Pathogenic Microorganisms Associated With the Southern Pine Coneworm (Lepidoptera: Pyralidae) Attacking Loblolly Pine
Larvae of the Southern pine coneworm, Diorycha amateella (Hulst) (Lepidoptera: Pyralidae), were collected monthly during the growing seasons of 1996 and 1997 from loblolly pine, Pinus taeda L., seed orchards in Alabama, Florida, Georgia, South Carolina, and Virginia, and examined for pathogenic microorganisms. One fungus, Beauueria bassiana (Bals.) Vuill, a granulosis virus (Baculoviridae: Eubaculovirinae), and a protozoan (phylum Microspora) were found. Five larvae from three localities were infected with B. bassiana, 37 larvae from six localities were infected with the granulosis virus, and 69 larvae from 5 locations were infected with the microsporidian. Laboratory trials confirmed that B. bassiana and the granulosis virus caused coneworm mortality. B. bassiana isolates from all three locations were equally virulent to late instar larvae. Spores of the unidentified microsporidian are free, elongate oval, binucleate and contain 13-14 turns of an isofilar polar filament. The primary sites of infection were the Malpighian tubules and the silk glands. The microsporidian was found in 2 to 51% of larvae sampled. It caused 100% mortality in early instar larvae allowed to feed on artificial diet contaminated with 3 x 103 or 4.5 x 103 spores. More work is needed to determine the importance of these pathogens in regulating populations of southern pine coneworms or their potential utility in an IPM program.
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