ADLib Glossary (B)

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Beneficial Insects - Carabidae Beetles

Carabid beetles, or Ground beetles as they are also known, are one of the largest and most successful families of beetles in the world. More than 30% of species are arboreal, though in general temperate species are terrestrial, most are also flightless and predatory. Field carabids are abundant on arable sites but numbers are affected by intensive agricultural cultivations.

They tend to live on the ground under leaves, logs, stones, in soil cracks and other debris.

Most carabids are omnivorous (feeding on both plants and animals) and polyphagous (being able to use a wide range of foods), feeding on live prey, carrion and plant material. Some species however are specialist feeders, i.e. Harpalus rufipes (the Strawberry Seed Beetle) on seeds and Cychrus caraboides on slugs and snails. The larvae are always carnivorous if the adults are. Many Carabids find their food by random foraging, but specialist feeders tend to use chemical cues.

From laboratory feeding records Carabids are known to have many beneficial activities in the area of arable pest control. They have been shown to reduce cereal and sugar beet aphid populations, although predation on the cabbage root fly may have been over estimated in the early literature. As Carabids are sensitive to habitat quality they are useful bio-indicators of soil impacts by cultivation. They may suffer negative effects from deep ploughing and positive effects from reduced tillage systems. They can be encouraged on site by green manuring and sound organic fertilisation.

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