Studies of the Interrelationships Among Inbreeding, Resistance to Herbivores, and the Transmission of Pathogens in Wild Gourds

Many plants suffer from diseases spread by insect herbivores. The damage experienced by plants depends both on their attractiveness to insects and on their resistance to disease. These, in turn, are influenced by the plants'genes. These studies investigate interactions among herbivory by beetles and aphids, infection by bacterial and viral diseases, and the level of genetic inbreeding in wild gourds, which are free-living forms of cultivated squashes. Field and greenhouse experiments will be conducted in which inbreeding, herbivory, and exposure to disease will be controlled. Serological analyses and transmission bioassays will determine infection levels in the plants.

The proposed studies both will shed light on basic ecological and evolutionary issues such the consequences of inbreeding in natural populations, the establishment and spread of diseases in natural populations, and the dynamics of food chains, and will be relevant for the management and conservation of species with small populations. Moreover, because the same herbivores and pathogens that attack squashes, melons, and cucumbers will be studied, the findings will be useful in the development of integrated pest management programs for cucurbit crop species. Furthermore, knowledge of the interactions among inbreeding, herbivores and pathogens is especially relevant now that transgenic squash cultivars with resistance to insect transmitted viruses are being cultivated. If these genes escape into wild gourd populations, information on the effects of viral pathogens will assist in predicting the impact of these transgenes in nature.