Biobest.be

Eretmocerus-System

Parasitic wasps for whitefly control

Whitefly is a typical greenhouse pest that affects many crops. The parasitic wasp Eretmocerus eremicus is a practical and economical biological agent for the control of whitefly.

Biology: Eretmocerus eremicus

Like Encarsia formosa, Eretmocerus eremicus is a parasitic wasp for whitefly control. Eretmocerus can develop in any larval stage of the whitefly, but it prefers the second and early third stage. Eretmocerus eremicus lays its eggs under the whitefly larva. After 3 days the translucent eggs turn brown. If an egg is laid in the first larval stage, a development rest occurs, Eretmocerus larvae will not develop before the whitefly larva has reached the second larval stage.

The complete life cycle takes 17 to 20 days, depending on temperature and the larval stage of whitefly. Two weeks after parasitation, the pupa will turn yellow, not black as is the case for Encarsia. In order to leave its host, Eretmocerus makes a small round hole in the parasitised whitefly, just as Encarsia. Both males and females are lemon-coloured. The males are only dark yellow on the upperside of the thorax, a part of their underside is brown.

Application

Eretmocerus eremicus can be applied to control greenhouse whitefly (Trialeurodes vaporariorum) and especially sweetpotato whitefly (Bemisia tabaci). Especially in protected cultures in which high temperatures can occur, Eretmocerus can be applied (e.g. eggplant cultures). Very good results can be obtained when applying Eretmocerus in ornamental cultures (e.g. gerbera).

Advantages

Eretmocerus is Encarsia formosa's welcome assistant in whitefly control because of the following advantages:

If the whitefly population is big (high insect pressure), Eretmocerus will perform more host feeding.

At high temperatures, Eretmocerus eremicus lives longer than Encarsia, and works better.

Eretmocerus californicus is more resistant to pesticides than Encarsia, which is more compatible with integrated pest management.

Both greenhouse whitefly and sweetpotato whitefly can be parasitised by Eretmocerus eremicus.

Parasitised pupae are very easy to recognize due to their yellow colour.

Side effects

As Eretmocerus is a fairly new product for whitefly control, less data on pesticide side effects is available compared to Encarsia formosa. Generally, Eretmocerus is more resistant to pesticides than Encarsia formosa (compared to Encarsia, there is a shorter persistance for Eretmocerus and it is more compatible with other products).

Biobest is currently carrying out numerous experiments to find out the side effects of pesticides on Eretmocerus eremicus.

Eretmocerus-System

Eretmocerus is available as loose pupae in tubes per 3000 units. With the help of these handy tubes, pupae can be spread very easily in the crop.

It is very important to scatter the pupae on a dry surface but protected from direct sunlight.

Biobest's technical advice

	Biobest advises to combine Eretmocerus with the Encarsia-System.
	At temperatures above 20°C, it is recommended to introduce curatively about 6 parasitic wasps/m² for several weeks (i.e. enough whiteflies need to be present to introduce Eretmocerus eremicus).
	In some cultures, introduction can begin at first signs of infestation (e.g. eggplant cultures), in other crops (e.g. tomato) start the introduction when daytime greenhouse temperatures are at least 20°C. Introduce weekly 1 Eretmocerus eremicus/m² until parasitation is sufficient.

Benefits

	Good activity at high temperatures.
	Longer lifetime.
	More resistant to pesticides than Encarsia formosa.
	Better action on Bemisia than Encarsia formosa.
	Simple introduction method.
	Offers a prolonged protection.
	Good results on eggplant and gerbera.