Beet armyworm fecundity and oviposition behavior

摘要

Longevity, duration of the oviposition period, realized fecundity, and potential fecundity of the beet armyworm, Spodoptera exigua (Hubner), were examined in the laboratory under different feeding regimes. All parameters were significantly reduced for the water-only diet compared with 10 percent honey or sucrose diets. Oviposition was highest the night after mating and decreased in a logarithmic fashion thereafter. In the carbohydrate-fed moths, 92 percent of lifetime realized fecundity occurred by the fourth night of oviposition. Although our data indicate that carbohydrates in the adult diet can increase realized and potential fecundity, most of the lifetime complement of oocytes (91 percent) is present at the time of eclosion from the pupa. Pupal weight was significantly correlated with lifetime potential fecundity, explaining 37 - 66 percent of the variation among moths depending on adult diet. In cotton, most egg masses were deposited on the undersides of leaves within the upper 50 percent of the canopy and horizontally within the inner 50 percent of the plant. In pigweed, egg masses were commonly laid within the inner 50 percent of the canopy, but along the upper 80 percent of the vertical axis. This positional information will aid in further efforts to investigate, predict, and manage beet armyworm populations in cotton and non-cotton hosts.