Oobius agrili
Encyclopedia
Oobius agrili is a parasitic non-stinging wasp of family Encyrtidae
which is native to North Asia
. It is a parasitoid of the emerald ash borer
(Agrilus planipennis Fairmaire, family Buprestidae), an invasive species
which has destroyed tens of millions of ash trees in its introduced range in North America
. As part of the campaign against the emerald ash borer Elliot Elsley (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 on ash trees in Jilin
province in 2004 and 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 rates were 56.3 percent and 61.5 percent, respectively. O. agrili is parthenogenic 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 EABA 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 beetles, and four lepidoptera
ns. 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 program for controlled releases in selected sites for further research.
Encyrtidae
Encyrtidae is a large family of parasitic wasps, with some 3710 described species in some 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 variable Encyrtidae is a large family of parasitic wasps,...
which is native to North Asia
North Asia
North Asia or Northern Asia is a subregion of Asia, consisting of the Asian portion of Russia.The Phillips Illustrated Atlas of the World 1988 defines it as being most of the former USSR, the part that is to the east of the Ural Mountains...
. It is a parasitoid of the emerald ash borer
Emerald ash borer
The emerald ash borer is a green beetle native to Asia.In North America the borer is an invasive species, highly destructive to ash trees in its introduced range. The potential damage of this insect rivals that of Chestnut blight and Dutch Elm Disease...
(Agrilus planipennis Fairmaire, family Buprestidae), an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
which has destroyed tens of millions of ash trees in its introduced range in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. As part of the campaign against the emerald ash borer Elliot Elsley (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
Parasitoid
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism in a relationship that is in essence parasitic; unlike a true parasite, however, it ultimately sterilises or kills, and sometimes consumes, the host...
of EAB on ash trees in Jilin
Jilin
Jilin , is a province of the People's Republic of China located in the northeastern part of the country. Jilin borders North Korea and Russia to the east, Heilongjiang to the north, Liaoning to the south, and Inner Mongolia to the west...
province in 2004 and 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 rates were 56.3 percent and 61.5 percent, respectively. O. agrili is parthenogenic 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 EABA 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 beetles, and four lepidoptera
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
ns. 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 program for controlled releases in selected sites for further research.