1a. Objectives (from AD-416):
To develop and formulate effective management strategies to reduce damages caused by insect pests to the tree fruit and vegetable crops.
1b. Approach (from AD-416):
Conduct laboratory and field experiments to gain understanding of behavior, ecology, physiology, genetics, and diseases of potato and tree fruit insect pests. Monitor and manage pest populations in crops.
3. Progress Report:
A set of six potato varieties were evaluated in a laboratory assay as food for larvae of bertha armyworm and cabbage looper. The study determined the survival of larvae on foliage, the development rate, and the size of pupae. Bertha armyworm larvae performed relatively poorly, but with some successful development on Norkotah and Russet Burbank varieties of potato. Cabbage looper larvae developed well on all varieties tested. These results reinforce prior findings that cabbage looper is a principal defoliator of potato, with a high rate of survival and rapid development on potato foliage. An additional experiment using the same assay design evaluated the development of alfalfa looper larvae on Norkotah and Alturas potato foliage. In past tests, there was some development on Norkotah and none on Alturas potatoes. In this test, all alfalfa looper larvae died before pupation on both varieties. The results indicate that alfalfa looper should not be considered a significant pest of potato. Field experiments evaluated floral chemical lures as trap baits for spotted cutworm. These experiments demonstrated significant attraction of male and female spotted cutworm moths to three chemicals found in the scent of moth-visited flowers. These chemicals may be useful either as a means of monitoring the activity of female spotted cutworm moths in potato fields, or for the development of an attract and kill formulation to replace pesticide cover sprays for management of spotted cutworm on vegetable crops. Link to in-house objectives. This work directly relates to the following objectives from the prior research Project Plan: Develop new knowledge of the behavior, genetics, systematics, physiology, ecology, and biochemistry of the insect pests of potato, and their natural enemies, that will aid in the discovery, development and application of management methods and technologies. Two graduate students described the biology and ecology of the potato psyllid and beet leafhopper, insect vectors of zebra chip and purple top diseases, respectively. These two emerging diseases of potato have caused losses of millions of dollars to the U.S. potato industry. It was discovered that transmission of the zebra chip pathogen by the potato psyllid was negatively affected by temperatures at 90 °F and above. It was also demonstrated that local movement of the beet leafhopper from weeds to nearby potato fields can successfully be traced by marking the insects with egg and milk protein markers. Information from this research will lead to development of effective management strategies for these two important insect pests of potato to reduce incidence of zebra chip and purple top diseases in commercial potato fields. The work reported here addresses objectives 2 and 3 of the parent project plan.