Corn rootworm, <i>Diabrotica virgifera</i> (Coleoptera: Chrysomelidae), subspecies differ in environmental niche space and potential distribution

Corn rootworms are the leading insect pests of corn in the growing regions of North and Central America, with an estimated direct loss in revenue exceeding $2 billion USD. Damage is primarily caused by western corn rootworm (Diabrotica virgifera virgifera LeConte); however, Mexican corn rootworm (Diabrotica virgifera zeae Krysan & Smith) also causes significant losses. Little life history is known about D. v. zeae, so information on D. v. virgifera is often referenced, which may lead to incorrect assumptions. We used niche space models to assess the potential differences in the niche space and potential distribution of both subspecies under current and future climatic scenarios (SSP126 and SSP585). Interestingly, the niche spaces of the subspecies did not overlap, and there was a mismatch of the bioclimatic variables that contributed most to the models. The current potentially highly suitable area of D. v. zeae was much smaller, and both subspecies' highly suitable areas expand in the models (2.26- and 1.35-fold for D. v. virgifera and D. v. zeae by 2080 SSP585) and shift to the north and west, with greater deviations noted in later time periods and with greater environmental change. However, the overlap of highly suitable areas is consistently small, ranging from 4.2% to 6.3%. More research effort is needed on the basic ecology, behavior, and toxicology of D. v. zeae, as it may further differ from D. v. virgifera. Additionally, more universal surveys of both subspecies are needed in the likely case of expansion.