''Hippodamia convergens'', commonly known as the convergent lady beetle, is one of the most common

lady beetles Coccinellidae () is a widespread family of small beetles ranging in size from . They are commonly known as ladybugs in North America and ladybirds in Great Britain. Some entomologists prefer the names ladybird beetles or lady beetles as they ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

and is found throughout the continent.

Aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s form their main diet and they are used for the biological control of these pests.

Range

Convergent lady beetles are native to North America, but have also been imported and established in South America by importing beetles from California.

Life cycle

The female lady beetle lays 200 to 300

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 ...

over several months during spring and early summer. The eggs are small and spindle-shaped and are laid near the prey in upright batches of fifteen to thirty eggs. The

larva A larva (; plural larvae ) 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. The ...

e are dark and somewhat alligator-shaped.Cornell University
/ref> Once the larvae begin feeding, they grow quickly and molt four times over a period of up to a month. The

pupal 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 their ...

stage lasts about a week and mating takes place soon after adult

eclosion 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 their ...

. If the food supply is abundant, the female may start laying within about a week of mating, but if it is scarce, she may wait for up to nine months.

Biology

The first larvae that hatch in each batch may start by eating the unhatched eggs. This may provide energy for the larvae before they find any aphids. Fourth-

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

larvae may consume about fifty aphids per day and adults may eat about twenty. When aphids are scarce, the adults can eat honeydew,

nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists ...

and

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

or even petals and other soft parts of plants. However they must consume aphids in order to reproduce. In the western United States, these beetles may spend up to nine months in

diapause In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...

in large aggregations in mountain valleys, far from their aphid food sources. In spring, the adults spread out and search for suitable sites to lay their eggs where aphids are plentiful. This dispersal trait is especially marked in this species as compared to other lady beetles.

Biological control

Convergent lady beetles are also used for augmentative biological control to temporarily increase predator numbers to control aphids. The species is available commercially in North America, but because of the overwintering habits of non-reproductive adults, released beetles tend to quickly disperse from their release site. Adults released in enclosed settings such as greenhouses can contribute to lower aphid numbers.

Natural enemies

Entomopathogenic fungi An entomopathogenic fungus is a fungus that can kill or seriously disable insects. Typical life cycle These fungi usually attach to the external body surface of insects in the form of microscopic spores (usually asexual, mitosporic spores als ...

used as biopesticides such as ''

Metarhizium anisopliae ''Metarhizium robertsii'' formerly known as ''M. anisopliae'', and even earlier as ''Entomophthora anisopliae'' (basionym) is a fungus that grows naturally in soils throughout the world and causes disease in various insects by acting as a paras ...

'', '' Paecilomyces fumosoroseus'', and ''

Beauveria bassiana ''Beauveria bassiana'' is a fungus that grows naturally in soils throughout the world and acts as a parasite on various arthropod species, causing white muscardine disease; it thus belongs to the entomopathogenic fungi. It is used as a biological ...

'' can also infect larvae.

References

External links

* http://www.ipm.ucdavis.edu/PMG/NE/convergent_lady_beetle.html * http://www.biocontrol.entomology.cornell.edu/predators/ladybeetles.html
OSU Agricultural Extension Fact Sheet - ENT-45
* http://bugguide.net/node/view/8374
Convergent Lady Beetle Video on Vimeo
Macro videography of Convergent Lady Beetle colony {{Taxonbar, from=Q1938912 Coccinellidae Insects used as insect pest control agents Biological pest control beetles Beetles of North America Beetles described in 1842