Number of ovarioles and fecundity in the black bean aphid, aphis fabae
1980
DIXON, A.F.G. | DHARMA, T.R.
The number of ovarioles in the gonads of the host alternating aphid, Aphis fabae Scop., is not constant. The apterous generations on spindle, emigrants and initial apterous colonists of the secondary host each have a characteristic range of number of ovarioles; subsequent generations in the yearly life cycle have twelve, except for alate exules which have a range and the lowest average number of ovarioles. Ovariole number is programmed and is not a function of adult weight or food quality. The generations with the largest number of ovarioles have the greatest fecundity, highest reproductive rate and smallest offspring, and develop early in the season when the environment is favourable. Later generations have a low fecundity and proportionately more fat, a possible adaptation to the harsher environment these aphids experience.
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