Biocontrol of Two Spotted Spider Mites
Overwintering and Effects of Autumn Habitat Manipulation and Carbofuran on Neoseiulus fallacis and Tetranychus urticae in Peppermint
MARK A. MORRIS, B. A. CROFT and R. E. BERRY
Department of Entomology, Oregon State
Experimental & Applied Acarology 20: 249-258
© 1996 Chapman & Hill
The percentage of Neoseiulus fallacis (Garman) in four subhabitats of peppermint fields in November were 37% on dead leaves, 45% in debris below dead levaes, 3% in hollow stems and 15% on live foliage. In December, the percentages were 36, 39, 7, and 18%, respectively, for these same sites. The values were 40, 37, 18, and 5% and 6, 80, 14, and 0% for January and February, respectively. By April, 95% of all predators were on new foliage feeding on Tetranychus urticae Koch, while the rest were still in debris. Augmenting plots with debris increased overwintering survival of N. fallacis compared to the natural condition while removal of debris decreased it. An autumn carbofuran (Furadan 4F) treatment completely eliminated overwintering N. fallacis, thus leading to outbreaks of T. urticae the following spring. The results of these overwintering studies are discussed in relation to improved biological control and spider mite management.