REPRODUCTIVE INVESTMENT IN BUSH-CRICKETS - THE ALLOCATION OF MALE ANDFEMALE NUTRIENTS TO OFFSPRING

Male bushcrickets provide their mates with a nutritious meal, the sper matophylax. that is attached to the sperm-containing ampulla of the sp ermatophore and transferred to the female at mating. Females feed on t he spermatophylax during insemination. We labelled males and females w ith different radioactive isotopes to examine the allocation of male- and female-derived nutrients to eggs. Both male and female labels were incorporated into developing eggs. Females provided with an ad libitu m diet allocated a greater proportion of their own and male-derived nu trients to reproduction and thereby produced more eggs than did nutrie nt-limited females. Conversely, nutrient-limited females retained more of their own and male-derived nutrients in their somatic tissue. Ther e were no sexual differences in the rate of allocation of label to ind ividual eggs, suggesting that male and female investment is qualitativ ely similar. These data support the idea that male bushcrickets contri bute pre-zygotic parental investment and, further, male investment in individual eggs is greater when females are nutrient limited.