''Delia floralis'', commonly known as the turnip root fly or summer cabbage fly, is a cosmopolitan pest of crops. The larvae or

maggots A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera flies, such as houseflies, cheese flies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and crane flies. Entom ...

feed on the roots of various plants in the family

Brassicaceae Brassicaceae () or (the older) Cruciferae () is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous plants, while some are shrubs. The leav ...

Morphology and biology

This species resembles the closely related

cabbage root fly ''Delia radicum'', known variously as the cabbage fly, cabbage root fly, root fly or turnip fly, is a pest of crops. The larvae of the cabbage root fly are sometimes known as the cabbage maggot or root maggot. The adult flies are about 1 c ...

in appearance though it is slightly larger at seven to eight millimetres long. The body is light gray and the yellowish wings are transparent with yellow veins. Over most of its range, there is only one generation of this fly each year. The

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

are laid seven to ten days after the adult has emerged from the

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...

. They are white and cigar-shaped and are laid in groups of thirty or forty eggs at the root collar of the host plant or on the ground nearby. Often several females lay eggs on one plant. The glossy white or yellow larvae hatch in five to fourteen days. They feed for about forty days, moulting three times, eating the young roots or tunneling into the main root of the host plantAgroAtlas
/ref> or even penetrating into the basal part of the leaves of hearting cabbage. The pupae are brown and about six millimetres in length. The insect overwinters as a pupa in the ground at a depth of five centimetres or more.
/ref> The pupae can endure frosts of -33 °C and in the following year the adults emerge at varying dates, doing so when the soil temperature reaches 18 °C at the depth of the pupae.

Distribution

The turnip root fly is found in

Western Europe Western Europe is the western region of Europe. The region's countries and territories vary depending on context. The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the ancient Mediterranean ...

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

Northeast China Northeast China or Northeastern China () is a geographical region of China, which is often referred to as "Manchuria" or "Inner Manchuria" by surrounding countries and the West. It usually corresponds specifically to the three provinces east of ...

Korea Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic o ...

, Japan and North America.

Economic significance

The larvae damage the roots of cabbage, turnip, radish, swede and other cruciferous crops. The growth of damaged plants is slow and development is poor resulting in a reduced yield. Large scale attacks cause cessation of growth with the plants exhibiting a leaden hue and wilting, subsequently turning yellow and dying. Control measures include the early planting of strong plants, the use of peat-compost pots, the use of additional fertilizer, deep autumn ploughing after the harvesting of cruciferous crops and insecticide treatments.

Research

* A study made in 1993 investigated the behavioural and neural mechanisms involved in the oviposition behaviour of the turnip root fly. * A study made in 2002 investigated the mortality rates of the eggs and larvae of the turnip root fly when treated with an insect pathogenic hyphomycetous fungus. * A study made in 2008 investigated the combined effect of intercropping and attack by turnip root fly larvae on the level of glucosinolates in the host plant.''Combined Effect of Intercropping and Turnip Root Fly (Delia floralis) Larval Feeding on the Glucosinolate Concentrations in Cabbage Roots and Foliage.''
/ref>

References

{{Taxonbar, from=Q4260197 Anthomyiidae Agricultural pest insects Diptera of Asia Insects described in 1824