Identification of potential vectors of the coconut lethal disease phytoplasma

Lethal disease (LD) is a lethal yellowing-type disease of coconuts associat ed with phytoplasmas in Tanzania, but the insect vector for it has not yet been identified. In this study, the auchenorrynchous insects in LD-infected coconut fields were surveyed to determine potential vectors for the diseas e. No significant correlation was found between disease incidence and numbe rs of insects collected from the field, possibly reflecting the unknown inc ubation period for the disease. However, analysis of more than 5000 individ ual insects by the polymerase chain reaction (PCR), using LD-specific prime rs derived from the phytoplasma 16S rRNA gene, revealed PCR products of the correct size from eight individuals of Diastrombus mkurangai and four of M eenoplus spp. When digested with restriction endonucleases, fragments of th e same size as the LD phytoplasma were obtained. No PCR products were detec ted in any of the other insect species tested. These results implicate D. m kurangai and Meenoplus spp. as probable vectors of the LD phytoplasma.