Role of insects in the transmission of banana bacterial wilt.

Abstract

The banana bacterial wilt caused by the Xanthomonas campestris pv. musacearum (Xcm) is one of the major constraints to banana production in Uganda. Field observations suggest that the primary means of disease spread is by insect transmission through the male flowers. This study carried out an inventory of insects found on banana inflorescence, investigated possible sources of inoculum in banana plants and determined insect species that carried the bacterium on their bodies and thus possible vectors of the disease. The most abundant insects visiting banana flowers are stainless bee, Plebeina denoiti (Vachal) (Apidae), fruit flies (Drosophilidae) and grass flies (Chloropidae). Female flowers had twice as many insects as male flowers. The bacterial cells have been isolated from the stainless bee P. denoiti, honey bees (Apis melifera), fruit flies and grass flies that had been collected from male flowers of both asymptomatic and symptomatic plants. The bacterial cells isolated from P. denoiti were more than two times as many as other insect groups. Further studies to confirm the mode of transmission by insects, to investigate transmission epidemiology and biology of banana Xanthomonas wilt have been initiated. (Author's abstract).[Le fletrissement bacterien du bananier cause par le Xa est l'une des contraintes majeures de la production de bananes en Ouganda. Les observations de terrain suggerent que les premiers moyens de la dispersion de la maladie sont les fleurs males transportees par les insectes. Au cours de cette etude, on a inventorie les insectes trouves sur le bananier pendant la floraison, les sources possibles d'inoculum sur les bananiers et pour determiner les especes d'insectes qui transportent les bacteries sur leurs corps et ainsi deviennent les vecteurs de la maladie. Les insectes qui visitent le plus souvent les fleurs du bananier sont les abeilles Plebeina denoiti (Vachal) (Apidae), les mouches (Drosophilidae) et les Chloropidae. Les fleurs femelles avaient deux fois plus d'insectes que les fleurs males. Les cellules bacteriennes ont ete isolees du P. denoiti, les abeilles (Apis melifera), les Drosophilidae et les Chloropidae qui ont ete collectees sur fleurs males et les plantes asymptomatiques et symptomatiques. Les cellules des bacteries isolees a partir de P. denoiti etaient deux fois plus importantes que les autres insectes. D'autres etudes sont necessaires pour confirmer le mode de transmission par les insectes et les aspects epidemiologique et la biologie de Xanthomonas sur le bananier. (Resume d'auteur).]