Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/1997
Publication Date: N/A
Interpretive Summary: Gypsy moth (GM) is one of the most serious pests of hardwood trees throughout an increasingly large region of the easteran and, now, north-central US. Large quantities of insecticides and insect-specific toxins produced by the bacterium BACILLUS THURINGIENSIS are used to control GM, but there is rising interest to use other agents, especially fungi, for rGM biocontrol. This study focussed on the conidial 'fungi imperfecti' that affect GM. Several species that are important pathogens of insect pests other than GM were isolated during 1991-92 surveys conducted in the states of MD, PA, VA, and WV. None of these conidial fungi caused mortality in GM larvae approaching that often caused by the best studied fungal pathogen of GM, ENTOMOPHAGA MAIMAIGA, a highly specific pathogen of GM, and none of these conidial fungi was as comparatively effective against GM larvae as they tend to be against a wide spectrum of other insect hosts. This study extended and confirmed earlier studies suggesting that common fungal pathogens useful for the biocontrol of other insect pests may show little practical potential for use against GM. Even though these common conidial entomopathogens might be easier to grow and manipulate in culture, ENTOMOPHAGA MAIMAIGA still remains the best fungal candidate for the biological control of gypsy moth larvae.
Technical Abstract: A population of potato cyst nematodes was discovered near Prattsburg, New York that reproduced freely on potato cultivars carrying the H1 gene for resistance to Globodera rostochiensis pathotype Ro1 . An isolate of this variant population was increased on the Ro1 resistant potato cultivar Hudson and tested for color sequence during cyst maturation, examined morphologically, and subjected to differential host tests. Color sequence during cyst maturation of this isolate paralleled that of G. Rostochiensis with short white (1 wk) and yellow (1 wk) phases followed by a longer (2 wks) golden phase before turning brown. Morphometries of males, females, and juveniles of the variant isolate were within the range of those for G. Rostochiensis. Differential hosts consisting of different potato genotypes that are used in the international scheme to distinguish pathotypes of potato cyst nematodes were obtained from the International Potato Center, Lima, Peru. In tests with these differential hosts, the isolate from the variant population reproduced freely on the standard susceptible differential host (Solanum tuberosum) and the differential host genotypes. According to the international pathotyping scheme for potato cyst nematodes, this pattern of reproduction on these differential hosts is typical of G. Rostochiensis pathotype Ro2.