The Two-spot ladybird (Adalia bipunctata)

The Two-spot ladybird (Adalia bipunctata) is a predatory beetle of the family Coccinellidae. It is very common in the wild, its natural habitat is Western and Central Europe, North America. It is commercially used worldwide to control aphids (primarily cotton, peach, and potato) in open ground and greenhouses. Adalia bipunctata has outstanding mobility and search ability, thanks to which it very effectively suppresses the foci of aphid development in gardens, parks, as well as when growing various vegetables and ornamental plants. Adult individuals of the entomophage can eat not only aphids, but also other pests: mealybugs, spider mites, caterpillars, and eggs of various types of pest.

Appearance

The colour of Two-spot ladybirds can vary from black with yellow dots to orange-yellow and red. Most often, the elytra are red with two or four dark spots, the pattern of which may differ in males and females. The colour of the wings can also be different: there are individuals with wings of black, red and yellow shades.

The body length of an adult beetle reaches 5.5 mm.

Development

The process of development, reproduction, and oviposition of ladybirds occurs close to the food source – aphid colonies.  Eggs are bright orange, about 0.4 mm in size, laid on the underside of the leaf. Depending on the amount of pest, the number of eggs laid can also be different: from 10 to 40 eggs in a group. On average, a female Adalia bipunctata can lay about 500 eggs in her lifetime. The sex ratio is close to 1:1.

Egg development lasts approximately 7 days. After leaving the egg, ladybird individuals go through 4 larval stages, during which their colour changes from black and gray to red. The imago stage is preceded by the pupal stage, which lasts 6-8 days. The temperature range from 24 to 28 degrees with a relative humidity of 70-80% is considered optimal for the development of an entomophage. Insects hunt most actively in the daytime when there is enough light.

Ladybirds spend the cold season in the bark of trees, under stones or fallen leaves, after which they come out of suspended animation with the arrival of heat.

Food

Ladybird larvae are active predators, they start hunting from the L3 and L4 stages and eat up to 150 aphids per day. They have no vision and find their prey by touch. At first, the victims are the younger stages of aphids, then ladybirds begin to actively move and feed on larger individuals.

Application

Depending on the degree of lesion, the application rates of Adalia bipunctata on average range from 1 to 4 individuals per square meter. In the case of many pests, the norm increases up to 10 individuals per plant. The greatest efficiency is achieved when the entomophage is introduced into the foci of aphid development. In this case, entomophages are able to suppress aphid colonies within 7 days from the moment of introduction.

Apply bioagents to plants not later than 18 hours after they had been delivered.