Parasitic wasps' genome sequencing paves way for improved pest control

Washington, Jan 15 (ANI): An international team of researchers have sequenced the genomes of three parasitoid wasp species-a feat that could open new avenues for pest control and offer insights in evolution as well as genetics.

Led by John Werren, a professor of biology at the University of Rochester and Stephen Richards at the Genome Sequencing Center at the Baylor College of Medicine, the advance could reveal many features that could be useful in pest control, medicine and the understanding of genetics and evolution.

Parasitoid wasps females are like "smart bombs" - they seek out specific insect, tick or mite hosts, inject venom and lay their eggs, with the wasp young emerging to devour the host insect- traits that make them valuable assets as agents for biological control.

"Parasitic wasps attack and kill pest insects, but many of them are smaller than the head of a pin, so people don't notice them or know of their important role in keeping pest numbers down. There are over 600,000 species of these amazing critters, and we owe them a lot. If it weren't for parasitoids and other natural enemies, we would be knee-deep in pest insects," said Werren.

The three genomes sequenced are in the wasp genus Nasonia, which is considered to be the "lab rat" of parasitoid insects.

The study's architects suggest that the genomes could enhance pest control by providing information about which insects a parasitoid will attack, the dietary needs of parasitoids (to assist in economical, large-scale rearing of parasitoids) and identification of parasitoid venoms.

Because parasitoid venoms manipulate cell physiology in diverse ways, they may also provide an unexpected source for new drug development.

Like the fruit fly Drosophila, a standard model for genetic studies for decades, Nasonia are small, can be easily grown in a laboratory, and reproduce quickly.

However, Nasonia wasps offer an additional feature of interest- the males have only one set of chromosomes, instead of two sets like fruit flies and people.

"A single set of chromosomes, which is more commonly found in lower single-celled organisms such as yeast, is a handy genetic tool, particularly for studying how genes interact with each other," said Werren.

Unlike fruit flies, these wasps also modify their DNA in ways similar to humans and other vertebrates - a process called "methylation," which plays an important role in regulating how genes are turned on and off during development.

"In human genetics we are trying to understand the genetic basis for quantitative differences between people such as height, drug interactions and susceptibility to disease," said Richards.

"These genome sequences combined with haploid-diploid genetics of Nasonia allow us to cheaply and easily answer these important questions in an insect system, and then follow up any insights in humans," he added.

The wasps have an additional advantage in that closely related species of Nasonia can be cross-bred, facilitating the identification of genes involved in species' differences.

"Because we have sequenced the genomes of three closely related species, we are able to study what changes have occurred during the divergence of these species from one another," said Werren.

"One of the interesting findings is that DNA of mitochondria, a small organelle that 'powers' the cell in organisms as diverse as yeast and people, evolves very fast in Nasonia. Because of this, the genes of the cell's nucleus that encode proteins for the mitochondria must also evolve quickly to 'keep up," he added.

The study appears in the latest issue of Science. (ANI)