Potential vectors of coconut lethal disease phytoplasma
Studies were done in Tanzania to identify potential insect vectors of the coconut lethal disease. It has been shown in Florida (US) that Myndus crudus (EU Annexes) transmits palm lethal yellowing phytoplasma (EPPO A1 quarantine pest). In Tanzania, M. crudus has not been observed. 15000 insects were collected from 2 areas (Chambezi: moderate disease incidence, and Kifumangao: high disease incidence) between August 1995 and July 1996. More than 5000 insects were tested by PCR. The phytoplasma was detected in 8 individuals of Diastrombus mkurangai (Homoptera: Derbidae) and 4 of Meenoplus spp (Homoptera: Meenoplidae). No correlation could be found between disease incidence and numbers of insects collected from the field, possibly reflecting the unknown incubation period for the disease. These studies showed that Diastrombus mkurangai and Meenoplus spp. can acquire the phytoplasma but experiments are still needed to verify whether they can transmit the disease to healthy palms.
Note: So far within EPPO, lethal diseases of coconut palms from different parts of the world have been gathered under a single entry: palm lethal yellowing phytoplasma (EPPO A1 quarantine pest), although differences in epidemiology and susceptibility of host plants were observed. Recent genetic studies have shown the phytoplasmas causing lethal palm diseases in the Caribbean, East and West Africa are distinct (but related) (see EPPO RS 99/109) and should henceforth be considered separately. In addition, other diseases have been reported from Sudan on date palms (EPPO RS 2000/122) and the phytoplasmas found were related to Bermuda grass white leaf phytoplasma. In the EPPO Reporting Service, the name palm lethal yellowing phytoplasma will be used only for the pathogen associated with the disease found in the Americas. In East and West Africa, the pathogens will be referred to as East Africa and West Africa coconut lethal disease phytoplasmas.
Mpunami, A.; Tymon, A.; Jones, P.; Dickinson, M.J. (2000) Identification of potential vectors of the coconut lethal disease phytoplasma.
Plant Pathology, 49(3), 355-361.