PS 39-5 - Preference and Performance of an Invasive Insect on New and Original Host Plant Species

Background/Question/Methods

Leptinotarsa decemlineata is one of the most widespread and destructive insect pests of cultivated potato (Solanum tuberosum). In the cold desert of northwestern China, L. decemlineata along with its original host plant species Solanum rostratum are exotic species, and the sympatric distribution area of these two invasive species has been increasing. The aim was to test the preference and performance hypothesis that female insects oviposit on hosts where their offspring fare best. Adult oviposition and feeding preference and offspring performance of were determined using five plant species (S. rostratum, S. tuberosum, S. melongena, Lycopersicon esculentum and S. nigrum). Effects of these host species on feeding, oviposition, development, and reproduction of different source populations of L. decemlineata were evaluated under field, common garden, and controlled environment conditions.

Results/Conclusions

Feeding preference of adult L. decemlineata were differed among five host plant species. Adult L. decemlineata preferred more leaf area of S. rostratum than the other four host plants. Oviposition preference of L. decemlineata differed among five host plant species; females laid more eggs on its original host plant species S. rostratum than other host plant species. Offspring performance of L. decemlineata was significantly different among host plant species but not between two insect source populations. L. decemlineata feeding on S. rostratum and S. tuberosum was similar, and insect offspring performance was greater on these two species than on S. melongena and L. esculentum. Thus, our results support the preference – performance hypothesis for L. decemlineata and S. rostratum in farmlands of northwest China, although the insect invaded ~15 years before the plant. We conclude that S. rostratum provides a safe habitat for L. decemlineata from agricultural pest control and also promotes development and reproduction of the insect. To control L. decemlineata in S. rostratum- invaded areas, insecticide treatment of vegetables is not likely to be effective unless the dispersal and growth of S. rostratum is controlled.