Negative Allometry for Egg Size in Ladybeetles (Coleoptera:Coccinellidae):Trade-Off between Egg Hatch Time and Size

Similar to a wide range of other organisms, large species of predatory ladybeetles lay proportionally small eggs when compared to smaller species. This study determines whether egg size in aphidophagous lady beetles is constrained by the time it takes for the eggs to hatch. The eggs of the large species, Anisolemnia dilatata (168 mg), and small species of ladybeetle, Coccinella septempunctata (27 mg), were collected immediately after they were laid, separated from one another and weighed. The time for the egg to hatch was determined at 22°C. As predicted, the eggs of the large species were a smaller proportion (0.0048) of their mother’s weight when compared to the eggs of the small species (0.0061). On an average, the eggs of the large species were about 4.9 times heavier and took 1.31 times longer to hatch than those of small species. These results indicate that in insects and aphidophagous ladybeetles, in particular, egg hatch time is not directly proportional to the egg size and reproduction may involve more than a trade-off between the number of eggs and size. It is likely that egg hatch time is a constraining factor and an important determinant of the inter-specific negative allometry for egg size in this group of insects.