Interactions between nymphs of Nilaparvata lugens and Sogatella furcifera (Hemiptera: Delphacidae) on resistant and susceptible rice varieties

Abstract

The planthoppers Nilaparvata lugens (Stal) and Sogatella furcifera (Horvath) co-occur on rice Oryza sativa L., throughout much of Asia. Nilaparvata lugens is regarded as the more destructive rice pest. Interactions between these two species on individual rice plants can be positive (interspecific facilitation) or negative (interspecific competition). However, the outcome of their interactions on resistant rice varieties has received little attention despite the potential consequences for adaptation to resistance. In this study, we examine interactions between nymphs of these two species on resistant (IR62 and ADR52) and susceptible (IR22) rice varieties. IR62 was resistant to N. lugens at all plant ages, but only older plants were resistant to S. furcifera. ADR52 was resistant to S. furcifera, and gained moderate resistance to N. lugens as the plants aged. Nilaparvata lugens facilitated weight gain in S. furcifera even on the resistant IR62 variety. However, facilitation by N. lugens was reduced on older ADR52 plants when resistance against S. furcifera was strongest. Sogatella furcifera reduced weight gain in N. lugens on susceptible varieties, but failed to out-compete N. lugens where plants expressed S. furcifera-resistance. Our preliminary results indicate that competition from S. furcifera could slow adaptation by N. lugens to resistant rice varieties. Facilitation by N. lugens of S. furcifera on resistant rice, which is expected to increase adaptation rates in the latter species, likely depends on the relative strengths of resistance against both planthoppers.