- 9 - 



slides were dipped for 5 

 dosages equivalent to IX 

 chemical was replicated 5 

 mortality was determined 

 pesticides to young larva 

 mortality) was determined 

 72 hours after treatment, 

 termined by immersing thi 

 mixtures for 10 seconds, 

 ment. 



seconds in chemi 

 concentration in 



times with 10 e 

 72 hours after t 

 e hatching from 



by counting the 



Toxicity to la 



rd and fourth in 



Mortality was c 



cals mixed with water at 



an orchard sprayer. Each 

 ggs per replicate. Egg 

 reatment. Toxicity of 

 treated eggs (early larval 



dead larvae on microslides 

 te instar larvae was de- 

 star larvae in pesticide 

 hecked 96 hours after treat- 



Table 1. Laboratory toxicity of orchard pesticides to eggs and 

 larvae of the predaceous cecidomyiid, Aphidoletes aphidimyza . 



Pesticide 



Imidan 50 WP 

 Guthion 50 WP 

 Guthion 50 WP 

 CFitchburg) 

 Sevin 50 WP 

 Zolone 3 EC 

 Thiodan 50 WP 

 Systox 6 EC 

 Phosphamidon 8 EC 

 Plictran 50 WP 

 Omite 30 WP 

 Thiram 50 WP 

 Captan 50 WP 

 Glyphosate 4 EC 

 Check 

 Check 

 (Fitchburg) 



% early 

 Dosage/100 % egg larval 

 gal spray mortality mortality 



1-1/2 lbs 



5/8 lb 



5/8 lb 



1 lb 



1-1/2 pts 



1 lb 

 5 ozs 



1/4 pt 



5 ozs 



1-1/2 lbs 



2 lbs 

 1 lb 

 4 qts 



larval 

 mortality 



8 



86 



6 



72 

 4 

 6 

 8 

 34 

 14 

 6 

 6 

 8 



4 

 5 



"2T 



14 



38 



21 







29 



57 



27 







2 







2 



6 

 



18 



18 



6 



10 

 46 

 32 

 16 

 12 



8 

 6 

 10 

 8 

 3 



Per ce 

 Guthion (Be 

 and 7 2% of 

 was moderat 

 toxicity of 

 mortality o 

 Marshall Fa 

 low (6%). 

 in Aphidole 

 The Marshal 

 Guthion tre 

 lb/100 gal. 

 which Aphid 

 had not rec 



nt mortality was gener 

 Ichertown population) 

 the eggs, respectively 

 ely toxic to Aphidolet 

 Guthion to Apnidolete 

 f eggs collected from 

 rm in Fitchburg, MA an 

 Thus, differential Gut 

 tes populations collec 

 1 Farm apple orchard i 

 atments annually for 7 

 The section of the B 

 oletes eggs were colle 

 eived insecticide or m 



ally low with the exception of the 

 and Sevin treatments, where 861 

 , failed to hatch. Phosphamidon 

 es eggs. In contrast to the high 

 s eggs collected from Belchertown, 

 a" commercial apple orchard at 

 d treated with Guthion was very 

 hion resistance appears to exist 

 ted from 2 areas of the state, 

 n Fitchburg has received 7 to 8 



years at the dosage rate of 1/2 

 elchertown apple orchard from 

 cted for use in toxicity tests 

 iticide treatments for 6 years. 



