The pick-up and penetration of ultra-low-volume and emulsifiable malathion formulations by tobacco budworm larvae
Awad, T.M.; Vinson, S.B.adleigh
J Econ Entomol 61(1): 242-245
The amount of an ultra-low-volume (ULV) and a water-diluted emulsifiable concentrated (EC) formulation of malathion picked up by larvae of the tobacco budworm, Heliothis virescens (F.), from treated cotton leaves and the amount penetrating into larvae were compared. Dead larvae on ULV-treated leaves contained a greater amount of malathion than larvae from EC treated leaves. The ULV droplet remained in a liquid form on the leaf while the EC dried and was less readily obtained by larvae crawling on the surface of leaves. Malathion EC rapidly disappeared from the surface of topically treated larvae both by evaporation and absorption of the dose by the cuticle and thus did not reach the site of action. A greater total amount of malathion was present internally in ULV than EC topically treated larvae.