DIFFERENTIATION BETWEEN TOBACCO BUDWORM (CHLORIDEA VIRESCENS) AND BOLLWORM (HELICOVERPA ZEA) EGGS AT THE ORGANISMAL LEVEL: NEW PERSPECTIVES

Two lepidopteran species, tobacco budworm, Chloridea virescens, and bollworm, Helicoverpa zea, are important pests of cotton agriculture in the United States. Pest management strategies for these species require different approaches. One major difference is that bollworm requires a higher dose for many commercialized Bt proteins and is evolving field resistance to Bt-transgenic crops in comparison to the budworm. In order to improve species identification for these caterpillars at the egg stage, which could improve foliar insecticide spray recommendations, we examined potential novel techniques to differentiate between species. Eggs were analyzed using Raman spectroscopy to characterize the surface chemical components, UV fluorescence and scanning light spectroscopy to determine differences in fluorescence or color, and digital, modern photography to visualize morphological differences. No fluorescence or color differences were found between bollworm and budworm eggs for caterpillars reared on artificial diet but additional opportunities were presented from this research. Differences in surface chemistry suggest the potential for using differential staining in species diagnostics. The potential was also established for a rapid and automated field diagnosis of species using modern approaches in digital photography and machine learning, to detect egg morphological differences with hand held cameras or even smart phones.