Lethal Effects of the Wild Potato Solanum bulbocastanum on the Planthopper Pentastiridius leporinus, a Vector of Bacterial Pathogens in Potato

Abstract

The planthopper Pentastiridius leporinus [Hemiptera: Cixiidae] is a vector of the two plant pathogenic bacteria ‘Candidatus Arsenophonus phytopathogenicus’ and ‘Candidatus Phytoplasma solani’ causing ‘bacterial potato tuber wilt’ in potato. An infection leads to symptoms such as rubbery and non-processable tubers and consequently to substantial decreases in yield and tuber quality as well as to abandonment of seed potato production in affected areas. Up to date, resistant potato varieties are not yet known, and the tool box of integrated pest management to prevent the spread of P. leporinus as causal vector is quite limited. Mortality experiments designed as no-choice trials on potato cultivar ‘Gala’ (Solanum tuberosum) and on its wild relative S. bulbocastanum revealed significant effects of the latter on the survival rate of the vector. LC/MS analysis of the insects and their intestines showed that C16:3-solamine, a bioactive compound of S. bulbocastanum, was retrieved only in individuals from the S. bulbocastanum plants. Furthermore, choice-tests were carried out to study the vector behaviour. A preference towards S. bulbocastanum vs. S. tuberosum ‘Gala’ was observed despite its lethal effects. Volatile organic compounds of the two different species were collected and analysed by GC/MS. The two profiles differed in 39 of 80 compounds. The wild potato species S. bulbocastanum and its compounds are discussed as potential starting points for further research on sustainable management of P. leporinus.