Cotesia

Cameron, 1891

Species Guides

7

Cotesia is a of braconid wasps widely recognized for their role as of caterpillars. Female use an ovipositor to deposit inside caterpillars, and simultaneously inject that suppress the host's immune system. Developing wasp larvae feed on host tissues, then emerge through the skin and spin white silk cocoons on the exterior of the caterpillar. Several are employed in programs against agricultural pests.

Cotesia glomerata by (c) Barry Cottam, some rights reserved (CC BY), uploaded by Barry Cottam. Used under a CC-BY license.Cotesia theclae by (c) Victor Engel, some rights reserved (CC BY), uploaded by Victor Engel. Used under a CC-BY license.Cotesia flaviconchae by (c) Andrew Meeds, some rights reserved (CC BY), uploaded by Andrew Meeds. Used under a CC-BY license.

Pronunciation

How to pronounce Cotesia: //koʊˈtiːʒə//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Cotesia are small, typically measuring only a few millimeters in length. The most visible field sign is the presence of numerous white, oval silk cocoons clustered on the back of a living or caterpillar. These cocoons are often mistaken for by observers. wasps have slender bodies characteristic of braconid wasps, with long and reduced wing venation.

Images

Habitat

Found wherever caterpillars occur, including agricultural fields, gardens, forests, and natural vegetation. Female actively hunt for caterpillars on foliage of host plants.

Distribution

Records from Denmark, Norway, Sweden, Vermont (USA), and other parts of the United States. The has a broad distribution corresponding to the ranges of their caterpillars.

Seasonality

Activity coincides with the presence of caterpillars; in temperate regions, are commonly observed in summer and autumn.

Diet

Larvae are obligate that feed on tissues of living caterpillar . have been observed feeding on honey and likely consume nectar from flowers.

Host Associations

Life Cycle

Females locate caterpillar on vegetation and use their ovipositor to deposit multiple inside the host body. Along with eggs, they inject that disable the caterpillar's immune system. larvae develop internally, feeding on host tissues without triggering an immune response. Upon completing development, larvae burrow through the host's skin and spin white silk cocoons on the exterior surface. occurs within these cocoons, after which wasps emerge to mate and seek new hosts.

Behavior

Female actively hunt for caterpillars on plant foliage. Upon encountering a , they jump onto the caterpillar and rapidly deliver multiple stings with the ovipositor to deposit . After emerging from cocoons, wasps immediately begin searching for new host caterpillars. Newly emerged adults have been observed attacking caterpillars within minutes of leaving their cocoons.

Ecological Role

Important agents that regulate of caterpillar herbivores. By parasitizing pest , they reduce defoliation of crops and native vegetation. Their - interactions represent a specialized coevolutionary relationship.

Human Relevance

Widely used in programs. Cotesia flavipes is deployed across more than 30,000 square kilometers in Brazil to control the sugarcane borer. C. congregata provides natural control of tomato and in gardens and agricultural settings. C. glomerata and C. rubecula are used against cabbage white caterpillars. Their presence is easily recognized by the white cocoons on parasitized caterpillars, which alerts growers to natural biological control activity.

Similar Taxa

  • Ageniaspis citricolaAnother small parasitic wasp used in , but belongs to Encyrtidae and attacks citrus leafminer rather than caterpillars
  • Trichogramma used in , but attack eggs rather than larval caterpillars and do not produce external cocoons on bodies

Misconceptions

The white silk cocoons of Cotesia on caterpillars are frequently mistaken for of the or of some other insect. These are actually pupal cocoons, not eggs. The wasp eggs are deposited internally and are never visible from the outside.

More Details

Polydnavirus symbiosis

Cotesia harbor mutualistic that are injected into caterpillars along with . These viruses integrate into the wasp and are vertically transmitted. In the caterpillar, they specifically suppress the host's cellular immune responses, including and melanization, that would otherwise kill the larvae.

Research applications

Cotesia have been important model organisms for studying - interactions, , and insect immunology. C. congregata in particular has been extensively studied for its polydnavirus effects on host immune systems and development.

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Sources and further reading