The beet armyworm in floricultural crops

Abstract

Common in field and vegetable crops, the beet armyworm has invaded flower crops. It's hard to control with insecticides and can quickly build resistance. Microbial insecticides may be an effective alternative. T h e beet armyworm is a common pest of numerous field and vegetable crops. Recently, this insect, Spodoptera exigua (HUbner), has also become the major lepi-dopterous pest in floricultural crops, causing serious losses in chrysanthe-mums, carnations, roses, gypsophila, ge-raniums, and many species of bedding plants. Chrysanthemum has been particu-larly hard hit with estimates of greater than 30 percent crop loss in San Diego County during 1984. This loss occurred de-spite regular weekly applications of broad-spectrum insecticides. The devel-opment of insecticide resistance and the compromising of successful biological control of the leafminer, Liriornyza trifo-lii (Burgess), (California Agriculture, Jan-uary-February 1986) by these insecticide applications were our primary concerns. We therefore conducted studies to de-termine the biology of beet armyworm on ornamentals such as chrysanthemum and to examine the possibility that this species has developed resistance to commonly used insecticides. Insecticides potentially compatible with parasites and less prone to cross-resistance in L. trifolii were eval-uated for beet armyworm control.