Fueling flight: nutritional impacts on Amyelois transitella (Lepidoptera: Pyralidae) dispersal

Amyelois transitella (Lepidoptera: Pyralidae) is an economically significant pest in California, damaging tree nuts by feeding on kernels. Early generations develop on overwintered “mummy” nuts, while later generations infest fresh nuts in summer and fall. The impact of kernel maturity on A. transitella dispersal remains unclear. To investigate, flight mill and nutritional assays were conducted to assess the effects of crop nutrition on moth dispersal and adult macronutrient composition. Larvae were reared on fresh and mummy almonds, pistachios, walnuts as well as figs and wheat bran. Adults (< 1 day old) flew for 10.5 hours overnight on a computerized flight mill measuring distance, duration, and speed. Macronutrient content (proteins, carbohydrates, and lipids) was analyzed using Bradford, phenol, and sulfo-phospho-vanillin assays. Both flown and unflown moths were weighed and analyzed. In total, 153 females and 138 males were tested. Males reared on wheat bran flew significantly farther and longer than those on other diets, while those reared on fresh pistachios had the shortest flights. Female flight performance did not differ significantly across treatments. Both sexes reared on mummy walnuts were smaller (by fresh weight) than those reared on fresh walnuts. Males reared on fresh pistachios were larger than those from mummy pistachios. These findings show that host crop type and maturity influence A. transitella development and male flight performance. Effects on macronutrient composition remain inconclusive.