The parasitoid wasp Plesiometa argyra (also known by the taxonomic designation Leucauge argyra), also occurs.is found throughout Costa Rica. An example of suitable habitat for is an African oil palm plantation near Puntarenas Province, where its host spider,
- Other Habitat Features
adults have forewings that are 6 to 14 mm long and vary in color. The wings can be completely black, orange with black markings, patterned with black and yellow, or translucent. The wasp has a black head; slender mandibles that are yellowish brown; large eyes; long, thin antennae; and thin legs (foreleg size varies among individuals).
The sexual dimorphism inis due in part to its egg-laying behavior, which requires the female to grasp its host, sting it, and lay an egg on the abdomen of the host spider. females have well-adapted ovipositors for properly handling eggs and stinging hosts. The ovipositor is not used for laying eggs, but rather to sting, kill, and remove the larvae or eggs of other wasps that previously had laid eggs on a selected host. The ovipositor structure can be straight or slightly upturned, and the ovipositor typically is 1 to 1.4 times longer than the hind tibia. The end of the ovipositor shaft narrows to a distinctly thin point. In addition, females have claws with a large basal lobe, while males have simple claws.
Cocoons often are pale yellow, but have been observed as bright orange in some cases. The color of the cocoon grows darker with time, and the larva is just visible through the thin walls of the cocoon. (Eberhard, 2000b; Gauld, 2000)
- Sexual Dimorphism
- female larger
- sexes shaped differently
- Range wingspan
- 12 to 28 mm
- 0.47 to 1.10 in
An adult female of the wasp Plesiometa argyra, by injecting it with venom from its ovipositor. Afterward, the wasp glues an egg to the abdomen of the spider. The first-instar larva hatches from the egg 2 to 3 days later. The larva only partially emerges from the egg chorion, because the egg is the only structure that enables it to stay attached to its host. As a first instar, the larva creates large holes in the abdomen of the spider to access the spider's hemolymph, which dries to form a type of “saddle”. Researchers believe that the larva may add a chemical to the hemolymph that slows its coagulation. The first-instar larva also feeds on the hemolymph of the host.immobilizes its host spider,
After another 2 to 3 days, the larva molts into the second-instar stage. As a second instar, the larva can insert a pair of hook-like structures into the "saddle" to hold itself in place on the host, outside of the egg chorion. Almost the entire body of the larva becomes visible as it emerges further from the egg chorion. This instar stage lasts less than a day, as the larva soon kills the host and pupates.
The exact number of instars inis unknown. During the final instar stage of the wasp, the wasp chemically induces the host spider into spinning a special "cocoon web" that is designed to hold and protect the cocoon of . The web design results from the repression of all subroutines of normal web construction except one, which is continuously repeated when the spider builds the web. Once it completes this task, the spider becomes paralyzed and dies. The larva feeds on any remaining hemolymph in the spider corpse, and then it dislodges from the abdomen of the spider. The larva weaves its cocoon while hanging from the web. The special cocoon web is strong and can support and protect the cocoon of .
- Development - Life Cycle
To optimize the chances of encountering female wasps,males fly in seemingly random patterns but typically drift above the leaves of undergrowth plants. This mate search pattern tends not to bring them into contact with the females that have recently emerged from their cocoons, which are typically protectively concealed deep in the vegetation of undergrowth plants.
A male encounters a female once she leaves her cocoon and lands on the leaf tips at the top of the undergrowth. No empirical evidence indicates thatproduces pheromones to attract males; however, the males usually locate females within minutes, suggesting that a long-range pheromone is used.
A male lands on a female and curls his abdomen forward to copulate, which usually lasts less than 10 seconds. Males vary in their ability to locate and successfully copulate with females, and they exhibit no aggressive behavior toward conspecific wasps. Females mate with one male at a time. They kill the offspring of other females if they find a larva or egg on a host they capture, and the removed offspring is replaced with their own egg. (Ayasse, et al., 2001; Eberhard, 2000b)
has a haplodiploid genetic system, in which unfertilized eggs develop into males, and fertilized eggs develop into females. Environmental change or stress can affect the sex ratio of a population. Unfertilized eggs may be laid more often than fertilized eggs during certain seasons or under certain ecological conditions and vice versa.
