Feeding-induced interactions between two rice planthoppers, Nilaparvata lugens and Sogatella furcifera (Hemiptera: Delphacidae): effects on feeding and honeydew excretion.

A series of laboratory experiments was conducted using electrical penetration graph, salivary flange, and honeydew measurement to study the effects of feeding-induced intra- and interspecific interactions on feeding behavior and honeydew excretion between planthoppers Nilaparvata lugens (Stål) and Sogatela furcifera (Horváth). Feeding-induced intra- and interspecific interactions affected many measures of feeding behavior. The number of salivary flanges, mean duration of pathway activities per insect, and mean duration from first probe to first sustained phloem ingestion for both N. lugens and S. furcifera were significantly shorter on rice plants with feeding-induced conspecific and heterospecific effects than those for planthoppers fed on control plants. Feeding-induced intra- and interspecific interactions also affected the duration per insect of phloem ingestion for both N. lugens and S. furcifera. The durations per insect of phloem ingestion on host plants with feeding-induced conspecific and heterospecific effects were significantly longer than those on control plants. An asymmetric facilitative effect of induced interspecific interactions on the weight of honeydew excreted was detected, because only the honeydew weights of S. furcifera were significantly increased by the induced heterospecific effect on both varieties. The results demonstrated that the facilitative effects on honeydew excretion were consistent with previously documented effects on performance. Both facilitative effects on honeydew excretion and performance were asymmetrical, with more benefits to S. furcifera from N. lugens. Such facilitative effects might be mainly related to altered nutrient status and induced allelochemistry in rice.