The effect of prey availability on ovarian development and oosorption in the ladybird beetle Harmonia axyridis (Coleoptera: Coccinellidae)
Osawa, N.(Kyoto Univ. (Japan). Lab. of Forest Ecology)E-mail:[email protected]
Four conditions were used to clarify the relationship between food abundance and ovarian development or oosorption in Harmonia axyridis: (1) fully fed for 24 h, (2) 24-h starvation, (3) 48-h starvation, (4) 24-h starvation followed by 24-h re-feeding. Both starvation conditions significantly increased the percentage of oosorptive individuals and ovarioles per female, and significantly decreased the percentage of mature ovarioles. In comparison with starvation, the fourth condition resulted in a significantly higher percentage of mature ovarioles, however, this value remained lower than in fully fed animals. Body length, initial body weight, and the number of ovarioles were significantly correlated with the number of eggs laid during the last 24 h of each experimental condition. The weight of the eggs may be determined by the amount of food digested. The ovarian development and oosorption were asymmetric in the right and left ovaries.
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