Susceptibility of Delia antiqua (Diptera: Anthomyiidae) to Eleven Isolates of Entomopathogenic Hyphomycetes

Abstract

Susceptibility of Delia antiqua (Meigen) to 11 isolates of entomopathogenic hyphomycetous fungi was studied in the laboratory. Newly formed pupae were sprayed directly with four concentrations of aqueous spore suspensions of Beauveria bassiana (Balsamo) Vuillemin (three isolates), Metarhizium anisopliae (Metschnikoff) Sorokin (three isolates), and one isolate each of Metarhizium flavoviride Gams & Rozsypal, Nomuraea rileyi (Farlow) Samson, Paecilomyces farinosus (Dickson ex Fries) Brown & Smith, Paecilomyces fumosoroseus (Wize) Brown & Smith, and Tolypocladium cylindrosporum Gams. Pupae were generally not susceptible to mycoses but deferred mortality was observed in adults that emerged from puparia treated with nine of the fungal isolates. N. rileyi 5 and M. anisopliae 120 did not induce mycosis in adult flies. Mortality due to the other isolates ranged from <5% ( T. cylindrosporum at 4 × 10 5 blastospores ml −1 ) to 75% for P. farinosus and P. fumosoroseus (4 × 10 5 conidia ml −1 ). The three Beauveria were moderately pathogenic at all four concentrations tested. Sporulation occurred on 56% of adults infected with M. anisopliae 71 and on 17% of those infected with M. flavoviride (4 × 10 5 conidia ml −1 ). Significant differences were thus found between isolates with regard to their ability to infect emerging adults, but dose-level differences for a given isolate were generally not significant. Overall, toxicity appeared to have been more evident than pathogenicity and resulted in reduction in numbers of viable and fertile adults that emerged from puparia treated with nine of the isolates. P. farinosus 46 and P. fumosoroseus 45 (LD 50 's in the range of 10 3 conidia cm −2 ) are promising candidates for the control of D. antiqua .