BEET ARMYWORMS (LEPIDOPTERA, NOCTUIDAE) IN NORTHEAST LUISISANA - OBSERVATIONS ON AN UNCOMMON INSECT PEST

Outbreaks of beet armyworm, Spodoptera exigua (Hubner), in cotton in Louisiana occurred in 1983, 1988, 1992 and 1993. The outbreaks generally followed historic patterns observed in other locations, i.e., (1) local endemic populations developed rapidly for one or two generations when climatic conditions were favorable and (2) biological control organisms were suppressed by pesticides. Outbreaks of beet armyworm in Louisiana usually are less severe than in other southeastern states, because populations are usually lower and they occur in the latter part of the growing season. In 1993, beet armyworms infested more ha and caused higher levels of economic damage in Louisiana than in prior years. Insecticide screening tests conducted in 1993 indicated that Pirate (AC 303630) was more efficacious compared to all other insecticides. Beet armyworm larvae (2nd-3rd instar) were confined to Monsanto transgenic Bacillus thuringiensis (Bt) cotton (line 1076) and untreated Coker 312 in the laboratory. No significant (Pless-than-or-equal-to0.05) differences in leaf area consumed, mortality or pupal weights were detected.