Estratégias reprodutivas de Doryctobracon areolatus (Szépligeti, 1911) (Hymenoptera: Braconidae) relacionadas à cópula e ao parasitismo

Abstract

Doryctobracon areolatus (Szépligeti, 1911) (Hymenoptera: Braconidae) is a koinobiont endoparasitoid, native to the Neotropics and has the larvae of second instar of the genus Anastrepha as preferred host, where its parasitism efficiency can reach 80% under natural conditions. Recent studies have investigated D. areolatus biology and multiplication; however, no studies have assessed its reproductive biology. This study investigated the biology and reproductive behavior of mating and oviposition of D. areolatus, using larvae of A. fraterculus as hosts. The maintenance rearing and experiments were carried out at the Laboratory of Entomology of Embrapa Clima Temperado, Pelotas, Rio Grande do Sul, Brazil, under controlled conditions of temperature (25±2 oC), air relative humidity (70±10 %) and a photophase of 12 hours. Experiments were conducted to assess the sequence of male and female emergence as well as possible occurrence of protandria in D. areolatus. We also determined the influence of insect age on its reproduction as well as the importance of mating on offspring, duration of mating period, occurrence of polygamy and monogamy in the species, in addition to observation of mating frequency during 24 hours. Protandria was confirmed on D. areolatus, with the sex ratio of 0, 0.06, 0.62, 0.87, 0.98, 1.0, and 1.0 for the 1st, 2nd, 3rd, 4th, 5th, 6th and 7th days of emergence, respectively, totaling a sex ratio of 0.61. Couples in which the females are younger produce more female offspring with thus a higher sex ratio. Virgin females only generate male descendants by arrenótoca parthenogenesis, contrary to what occurs with the mated females, which produced males and females. Fertilized females showed an average of 30.4 offspring with a sex ratio of 0.63, while virgin females had an average of 14 offspring, all males. Observations of polygamy and monogamy showed that 40% of males mated more than once, while females mated only once. However, the mating frequency during 24 hours showed that despite monogamous, females had multiple copulations. The duration of the first copulation did not differ significantly from the second with a reduction of 6.53 sec. D. areolatus has reproductive activities during the photophase, considered a diurnal species. Comparison of mating and re-mating frequencies between couples, considering the influence of feed on the male, showed that among males fed only on pairing time, 60% did not mate during the 24-hour period of observation. Among males fed previously, there were 57 attempts to mate, whereas in males fed during the experiment, there were 24 attempts for copulation in the 24-hour period of observation. The results of this study contribute to improve the basic knowledge of reproductive biology of D. areolatus, since knowing reproductive strategies is important for a biological control program.