Cereal leaf beetle
Encyclopedia
The cereal leaf beetle (Oulema melanopus or Lema melanopa) is a coleopter
, belonging to the family of Chrysomelidae
, and an agricultural pest and biological control
success story. The beetle
is mostly blue-black in color, with an area of deep red just behind the head. The legs are dull orange.
, oat
s, and wheat
, but they are also found on rye
, millet
, rice
, many types of wild grasses
, and new corn
shoots. The beetle has a history as a major crop pest in Europe, Asia, and parts of north Africa, but serious eradication efforts did not begin until the pest began to destroy oat fields in the United States in the 1960s. Insecticide
s were used without success, but when natural enemies of the beetle were discovered, imported, and released in affected fields, the cereal leaf beetle came under control.
The cereal leaf beetle overwinters in fields of wild grasses, and as the weather warms in the spring, it enters cultivated fields and deposits eggs. The larvae emerge and cover themselves with their own excreta to mimic the droppings of birds or other insects. They usually appear as shiny, wet lumps adhered to the surface of leaves. They gorge on the plants, then drop off and pupate in the soil for about three weeks, emerging full-grown to continue feeding on the plants. Both adults and larvae prefer young plant shoots or areas of new growth on established plants. Damage from cereal leaf beetles is apparent when the tips of leaves turn white and the leaves develop white stripes or slits where the beetle has consumed a strip. A field with extensive damage will look frosted or whitewashed.
Parasitoid
s successfully employed against the cereal leaf beetle as agents of biological control include the parasitic wasp
s Diaparsis carinifer, Lemophagus curtus, and Tetrastichus julis, which attack larvae, and Anaphes flavipes, which is an egg parasitoid. Coccinellidae
eat the eggs and larvae.
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
, belonging to the family of Chrysomelidae
Leaf beetle
Beetles in the family Chrysomelidae are commonly known as leaf beetles. This is a family of over 35,000 species in more than 2,500 genera, one of the largest and most commonly encountered of all beetle families....
, and an agricultural pest and biological control
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
success story. The beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
is mostly blue-black in color, with an area of deep red just behind the head. The legs are dull orange.
Overview
The most common host plants of the cereal leaf beetle are barleyBarley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...
, oat
Oat
The common oat is a species of cereal grain grown for its seed, which is known by the same name . While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed...
s, and wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
, but they are also found on rye
Rye
Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...
, millet
Millet
The millets are a group of small-seeded species of cereal crops or grains, widely grown around the world for food and fodder. They do not form a taxonomic group, but rather a functional or agronomic one. Their essential similarities are that they are small-seeded grasses grown in difficult...
, rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
, many types of wild grasses
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
, and new corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
shoots. The beetle has a history as a major crop pest in Europe, Asia, and parts of north Africa, but serious eradication efforts did not begin until the pest began to destroy oat fields in the United States in the 1960s. Insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s were used without success, but when natural enemies of the beetle were discovered, imported, and released in affected fields, the cereal leaf beetle came under control.
The cereal leaf beetle overwinters in fields of wild grasses, and as the weather warms in the spring, it enters cultivated fields and deposits eggs. The larvae emerge and cover themselves with their own excreta to mimic the droppings of birds or other insects. They usually appear as shiny, wet lumps adhered to the surface of leaves. They gorge on the plants, then drop off and pupate in the soil for about three weeks, emerging full-grown to continue feeding on the plants. Both adults and larvae prefer young plant shoots or areas of new growth on established plants. Damage from cereal leaf beetles is apparent when the tips of leaves turn white and the leaves develop white stripes or slits where the beetle has consumed a strip. A field with extensive damage will look frosted or whitewashed.
Parasitoid
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
s successfully employed against the cereal leaf beetle as agents of biological control include the parasitic wasp
Wasp
The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...
s Diaparsis carinifer, Lemophagus curtus, and Tetrastichus julis, which attack larvae, and Anaphes flavipes, which is an egg parasitoid. Coccinellidae
Coccinellidae
Coccinellidae is a family of beetles, known variously as ladybirds , or ladybugs . Scientists increasingly prefer the names ladybird beetles or lady beetles as these insects are not true bugs...
eat the eggs and larvae.