How species-specific is the phoretic relationship between the broad mite, Polyphagotarsonemus latus (Acari : Tarsonemidae), and its insect hosts ?

Broad mite, Polyphagotarsonemus latus (Acari: Tarsonemidae), is a serious p lant pest in tropical and subtropical regions. Phoretic associations betwee n broad mite and two genera of whiteflies (Insecta: Homoptera: Aleyrodidae) , namely Bemisia and Trialeurodes, have been reported from different parts of the world. Our purpose was to determine the specificity of the associati on between the mite and its phoretic hosts. Two host plants, potatoes and c ucumbers, were used to study these relationships in the laboratory. Insects frozen for 24 h were used as potential phoretic hosts in all experiments. Attachment levels were monitored by counting the number of mites attached t o each insect. All tests were conducted for 4-6 h, as attachment to Bemisia tabaci on potato shoots leveled off after 4 h, increasing only marginally after 8 h. Attachment levels to thrips (the western flower thrips, Franklin iella occidentalis) and to allate aphids (Myzus persicae) was negligible re lative to the attachment to B. tabaci. Broad mite also attached to the whit eflies Dialeurodes citri, Aleyrodes singularis and Trialeurodes lauri, the latter being the least attractive species (including B. tabaci). Washing B. tabaci with pentane greatly reduced attachment. Using cucumbers as hosts d id not substantially change the general trend, but attachment levels were l ower. The phoretic relationship between broad mite and its insect hosts app ears to be specific to whiteflies, with some whiteflies having a higher pot ential as phoretic hosts.