Comportamento e fisiologia reprodutiva do macho de Podisus nigrispinus (Dallas) (Hemiptera : Pentatomidae)

Abstract

The reasons of multiple and long successive mates accomplished by Podisus nigrispinus (Dallas) (Hem.: Pentatomidae) males has been unknown. Thus, mating behavior of P. nigrispinus was investigated as function of male body size (i), previous mating status (ii), risk of predation (iii), interrupted mating (iv), and spermatogenesis (v). The female choice for mating with large or small body size males was investigated under three conditions: multiples choice within a population of large and small males; partial choice (ca. only one pair of small and large male) and no choice (only small or large male). Time to initiate a copula and its duration was observed after pairing males and females under the risk of predation imposed by the presence of the predatory wasp Polistes versicolor Oliver (Hym.: Vespidae). Furthermore, females had their reproductive success evaluated with interrupted mating at different intervals (30, 60, 120 and 240 minutes afterinitiating a mating) and when mating with males previously mated. The spermatogenesis of these mated and unmated males was investigated. The outcomes show that P. nigrispinus female mates with males disregarding their body size, previous mating status and, exhibits no mating partner preference in successive mates. In addition, duration of mating, partner choice and female fertility were not influenced by male body size. The risk of predation did not alter mating behavior and duration of mating. However, females with interrupted mating at 30, 60, 120 and 240 minutesexhibited low egg viability (0, 3.1, 7.7, and 34%, respectively) compared to females with uninterrupted mating (338 to 671 minutes) that showed egg viability of 74.2%. The dissection of males of different mating status shows that P. nigrispinus exhibits continuous spermatogenesis and absence of a storage seminal vesicle. Spermatozoa were present in the lumen of the vas deferents independent of mating status. The spermatheca does not change size according to the duration of mating, although its duct exhibited elasticity with significant deformation after mating for 30 minutes. Females under uninterrupted mating exhibited spermathecal duct fully expanded and spermatheca filled with spermatozoa. Based on the results, the reproductive success of P. nigrispinus male is related to the duration of copula and female requires multiple mates to fill spermatheca with spermatozoa. However, the reproductive success of the species does not depend on males’ body size and their mating status.