Do male seminal donations shape female post-mating receptivity in a usually monandrous moth?
Male ejaculates in insects include a complex array of substances other than sperm whose proximate functions have proven to be diverse. Some function as allohormones that manipulate post-mating female physiology and behaviour. As each sex pursues their own reproductive interests to maximise fitness, seminal allohormones are expected to promote outcomes ranging from reproductive cooperation to sexual conflict and antagonistic coevolution. Most research on the evolutionary importance of male seminal donations has targeted highly polyandrous species, and more research is needed on usually monandrous species. Here, we explore in the mostly monandrous moth Lobesia botrana if there is variation among males in their ability to influence female post-mating receptivity (PMR), if the trait covariates with the polyandry level of the parental strain and if it could be mediated by ejaculate composition when taking into account spermatophore size. To do this, we conducted controlled reciprocal crosses between field-collected mostly monandrous strains and laboratory-selected highly polyandrous strains. We found that laboratory strain males were significantly less efficient than field strain males at inhibiting female PMR, and that such variation covariate with the polyandry level of the parental strain. Male strain also influenced the duration of the female refractory period, fecundity and fertility being high and roughly similar. Between-strain differences in the ability of males to influence female PMR suggest an effect of seminal fluid composition and its underlying genetic variation in male strains. Further research is needed to assess whether male donations that regulate female PMR are widespread in monandrous insect species to better understand the wider evolutionary significance of these findings in L. botrana.
The available evidence suggests that male-donated allohormonal substances (including parasperm) can influence/manipulate female PMR in insects. Most research on this issue has targeted polyandrous species, as it is often implicitly assumed that in monandrous species eupyrene sperm itself plays the key role in inhibiting female PMR. We studied whether male donations could have some allohormonal effect on female PMR in the usually monandrous moth Lobesia botrana. Controlled crosses between field-collected mostly monandrous strains and artificially selected highly polyandrous strains suggest that there is genetic variation in ejaculate composition-mediated male ability to influence/manipulate female PMR.
KeywordsMale seminal donations Female post-mating receptivity Monandry Polyandry Genetic variation
We are grateful to all colleagues who provided technical assistance in the field and laboratory, especially Paco Ponce, Álvaro Sánchez and Juanjo Ferrero. We also recognize the valuable comments and suggestions made by Michael D. Jennions and two anonymous reviewers.
This research was supported by the Servicio de Sanidad Vegetal (SSV, Junta de Extremadura).
Compliance with ethical standards
The experiments conducted conform to the normative of the institution, region and country in which they were performed.
Conflict of interest
The authors declare that they have no conflict of interest.
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