Ecology and Conservation of Crickets
1.1 The Ecology and conservation of the Scaly cricket, Pseudomogoplistes vicentae.
The Scaly Cricket, Pseudomogoplistes vicentae, is amongst the rarest and most enigmatic of the U.K.’s grasshoppers and crickets (Orthoptera). It occurs in only four populations (Marloes Sands and Dale in Pembrokeshire, Branscombe in Devon and Chesil Beach in Dorset) in the U.K., where it lives close to the strand line amongst shingle. Research has used pitfall trapping throughout the year, combined with laboratory rearing of eggs and nymphs to elucidate the details of the life cycle of this species.
Populations of this coastal species are potentially threatened due to increasing storm activity, sea-level rises and the resultant “coastal squeeze”. Another aspect of on-going research on this species is to survey and monitor the extent of the main populations of this species in the U.K.
1.2 The function and evolution of copulatory structures in male bush-crickets (Orthoptera: tettigoniidae).
Copulatory structures in male animals are extremely diverse, even amongst closely related taxa. The selective pressures responsible for the evolutionary elaboration of copulatory structures have been the subject of considerable debate. Research in this area has focussed on two different types of copulatory structure in bush-crickets: the titillators and the cerci. Titillators are inserted into the entrance of the female’s genital chamber before spermatophore transfer, while cerci act as claspers during copulation.
In a recent study in collaboration with colleagues from Humboldt University, Berlin and the University of Hull, we examined the relationship across bush cricket species between the complexity of titillators and the frequency and extent of multiple mating in females. Studies have also explored the relationship between the functional morphology of cerci and copulation duration in bush-crickets, in collaboration with colleagues from Mexico (Instituto Technologico de Cd. Victoria) and the U.S.A. (California Academy of Sciences). The results of this study were published in the journal Evolution in 2014. We found that prolonged copulation during ejaculate transfer was associated with cerci that were adapted to grasp the female firmly (by either encompassing the end of the female’s abdomen and/ or having sharp projections to anchor on to the female’s cuticle).
1.3 Polyandry and patterns of sperm use in the dark bushcricket (Pholidoptera griseoaptera).
It is becoming increasingly clear that polyandry (female mating with more than one male) is extremely widespread in the animal kingdom. While there have been a growing number of studies of the extent of polyandry in natural populations, very few of these studies have been able to quantify the extent to which females mate repeatedly with the same male, as opposed to mating with multiple males, or to examine factors that determine which of her mate’s sperm the female will use to fertilise her eggs. In a recent study (which now in press in Molecular Ecology), in collaboration with colleagues from the University of St Andrews, we used DNA analysis (using seven hypervariable microsatellite loci) to examine polyandry and patterns of sperm use in field-mated dark bush-crickets, Pholidoptera griseoaptera. We found that females mated up to six times and that in 80% of females, each mating was with a different male. Sperm use was biased towards the female’s most recent mates and males that had transferred bigger ejaculates.
Contact: Professor Karim Vahed
Professor Aradhana Mehra
Head of Environmental Sustainability Research Centre
T: 01332 591133