Abstract
Expansion of the areas in Louisiana infested with chlorinated hydrocarbon resistant boll weevils ( Anthonomus grandis Boheman) has occurred yearly since 1955, with the result that all cotton-producing areas of the State are now affected. Considerable reversion to susceptibility to the chlorinated hydrocarbon insecticides has occurred in field populations, but resistance remains at a level sufficiently great to prevent effective control with these insecticides. After 5 to 6 years of intensive use of organic phosphorus insecticides or toxaphene-DDT mixtures in certain areas, there has been no measurable change in response of the boll weevil to these insecticides. Under laboratory conditions, a 10- to 12-fold increase in the LD-50 of a boll weevil culture to toxaphene-DDT mixture was obtained in 22 generations.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
