Trichogramma
| Trichogramma | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Suborder: | Apocrita |
| Superfamily: | Chalcidoidea |
| Family: | Trichogrammatidae |
| Genus: | Trichogramma |
| Species | |
|
230+, see text |
|
230+, see text
Trichogramma are minute polyphagous wasps that are endoparasitoids of insect eggs.Trichogramma is one of around 80 genera from the family Trichogrammatidae, with over 200 species worldwide.
Although there are several groups of egg parasitoids commonly employed for biological control throughout the world, Trichogramma have been the most extensively studied. There have been more than a thousand papers published on Trichogramma and they are the most used biological control agents in the world. Trichogramma are unique to the size limit of how small an insect can be, which would be determined by how few neurons they can fit in their central nervous system, yet exhibit a complex behavior to sustain their life. Trichogramma have less than 10,000 neurons, which is a hundred times fewer than the next smallest insect.
To locate host eggs, adult females use chemical and visual signals, such as egg shape and colour. After she finds a suitable egg, an experienced female will attempt to determine if the egg has previously been parasitized using her ovipositor and antennal drumming (tapping on the egg surface). Females also use antennal drumming to determine the size and quality of the target egg, which determines the number of eggs the female will insert. A single female can parasitize one to ten host eggs a day.
Trichogramma are small and very uniform in structure which causes difficulty in identifying the separate species. As females are all relatively similar, taxonomists rely upon examination of males to tell the different species apart using features of their antennae and genitalia.
The first description of a Trichogramma species was in North America in 1871 by Charles V. Riley. He described the tiny wasps that emerged from eggs of the Viceroy butterfly as Trichogramma minutum. In taxonomy, original specimens are very important as they are the basis of reference for subsequent descriptions of species. The original specimens, however, were lost. Riley also described a second species in 1879 as Trichogramma pretiosum, but these specimens were also lost. To correct these errors, entomologists returned to the areas where Riley originally found the species and obtained neotype specimens of T. minutum and T. pretiosum. These specimens are now preserved properly in the United States National Museum. Currently the number of Trichogramma species is over 200 but as of 1960 only some 40 species of Trichogramma had been described.
...
Wikipedia