Nasonia in Undergraduate Research and Teaching
Nasonia is a small insect that is ideal for undergraduate research and teaching. It has a number of useful features, particularly for the teaching of genetics, ecology, evolution, development and behavior. First, Nasonia is very easy to rear and handle. The insects are easily 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. This is particularly useful for faculty with heavy teaching loads, as wasps pupae can be stored for several months under refrigeration, to be taken out for experiments when time is available. Adults can be routinely stored under refrigeration for over a month, and the wasp has a diapausing larval stage which allows storage for up to two years. Both visible mutants and molecular markers are available for genetic mapping and instruction in genetics.
Second, Nasonia has interesting and diverse biology. It is a parasitoid insect that kills and lays its eggs upon the pupae of various flies. Parasitic insects are widespread in nature and play an important role in regulating populations of other insects. As such, Nasonia can be used to teach basic principles of ecology, including life-cycles, parasite-host interactions, food webs and the role of natural enemies. A key feature of Nasonia is its interesting form of sex determination called “haplodiploidy”. Males are haploid (have only one set of chromosomes) and develop from fertilized eggs whereas females are diploid (two sets of chromosomes) and develop from fertilized eggs. This feature is very useful for a number of reasons. Among them are easy detection and mapping of visible mutations to one of the five chromosomes present in haploid males. Haplodiploidy also affords the insect the ability to control the sex of its offspring (by controlling whether sperm fertilize eggs), which it does in interesting (and entertaining) ways. Three closely related species provide an abundance of molecular markers for comparative genomic and evolutionary studies. Differences between the species in behavior (e.g. courtship and mate preference), development and morphology provide excellent instructional opportunities for teaching the principles of evolution.
Finally, there are many opportunities for new discovery in Nasonia. Even students in large undergraduate laboratories can make new discoveries, something not easily done for the more standard model organisms. For example, unlike Drosophila melanogaster, students working with Nasonia can easily discover and map new mutations previously unknown to science. Their work can contribute to the base of genetic knowledge on this insect, which is emerging as a model for comparative genetic studies. Students working with Nasonia hybrids can contribute to original studies on the genetic basis of behavioral, developmental or morphological differences between the species while learning important genetic and evolutionary principles. Some topics that students can conduct original research on include
1. Discovery and mapping of new visible mutations.
2. Mapping of molecular markers (polymorphisms)
3. Genetic investigations of species differences in courtship, development and behavior.
4. Analysis of early and late developmental mutants
5. Behavioral studies of courtship, sex ratio variation
6. Genetic analysis of B chromosomes
7. Studies of associated microorganisms, including the “son killer” bacterium and Wolbachia
8. Studies of sex ratio adaptations
9. Male aggression and territoriality
10. Comparative genomics (e.g. sequence differences and similarities between Nasonia and Drosophila).
11. Population genetics, such as mitochondrial variation, intraspecific and interspecific variation in behavior, morphology, development.
12 Ecology and genetics of associated microorganisms (Wolbachia, Arsenophonus).
Workshops: We have begun to offer workshops on use of Nasonia in undergraduate teaching and research, through Research Links . Your can view and download the Nasonia Workshop Notebook, but please note that this is only for instructors who wish to use the notebook for their own instructional or research purposes. If you are interested in organizing a Nasonia workshop, please contact Jack Werren (firstname.lastname@example.org). My laboratory can provide instructors for such workshops.
University of Rochester, Department of Biology, Rochester NY 14627 (585)275-3889