rates virtually decimated field populations of A. fallacis , thereby 

 creating large spider mite outbreaks. 



Here, ive summarize our most recent laboratory results, which 

 deal with pesticides not heretofore tested on a Massachusetts strain 

 of A. fallacis . Two of the insecticides tested (the synthetic 

 pyrethroids Pydrin and Pounce) have experimental permits only; we 

 screened them to determine their effects should they become available 

 for possible future use in integrated pest management programs in 

 Massachusetts. Because A. fallacis spends considerable time in the 

 orchard understory, especially m spring and early summer, careless 

 use of herbicides can be highly detrimental to predator populations. 

 This is the reason for inclusion of herbicides in our pesticide screen- 

 ing program. 



Methods 



As in our previous laboratory trials, we employed here the 

 slide dip assay technique in which A. fallacis adults (Bishop strain) 

 were dipped into orchard concentrations of pesticide. As before, 

 we determined the percent mortality 48 hours after dipping. 



Results 



The results are presented in Table 1. Insecticides which 

 proved highly toxic (70-100-0 mortality) to A. fallacis were Lannate 

 (methomyl) 1.8 EC, Cygon (dimethoate) 2.7 EC, Pydrin ^f envalarate) 

 2.4 EC, and Pounce (permethrin) 3.2 EC. Penncap M (parathion) 2 FM 

 was within our range of low toxicity (0-30% mortality). Although 

 A. fallacis has received little exposure to Penncap M in Massachusetts, 

 this low toxicity could very well have been pre-selected by long- 

 term exposure of A. fallacis to such chemically closely related mater- 

 ials as Imidan (pEosmet) 50 WP and Guthion (azinphosmethyl) 50 WP . 

 The high toxicity of the first four materials does not favor their 

 use in integrated pest management programs. 



The fungicide Karathane (dinocap) 25 WP was within the moder- 

 ately toxic range (30-70% mortality), while Polyram 80 WP, Phygon XL 

 (dichlone) 50 WP and Manzate D 80 WP were of low toxicity. Of these 

 materials, only Karathane would be likely to have a negative impact 

 on orchard populations of A. fallacis . 



Of the herbicides tested, Ammate X (ammonium sulfamate) was 

 highly toxic to A. fallacis , while Dowpon M (dalapon) was of low 

 toxicity. Dowpon M and Princep (simazine) 80 WP (see Fruit Notes 

 43 (5): 14-18) are thus the herbicides recommended for use in inte- 

 grated pest management programs. When applying herbicides, be care- 

 full to preserve at least 50% ground cover under the trees to provide 



