EFFECTS OF DIETARY AND GASEOUS FLUORIDE ON THE APHID APHIS-FABAE

A large proportion of leaf fluoride consists of surface deposits and a sucking herbivore would be expected to take in a smaller load of fluo ride in its food than a chewing herbivore. In these experiments, fluor ide was applied aerially, through the leaves, and systemically, via th e roots, to compare uptake by aphids and effects on their fecundity. F luoride applied via roots was taken up by both the plants and the aphi ds, but at high treatment rates the aphids had much lower concentratio ns than the foliage. When the plants and aphids were fumigated with HF the aphids had much greater loads than the plant shoots, which was du e to deposition of F on the insect surfaces. There were no effects of the treatments on aphid reproduction or development time. The aphids o btained some fluoride through their diet which suggests that fluoride is present in the phloem sap, previously thought to be of minor import ance. (C) 1998 Elsevier Science Ltd. All rights reserved.