Life history traits and a method for continuous mass rearing of the planthopper Pentastiridius leporinus, a vector of the causal agent of syndrome "basses richesses" in sugar beet

BACKGROUNDThe planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) is the main vector of the {gamma}-3 proteobacterium Candidatus Arsenophonus phytopathogenicus which causes the syndrome "basses richesses" (SBR) in sugar beet. SBR is a new and fast spreading disease in Central Europe that leads to high yield losses. To date the development of management strategies is hampered by insufficient knowledge about general life history traits of the planthopper and, most importantly, the year round availability of insects reared under controlled conditions. Rearing of P. leporinus has been considered challenging and to date no protocol exists. RESULTSHere we describe a method for mass rearing P. leporinus on sugar beet from egg to adult, which has produced five generations and >20,000 individuals between June 2020 and March 2022. An alternative host such as wheat is not necessary for completing the life cycle. No-choice experiments showed that P. leporinus lays 139.1 {+/-} 132.9 eggs on sugar beet, whereas no oviposition was observed on its nymphal host wheat. Head capsule width was identified as a trait that unequivocally distinguished the five nymphal instars. Developmental time from first instar to adult was 193.6 {+/-} 35.8 days for males and 193.5 {+/-} 59.2 days for females. Infection rates of adults were tested with nested polymerase chain reaction (PCR). The results demonstrated that 70-80% of reared planthoppers across all generations carried the SBR proteobacterium. CONCLUSIONThe mass rearing protocol and life history data will help overcome an important bottleneck in SBR research and enhance efforts in developing integrated pest management tools.