Wing morph- and age-related differences in fertilization success of adult males of a flightless bug, Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)

Radomír Socha

doi:10.14411/eje.2008.013

Abstract

The aim of the present study was to test the hypothesis that short-winged (brachypterous) and long-winged (macropterous) adult males of a flightless bug Pyrrhocoris apterus differ in fertilization success. For this purpose, 5, 10 and 28 days old brachyp- terous and macropterous males were mated for the same period of time with reproductively active 5 days old brachypterous females. The average hatchability of five egg batches of these females was used as a measure of the fertilization success of the males. The results revealed significantly higher hatchability of the eggs laid by females that copulated with 5 or 10 days old brachypterous males than with same-aged macropterous males. In contrast, the average hatchability of eggs of females that copulated with 28 days old brachypterous males was significantly lower than of those mated with same-aged macropterous males. It is the first report of wing morph- and age-related differences in fertilization success of males in insects with a non-functional wing-polymorphism. The possible relationship between wing- and age-related differential fertilization and the mating success of P. apterus males, and differ- ences in the amount of secretion transferred from their accessory glands into the reproductive tract of females during copulation, is discussed.

Highlights

The widespread occurrence of dispersal polymorphisms among insects is consistent with the hypothesis that fitness costs are associated with flight capability
Similar decreasing trends in the egg hatchability with increasing number of egg batches and significantly higher average percentages of egg hatchability (Fisher’test, P < 0.0001) were recorded in the 3rd (62.55% vs. 44.28%), 4th (57.06% vs. 24.80%) and 5th (36.45% vs. 19.07%) egg batches laid by females that copulated with 10 days old brachypterous males than of females mated with macropterous males of the same age (Table 2)
The total average percentages of egg hatchability evaluated for all the egg batches laid by females that copulated with 28 days old males of both morphs were significantly higher (P < 0.0001) for the matings with macropterous males

Summary

Introduction

The widespread occurrence of dispersal polymorphisms among insects is consistent with the hypothesis that fitness costs are associated with flight capability. Macropterous individuals of P. apterus differ from brachypters in various physiological and behavioural parameters, e.g. longer preoviposition period (HonČk, 1985; Socha & Šula, 1996), lower feeding and digestive enzyme activities (Socha et al, 1997, 1998), higher adipokinetic response and titre of adipokinetic hormone in CNS (Socha & Kodrík, 1999; Kodrík et al, 2003) and enhanced dispersal by walking (Socha & Zemek, 2000b, 2003). These data indicate that these two morphs in P. apterus differ in their life history strategies

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Conclusion