Larra bicolor
Encyclopedia
Larra bicolor is a parasitoid
wasp
native to South America
. After two unsuccessful attempts, it was introduced successfully into a limited area of Florida
in 1981 as an biological pest control
of invasive mole cricket
s.
Scapteriscus, stinging them on the underside to paralyze them for several minutes. A single egg is deposited between the first and second pairs of legs. The wasp then flies off, and the cricket returns to its burrow. Nymph
s as well as adult crickets are attacked, as long as they are large enough.
Upon hatching, the larva
feeds upon its host, eventually killing it. It pupates within 12 to 30 days (depending on temperature), forming a cocoon in the remains of the cricket by gluing sand grains together. The pupa
l phase may be as short as 50 days, but the pupa may enter diapause
in the winter, delaying emergence for months. Adults are solitary and do not form nests or colonies.
Other than the winter diapause mentioned above, there is no seasonal component to wasp activity. Several generations of wasps may occur in a year, one of the facets that allows these wasps to out-reproduce their hosts, an important attribute for a successful biological control agent.
, at least as early as the 18th century, probably by flight, and as early as 1899 in the southeastern United States, probably as contaminants of ship ballast. They became serious pests, damaging crops and pasture- and turfgrasses. Although the related L. analis attacks native mole crickets, it does not attack non-native species. In an early example of biological pest control, L. bicolor was introduced into Puerto Rico in 1938, where it became successfully established. This suggested the possibility of its use on the mainland; however, failed attempts and the development of chlordane
pesticide
in the 1940s brought an end to these efforts.
When chlordane use on food crops was banned in 1978, the Florida legislature inaugurated a program at the University of Florida
to find alternative controls for pest mole crickets. Budgetary limitations led to a repetition of the Puerto Rico to the mainland effort. But this population, which originated in Brazil, failed to establish itself except in an area around Fort Lauderdale. Research suggested that these wasps were insufficiently cold-tolerant, and a second effort in 1988-89 used wasps from Bolivia
. This introduction was much more successful, and the wasps have gradually spread through most of the state and into neighboring states. They remain highly adapted to the non-native species and have not diversified to attack (for instance) the native mole cricket. Also, they are non-aggressive, and their sting is reported to be mild compared to more familiar wasps. The principal limitation in its use as a biological control agent has been the need to find appropriate nectar sources for the adults. Research has found that some other plants, especially pentas
, are also found acceptable; nonetheless provision of suitable plants is necessary.
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...
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...
native to South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. After two unsuccessful attempts, it was introduced successfully into a limited area of Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
in 1981 as an biological pest 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...
of invasive mole cricket
Mole cricket
The mole crickets compose family Gryllotalpidae, of thick-bodied insects about long, with large beady eyes and shovel-like forelimbs highly developed for burrowing and swimming. They can also fly: the adult mole cricket may fly as far as during mating season, is active most of the year, and...
s.
Description
Adult females of this species are about 22 mm long, with the males somewhat smaller. The head and thorax are black, with silver markings on the former; the abdomen is red. The wings are variable in color, of a dusky hue.Life cycle
These wasps feed on nectar as adults, with the shrubby false buttonweed (Spermacoce verticillata) preferred. Females hunt mole crickets in the genusGenus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Scapteriscus, stinging them on the underside to paralyze them for several minutes. A single egg is deposited between the first and second pairs of legs. The wasp then flies off, and the cricket returns to its burrow. Nymph
Nymph
A nymph in Greek mythology is a female minor nature deity typically associated with a particular location or landform. Different from gods, nymphs are generally regarded as divine spirits who animate nature, and are usually depicted as beautiful, young nubile maidens who love to dance and sing;...
s as well as adult crickets are attacked, as long as they are large enough.
Upon hatching, the larva
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...
feeds upon its host, eventually killing it. It pupates within 12 to 30 days (depending on temperature), forming a cocoon in the remains of the cricket by gluing sand grains together. The pupa
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...
l phase may be as short as 50 days, but the pupa may enter diapause
Diapause
Diapause is the delay in development in response to regularly and recurring periods of adverse environmental conditions. It is considered to be a physiological state of dormancy with very specific initiating and inhibiting conditions...
in the winter, delaying emergence for months. Adults are solitary and do not form nests or colonies.
Other than the winter diapause mentioned above, there is no seasonal component to wasp activity. Several generations of wasps may occur in a year, one of the facets that allows these wasps to out-reproduce their hosts, an important attribute for a successful biological control agent.
Biological pest control use
Non-native mole crickets arrived in Puerto RicoPuerto Rico
Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...
, at least as early as the 18th century, probably by flight, and as early as 1899 in the southeastern United States, probably as contaminants of ship ballast. They became serious pests, damaging crops and pasture- and turfgrasses. Although the related L. analis attacks native mole crickets, it does not attack non-native species. In an early example of biological pest control, L. bicolor was introduced into Puerto Rico in 1938, where it became successfully established. This suggested the possibility of its use on the mainland; however, failed attempts and the development of chlordane
Chlordane
Chlordane, or chlordan, is an organochlorine compound that was used as a pesticide. This white solid was sold in the U.S. until 1983 as an insecticide for crops like corn and citrus and on lawns and domestic gardens.-Production and uses:...
pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
in the 1940s brought an end to these efforts.
When chlordane use on food crops was banned in 1978, the Florida legislature inaugurated a program at the University of Florida
University of Florida
The University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
to find alternative controls for pest mole crickets. Budgetary limitations led to a repetition of the Puerto Rico to the mainland effort. But this population, which originated in Brazil, failed to establish itself except in an area around Fort Lauderdale. Research suggested that these wasps were insufficiently cold-tolerant, and a second effort in 1988-89 used wasps from Bolivia
Bolivia
Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...
. This introduction was much more successful, and the wasps have gradually spread through most of the state and into neighboring states. They remain highly adapted to the non-native species and have not diversified to attack (for instance) the native mole cricket. Also, they are non-aggressive, and their sting is reported to be mild compared to more familiar wasps. The principal limitation in its use as a biological control agent has been the need to find appropriate nectar sources for the adults. Research has found that some other plants, especially pentas
Pentas
Pentas is a genus of the Rubiaceae family of flowering plants. Pentas lanceolata is a particularly popular species. The plants have dark green, lance-shaped, somewhat furry and deeply veined leaves providing a backdrop for prolific clusters of never-ending, five-petaled flowers. These may be red,...
, are also found acceptable; nonetheless provision of suitable plants is necessary.
External links
- Larra wasps, mole cricket hunters on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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