Lethal and Sublethal Effects of Methoxyfenozide on the Development, Survival and Reproduction of the Fall Armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The lethal and sublethal effects of the ecdysone agonist methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith), were investigated by feeding a methoxyfenozide-treated diet to fifth instars until pupation in doses corresponding to the LC10 and LC25 for the compound. Larval mortality reached 8 percent and 26 percent in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12 percent for the LC10 and 60 percent for the LC25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a significant effect on the timing of larval development. The development period for males and females was about seven days longer than the controls for both concentrations tested. In contrast, the compound affected neither pupae nor adult longevity. Finally, S. frugiperda adults that resulted from fifth instars treated with methoxyfenozide were not affected in their mean cumulative number of eggs laid per female (fecundity), nor percentages of eggs hatched (fertility), or the sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm.

Biologia de Holhymenia rubiginosa Breddin (Hemiptera: Coreidae) em Passiflora alata (Passifloraceae) / Biology of Holhymenia rubiginosa Breddin (Hemiptera: Coreidae) on Passiflora alata (Passifloraceae)

The biology of Holhymenia rubiginosa Breddin is described on sweet-passion-fruit, Passiflora alata, and the developmental time, viability and thermal requirements of the egg stage, the developmental time and mortality of the nymphal stage, and adult longevity and reproductive parameters were assessed. Insects were reared at laboratory controlled conditions (25 ± 1°C, 65 ± 10 percent RH, photophase 12h) on branches of P. alata, 20 percent honey solution and pollen. The lower thermal threshold (10.8°C) and thermal requirements (140.8 DD) for egg development were determined using four temperatures (17, 21, 25 and 30°C). The average egg development time (days) and viability were 25.4 ± 0.45, 88 percent; 13.2 ± 0.28, 88 percent; 8.8 ± 0.16, 94 percent; and 7.7 ± 0.17, 92 percent, at 17, 21, 25 and 30 ± 1°C, respectively. When reared at 25 ± 1°C, the first instar had the shortest development time (4.0 ± 0.02 days) and the second the longest (15.7 ± 3.50 days), which also had the highest mortality (75 percent). Males and females had similar longevity (185.3 ± 17.52 days for females and 133.6 ± 18.94 days for males). Females mated 33.0 ± 7.71 times, with a mean duration of 99.0 ± 9.25 min, laying 11.5 ± 2.55 eggs/female. Periods of pre-oviposition, oviposition and post-oviposition were respectively 96.4 ± 18.08; 88.5 ± 23.48 and 19.3 ± 12.18 days.

A biologia de Holhymenia rubiginosa Breddin, em maracujazeiro-doce, Passiflora alata é descrita e são avaliados o tempo de desenvolvimento, a viabilidade e as exigências térmicas embrionárias, a duração e a mortalidade na fase ninfal, assim como a longevidade e os parâmetros reprodutivos. Os insetos foram criados em laboratório, em condições controladas (25 ± 1°C, 65 ± 10 por cento UR, fotofase 12h), alimentados com ramos de P. alata e solução de mel a 20 por cento e pólen. A temperatura base estimada para a fase embrionária foi de 10,8°C e a constante térmica 140,8 GD, determinadas para fase de ovo usando quatro temperaturas (17, 21, 25 e 30 ± 1°C). A duração média, em dias, e a viabilidade da fase de ovo foram de 25,4 ± 0,45 (88 por cento); 13,2 ± 0,28 (88 por cento); 8,8 ± 0,16 (94 por cento) e 7,7 ± 0,17(92 por cento), nas temperaturas de 17, 21, 25 e 30 ± 1°C, respectivamente. Quando criado a 25 ± 1°C, o primeiro ínstar teve o menor tempo de desenvolvimento (4,01 ± 0,02 dias) e o segundo o mais longo (15,7 ± 3,50 dias), além de ser o que apresentou maior mortalidade (75 por cento). Machos e fêmeas tiveram longevidade similar (185,3 ± 17,52 dias para fêmeas e 133,6 ± 18,94 dias para machos). Fêmeas copularam 33,0 ± 7,71 vezes, com duração média de 99,0 ± 9,25 minutos, ovipositando 11,5 ± 2,55 ovos. Períodos de pré-oviposição, oviposição e pós-oviposição foram, respectivamente, 96,4 ± 18,08; 88,5 ± 23,48 e 19,3 ± 12,18 dias.