Pupal Cues Increase Sperm Production but Not Testis Size in an Insect

Theoretic and empirical studies show that social surroundings experienced by male insects during their larval or adult stage can influence testicular investment in diverse ways. Although insect pupae do not feed crawl, they communicate using sex-specific and/or non-sex specific cues. Yet, it is unknown, any insect, whether how fine-tune resource allocation to sperm production testis size response socio-sexual environments. We investigated this question a moth, Ephestia kuehniella, which produces fertile eupyrene unfertile apyrene sperm. held individually groups with different sex ratios, dissected adults upon eclosion, measured size, counted both types of demonstrated after exposure conspecific pupal cues regardless sex, increased eupyrenes apyrenes at the same rate but kept unchanged. suggest fixed pupation because most morphological traits are formed stage, allowing little room for adjust size. Like adults, fully grown testes have sufficient resources produce more according perceived increase competition risk.