Wl. Yee et Nc. Toscano, LABORATORY EVALUATIONS OF SYNTHETIC AND NATURAL INSECTICIDES ON BEET ARMYWORM (LEPIDOPTERA, NOCTUIDAE) DAMAGE AND SURVIVAL ON LETTUCE, Journal of economic entomology, 91(1), 1998, pp. 56-63
Laboratory studies were conducted to test the effects of synthetic and
natural insecticides on lettuce leaf consumption by beet armyworm. Sp
ondoptera exigua (Hubner). Two synthetic and 4 natural insecticides we
compared: Capture (bifenthrin), Lannate (methomyl), Success (spinosad
), Xentari (Bacillus thuringlensis subsp. alzawai), Kryocide (cryolite
), and Trilogy (90% neem oil extract). Capture. Lannate, Success, and
Xentari at 50 ppm (AI) caused 100% mortality within 1 d after exposure
and prevented any detectable feeding on leaf disks by neonate S. exig
ua larvae. Capture, Lannate, Success. and Xentari at 50 ppm allowed on
ly minor feeding by 3rd and 5th instar S. exigua before causing nearly
100% mortality. Xentari at 50 ppm appeared less effective than the sy
nthetic insecticides and Success, but statistical differences among th
em were not significant. Neither Kryocide nor Trilogy at 50 ppm reduce
d leaf consumption by neonate, 3rd instar, and 5th instar S. exigua co
mpared with controls. Higher concentrations of Kryocide and Trilogy (1
,000 and 10,000 ppm) did significantly reduce leaf consumption by 3rd
instar S. exigua. The most effective natural insecticides we tested fo
r reducing lettuce consumption by S. exigua were Success and Xentari.