The hypothesis that prolonged copulatory mate guarding coexists with last male sperm precedence was tested for the sugarcane rootstalk borer weevil, Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae). Male D. abbreviatus showed a long copulatory guarding. Both males and females were less likely to remate when prolonged guarding occurred compared with terminating copulation early. Guarding was generally terminated by the struggling behavior of the female. Mating experiments using normal and sterile (X-ray irradiated) males revealed a similar value of last-male sperm precedence for both irradiated and normal males. The P2 values of normal and sterile males were similar when all oviposited eggs were counted over 30 days. These data made it possible to calculate the expected gain to a male from prolonged guarding compared with leaving a female early and seeking out an additional mate. We show that guarding has the higher fitness. Eggs were deposited in clutches in which normal fertilized eggs were grouped together and were attached to a group of sterile eggs. This, together with identifying the form of the cul-de-sac type spermatheca, allowed us to suggest a unique repositioning process, which has not been described elsewhere, as the likely mechanism by which last-male sperm precedence was achieved.
Bibliographical noteFunding Information:
We thank W. J. Schroeder and H. Smith, USDA-ARS, Orlando, Florida, for supplying laboratory-reared weevils and B.J. Smittle, FDACS, Division of Plant Industry, Gainesville, Florida, for irradiating the weevils. We also thank Dr. V. Chew, USDA-ARS, South Atlantic Area, for advice on statistical analysis and Dr. J. Sivinski, USDA-ARS, Gainesville, Florida, for helpful comments on an earlier draft. This research was supported by Postdoctoral Fellowship Award No. IF-0183-94 from the United States-Israel Binational Agricultural Research and Development Fund (BARD) and the University of Florida Foundation. C.W.O. was supported in part by grant FLAX 97007 from CSREES (Cooperative State Research, Education, and Extension Service, USDA).
- Copulation guarding
- Cul-de-sac spermathecae
- Sperm precedence
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Animal Science and Zoology