasing concentration (> 20 %) of this extract or to evaluate other extraction type e.g., ethanolic extract to gain maximum mortality against this notorious pest.