Population growth of two strains of the larger grain borer, Prostephanus truncatus on three maize hybrids grown in Europe

The larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae), continues to threaten maize worldwide, with an endemic range in Mexico, Central and Northern South America, and an exotic range in Sub-Saharan Africa. There was a targeted effort beginning in the 1990s to create maize hybrids in the hope of controlling P. truncatus. Through those efforts, several resistant maize hybrids were developed, which were able to reduce progeny production by P. truncatus. However, where P. truncatus has yet to fully establish, including parts of Europe such as Italy and Greece, existing maize hybrids developed for production in Europe have not been investigated for resistance against P. truncatus. In this study, we sought to compare the fitness of two different strains of P. truncatus, one from the native range in Mexico and the other from the invaded range in Ghana, by investigating the progeny production, number of damaged kernels, and frass production of both strains on three maize hybrids (Pico 1, Hamilton 2, and AGN 672) developed for use in Greece and wider Europe to evaluate susceptibility and/or tolerance to P. truncatus. The Mexico strain of P. truncatus produced more progeny on the Pico 1 than the AGN 672 hybrid, while the Ghana strain did not significantly differ in progeny production among hybrids. All hybrids were susceptible to both strains of P. truncatus. There were no real differences in damaged kernels or frass production between the two strains and across the three maize hybrids. Overall, this study provides a foundation for exploring maize resistance in European cultivars to P. truncatus as a possible new tool. •We compared fitness of two different strains of P. truncatus (Mexico and Ghana) on different maize hybrids.•We found progeny production differed among insect strain and hybrids.•The native P. truncatus (Mexico) fitness was decreased on European hybrids compared to the invasive strain (Ghana).