Desarrollo post-embrionario, fecundidad y consumo de alimento de Dichroplus exilis (Orthoptera: Acrididae) bajo condiciones controladas

ABSTRACT

Postembryonic development, fecundity and food consumption of Dichroplus exilis (Orthoptera Acrididae) under controlled conditions. Dichroplus exilis is a widely distributed species in Southern South America. Although there have been reports of D. exilis as an agricultural pest, some recent observations suggest that the damage attributed to D. elongatus may actually have been caused by D. exilis. This study was conducted to determine the postembryonic life cycle stages, fertility and food consumption of this species under controlled conditions (30°C, 14L-10D, 40% RH).Individuals employed belong to the laboratory-hatched first generation (F1), from adults (n=64, ♀=28, ♂=36) collected in natural grasslands near Rafaela, Santa Fe province in North- Eastern Argentina. Three cohorts of 16, 17 and 20 individuals were monitored independently in acetate tubes on a daily basis, until death of the last insect. Average fecundity was 381.84, 38.54 eggs per female. Egg-pod incubation time was 14.4, 1.08 days and six nymphal instars were recorded. Nymphal development time was 41.38, 0.71 days (I=8.73, 0.20; II=6.38, 0.24; III=5.64, 0.33; IV=7.15; 0.43; V=9.76, 0.54; IV=7.85, 0.95). The recorded food consumption was 9.89, 1.08 (mg/ind/day) for nymphs IV, 18.04, 0.73 (mg/ind/day) for nymphs V-IV, 16.76, 1.06 (mg/ind/day) for pre-reproductive males, 28.09, 1.81 (mg/ind/day) for pre-reproductive females, 7.71, 0.91 (mg/ind/day) for reproductive males and 13.06, 0.71 (mg/ind/day) for reproductive females, while the average adult food consumption, regardless of sex and reproductive status, was 16.41, 4.32mg/day. Average food consumption of adult females was 17.47, 1.15mg, and was significantly higher than that of males (10.83, 0.91mg). Data obtained in this study showed that D. exilis exhibits at least some of the biological attributes needed to configure an actual or potential agricultural pest, albeit not yet recognized as such. Field monitoring ...

RESUMEN

La Subfamilia Melanoplinae tiene una relevancia central dentro de la acridiofauna Argentina. Varias especies suelen ser numéricamente dominantes en las comunidades de acridios del país y algunas constituyen serias plagas. El objetivo de este trabajo fue conocer el ciclo de vida postembrionario, la fecundidad y supervivencia de las hembras y el consumo de alimento de Dichruplus exilis bajo condiciones controladas (30°C; 40%HR y 14L-10O). Para ello se realizó el seguimiento de tres cohortes de 16, 17 y 20 individuos. El tiempo de incubación fue de 14.4±1.08 días. La duración del desarrollo ninfal fue 41.38; 0.71 días (I 8.73; 0.20, II 6.38; 0.24, III 5.64; 0.33, IV 7.15; 0.43, V 9.76; 0.54; IV 7.85; 0.95); la fecundidad promedio fue de 381.84, 38.54huevos/hembra. El consumo registrado fue de 9.89; 1.08 (mg/ind./día) para las ninfas de IV, 18.04; 0.73 (mg/ind./día) para las de V y IV, mientras que el consumo promedio de los adultos, sin diferenciar sexo y estado reproductivo, fue de 16.41; 4.32mg/día. Estos parámetros, al ser comparados con los de otras especies afines, indican que D. exilis exhibe atributos biológicos que condicen con los de otros melanoplinos considerados plaga.