i5K: Parasitic wasp
Parasitic wasp (Trichogramma pretiosum)
Contact: Richard Stouthamer
Researchers involved: 150
Size (or size of nearest relative): (Trichogramma kaykai 216 MBp)
Keywords (and why important): Novel behavior, mobile genetic elements - jumping genes, (agriculture, model organism)
Trichogramma pretiosum is a tiny egg parasitoid that is released by the millions as a biological control agent in Central and South America and to a lesser extent in North America and Asia. It is under consideration for the control of Tomato pests in Europe. It occurs naturally in North and South America. It has become established in Australia and on islands in the Pacific.
Several other Trichogramma species are also used in biological control and these are closely related to T. pretiosum. T. pretiosum has a short lifecyle of 11 days at 25 degrees Celsius and can be maintained on the eggs of the grainmoth Ephesia kuehniella.
Eggs of this moth species can be acquired through commercial suppliers. Because of their small size many different cultures can be maintained in a small space, we maintain our Trichogramma cultures in glass vials of 10cm*1.5cm.
In addition to its importance in biological control of lepidopteran pests, it is also very interesting because some populations are completely asexual because of an infection with parthenogenesis-inducing Wolbachia. The age of these completely infected populations varies and their prolonged asexual reproduction has led to a decay in traits involved in sexual reproduction. For instance, in the asexual populations from Peru, females have lost the ability to fertilize their eggs, while males, when produced by antibiotic treatment, still are sexually functional. In some Hawaiian populations of this species, males that are produced by antibiotic treatment appear to be completely sterile.
Having a genome of a sexual form of this species sequenced will allow us to determine the genes that are affected when a population becomes completely asexual, by later comparing the genome of asexual forms to that of the sexual form. Many labs maintain populations of Trichogramma pretiosum. In our lab, we maintain a large number of highly inbred lines that originate from California and have been inbred by sibmating for 9 generations. These parasitoid wasps are tiny but sufficient material for sequencing can be generated within a month.