Desarrollo postembrionario, fecundidad y consumo de alimento de Dichroplus exilis (Orthoptera: Acrididae) bajo condiciones controladas.

BARDI CHRISTIAN; MARIOTTINI YANINA; DE WYSIECKI MARIA LAURA; LANGE CARLOS

REVISTA DE BIOLOGíA TROPICAL

REVISTA DE BIOLOGIA TROPICAL

Lugar: San José, Costa Rica; Año: 2011 vol. 59 p. 1579 - 1587

0034-7744

Dichroplus exilis has a wide geographic distribution in Southern South America, Although there are no formal records of D. exilis as an agricultural pest, some recent circumstantial observations suggest that damages attributed to Dichroplus elongatus, a sympatric pest species easily confused with D. exilis when diagnosis is solely based on external morphology, might actually have been caused by D. exilis. Since little is known on the biology of D. exilis, this study was conducted in order determine the postembryonic life cycle stages, fecundity, and food consumption under controlled conditions (30° C, 14L-10D, 40% RH). Laboratory-hatched, first generation (F1) individuals coming from adults originally collected on natural pastures near Rafaela (31 ° 15´25 .94 "S, 61 ° 29´14 .48" W), Santa Fe province, North-Eastern Argentina, and maintained in a rearing room for egg-pod laying, were employed in this study. Three cohorts of 16, 17 and 20 individuals were monitored daily until death of the last specimen. Egg-pod incubation time was 14.4, 1.08 days. 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). Average fecundity was 381.84, 38.54 eggs per female. 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, while the average adult food consumption, regardless of sex and reproductive status, was 4.32, 16.41 mg / day. Average food consumption of adult females was 17.47, 1.15 mg, and was significantly higher than that of males (10.83, 0.91 mg). When compared to other melanopline species under similar conditions, particularly in genera Dichroplus and Melanoplus, data obtained in this study show 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 of grasshopper communities in areas where damage by D. exilis is suspected, like parts of Santa Fe province and north-western Pampas region (north-western Buenos Aires, northern La Pampa, and southern Córdoba provinces) is envisaged in order to determine its possible status as a pest.