A female wasp uses one of two methods to attack a Plesiometa argyra host. In one method, the wasp hovers above the spider web for a few seconds, quickly dips down, and puts her legs through the web to grab the spider and hold on tightly. The spider tries to fight off the attacking wasp while the wasp jabs the spider repeatedly with her ovipositor. The second method is to deceive the host. The female wasp may lay in the middle of the web, with her legs stiffened. When the spider approaches the wasp, she grabs the spider and stings it repeatedly with her ovipositor. After these short stings, the wasp inserts her ovipositor directly into the cephalothorax of the spider and stings the host for almost 2 minutes. The spider initially struggles but eventually grows still as it becomes paralyzed by the venom. Once the host is completely paralyzed, the wasp continues to stab the spider, inserting more venom. The spider host remains paralyzed for 5 to 10 minutes.
While the host is paralyzed, the wasp probes the spider's abdomen for existing larvae. This behavior allows her to insert venom into the eggs or larvae and remove them. It is uncommon for more than one egg or larva to be found on one host, because female wasps are skilled at finding and removing previously laid eggs and larvae. Experimental observations of parasitized spiders indicate that infanticide is relatively common, based on aged feeding scars in nearly half of the hosts. If two eggs happen to be laid on the same spider host, the smaller larva is extricated from the host by the larger one.
- Key Reproductive Features
- gonochoric/gonochoristic/dioecious (sexes separate)
Dissections offemales have indicated that they contain massive fat bodies and uric acid, both of which decrease as the eggs in her body increase in size. These observations suggest that the females provision the eggs as they develop inside her body.
Females show preferences in their host selection, which provides their offspring with adequate resources as the larvae develop. Females prefer to lay eggs on mature female Plesiometa argyra spiders. The female wasp finds a suitable host, likely by following a chemical stimulus. After the wasp has removed any competing larvae, she glues her egg to the abdominal cuticle of the spider. After the egg is attached to the spider, the wasp offspring gets no further parental care.
The male’s role ends at copulation in this wasp species. (Eberhard, 2000b)
- Parental Investment
- female parental care
The lifespan of (Eberhard, 2000b)is about 4 weeks. However, larval growth can be delayed if the spider host has limited access to food resources.
- Typical lifespan
- 14 to 28 days
- Typical lifespan
Adultfemales exhibit high rates of infanticide on the larvae and eggs of other females. Males are not aggressive toward other individuals.
Adult females and Plesiometa argyra hosts. (Eberhard, 2000b)larvae can chemically control the behavior of their
Communication and Perception
- Other Communication Modes
Larvae feed on the hemolymph of the spider host, while adults rely on sugar and nectar food sources. (Eberhard, 2000b)
- Animal Foods
- body fluids
- terrestrial non-insect arthropods
- Plant Foods
Conura), although it suffers relatively less mortality at this stage than other parasitoid wasp species. Other predators can remove the cocoon or its contents from the cocoon web. Sometimes predators eat the host spider, and they might also prey on the wasp. Spiders also sometimes eat adults. When attacked, the wasp defends itself chemically, releasing a foul odor. (Eberhard, 2000b)larvae may be more susceptible to predation than adults. The eggs and larvae of can be killed by conspecific adult females. As it pupates, can be attacked by idiobiont parasitoids (chalcid wasps in the genus
- Anti-predator Adaptations
Plesiometa argyra. This interaction is important because P. argyra helps regulate crop pest insects. (Shaw, 2006)may regulate the population size of its host,
- Ecosystem Impact
- Plesiometa argyra (also called Leucauge argyra)
- Chalcid wasps (Conura)
Economic Importance for Humans: Positive
Highly specialized parasitoids can be used as biological control to limit the population size of a pest species. However, Plesiometa argyra as a host may lead to discoveries in biochemistry, physiology, ecology, and related fields. (Shaw, 2006)parasitizes a host spider that is not likely to grow out of control or cause any economic problems. Rather, studying the ways in which manipulates
- Positive Impacts
- research and education
Economic Importance for Humans: Negative
is not known to be harmful to humans.
