Some effects of x-irradiation on larvae of Galleria mellonella.

During the summer of 1965, the fungus Spicaria rileyi was frequently associated with dead Pseudoplusia includens larvae on various crops in southeastern Alabama. Since this insect, sometimes referred to as the false looper, has become of increasing economic importance in Alabama (Canerday, J. Econ. Entomol., in press, 1966), the pathogenicity and potential control value of S. rileyi for P. k&dens were investigated. Diseased larvae collected in the field were stiff and covered with white to tan mycelial growth. Spicaria rileyi was isolated from the larvae and increased on egg-yolk agar (L. W. Getzin, J. Insect Pathol., 3, 2-10, 1961) in petri dishes held at 25°C. Under these conditions, the white mycelium developed rapidly and abundant green conidia usually were produced within 7-10 days. Inoculum for one pathogenicity test consisted of a heavy spore suspension in sterile demineralized water containing 0.01% Triton X-100. The suspension was hand-atomized onto 28 lab-reared secondand third-instar larvae of P. includens in l-ounce plastic cartons (1 larva/carton) containing an artificial diet. Thirty-four larvae treated with 0.01% Triton X-100 in water served as controls. In a second test, 30 ,wondand third-instar larvae in individual cartons were dusted with spores erumpent from field-collected cadavers of P. includens. Twenty untreated larvae served as controls. All larvae were held at 25°C; relative humidity within cartons ranged between 75 and 8S5r,. Fungus-induced mortality occurred among treated larvae in both tests. Fifty per cent of the larvae dusted with spores succumbed by the 6th day following inoculation, and loot:& mortality had occurred by the 10th day. The mortality level in larvae treated with the spore suspension was considerably lower! not exceeding a maximum of 50% through pupation of the larvae. S&aria rileyi was consistently reisolated in pure culture from dead larvae in both pathogenicity tests. Symptoms of S. rileyi infection in P. includens closely resembled those described by Getzin (lot. cit.) for the same fungus in the cabbage looper, Trichoplusi~ ni. Infected larvae became sluggish, died, and were rapidly mummified.