Date of Award:

5-1-1973

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology (Entomology)

Committee Chair(s)

William A. Brindley

Committee

William A. Brindley

Committee

G. E. Bohart

Committee

D. W. Davis

Committee

L. C. Ellis

Committee

R. P. Sharma

Abstract

Carbaryl penetration into and metabolism by adult alfalfa leafcutting bees, Megachile pacifica (Panzer), was studied in relation to sex, age, exposure to piperonyl butoxide, and after feeding with chlorcyclizine, phenobarbital, or aminopyrine. Specifically the study included 1- and 4-day-old male bees and 4-day-old female bees representing LD50 values of about 240, 51, and 262 µg/gm and carbaryl-piperonyl butoxide synergist ratio of 12, 53, and 15, respectively. Penetration rates/hour and percent penetrated were calculated for the first 8 hours after application. More carbaryl penetrated more rapidly into the most sensitive insects, but the differences were not statistically significant. Piperonyl butoxide, and aminopyrine slightly increased the percent of carbaryl penetrated after 4 hours in both sexes while chlorcyclizine and phenobarbital very slightly decreased penetration. Unchanged carbaryl was the principal compound isolated from the bees after 4 hours, being more prominent in 4-day-old males (48% of extractable metabolites) and less prominent in 4-day-old females (22%) and 1-day-old males (26%). Recovery of carbaryl based on the total applied ranged from 5. 8% to 14.1%. Hydroxylation products, totally blocked in formation by piperonyl butoxide pretreatment to 1-day-old males and 4-day-old females, accounted for the metabolites of the organic-solvent extract. The 4, 5, and 5 + 6 position of the naphthyl ring were most susceptible to hydroxylation. Hydroxylation products accumulated with time only in 4-day-old males indicating less extensive metabolism or conjugation. Hydrolysis to 1-naphthol was less prominent as a detoxication mechanism and relatively more accumulated in 4-day-old male bees (3. 75% total metabolites, 1.11% total dose). 1-Naphthol, N-hydroxycarbaryl, 5, 6- dihydro-5, 6-dihydroxycarbaryl, 5-hydroxycarbaryl, and carbaryl were recovered from acid hydrolysis of water-soluble conjugates. Two minor organosoluble metabolites were not identified as were none of the conjugating moieties. Aminopyrine administration markedly enhanced carbaryl persistance in the bees, which may have been responsible for its tendency to make the bees less tolerant, and in fact exceeded piperonyl butoxide in its effect in extending carbaryl persistance. Chlorcyclizine and phenobarbital both led to less persistance (from 1. 8 to ca .5% of the total extracted metabolites) of unchanged carbaryl in both sexes. None of the drugs were particularly effective in stimulating detoxication activities in the male bees. In general, there is a correlation between the amount of unchanged carbaryl in the organosoluble fraction and the toxicity of carbaryl to the bee.

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