Spotted lady beetle
Encyclopedia
Coleomegilla maculata, commonly known as the spotted lady beetle, pink spotted lady beetle or twelve-spotted lady beetle, is a large coccinellid
beetle
native to North America. The adults and larvae feed primarily on aphid
s and the species has been used as a biological control agent
.
. The thorax is a similar shade of red with two large triangular black patches. The larvae
resemble miniature alligators and are dark coloured. They have three pairs of legs and grow to about six millimetres long. The eggs
are spindle shaped and laid upright in groups near potential prey
.
actively seek out prey and may travel as far as twelve metres in their search for food. The larvae grow rapidly, moulting four times before attaching themselves by the abdomen to a leaf or other surface to pupate
. The adult beetles emerge from three to twelve days later depending on the temperature. There are two to five generations per year. This species is most abundant in September when they congregate before mating and winter hibernation
. They overwinter in large aggregations in leaf litter, under stones and in other protected sites at the edge of fields and hedgerows. They emerge in spring and look for suitable prey and egg laying sites in nearby crop
s, often dispersing by walking along the ground.
, sorghum
, sweet corn, alfalfa
, soybean
s, pea
s, bean
s, cotton
, potato
es, brassicacious
crops, tomato
es, asparagus
and apple
s. Besides aphids, they include in their diet adelgids
, mite
s, insect
eggs and small larvae. They also eat pollen
which may constitute up to 50% of their food intake, nectar, water and honeydew
. When normal prey is scarce, both adults and larvae sometimes exhibit cannibalistic
tendencies, eating eggs, larvae and pupae of their own species.
, Taraxacum officinale, encouraged predation
on aphids because the spotted lady beetles were attracted to their pollen-rich flowers.
The spotted lady beetle commonly oviposit
s on the native weed, Acalypha ostryaefolia
, when it grows near sweet corn crops in Kentucky. A research study showed that the insect favoured the weed over the corn even though it housed no prey insects. The first instar larvae fell from the weed plants and crawled across the soil for a distance of up to eight metres a day before ascending a sweet corn plant or another weed plant. The presence of this weed, in close proximity to the crop, resulted in more beetle larvae on the crop than was the case when the weed was absent.
Research showed that spotted lady beetle larvae were an important cause of natural mortality for Helicoverpa zea
eggs on sweet corn.
A study identified the spotted lady beetle as a significant predator of the eggs of the European corn borer, Pyrausta nubilalis, with consumtion averaging sixty eggs per day.
Another study has shown that the spotted lady beetle reduced populations of eggs and small larvae of the Colorado potato beetle
, Leptinotarsa decemlineata, on potatoes and that the rate of consumption was highly correlated with the air temperature.
Augmentative biological control recognises that lady beetles may be present but may be insufficient in numbers to control the pest species and seeks to make up this deficit.
Classical biological control seeks to introduce a species that is not already present in the environment in the hope that it will become established and eventually control the pest. Supplies of the spotted lady beetle are available commercially for this purpose.
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...
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...
native to North America. The adults and larvae feed primarily on aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...
s and the species has been used as a biological control agent
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...
.
Description
The spotted lady beetle is about six millimetres long, more flattened than most species of lady beetle, pink or red with six spots on each wing coverElytron
An elytron is a modified, hardened forewing of certain insect orders, notably beetles and a few of the true bugs ; in most true bugs, the forewings are instead called hemelytra, as only the basal half is thickened while the apex is membranous...
. The thorax is a similar shade of red with two large triangular black patches. The larvae
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
resemble miniature alligators and are dark coloured. They have three pairs of legs and grow to about six millimetres long. The eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
are spindle shaped and laid upright in groups near potential prey
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
.
Life cycle
A female beetle may lay up to 1,000 eggs in small groups in protected sites on stems and leaves over a three month period. The larvaeLarva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
actively seek out prey and may travel as far as twelve metres in their search for food. The larvae grow rapidly, moulting four times before attaching themselves by the abdomen to a leaf or other surface to pupate
Pupa
A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...
. The adult beetles emerge from three to twelve days later depending on the temperature. There are two to five generations per year. This species is most abundant in September when they congregate before mating and winter hibernation
Hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...
. They overwinter in large aggregations in leaf litter, under stones and in other protected sites at the edge of fields and hedgerows. They emerge in spring and look for suitable prey and egg laying sites in nearby crop
Crop
Crop may refer to:* Crop, a plant grown and harvested for agricultural use* Crop , part of the alimentary tract of some animals* Crop , a modified whip used in horseback riding or disciplining humans...
s, often dispersing by walking along the ground.
Habitat
These lady beetles can be seen wherever the insects on which they prey are found. Crops which support aphid populations include wheatWheat
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...
