Polyandry in the mirid bug Lygocoris pabulinus (L.) - effects on sexual communication and fecundity

Lygocoris pabulinus females are polyandrous under laboratory conditions (Gr oot et al., 1998). As the insect mating system affects sexual communication and thus sexual behavior as a whole, we studied sperm transfer, storage an d displacement in L. pabulinus. To be able to fully understand these proces ses, detailed information on the female reproductive tract is essential. Th erefore, we first studied the female genitalia in detail. The bursa copulat rix consists of four plates, and a spermatheca is connected anteriorly to t he bursa. At copulation a spermatophore is formed in the spermatheca. The s permatophore is compartmentalized, consisting of a sperm-containing portion , a large sperm-free portion and a mating plug. After 24 h the spermatophor e has partially disintegrated. The mating plug is still intact but reduced in size. Sperm are found throughout the spermatheca and in the median and l ateral oviducts where fertilization most likely takes place. The amount of male-derived substances transferred to females during first matings was ca. 5.2% relative to male body weight. To understand the effects of matings on the sexual communication, we determined sexual attraction of mated females at long and close range. At long range females were unattractive for only 1-2 h after mating, while they remained attractive at close range. Mated ma les were not attracted to virgin females for 2 h after mating, and only 23% of the tested males mated again within 24h. Together, these results sugges ted a high paternal investment that may affect reproductive output. To dete rmine if this is the case, and hence if multiple matings affect fecundity a nd/or longevity, we conducted two oviposition experiments. From these exper iments no positive effects on total fecundity or longevity in multiply mate d females were apparent.