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

Outbreaks of beet armyworm, Spodoptera exigua (Hubner), in cotton in L ouisiana occurred in 1983, 1988, 1992 and 1993. The outbreaks generall y followed historic patterns observed in other locations, i.e., (1) lo cal endemic populations developed rapidly for one or two generations w hen climatic conditions were favorable and (2) biological control orga nisms were suppressed by pesticides. Outbreaks of beet armyworm in Lou isiana usually are less severe than in other southeastern states, beca use populations are usually lower and they occur in the latter part of the growing season. In 1993, beet armyworms infested more ha and caus ed higher levels of economic damage in Louisiana than in prior years. Insecticide screening tests conducted in 1993 indicated that Pirate (A C 303630) was more efficacious compared to all other insecticides. Bee t armyworm larvae (2nd-3rd instar) were confined to Monsanto transgeni c Bacillus thuringiensis (Bt) cotton (line 1076) and untreated Coker 3 12 in the laboratory. No significant (Pless-than-or-equal-to0.05) diff erences in leaf area consumed, mortality or pupal weights were detecte d.