Abstract:
Oviposition site selection by gravid female insects is an important determinant in
species distribution, abundance, and population dynamics. Females may assess the
suitability of a potential oviposition substrate by using cues from conspecific or
heterospecific individuals already present. Here, we assessed whether the presence
of conspecific or heterospecific larvae and parasites influenced oviposition decisions
by the stable fly, Stomoxys calcitrans (Linneaus). Using dual and multiple-choice
oviposition bioassays, we found that gravid female S. calcitrans avoided substrates with
conspecific larvae, the larvae of house flies, Musca domestica (Linneaus), and the mite
Macrocheles muscaedomesticae (Scopoli). Avoidance of conspecific and heterospecific
larvae persisted in the dark, suggesting that this behavior is mediated by chemical
rather than visual cues. When we reared S. calcitrans in the presence of conspecific
larvae and the larvae of house flies at different densities we found that this negatively
affected emergence time, larval weight, larval survival, pupal weight, pupal survival, and
adult weight. We also demonstrated that individuals of S. calcitrans developed in the
presence of mites exhibited low egg hatchability, and poor larval and adult survival.
Our study provides additional support for the “preference-performance” hypothesis in
S. calcitrans, with gravid females preferring to lay eggs on a substrate that will enhance
offspring fitness. We recommend that the chemical cues involved in avoidance by gravid
female S. calcitrans of substrates with conspecific and heterospecific larvae should
be elucidated. This could lead to the discovery of repellent chemicals important for
S. calcitrans management.
