Alfalfa Plant Bug

Appearance

Adelphocoris lineolatus have an elongated body shape and are large in body size. Alfalfa plant bug males body size ranges from, 8.3-9.5 millimetres. Whereas, the females are a little bit smaller than the males having a body size between, 7.6 and 8.3 millimetres.

Their antennae are usually the same length as their body size, sometimes a bit shorter. A longitudinal brown triangle is located on the middle of their corium.

The scutellum of A. lineolatus have two longitudinal brown lines on the surface. The pronotum of the alfalfa plant bug will have two black spots on it. It commonly observed that their femora are spotted with brown specks. Also, the ocular index between male and female Adelphocoris lineolatus differs. Males have an ocular index of 0.83 millimetres. Whereas, females have an ocular index of 1.5 millimetres.

Certain regions of their bodies are covered with black hairs, and others with pale coloured hairs. The body colour can range from a light green to a pale brown.

Nymphs are green and have red eyes. In A. lineolatus nymphs there is an absence of wings, but in adult species wings are seen.

Naming

In North America "Adelphocoris lineolatus" is an introduced species from Eurasia. The date of introduction is currently unknown but believed to have been in 1917.

Distribution

Native to the Palaearctic. Adventive and widespread in North America.

Adelphocoris lineolatus are an Old World Species native to Western Europe, Northern Africa, Asia, and the Middle East. In 1917, this species had been introduced into Canada and the United States. In the Nearctic ecozone, these insects range from Southern Ontario and Northeastern United States, to the south of North Carolina, and west of Colorado.

Behavior

Adults are attracted to light.

Habitat

Alfalfa plant bugs require a certain set of optimal conditions in order to thrive and become a pest in any country. A. lineolatus are primarily located in humid environments with cold temperatures.

Commonly one can find these plant bugs in either fields or grasslands, in both dry and damp areas. However, alfalfa plant bugs are not successful in salty lakes, deserts, sand dunes, windy weather, or very warm climates.

Adelphocoris lineolatus will easily adapt to cooler environmental conditions, which has allowed them to invade a large amount of territory in Canada.

Reproduction

Alfalfa plant bugs exhibit migratory behaviour, which allows Adelphocoris lineolatus to rapidly increase their population sizes.

Adult females can lay 80 to 300 eggs, into branches and young stems of host plants, females will begin to lay eggs in the end of July. The eggs will develop in 8–12 days, but some of the eggs will overwinter. Eggs that have overwintered in stems, hatch in late May or early June.

Less than five percent of alfalfa plant bug eggs will hatch in the same year they are laid. A majority of the eggs will enter a period of diapause. This causes a decline in the reproductive activity of second-generation adults. The developmental process of A. lineolatus involves five nymphal instars, and between late June and October adults are seen.

Food

Nymphs and adults feed on legumes including alfalfa (Medicago sativa), crownvetch (Securigera varia) and grasses. It is an agricultural pest causing vast amounts of damage to numerous crops, but primarily to alfalfa crops around the globe.

Predators

Nymphs are parasitized by the braconid wasps Peristenus conradi and P. pallipes, which have been used to control of A. lineolatus in the northeastern US.