Glassy-winged sharpshooter biocontrol
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in French Polynesia

Gonatocerus ashmeadi biology

The egg parasitoid, Gonatocerus ashmeadi Girault (Hymenoptera : Mymaridae), is a natural enemy of GWSS. It is native to south-eastern USA and north-eastern Mexico where it is a common and very effective parasitoïd associated with GWSS.

Gonatocerus ashmeadi attacks the eggs of GWSS. Female G. ashmeadi lay one egg inside a single GWSS egg. The parasitoid larva hatches from the egg and grows inside the GWSS egg consuming the contents of the host egg. fter approximately 12 days of development, an adult parasitoid emerges from the parasitized GWSS egg and begins to hunt for new GWSS eggs to attack. The life span of an adult G. ashmeadi is approximately 15 days.

Gonatocerus ashmeadi adult
Life cycle of Gonatocerus ashmeadi

 

Advantages

This parasitoïd was chosen for use in a biological control program in French Polynesia because:

- it is one of the most abundant parasitoids attacking GWSS eggs in the pest’s natural range
- it is the most efficient parasitoïd of GWSS in California
- it is well adapted to the tropical climate
- its development is 3 to 4 times faster than GWSS
- it attacks GWSS eggs on a wide variety of host plants
- it is easy to mass rear in the laboratory ensuring lots of parasitoids can later be released at field sites

 

Potential risks

The introduction of an exotic species into a new habitat always represents a potential threat for the local biodiversity. It is crucial to assess the risk caused by G. ashmeadi on non-targeted species.

Gonatocerus ashmeadi is a micro-wasp, and it is harmless to humans and plants. It doesn't sting and adults may at times feed on flower nectar. Nectar feeding enables the parasitoid to live longer and produce more eggs for laying inside GWSS eggs.

Gonatocerus ashmeadi is a specialist natural enemy, it has a very restricted host range which means it can only attack a limited number of host species for successful reproduction. Gonatocerus ashmeadi is only known to attack cicadellid eggs in the new world tribe Proconiini (sub-family Cicadellinae). There are no native cicadellids in French Polynesia that belong to the Proconiini so risk to native insects from G. ashmeadi appears to be very low.

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Jérôme N. Petit © juillet 2006 - Gump station