Characteristics of the transmission of Sumatra disease of cloves by tube‐building cercopoids, Hindola spp

Repeated transmission tests showed that the tube‐building cercopoids Hindolafulva (in Sumatra) and H. striata (in Java) were natural vectors of Sumatra disease of cloves, caused by Pseudomonas syzygii. In tests on experimental transmission of P, syzygii, H, striata collected from a disease‐free area acquired bacteria within 4 h of access to infected plants and transmitted them within 4 h of access to healthy test plants. Transmission was persistent and commenced within 24 h of acquisition feeding, but there was evidence for a short latent period between acquisition and transmission of bacteria. After acquisition feeding, P. syzygii was isolated from 67% of insects that transmitted the disease and also from 3% of those that did not. Times to death of test plants following first exposure to both naturally and experimentally infective insects showed log‐normal distributions with similar slopes. Younger (1‐year) seedlings died slightly sooner (median response time = 200 days) than older (2‐ to 3‐year) test plants (median response time = 280 days). The bacterial content of test plants was positively correlated with time to death.