Nuptial feeding in tettigoniids male costs and the rates of fecundity increase

A recent debate has centred on the importance of paternal investment for the origin and maintenance of nuptial feeding in insects. Some authors have argued that the rates of nutrient incorporation are likely to be too slow to allow a male to fertilize the eggs that he helps to produce and cannot be considered as paternal investment. Here I report the results of some experiments that show that the positive effects of nutrient donation on female reproduction for one species of spermatophylax producing tettigoniid can be realized within 24 to 48 h. Furthermore, mating was found to induce a refractory period in the female that was longer than the time taken for the incorporation of nutrients and oviposition. Thus, the nurturant male is likely to fertilize the eggs even if last-male sperm precedence is high. The cost of spermatophylax production was manifest as a 5-day recovery period between matings. Thus males and their donations are likely to be limited resources for females resulting in a reversal of the typical sex roles.