Broad Spectrum Potential ofIsaria fumosoroseaAgainst Insect Pests of Citrus

Abstract

Renewed interest in the use of entomopatho genic fungi in the management of insect pests led to the evaluation of Isaria fumosorosea Wize (Ifr) (= Paecilomyces fumosoroseus (Wize) A.H.s. Br. & G. Sm.) on citrus pests due to finding the inva sive, Asian citrus psyllid, Diaphorina citri (Ku wayama) (Hemiptera: Psyllidae) infected with a strain of this fungus in a citrus grove (Meyer et al. 2008). The fungus was isolated from mycosed D. citri collected from the underside of foliage on or ange trees in Polk County, Florida. In this study, 3 hemipteran insects (psyllid, leafhopper, aphid) and 1 coleopteran (Diaprepes citrus root weevil) were evaluated for susceptibility to Ifr under lab oratory conditions. The Asian citrus psyllid, D. citri, is the vector of the citrus-infecting bacteria associated with citrus yellow shoot disease, known as Huanglongbing (Bove, 2006; 2008), and the glassy-winged sharpshooter, Homalodisca vitripennis Germar (Hemiptera: Cicadellidae) is a vector for the plant-infecting bacteria, Xylella fas tidiosa which causes citrus variegated chlorosis, scorch-like diseases of fruit crops, and Pierce's disease of grapevine (Daugherty & Almeida 2009). the brown citrus aphid, Toxoptera citrici dus (Kirkaldy) (Hemiptera: Aphididae), is a vec tor of citrus tristeza virus, CTV (Roy & Brlansky 2009) and the root weevil, Diaprepes abbreviatus L., is a common pest of citrus which has a broad host range and damages the roots of trees which permits phytopthora infections (Graham et al. 2003). Thus these insect pests of citrus trees were evaluated for susceptibility to strains of the ento mopathogenic fungus, Ifr. Presently, 3 Ifr strains are available for re search as blastospore formulations in the U.S.A. There is the Ifr APOPKA strain, in PFR 97 20% WDG® (Certis, Columbia, Maryland, USA), la beled for controlling psyllids, leafhoppers, and aphids; the Ifr 9901 strain, in NoFlyTM WP (Natu ral Industries, Houston, Texas labeled for control ling whiteflies, aphids and thrips and lastly, the non-commercial strain, Ifr 3581 available from the USDA/ARS, NCAUR, Peoria, Illinois, USA (Jackson et al. 1997). Ifr has several characteris tics that favor evaluation for controlling insect pests of citrus: 1) it is native to Florida, 2) it is compatible with non-target arthropods and 3) it can be horizontally transferred and infect conspe cifics (Sterk et al. 1995a, b; Avery et al. 2008, 2009, 2010). In our experiments only Ifr strain 3581 and PFR 97 were tested on the citrus pest insects. This is the first report indicating that H. vitripennis, T. citricidus and D. abbreviatus were susceptible to Ifr strains under laboratory condi tions.