DYNAMICS OF EJACULATE NUTRIENT TRANSFER IN LOCUSTA-MIGRATORIA

Crosses were made to investigate whether males of Locusta migratoria p erform cryptic reproductive investment by means of the transference of proteinaceous nutrients to females and eggs and, if so, the dynamics with which these substances are incorporated into the receptor individ uals. The results show that males transferred very significant amounts of a mixture of 16 amino acids, radioactively labelled with C-14, thr ough the ejaculate and that females transferred these to the eggs they subsequently laid: Whereas radioactive label in male and female haemo lymph was only dependent on time from male injection (negatively and p ositively correlated, respectively), ejaculate nutrient transfer to th e eggs was positively correlated with the time from first mating. The amount of radioactive amino acids transferred to females in the ejacul ate with the first mating increases with the number of days since the male was injected with the radioactive solution, which suggests that i t is dependent on the time available for their incorporation into the ejaculate. The amount of ejaculate nutrients transferred to the eggs w as dependent only on the number of copulations of the female with the injected male before laying. Male nutrients appear to be incorporated into eggs proportionately to their concentration in the female, sugges ting a generalized investment. These results are discussed in relation to the expectations of parental investment theory on mating behaviour and confidence of paternity.