Tabela de vida de fertilidade de Lysiphlebus testaceipes (Cresson, 1880) (Hymenoptera, Aphidiidae) em Schizaphis graminum (Rondani, 1852) (Hemipera, Aphididae)

Abstract

Life table analyses have been developed to understand the impact of various sources of intrinsic and extrinsic mortalities on the rate of population growth. The understanding of the population increase of the parasitoids related to their hosts is important in biological control programmes. This study evaluated the survival and fertility of the parasitoid L. testaceipes on Schizaphis graminum as a host under fertility life table, in a climatic chamber at 25 plus or minus 1 deg C, 60 plus or minus 10% RH and 10-h photophase. To determine the immature mortality, the development time and the sex ratio of the parasitoid, 12 females (less than one day old) and 240 nymphs of S. graminum (3 days old) were used. To evaluate the longevity and fertility of L. testaceipes, 15 females (less than one day old) were used. Nymphs of S. graminum (3 days old) were offered for each parasitoid female daily, until the female died, being in the 1st day 300 nymphs; 2nd day 250 nymphs; 3rd day 200 nymphs; 4th day 150 and in the other days 50 nymphs. L. testaceipes had an immature mortality of 22,2%, and a development time of males and females of 9.0 and 9.1 days, respectively. The females of L. testaceipes laid, in it first life day, 257.8 eggs, and they survived up until seven days. The net reproduction rate and the intrinsic rate of increase were, respectively, 301.9 and 0.513. The finite rate of increase was 1.67 females per day, the mean length of a generation was 11.13 days and the time to duplicate the population was 1.35 weeks. The parasitoid L. testaceipes have a high potential of population growth on S. graminum as a host under the analysed conditions.