Ataenius spretulus, A Potentially Important Turf Pest, and Its Associated Milky Disease Bacterium1

Abstract

Grubs of Ataenius spretulus Harold, a scarabaeid turf pest, were encountered at 2 widely separated locations in New York during 1969–71. All field-collected grubs were infected with a bacillus producing a milky disease similar to that produced by Bacillus popilliae Dutky or B. lentimorbus Dutky in other scarabaeid grubs. This bacillus was noninfective to grubs of the Japanese beetle, Popillia japonica Newman, and northern masked chafer, Cyclocephala borealis Arrow, and only mildly infective to the European chafer, Amphimallon majalis (Razoumowsky). Histological examination of infected Ataenius grubs indicated that sporulation occurred in connective tissue sheaths and possibly also in lobes of the fat-body. Cytological studies showed the general ultrastructure of the spore to be similar to those reported for the other milky disease bacteria. It differed in the smallness of the endospore relative to the size of the whole sporangium, the greater number of ridges formed by the spore coat, and the presence of conspicuous exosporium. The results of our investigations suggest that the etiological agent of the A. spretulus disease is a new milky disease organism.