The Effect of Age and Stress on the Oviposition Preferences of Tribolium castaneum females
Maternal oviposition preference is a form of indirect maternal care shown by holometabolous insects (insects that metamorphosize). Since young larvae have lower mobility than the adult form, they depend on their mother to choose a patch with the required resources. Female oviposition preference has been studied for several decades, resulting in a general consensus that females prefer to oviposit on host plants that maximize offspring fitness (the ‘Preference Performance Hypothesis’). However, there have also been reports that female oviposition preference is not correlated with larval performance, suggesting that there are other factors that may impact this behaviour. In this study, we tested the impact of two specific factors on maternal oviposition preference - maternal age, and one form of stress (cold shock), using the red flour beetle (Tribolium castaneum) as the model organism. The choice combination of resources presented to Tribolium females for oviposition was the following - wheat flour, and finger millet (ragi) flour. To determine the impact of age on oviposition preference, we tested females at two ages (11 day post eclosion, and 37 day post eclosion). The second factor we looked at was the effect of stress (in this case, a cold shock). Females were put on ice for varying amounts of time, and the subsequent oviposition behaviour was measured. It was observed that neither factor had a significant effect on the oviposition preference. Thereby, we can conclude that oviposition preference of T. castaneum females grown in isolation is independent of the age of beetles, and to a short cold shock.
Keywords: holometabolous insects, red flour beetle, preference performance hypothesis, cold shock