Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2004
Publication Date: 2/22/2005
Citation: Greenberg, S.M., Showler, A.T., Liu, T. 2005. Effects of neem-based insecticides on beet armyworm (Lepidoptera: Noctuidae). Insect Science. 12(1):17-23. Interpretive Summary: There are presently no tactics for beet armyworm control on cotton other than conventional pesticides, and the beet armyworm is known to become a serious pest of cotton particularly after insecticides suppress natural enemies. This study demonstrated that several formulations of neem, a botanical extract containing azadirachtin and other possibly insecticidal components, are effective at deterring beet armyworm oviposition, reducing feeding by larvae, and causing mortality among eggs. Alternative tactics to conventional insecticides, such as neem-based products, can provide protection of cotton after conventional insecticide applications, and this might be particularly important once the boll weevil eradication program is underway in the Lower Rio Grande Valley of Texas.
Technical Abstract: Three commercial neem-, Azadirachta indica A. Juss (Meliaceae), based insecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder were evaluated for oviposition deterrence, deterrence of larval feeding, and toxicity to eggs and larvae of the beet armyworm, Spodoptera exigua (Hübner) Lepidoptera: Noctuidae), on cotton leaves in the laboratory. Significant oviposition deterrence in no choice, and two-choice and five-choice assays was observed for neem-based insecticides treatments when compared to a non-treated control. Neem-based insecticides also significantly deterred feeding by beet armyworm larvae. Direct contact with neem-based insecticides significantly decreased the survival of beet armyworm eggs. Survival of beet armyworm larvae fed for 7 d on leaves treated with neem-based insecticides was reduced to 27%, 33%, 60%, and 61% for neem leaf powder, Ecozin, Agroneem, and Neemix, respectively. Potential for adoption of neem-based insecticides in commercial cotton for beet armyworm control is discussed.