''Oobius agrili'' is a parasitic non-stinging wasp of family

Encyrtidae Encyrtidae is a large family of parasitic wasps, with some 3710 described species in about 455 genera. The larvae of the majority are primary parasitoids on Hemiptera, though other hosts are attacked, and details of the life history can be variab ...

which is native to

North Asia North Asia or Northern Asia, also referred to as Siberia, is the northern region of Asia, which is defined in geographical terms and is coextensive with the Asian part of Russia, and consists of three Russian regions east of the Ural Mountains ...

. It is a parasitoid of the

emerald ash borer The emerald ash borer (''Agrilus planipennis''), also known by the acronym EAB, is a green buprestid or jewel beetle native to north-eastern Asia that feeds on ash species. Females lay eggs in bark crevices on ash trees, and larvae feed undern ...

('' Agrilus planipennis'' Fairmaire, family Buprestidae), an invasive species which has destroyed tens of millions of

ash trees ''Fraxinus'' (), commonly called ash, is a genus of flowering plants in the olive and lilac family, Oleaceae. It contains 45–65 species of usually medium to large trees, mostly deciduous, though a number of subtropical species are e ...

in its introduced range in North America. As part of the campaign against the emerald ash borer (EAB), American scientists in conjunction with the Chinese Academy of Forestry searched since 2003 for its natural enemies in the wild leading to the discovery of several parasitoid wasps, including ''Oobius agrili,'' which is a solitary egg parasitoid of EAB found on ash trees in

Jilin Jilin (; alternately romanized as Kirin or Chilin) is one of the three provinces of Northeast China. Its capital and largest city is Changchun. Jilin borders North Korea ( Rasŏn, North Hamgyong, Ryanggang and Chagang) and Russia (Prim ...

province in 2004; it has been recorded to kill up to 60 percent of EAB eggs. Field studies were carried out in 2005 which revealed that ''Oobius agrili'' completes at least two generations per year. The peak period for parasitism was during July and August where

egg parasitism An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...

rates were 56.3 percent and 61.5 percent, respectively. ''O. agrili'' is

parthenogenic Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...

and has a sex ratio of 14.5:1 (female:male). ''O. agrili'' achieves synchrony with its host life cycle—part of the ''O. agrili'' larvae population in eggs of EAB undergoes diapause within the eggs during winter and emerges the following summer. The USDA carried out paired choice assays with eggs of six different native Agrilus species, two

cerambycid The longhorn beetles (Cerambycidae), also known as long-horned or longicorns, are a large family of beetles, with over 35,000 species described. Most species are characterized by extremely long antennae, which are often as long as or longer than ...

beetles, and four lepidopterans. ''O. agrili'' ignored eggs of all other species except of three of the Agrilus species of egg size in the same range as that of EAB. ''O. agrili'' strongly preferred to oviposit in EAB eggs laid on ash than in eggs of other Agrilus species on their respective host plants. The selectivity shown by ''O. agrili'' has led to its being included in the

biological control Biological control or biocontrol is a method of controlling pests, such as insects, mites, weeds, and plant diseases, using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also i ...

program for controlled releases in selected sites for further research.

References

{{Taxonbar, from=Q7095229 Encyrtinae Biological pest control wasps Insects described in 2005