Autoparasitoid Wasps Essay -- Biology Encarsia Pergandiella Parasite

A parasite lives in a close relationship with another organism, its host, and causes it harm. The parasite is dependent on its host for its life functions. For example, viruses are common parasites. The parasite has to be in its host to live, grow, and multiply. Parasites rarely kill their hosts. A common, well-known type of a parasite is a hookworm. It is possible for humans or their pets to get them. Hookworms attach themselves in the lining of the small intestine, and cause diseases, and malnutrition as well, as they eat the nutrients and keep them from going to the host. Here, we'll be talking about a different type of parasite, called a parasitoid. The parasitoid Encarsia pergandiella is a tiny wasp that lays its eggs in developing whiteflies. The wasp larva eventually kills the whitefly, and then emerges as free-living adults. This is why it is said that the wasps are parasitic. If you have ever seen Aliens, the developing aliens are parasitoids. Parasitods are different from normal parasites because they kill their hosts when they develop. Encarsia pergandiella develops in a strange way. Unlike most parasitoid species, they are autoparasitoids. This means females develop on whitefly immatures and males develop on immature parasitoids. This means males are parasitoids of other parasitoids, including females of their own species! The fertilization process is a female decision. The female stores the male sperm for later fertilization of eggs. All bees and wasps, including parasitoid wasps are haplodiploid. This means not all eggs have to be fertilized to develop. Unfertilized eggs become males, which are haploid. Fertilized eggs become female, and are diploid. In autopara... ...romosome carried by the males was killing the whole male set of chromosomes, leaving only one set of female chromosomes along with this extra chromosome, which becomes a male haploid wasp. This PSR chromosome is also called a supernumerary chromosome in the nuclei. In the study of Encarsia pergandiella, male wasps were also found to come from fertilized eggs that had been placed on the whitefly host and it was found that, similar to N. vitripennis, the entire paternal set of chromosomes was being lost. It was thought that perhaps an extra chromosome, such as the PSR chromosome, was also being carried in them. However, after further study a supernumerary chromosome was not found. The casue of genome loss in E. pergandiella is still a mystery. Perhaps the male set of chromosomes were being killed by another source, such as a virus or transposable element.