Ovarian dynamics and specialisation in ladybirds

Generalist predatory insects that exploit unpredictable and ephemeral prey should allocate metabolic resources differently to soma and gonads than specialist species. As the former have more opportunities to encounter a wide array of prey than specialists, the expectation is that they will more rapidly resorb oocytes when food is scarce. By doing so, they reallocate resources to the soma to support the search for oviposition sites of a better quality. Similarly, they are expected to resume oogenesis faster than the specialist when good conditions return. 2. This hypothesis was tested by comparing a generalist and a specialist ladybird species belonging to the same genus. 3. A resorption index was calculated for females of both species subjected to several starvation regimes. This index indicated that over a period of fasting of 3 days, the intensity of resorption was greater in the generalist than the specialist. When food was again supplied, oogenesis resumed and within 1 day was faster in the generalist than in the specialist. 4. As predicted, the resorption of oocytes and replenishment occurred faster in the generalist than in the specialist species. This is the first time, to our knowledge, that the speed and intensity of the ovarian dynamics of a predatory insect have been linked to its way of life.