-14 



Assuming that a mid-winter thaw will occur, make plans to 

 check those orchard areas known to have high mouse populations. 

 Have sufficient bait available to hand treat those blocks that* 

 have mouse holes and runways in the snow. This spot treatment 

 should reduce possible mid-winter tree damage. 



Do not exceed label restrictions when baiting and distribute 

 them carefully. Baits, when properly placed, should be in vege- 

 tation at soil level; this is where the mice are. Baits on bare 

 ground or suspended in the vegetation are wasted and may be easily 

 found by animals other than orchard mice. 



**************** 



LABORATORY TOXICITY OF PESTICIDES AND GROWTH REGULATORS 

 TO AMBLYSEIUS FALLACIS , AN IMPORTANT SPIDER MITE 

 PREDATOR IN MASSACHUSETTS APPLE ORCHARDS 



Robert G. Hislop, Charles Acker, Nancy Alves, and Ronald J. Prokopy 

 Department of Entomology, Fernald Hall 

 University of Massachusetts 



In the last issue of Fruit Notes (July/August, 1978), we 

 described results of 1977 studies aimed at determining the toxicity 

 of orchard pesticides to field populations of Amblyseius fallacis, 

 a key predator of red and two-spotted spider mites in Massachusetts 

 apple orchards. Combined results from several commercial orchards 

 and our Belchertown research plots demonstrated that application 

 of orchard concentrations of Zolone, Benlate, and perhaps also 

 Glyodin reduced populations of A. fallacis in the trees, resulting 

 in spider mite outbreaks. On tEe" other hand, use of Imidan, Guthion 

 Captan, and Cyprex permitted buildup of A. fallacis , usually result- 

 ing in effective suppression of spider mTtes, especially two- 

 spotted mites. 



Here, we discuss results of laboratory tests, carried out in 

 conjunction with our 1977 and current field trials, aimed at deter- 

 mining the direct and residual toxicities of pesticides to a 

 strain of A^ fallacis from the Bishop orchard in Shelburne. 



Three principal experiments were performed: (A) toxicity 

 tests of orchard materials at recommended field rates; (B) toxicity 

 tests of principal pesticides (i.e. those in greatest use) at three 

 different rates; and (C) tests of the influence of pesticide resi- 

 dues on the reproductive capability of A^ fallacis . 



Direct Toxicity of Spray Materials to A, fallaois 



To determine the direct toxicity of orchard spray materials to 

 A- fallacis , we used double-stick tape to affix adult females to 

 microscope slides. The slides were then dipped into solutions of 



