Lab Le FL. 
Methyl parathion Methyl paraoxon 
activation degradation 
Plso Pleo 
Animal é 9 b 9 
Mouse 6.6440.04 6.77#0.03 F.15+6.. 06 7.10#0,.01 
Rat POL 210 5.68 .05 Pvl42 01 te 7 401 
Guinea pig 32327 ,OA 5 e720 307 bao> 12 6.917. 200 
Cattle O69" 09 6.104 .02 7.447 .07 703% 208 
Hog 5. 3645.03 Di GG* «02 ao a OP iLO -.03 
Sheep Pad See 450+. 201 Vile 9% OS @.62*.. 10 
Chicken 5.344 .06 bo LES 5 OZ PaO 20S #.308 402 
Duck 6.682 .02 POE ey: soe Od Dees = pe) I 
Studies with insects indicated paths of metabolism similar to that 
of mammals, via paraoxon and/or dealkylation, but at varying rates (500, 
840, 891, 940, 995, 1022, 1096, 1166, 1299). In larvae of the rice stem 
borer, ethyl parathion, ethyl paraoxon, diethyl thiophosphate, and diethyl 
phosphate were found after topical application (818, 819). 
From army worms (Mamestra brassicae, Noctuidae), three enzymatic 
fractions were obtained that were capable of hydrolyzing phosphate esters 
(722, 723). Other studies showed that the fat body of Periplaneta ameri- 
cana L. shared with mammalian liver the ability to convert parathion to 
paraoxon (820). When methylparathion was incubated with preparations from 
mid-gut of horn beetle larvae (Xylotrupes dichotomus L.), both the desmethy] 
analog of methylparathion and phosphoric acid were detected (501). 
267 
