Nasonia Genetics -Introduction to the Jewel Wasp

Authors Avatar

Nasonia Genetics -Introduction to the Jewel Wasp

Nasonia are excellent organisms for research and teaching. These parasitoid wasps have been the subject of genetic, ecological, evolutionary and developmental research for over 40 years. Two general features that make these insects such excellent study organisms are (a) ease of handling and rearing, and (b) interesting and diverse biology. Nasonia are readily reared on commercially available fly pupae (the hosts). Virgin females and males are easily collected in the pupal stage (there is a 3 day time window for virgin collection). Adults are "user friendly" and can be handled without the need for anaesthetization. Nasonia has a short generation time (two weeks), but can be stored under refrigeration for periods of time, allowing for flexibility in experimental timing. A key feature of Nasonia is haplodiploid sex determination; males are haploid and develop from unfertilized eggs and females are diploid and develop from fertilized eggs. Nasonia are small parasitoid wasps (Hymenoptera: Pteromalidae) that sting and lay eggs in the pupae of various fly species, primarily blowflies and fleshflies. There are three closely related species in the genus, N. vitripennis, N. longicornis, and N. giraulti. N. vitripennis is found throughout the world; N. giraulti is found in eastern North America and N. longicornis is found in western North America. The species you will be working with is Nasonia vitripennis

Life Cycle

When a female encounters a host puparium, she first examines the host, then drills through the host puparial wall with her ovipositor. She injects venom into the pupa, which will eventually kill the fly. The female then commences laying eggs upon the host, underneath the puparial wall. She typically lays from 20 to 50 eggs per Sarcophaga bullata pupa. The female may lay these eggs in one bout or may take a number of hours to complete oviposition. The female also uses excretions from her ovipositor to construct a feeding tube from the pupa to the puparial wall. From this she feeds on host hemolymph, which appears to be important in the production of additional eggs. At 25 C, eggs hatch around 36 hours after being laid. Developing larvae complete 3 instars and then pupate within the host around 9 days after laying Pupal development takes approximately 3 days at which time the pupa go through three visible stages: whites, black and whites, and blacks. When the pupa looks almost black, you know that your adults are soon to emerge. Male and female pupae can easily be distinguished during this time. Adults eclose from pupation within the host, and then chew an exit hole. Emergence typically occurs by 14 days. At the black and white stage, you can also distinguish male from female wasps, at this time it is best to separate them to insure virgin females for later crosses.  Mating occurs immediately upon emergence from the host. Courtship behavior is brief (typically taking 1-2 minutes) and involves stereotypic courtship displays. After mating, females disperse from the natal patch in search of new hosts.

Join now!

 

Genetics

In many respects, Nasonia is a superior organism for genetic research. The important features that make it so are (a) short generation time (b) large family sizes, (c) ease of handling (including virgin collection), (d) ability to inbreed and produce healthy lines. Nasonia is particularly suited for the study of complex genetic traits, due to advantages provided by haploid males and the ability to easily produce inbred lines and genetically identical recombinant individuals. All three species of Nasonia have 5 chromosomes, corresponding to 5 linkage groups. currently there are about 20 mutant strains available, most of which are ...

This is a preview of the whole essay