, sorghum
Sorghum
Sorghum is a genus of numerous species of grasses, one of which is raised for grain and many of which are used as fodder plants either cultivated or as part of pasture. The plants are cultivated in warmer climates worldwide. Species are native to tropical and subtropical regions of all continents...
, sweet corn, alfalfa
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...
, soybean
Soybean
The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...
s, pea
Pea
A pea is most commonly the small spherical seed or the seed-pod of the pod fruit Pisum sativum. Each pod contains several peas. Peapods are botanically a fruit, since they contain seeds developed from the ovary of a flower. However, peas are considered to be a vegetable in cooking...
s, bean
Bean
Bean is a common name for large plant seeds of several genera of the family Fabaceae used for human food or animal feed....
s, cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
, potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...
es, brassicacious
Brassica
Brassica is a genus of plants in the mustard family . The members of the genus may be collectively known either as cabbages, or as mustards...
crops, tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
es, asparagus
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...
and apple
Apple
The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...
s. Besides aphids, they include in their diet adelgids
Adelgidae
The Adelgidae is a small family of the Homoptera closely related to the aphids, and often traditionally included in the Aphidoidea with the Phylloxeridae. Adelgids are often known as "woolly conifer aphids". The family is composed of species associated with pine spruce or other conifers, known...
, mite
Mite
Mites, along with ticks, are small arthropods belonging to the subclass Acari and the class Arachnida. The scientific discipline devoted to the study of ticks and mites is called acarology.-Diversity and systematics:...
s, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
eggs and small larvae. They also eat pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
which may constitute up to 50% of their food intake, nectar, water and honeydew
Honeydew (secretion)
Honeydew is a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap. When their mouthpart penetrates the phloem, the sugary, high-pressure liquid is forced out of the gut's terminal opening. Honeydew is particularly common as a secretion in the Hemipteran...
. When normal prey is scarce, both adults and larvae sometimes exhibit cannibalistic
Cannibalism
Cannibalism is the act or practice of humans eating the flesh of other human beings. It is also called anthropophagy...
tendencies, eating eggs, larvae and pupae of their own species.
Research
It has been found experimentally that interplanting a crop susceptible to aphid attack with a flowering plant such as the dandelionTaraxacum officinale
Taraxacum officinale, the common dandelion , is a herbaceous perennial plant of the family Asteraceae . It can be found growing in temperate regions of the world, in lawns, on roadsides, on disturbed banks and shores of water ways, and other areas with moist soils. T...
, Taraxacum officinale, encouraged predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
on aphids because the spotted lady beetles were attracted to their pollen-rich flowers.
The spotted lady beetle commonly oviposit
Oviposition
Oviposition is the process of laying eggs by oviparous animals.Some arthropods, for example, lay their eggs with an organ called the ovipositor.Fish , amphibians, reptiles, birds and monetremata also lay eggs....
s on the native weed, Acalypha ostryaefolia
Acalypha ostryaefolia
Acalypha ostryifolia is a plant in the Euphorbiaceae family and is commonly known as hophornbeam copperleaf or pineland three-seed mercury. It is a native of North and Central America and is generally considered a weed.-Distribution:A...
, when it grows near sweet corn crops in Kentucky. A research study showed that the insect favoured the weed over the corn even though it housed no prey insects. The first instar larvae fell from the weed plants and crawled across the soil for a distance of up to eight metres a day before ascending a sweet corn plant or another weed plant. The presence of this weed, in close proximity to the crop, resulted in more beetle larvae on the crop than was the case when the weed was absent.
Research showed that spotted lady beetle larvae were an important cause of natural mortality for Helicoverpa zea
Helicoverpa zea
The larva of the moth Helicoverpa zea is a major agricultural pest. It can feed on many different plants during the larval stage. Accordingly, the species has been given many different common names. When the larva consumes cotton, it is known as the cotton bollworm...
eggs on sweet corn.
A study identified the spotted lady beetle as a significant predator of the eggs of the European corn borer, Pyrausta nubilalis, with consumtion averaging sixty eggs per day.
Another study has shown that the spotted lady beetle reduced populations of eggs and small larvae of the Colorado potato beetle
Colorado potato beetle
The Colorado potato beetle , also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle or the potato bug, is an important pest of potato crops. It is approximately 10 mm long, with a bright yellow/orange body and five bold brown stripes along the length of each...
, Leptinotarsa decemlineata, on potatoes and that the rate of consumption was highly correlated with the air temperature.
Biological control
Manipulative biological control aims to make use of the lady beetles already present in the environment by making conditions as favorable as possible for them and by avoiding spraying chemicals that will interfere with their predation.Augmentative biological control recognises that lady beetles may be present but may be insufficient in numbers to control the pest species and seeks to make up this deficit.
Classical biological control seeks to introduce a species that is not already present in the environment in the hope that it will become established and eventually control the pest. Supplies of the spotted lady beetle are available commercially for this purpose.