Biology subjects

Auguste, A.

Publications and source records attributed to Auguste, A..

3 recordsLinked to original sources

bioRxiv2026

Scents for safe sex: a volatile sex pheromone promotes outbreeding in a parasitoid wasp with severe genetic load

When mating among genetically related individuals results in inbreeding depression, various behaviors and life-history traits evolve to favor outbreeding. Long-range sexual communication following natal dispersal is one such adaptation. In parasitoid wasps with single-locus complementary sex determination (sl-CSD), inbreeding increases the production of unviable or sterile diploid males. Mastrus ridens is such a species, with a genetic load underpinned by sl-CSD, combined with a high potential for sibmating because siblings emerge in close proximity from the same host and become sexually active shortly after emergence. With this context in mind, we investigated the mate-finding strategy of M. ridens using complementary behavioral, chemical, and electrophysiological approaches. Wind-tunnel bioassays and field experiments showed that males orient toward virgin females and, to a lesser extent, mated females. This attraction from a distance appeared to be the sole form of conspecific attraction. Chemical analyses using static and dynamic headspace sampling and solvent extracts, followed by GC-MS, revealed several potential pheromonal candidates, including methyl 6-methylsalicylate. This compound elicited reproducible antennal responses in males in GC-EAD recordings. Altogether, our results suggest that mate finding in M. ridens is guided by a volatile sex pheromone emitted by females, with methyl 6-methylsalicylate as one putative component. Such mate-finding mechanisms promote outbreeding and may explain the low proportion of unfit diploid males observed in natural populations. Surprisingly, chemical analyses suggested that males also emit this compound, whereas neither males nor females showed behavioral responses to males. This apparent discrepancy suggests that attraction may depend on a more complex pheromonal signal and opens further avenues for investigation.

ecology↗

bioRxiv2023

Insect population dynamics under Wolbachia-induced cytoplasmic incompatibility: puzzle more than buzz in Drosophila suzukii

In theory, the introduction of individuals infected with an incompatible strain of Wolbachia pipientis into a recipient host population should result in the symbiont invasion and reproductive failures caused by cytoplasmic incompatibility (CI). Modelling studies combining Wolbachia invasion and host population dynamics show that these two processes could interact to cause a transient population decline and, in some conditions, extinction. However, these effects could be sensitive to density dependence, with the Allee effect increasing the probability of extinction, and competition reducing the demographic impact of CI. We tested these predictions with laboratory experiments in the fruit fly Drosophila suzukii and the transinfected Wolbachia strain wTei. Surprisingly, the introduction of wTei into D. suzukii populations at carrying capacity did not result in the expected wTei invasion and transient population decline. In parallel, we found no Allee effect but strong negative density dependence. From these results, we propose that competition interacts in an antagonistic way with Wolbachia-induced cytoplasmic incompatibility on insect population dynamics. If future models and data support this hypothesis, pest management strategies using Wolbachia-induced CI should target populations with negligible competition but a potential Allee effect, for instance at the beginning of the reproductive season.

ecology↗

bioRxiv2017

Insects and incest: field evidence for dangerous liaisons in a parasitoid wasp

O_LISib mating avoidance is a pervasive behaviour, which likely evolves in species that sare subject to inbreeding depression. Laboratory studies have provided elegant demonstrations, but small-scale bioassays often minimize the costs associated with mate finding and mate-choice and may for this reason produce spurious findings.\nC_LIO_LIWe inferred the mating behaviour of the parasitoid wasp Venturia canescens from the genetic analyses of natural populations. We used V. canescens as a model organism because in this species, laboratory experiments have shown that sib mating yields a 25% decrease in fertile offspring, and congruently, sib mating is partially avoided.\nC_LIO_LIOur study consisted in genotyping 86 wild-caught males, 155 wild-caught-females and their 226 daughters at eighteen microsatellite loci. With these data, we were able to reconstruct the genotype of females mate and estimate the relatedness of each mating pairs.\nC_LIO_LIWe found that the effective rate of sib mating does not differ from the probability that sibs encounter one another at random, which suggest a sib mating tolerance in this species. However, complementary lab experiments confirmed that kin discrimination exist in this species, with related pairs having a lower mating latency.\nC_LIO_LIThese results suggest that V. canescens tolerate sib mating in the field despite kin discrimination, and therefore call into question the common beliefs on inbreeding depression in species with single-locus complementary sex determination. This inbreeding tolerance also opens up the question of the maintenance of the kin discrimination in this species.\nC_LI

animal behavior and cognition↗