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| Publication Type:
| Report |
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| Author(s): | Warren, G. W.;
Potter, D. A. |
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| Title: | Pathogenicity of milky disease bacteria in grubs of the southern masked chafer |
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| Source: | Kentucky Turfgrass Research. 1981, p. 21. |
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| Publishing Information: | Lexington, KY: University of Kentucky, College of Agriculture, Cooperative Extension Service |
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| Keywords: | TIC Keywords: Bacillus popilliae; Biological control; Cyclocephala lurida; Field tests; Poa pratensis; Laboratory tests; Grubs; Developmental stages; LC50; LD50; Milky disease; Milky disease spores
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| Abstract/Contents: | Describes laboratory and field tests on use of milky disease to control southern masked chafer grubs. Milky spore suspension was prepared by homogenizing naturally infected grubs in a tissue grinder, centrifuging to separate bacterial sporangia from vegetative rods and re-suspending the sporangia in distilled water. Milky spore powder was prepared by mixing sporangia with talc. First, 2nd and 3rd instar grubs were held in soil mixed with known amounts of spore-talc powder and checked for disease incidence after 3 weeks. Third instar grubs were also tested by injection of known doses of sporangia. Field tests were conducted on Kentucky bluegrass turf by applying freshly prepared masked chafer spore powder. Grubs were dug after 2 and 7 months to determine if increase in disease incidence had occurred. To test for virulence of other milky disease pathogens, 17 other species or strains of bacteria (Bacillus spp.) from 15 different scarob hosts were tested by injection in southern masked chafer grubs. Injection and feeding tests indicated that infectivity of milky disease within each instar is a probit response to the log of sporangia dose or concentration. The calculated LC50 values for larvae held in contaminated soil were 280,000, 260,000, and 130,000 sporangia/g soil for 1st, 2nd, and 3rd instars respectively. The lower LD50 value for 3rd instar grubs is probably a consequence of greater intake of food and soil. The calculated LD50 value for 3rd instars infected via intrahemocoelic injection was 32,000 sporangia/grub. These tests indicate that virulence of the masked chafer strain of milky disease is comparable to that of the commercial, Japanese beetle strain. In tests with other milky disease pathogens, strains from 3 Australian white grubs and a native strain from Phyllophaga fusca (a May beetle) were most infective. These strains could be potentially useful biological control agents for masked chafers. Preliminary field studies suggested that, given time to build up in the soil, a sporangia-talc mixture could provide long-lasting control of masked chafer grubs. |
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| Language: | English |
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| References: | 0 |
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| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Warren, G. W., and D. A. Potter. 1981. Pathogenicity of milky disease bacteria in grubs of the southern masked chafer. KY. Turfgrass Res. p. 21. |
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