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Abstract
SUMMARY: At 21°, conidia of Entomophthora thaxteriana were first discharged from infected pea aphids about 6 to 9 h. after the aphids died and the rate of discharge was highest during a short period about 9 h. later. In constant light, the rate then decreased and discharge ended about 36 h. after an infected aphid died; in constant darkness the maximum rate (2 × 103 conidia/h./aphid) was only one-quarter of that in constant light but it was maintained for 10 h. In alternating 12 h. light, 12 h. darkness, the rate of conidium discharge increased substantially 2 h. after the admission of light and much decreased 2 h. after light was excluded. In constant light, the average number of conidia discharged from one adult apterous aphid was at least 105, twice that in constant darkness. Discharge of conidia began earliest at 20° but the rate of discharge was highest at 25°. Ultimately, similar numbers of conidia were discharged at any temperature from 5 to 25°; conidia were not discharged at 0 or 30°.
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