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ladibird (30)
marjan
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Coccinellids are typically predators on Hemiptera such as aphids and scale insects, though members of the subfamily Epilachninae are herbivores, and can be very destructive agricultural pests (e.g., the Mexican bean beetle). While they are often used as biological control agents, introduced species of ladybugs (such as Harmonia axyridis or Coccinella septempunctata in North America) can outcompete and displace native coccinellids, and become pests in their own right.
Coccinellids are often brightly coloured to ward away potential predators. This defence works because most predators associate bright colours (especially orange and black or yellow and black) with poison and other unpleasant properties. This phenomenon is called aposematism. In fact, most coccinellids are indeed poisonous to smaller predators, such as lizards and small birds; however, a human would have to eat several hundred coccinellids before feeling any effects. Adult coccinellids are able to reflex-bleed hemolymph from their leg joints, releasing their oily yellow toxin with a strong repellent smell. This becomes quite obvious when one handles a coccinellid roughly.
Most Coccinellids mate in the spring or summer, and the female lays a cluster of eggs (numbering from a few to a few hundred, depending on species) as near as possible to an aphid colony. In most species these eggs hatch into a larval state within a week. This state lasts 10–15 days, and they then go into a pupal stage before becoming an adult coccinellid. The entire life cycle of the Coccinellid is only 4–7 weeks. Most ladybird species are univoltine, producing only one generation a year, although some are bivoltine.
Coccinellids lay extra infertile eggs with the fertile eggs. These appear to provide a backup food source for the larvae when they hatch. The ratio of infertile to fertile eggs increases with scarcity of food at the time of egg laying.[1] |
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