Data for: The costs and benefits of polyandry in a sexually cannibalistic mantis

Mating with more than one male often provides direct or indirect benefits
to female fitness but can also increase the chance of injury and death.
Costs of mating are expected to increase linearly with increasing mating
number. But how such costs interact with benefits to determine the net
payoff of mating multiply is not well understood. Using the highly
cannibalistic Springbok mantis, Miomantis caffra, a species where females
are stabbed in the abdomen by males during violent premating struggles
that males initiate to avoid being cannibalised, we took an experimental
approach to assess the economics of polyandry under the risk of external,
male-inflicted injury. We predicted that females that mate multiply would
be more likely to show abdominal injuries, have higher prereproductive
mortality, produce fewer offspring, and be more likely to engage in
pre-mating cannibalism to avoid unwanted matings. In line with our
predictions, we found that the likelihood of abdominal injury was highest
among females that mated at least once, and prereproductive death was
highest among females that mated twice or three times. Virgin females
completely avoided these costs and produced some offspring
parthenogenetically but not enough to provide a net benefit. Although
mating was better than not mating, there was no singularly optimal mating
number: females that mated once and three times produced similarly high
numbers of offspring from the first ootheca, which resulted in an
intermediate trough in offspring production at two matings. We also found
little evidence that cannibalism was deployed as a mate-avoidance
strategy: females consistently attacked and consumed males regardless of
how many times they mated or how long they were housed with males. Our
results suggest the possibility of two distinct mating strategies in M.
caffra, where females either mate at a lower frequency to minimise costs
or at a higher frequency to maximise benefits. We discuss possible
explanations for this bimodal pattern in offspring production.