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Entomology
Program and Japanese Beetle Research
Catharine
Mannion and Jason Oliver
Cooperative
Agricultural Research Program
Seminar Series
Tennessee State University, McMinnville, TN
March 10,
1999
Introduction. The entomology program at the TSU
Nursery Crop Research Station has been ongoing for approximately 3 years
and is staffed with an Associate and Assistant Investigator. The
researchers in this program investigate and research insect problems in
the field-grown nurseries. There are currently 5 projects: Japanese
beetle, imported fire ant, Asian ambrosia beetle, flatheaded apple tree
borer, and the Midway beetle. The Japanese beetle project has been the
primary project in the program. Japanese beetle is a regulated pest;
numerous states and counties maintain exterior quarantine or
certification requirements. Nursery stock shipped from infested areas to
non-infested areas can potentially contain the immature stages of
Japanese beetle, and therefore, are at risk of spreading this pest to
non-infested areas.
Objectives. The objectives of the Japanese beetle
project are to develop management strategies to reduce the number of
Japanese beetle grubs in the field-grown nurseries. There have been
three major areas of focus: insecticides (use of new, low-impact
compounds; application technology; formulation; rate; and timing),
biological control [entomopathogenic nematodes (Heterorhabditis
spp.), Bacillus thuringiensis, and Tiphia vernalis] and
cultural control (clean cultivation, deterrents and barriers to
oviposition).
Methodology. Field tests have been conducted to
evaluate treatments and application technologies for three years.
Methodology varied among tests; however, all field tests were conducted
and evaluated similarly. Treatments were applied at the appropriate
times and rates around trees in commercial nurseries. At the time of
evaluation, trees were dug with a mechanical digger and the root ball
examined for scarab larvae. All scarab larvae were identified and
counted. Cultural practices being evaluated, such as clean cultivation,
were maintained during the period of Japanese beetle flight. Methods or
treatments to deter oviposition were also examined. Laboratory studies
were conducted on rearing a parasitoid of Japanese beetle (Tiphia
vernalis) and the interaction of the parasitoid and commonly used
pesticides. Laboratory studies were also conducted to examine the
interaction between the entomopathogenic nematode, Heterorhabditis
marelatus and an insecticide used against Japanese beetle larvae.
Results. As a result of the insecticide work, a
soil application of imidicloprid was approved as an acceptable treatment
for regulatory control. Dipping root balls in chlorpyrifos also provided
excellent results. Entomopathogenic nematodes and B. t. provided
approximately 50% reduction in the grub population. Laboratory tests
demonstrated no interaction between an insecticide used for grub control
and an entomopathogenic nematode. Testing with Tiphia are
ongoing.
Impact. Japanese beetle is a serious problem for
the nursery industry. The need for reliable, consistent treatments to
reduce the risk of spreading this pest is tremendous. Currently, there
are very few options available to growers; however, new options are now
available as a result of this work. Additionally, data generated in this
program will help establish a long-term, sustainable reduction in the
Japanese beetle population. Information generated on cultural practices
and biological control in conjunction with the use of low-impact,
environmentally safe insecticides will help reduce the risk of spread.
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