The conservation status ofhas not been evaluated.
Erin Fowler (author), Radford University, Elizabeth Wason (author, editor), Animal Diversity Web Staff.
living in the southern part of the New World. In other words, Central and South America.
living in landscapes dominated by human agriculture.
having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
- active during the day, 2. lasting for one day.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- female parental care
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly plants or parts of plants.
- internal fertilization
fertilization takes place within the female's body
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats nectar from flowers
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
chemicals released into air or water that are detected by and responded to by other animals of the same species
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
- scrub forest
scrub forests develop in areas that experience dry seasons.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
Ayasse, M., R. Paxton, J. Tenjo. 2001. Mating behavior and chemical communication in the order Hymenoptera. Annual Review of Entolomology, 46: 31-78.
Eberhard, W. 2000. Spider manipulation by a wasp larva. Nature, 406/20: 255-256. Accessed May 31, 2013 at http://www.stri.si.edu/sites/publications/PDFs/2000_Nature_Spider_manipulation_by_a_wasp_larva.pdf.
Eberhard, W. 2000. The natural history and behavior of Hymenoptera: Ichneumonidae) a parasitoid of Plesiometa argyra (Araneae: Tetragnathidae). Journal of Hymenoptera Research, 9/2: 220-240. Accessed May 31, 2013 at http://www.biodiversitylibrary.org/pdf3/008747200021556.pdf.(
Eberhard, W. 2001. Under the influence: webs and building behavior of Plesiometa argyra (Araneae, Tetragnathidae) when parasitized by (Hymenoptera, Ichneumonidae). The Journal of Arachnology, 29: 354-366. Accessed May 31, 2013 at http://www.stri.si.edu/sites/publications/PDFs/08_2000_Under_the_influence_JoA.pdf.
Gauld, I. 2000. The Re-definition of Pimpline Genus Hymenoepimecis (Hymenoptera: Ichneumonidae) with a Description of a Plesiomorphic New Costa Rican Species. Journal of Hymenoptera Research, 9/2: 213-219. Accessed May 31, 2013 at http://biostor.org/reference/270.
Gauld, I., J. Dubois. 2006. Phylogeny of the Polysphincta group of genera (Hymenoptera: Ichnemonidae; Pimplinae): a taxonomic revision of spider ectoparasitoids. Systematic Entomology, 31: 529-564. Accessed May 31, 2013 at http://hbs.bishopmuseum.org/fiji/pdf/gauld-dobois2006.pdf.
Godfrey, H. 1994. Parasitoids: Behavioral and Evolutionary Ecology. Princeton, New Jersey: Princeton University Press.
Gonzaga, M., J. Sobczak. 2007. Parasitoid-induced mortality of Araneus omnicolor (Araneae, Araneidae) by Hymenoepimecis sp. (Hymenoptera, Ichneumonidae) in southeastern Brazil. Naturwissenschaften, 94: 223-227.
Mendez, A., R. Bermudez, J. Cardona, N. Franz. 2009. "Leucauge argyra (Walckenar, 1842)" (On-line). Accessed November 13, 2011 at http://rolemodel.uprm.edu/student-outcomes/zoology/reports/Leucauge-argyra-Page-Mendez-Bermudez-Spring2009.pdf.
Shaw, M. 2006. Habitat considerations for parasitic wasps (Hymenoptera). Journal of Insect Conservation, 10: 117-127.