Tomatillo resistance to Colorado potato beetle (Coleoptera:Chrysomelidae)

Tomatillo (Physalis ixocarpa Brot ex Hornem) resistance to the Colorado potato beetle, Leptinotarsa decemlineata (Say), was evaluated in the laboratory. In vivo assays confirmed that L. decemlineata larvae fed tomatillo leaves had lower weights and survival than larvae fed potato leaves. Larvae fed potato leaves coated with a-tomatine also had lower weights and survival than controls. Larvae were also fed potato leaves coated with tomatillo leaf extracts. These larvae exhibited lower weights but equal survival compared with the controls. Removal of trichome exudates from tomatillo leaves did not affect the detrimental effects of the leaves on larvae. These results confirm the negative effects of tomatillo leaves and a-tomatine on L. decemlineata larval survival and weight. However, HPLC and mass spectrometry results show that a-tomatine was not present in the tomatillo leaf samples we studied. These results suggest that further research is warranted to isolate compounds for further plant resistance research within tomatillo.