domingo, 18 de setembro de 2011

Habitats


Coccinellids are generally considered beneficial to gardeners, as they typically eat aphids, scale insects, mealybugs, and mites throughout the winter. As in many insects, ladybugs in temperate regions enter diapause during the winter, so they often are among the first insects to appear in the spring. Some species  gather into groups and move to higher land, such as a mountain, to enter diapause. Predatory ladybugs are usually found on plants where aphids or scale insects are, and they lay their eggs near their prey, to increase the likelihood the larvae will find the prey easily. Ladybugs are cosmopolitan in distribution, as are their prey.
Coccinellids also require a source of pollen for food and are attracted to specific types of plants. The most popular ones are any type of mustard plant, as well as other early blooming nectar and pollen sources, like buckwheat, coriander, red or crimson clover, and legumes like vetches, and also early aphid sources, such as bronze fennel, dill, coriander, caraway, angelica, tansy, yarrow, of the wild carrot family, Apiaceae. Other plants that also attract ladybugs include coreopsis, cosmos, dandelions and scented geraniums.
Coccinellids are sensitive to most synthetic insecticides. If food sources are limited, oviposition is reduced. A larva uses its sharp jaws to crush an aphid's body and sucks out the aphid's juices.

sábado, 17 de setembro de 2011

Biology

 Coccinellids are typically predators of Hemiptera such as aphids and scale insects, though larvae and eggs of their own species can also be important resources when alternative prey are scarce. Members of the subfamily Epilachninae are herbivores, and can be very destructive agricultural pests . While predatory species are often used as biological controlagents, introduced species of ladybirds (such as Harmonia axyridis or Coccinella septempunctata in North America) outcompete and displace native coccinellids and become pests in their own right. Coccinellids are often brightly colored to ward away potential predators.
  Mechanical stimulation (such as by predator attack) causes "reflex bleeding" in both larval and adult lady beetles, in which an alkaloid toxin is exuded through the joints of the exoskeleton, deterring feeding. Lady beetles, as well as other Coccinellids are known to spray a toxin that is venomous to certain mammals and other insects when threatened. 
  Most coccinellids overwinter as adults, aggregating on the south sides of large objects such as trees or houses during the winter months, dispersing in response to increasing day length in the spring. In Harmonia axyridis, eggs hatch in 3–4 days from clutches numbering from a few to several dozen. Depending on resource availability, the larvae pass through four instars over 10–14 days, after which pupation occurs. After a teneral period of several days, the adults become reproductively active and are able to reproduce again, although they may become reproductively quiescent if eclosing late in the season. Total life span is 1–2 years on average.

quinta-feira, 15 de setembro de 2011

Coccinellidae



Coccinellidae is a family of beetles. Coccinellids are small insects, ranging from 1 mm to 10 mm (0.04 to 0.4 inches), and are commonly yellow, orange, or scarlet with small black spots on their wing covers, with black legs, head and antennae. A very large number of coccinellid species are mostly, or entirely, black, grey, or brown and may be difficult for non-entomologists to recognize as coccinellids. Conversely, there are many small beetles that are easily mistaken for coccinellids, such as the tortoise beetles.
   Coccinellids are found worldwide, with over 5,000 species described, more than 450 native to North America  alone. A few species are considered pests in North America and Europe, but they are generally considered useful insects as many species feed on aphids or scale insects, which are pests in gardens, agricultural fields, orchards, and similar places. Harmonia axyridis (or the Harlequin ladybug) was introduced into North America from Asia in 1988 to control aphids but is now the most common species as it is out-competing many of the native species. It has since spread to much of western Europe, reaching the UK in 2004. A common myth is that the number of spots on the insect's back indicates its age.