<I>Diaphorina citri</I> (Hemiptera: Psyllidae) Infection and Dissemination of the Entomopathogenic Fungus <I>Isaria fumosorosea</I> (Hypocreales: Cordycipitaceae) under Laboratory Conditions

Abstract

The infectivity and horizontal transfer of Isaria fumosorosea Wize among Diaphorina citri Kuwayama was measured using a detached leaf bioassay in which blastospores were sprayed on citrus leaf sections or yellow plastic tags (artificial attractant surface). Four leaf sections or three leaf sections and one yellow tag were placed together in a Petri dish chamber. One to four of the leaf sections or the yellow tag was sprayed with I. fumosorosea (1.2–1.7×103 blastospores/mm2). After treatments dried, a single adult psyllid was released into each chamber. Mortality due to I. fumosorosea for the adult psyllid was observed 4.9 ± 0.21–6.1 ± 0.37 d following exposure to the pathogen. The rate of colonization by I. fumosorosea on adults in chambers with untreated leaf sections and one treated yellow tag was as effective in inducing mortality as in chambers with one treated leaf section at 8 days post application. Under high humidity, I. fumosorosea blastospores readily produced hyphae on the surface of leaves, which was useful for determining if adults were responsible for transmission of the fungus. In chambers with a single treated leaf section, adults came into contact with blastospores and moved these around to the non-treated leaves. The same phenomenon, of psyllid infection and subsequent spreading of the fungus to non-treated leaves, was observed when psyllids were placed into chambers with a treated yellow tag. The use of I. fumosorosea inoculated yellow tags has potential as a psyllid dissemination technique for managing pest populations.

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