Two species of whitefly commonly occur in greenhouses: the greenhouse whitefly (Trialeurodes vaporariorum) and the tobacco or silverleaf whitefly (Bemisia tabaci or B. argentifolii). Bemisia whitefly occurs most often in warm climate such as the Mediterranean region and southern United States. Bemisia whitefly does not survive cold winters, which explains its low occurrence in northern regions of Europe and North America. Greenhouse whitefly can be found in more regions than Bemisia.

An adult whitefly measures about 1 mm and is typically covered with a white waxy powder. The female whitefly deposits its oval shaped eggs of 0,2 mm on the underside of young leaves at the top of the plant. The newly hatched larva is mobile during a few hours until it finds a suitable place on the leaf to settle. In subsequent larval stages and in the pupal stage, it does not move anymore. The four larval stages look very similar, but differ clearly in size. At the end of the pupal stage, an adult whitefly finally emerges from the pupa through a T-shaped exit hole. On tomato, development from egg to adult takes 20 days at 27°C and 38 days at 17°C, but on other host plants this can be quite different. Fertility also depends on temperature and host plant. At 17°C, a female lays 100-150 eggs on tomato, 250-300 eggs on cucumber and 450-600 eggs on eggplant.

Both larvae and adults suck plant juice. Extra plant juice absorbed by whitefly larvae is secreted as honeydew (sugar solution). Honeydew fouls the leaves and the fruits, which then become unmarketable. Often, moulds (Cladosporium spp.) grow on the honeydew, which interferes with photosynthesis and respiration of the plant. Moreover, whiteflies (especially Bemisia spp.) can transmit several viruses.

The North American parasitic wasp Eretmocerus eremicus is a close relative of Eretmocerus mundus, which originates from the Mediterranean region. Unlike E. mundus, which only parasitizes the tobacco whitefly, E. eremicus can parasitize Bemisia whitefly as well as greenhouse whitefly.

The adult parasitic wasp E. eremicus is as big as its close relative Encarsia formosa, but the adult is lemon-coloured. The males distinguish themselves from the females by the colour of their thorax, which is dark yellow on the upper side and brown on part of the underside. Usually, there are as much males as females in a population.
The female E. eremicus can parasitize all larval stage of the whitefly, but prefers the second or early third stage. The female lays its egg under the whitefly larva and not inside the larva like Encarsia does. Five days after oviposition, the Eretmocerus larva emerges and will penetrate the host via the back after 2-3 days. Host penetration is postponed if the egg is laid under an L1-larva, thus resulting in a development pause. During this pause, the E. eremicus larva waits until the whitefly larva has reached its second larval stage. The next two larval stages, the pre-pupal and the pupal stage occur inside the host. When E. eremicus reaches the pupal stage (about 14 days after parasitation), the whitefly pupa turns to a yellow colour. Finally, the adult parasitic wasp eats its way out of the whitefly and emerges through a round hole in the whitefly pupal skin.
Total development duration of E. eremicus depends on temperature, relative humidity, kind of host and development stage of the host. Development duration ranges from about 16 days at 25°C to 44 days at 14°C when parasitizing an L2-larva of a Bemisia whitefly. In general, E. eremicus develops a little slower than Encarsia, but E. eremicus is more active at high temperatures than Encarsia. The adult E. eremicus lives about 20 days at 24°C. The female lays most of its eggs during the first days of its adult life. Total number of eggs laid strongly depends on climate and host, and can vary from 40 eggs up to more than 100. The adult parasitic wasps feed themselves with honeydew or with body fluid of the whitefly larvae (host feeding). When feeding on a whitefly larva, the female E. eremicus stings the larva (preferably an L1-larva) with its ovipositor, then turns around and consumes the body fluid.

The main advantages of E. eremicus are that it is an effective parasite of both types of whitefly (greenhouse and Bemisia spp.) and that it works well at high temperatures. This parasitic wasp can be used in ornamental plant productions (e.g. gerbera) and in vegetable crops (e.g. tomato, eggplant, cucumber, melon). However, it is still preferable to always introduce E. eremicus in combination with Encarsia because Encarsia has a quicker population growth, except under difficult circumstances.
With weekly introductions upon first detection of whitefly, it is possible to obtain equilibrium between pest and parasite. Introduction rates strongly depend on climate, crop and kind of whitefly. However, number of E. eremicus introduced must be sufficiently high, because half of the population consists of males. Parasitation rate can be monitored easily by evaluating the percentage of yellow pupae in the crop.
Another advantage of E. eremicus is that it seems to be more to pesticides than Encarsia, which is important in integrated production system

This mix of parasitic wasps consists for 50% of Encarsia formosa and 50% of Eretmocerus eremicus.

Deliverable on cards per 5.000 or 10.000 parasitic wasps (50 or 100 cards) and as loose pupae packed per 10.000 pieces in a tube with sawdust.

It is important to place the pupae on a dry place and to avoid direct sunlight.

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