Measuring oviposition preference and survival of an invasive stem borer (Lepidoptera: Crambidae) on conventional and bioenergy crops

The Mexican rice borer, Eoreuma loftini (Dyar), is a serious pest of sugarcane and rice, and also threatens production of related bioenergy feedstocks in the Gulf Coast region. A greenhouse experiment was conducted to compare oviposition preference of E. loftini between cultivars of conventional and bioenergy sugarcane and sorghum at two phenological stages (immature and mature). Oviposition events occurred exclusively on dry leaf material. Abundance of eggs per plant was significantly greater in the mature phenological stage, increasing 2.3-fold when compared to egg abundance on immature plants. The number of eggs per oviposition event was impacted by phenological stage, increasing 2.4-fold in mature plants. A second greenhouse experiment was conducted to examine survival of E. loftini using the same cultivars and phenological stages. A 2.4-fold increase in survival to adulthood was detected in mature plants, with higher rates of neonate mortality occurring in immature plants. Of the mature plants, energycane cultivars expressed the lowest rates of survival. Results from this study suggest that while mature plants are more favorable for oviposition, rates of survival decrease as plants mature, especially in bioenergy crops.