Aspectos biológicos de <i>Deroceras reticulatum</i> (Müller, 1774) (Pulmonata: Stylommatophora) en condiciones controladas

Abstract

Se estudió la biología de Deroceras reticulatum a 12 y 18 °C, en laboratorio. La experiencia se inició en cada temperatura con 20 babosas recién nacidas. Los individuos se criaron individualmente, alimentándolos con hojas de lechuga (Lactuca sativa L.). Semanalmente se registraron longitud de cada babosa, mortalidad, oviposición e ingesta de cada individuo. Se identificaron 3 fases de desarrollo: la 1ra de crecimiento rápido, la 2da de crecimiento mas lento y la 3ra de crecimiento nulo a 18 °C y escaso a 12 °C. También se observaron diferencias en la 2da fase que alcanzó mayor duración a 12 °C. A 12 °C se observaron desoves a partir de la 3ra fase de desarrollo mientras que, a 18 °C, no se registró oviposición. Aunque la longevidad promedio no fue significativamente diferente entre ambas temperaturas, fue mayor a 12 °C con 221,2 días que a 18 °C con 192,8 días. La supervivencia no cambió en ambas temperaturas y la relación entre longevidad total y longevidad media fue 1,48: 1 (12 °C) y 1,81: 1 (18 °C). De las dos temperaturas evaluadas, 12 °C resultó la temperatura mas apropiada para el desarrollo de la población. El tamaño de D. reticulatum estuvo relacionado con el diámetro de las perforaciones producidas en las hojas de lechuga. Los individuos menores a 1 cm de longitud provocaron un raído de las hojas; los de 1 a 3 cm, perforaciones de 2 a 6 mm de diámetro y aquellos de más de 3 cm, grandes perforaciones en las hojas.

Crop management practices can have a deep influence on the biological community of agricultural systems. Conservation-tillage practices disturb the soil only enough to insert the seeds, and a variety of studies documented that conservation-tillage results in more substancial leaf litter and large weed community, and tend to host more diverse communities of soil organisms. However, most dangerous species of slugs, as Deroceras reticulatum, are epigeal herbivores that inhabit the soil surface, and have been cited causing damages on several crops. Since 1997, it was found in southeast Buenos Aires province, Argentina, on sunflower under not tillage systems. An assumption of our experiment is that Deroceras populations in South America may be genetically distinct because of differences in climate or colonization histories. The objective of this study was to determine the growth curve, reproduction, longevity, and survival of D. reticulatum, under controlled laboratory conditions at 12 °C and 18 °C. The experience was initiated at each temperature with 20 recently bom slugs. Individuals were kept in 385 cm3 plastic boxes each and food consisted of leaves of lettuce (Lactuca sativa L.). The length of each slug, mortality, egg-laying, and food eaten by each individual on the leaf of lettuce were registered weekly. Three phases of development were identified: the 1st one was of fast growth , the 2nd one of slower growth, and the 3rd one with absence of growth at 18 °C and scarce growth at 12 °C. Second phase was longer at 12 °C. At 12 °C, eggs were observed from 3rd phase of development whereas no egg-laying was recorded at 18 °C. Although average longevity was not significantly different in both temperatures, longevity was greater at 12 °C with 221,2 days than at 18 °C with 192,8 days. The survival was not significantly different with both temperatures and the relation between total longevity and average longevity was 1,48: 1 (at 12 °C) and 1,81: 1 (at 18 °C). Considering both temperatures studied, 12 °C resulted the most appropriate temperature for development of the population. The size of D. reticulatum was related with the diameter of the perforations in me lettuce leaf; individuals smaller than 1 cm caused a frayed on the leaves, those specimens of 1 to 3 cm long made perforations between 2 and 6 mm diameter, and those ones longer than 3 cm have done great perforations on the leaves.