On receipt, place the bottles in a cool shaded area. Do not expose to direct sunlight.For the product in bottles:
For the product in blisters:
Remove the sheet of blister packs from the envelope and separate along the perforations. Open the flap at the back of the blister. Hang on the plant in the shade, out of direct sunlight.
Open the bottle in the glasshouse in the early morning or evening when light conditions are low. Do not release in bright sunlight. Sprinkle the product directly onto the leaves in areas where whitefly occurs. Spread evenly in the crop. Use as many release points as possible. Keep bran carrier out of reach of rodents and excessive humidity.
Eretmocerus populations are 50% female and 50% male, unlike Encarsia where males occur only rarely. If there is a risk of virus transmission to plants from invading Bemisia adults, it may be preferable to use an insecticide and follow up later with Eretmocerus releases. Where only Trialeurodes is present, consider using Encarsia rather than Eretmocerus.
Eretline e is a proprietary product containing pupae of the whitefly parasitoid Eretmocerus eremicus Rose and Zolnerowitch, Aphelinidae, Hymenoptera. This species was known as Eretmocerus nr sp. californicus until the taxonomy of the genus was revised in 1997 by Rose and Zolnerowitch.Unlike Encarsia formosa, Eretmocerus eremicus is unable to turn within the host integument, so does not emerge well when attached to cards. Syngenta Bioline has developed a Blister Pack as an alternative method of distribution. This can be suspended in the crop in the same way as an Encarsia card. It makes the product clearly visible, and allows the grower to judge quality and emergence more easily.The product is also available in a bran base for distribution around the crop.Eretmocerus eremicus originates in the desert regions of Arizona and California, and is able to tolerate higher temperatures than Encarsia formosa.Eretmocerus eremicus is available for release in the United Kingdom under licence from DEFRA.
Eretmocerus eremicus is a parasite of Trialeurodes vaporariorum and Bemisia tabaci. It is in the same family as Encarsia formosa, and is similar in size and shape, but does not have the familiar black and yellow coloration. Instead it is a pale yellow or orange, and can be quite difficult to see amongst whitefly larvae. Unlike Encarsia, in which almost all the individuals are female, Eretmocerus populations consist of males and females in almost equal numbers.Eretmocerus eremicus females search leaves for the larvae of either Bemisia or Trialeurodes. On finding a suitable host, they palpate it with their antennae and then turn to insert an egg between the host and the leaf surface. The larva that hatches from this egg burrows into the host larva, and a capsule forms around it. The larva initially lives within this capsule, but is not apparently damaged by it. Thus the capsule is different from those formed as part of the hosts’ normal immune response to parasitism. The host continues to feed and grow, and is only killed once it has fully grown and ceased to feed.Females select mainly second instar host larvae for parasitism, but will lay eggs under other instars. Egg laying is influenced by the leaf structure of the whitefly host plant: hairy leaves lift the margins of the whitefly larvae and make it easier for Eretmocerus to insert eggs beneath them. The host plant also influences the success of parasite development.Whitefly parasitised by Eretmocerus do not develop the black colour so characteristic of Encarsia parasitism. They are harder to detect within the crop, and so more careful examination of the host is necessary. Using a microscope, it is possible to see one or both of the yellow ‘mycetomes’, which are normally symmetrically placed either side of the midline, displaced to the side. As the pupa reaches maturity the darker yellow or orange of the adult can be seen with the naked eye.Although Eretmocerus females cannot penetrate the host cuticle with their ovipositors, they nevertheless kill large numbers of host larvae that do not develop into parasites. Females have been observed probing around the vasiform orifice of whitefly larvae, and it is believed that this is host feeding. Up to 40% of the mortality which occurs has been attributed to this host feeding.
Eretline e should be used wherever Bemisia is present. It can also be used to control the Glasshouse Whitefly, Trialeurodes vaporariorum, so is useful in mixed populations. Eretmocerus eremicus is better adapted to high temperatures, and those that fluctuate strongly from day to night, than is Encarsia formosa. Where the two are used together to control Trialeurodes, Eretmocerus becomes dominant during periods of hotter weather The use of the two species in combination provides improved control of Trialeurodes throughout the season. Eretline e should always be used preventively, before whitefly populations become established. High release rates may be able to reduce existing populations, but the cost will be high, and it may be more appropriate to use a compatible insecticide to reduce initial numbers.
Eretline e is supplied in two forms: a bottle product containing 3,000 pupae mixed into a bran carrier material, and a blister pack containing 5,000 in total, as 20 blisters each producing a minimum of 250 adult Eretmocerus eremicus.
The blisters should be opened by gently flexing the card until the tab on the back of the blister can be pulled open. This tab then needs to be bent so that it does not re-close the blister. Opened blisters should then be hung amongst foliage in the crop.
The bottle product should be laid on its side and rolled gently to ensure uniform distribution, and portions of the bran emptied out into Universal Release Boxes or other small containers that are distributed around the crop.
Use of Eretmocerus eremicus is not recommended as a first option where there is a substantial risk of virus transmission from invading adult Bemisia. Other available biological controls are also not recommended in this situation, and use of an appropriate chemical remains the solution of choice. Eretmocerus may then be introduced when the risk of invasion is lower.Where Trialeurodes is the pest and Bemisia is not present, consider using Encarsia formosa alone. On tomato (not Cherry tomatoes) and Aubergine crops in Northern Europe the Mirid Bug Macrolophus caliginosus provides excellent control of both whitefly species after an initial period of establishment. It should be used in conjunction with Encarsia and Eretmocerus.
Used as recommended, Eretline e will provide season long control of Bemisia and Trialeurodes.
Eretline e will not control existing high populations of either Bemisia or Trialeurodes when used alone. It will not directly reduce adult populations of whitefly, and cannot protect crops from virus infection carried by invading adult whitefly. It may reduce the subsequent spread of viral infection by reducing the numbers of larvae which reach maturity.The predatory Phytoseiid mite Amblyseius (Typhlodromips) swirskii has recently been shown to control whitefly in some crops and some situations, and may be a useful addition to Bemisia control programmes. It is not suitable for use in crops grown at low temperatures.
A range of chemical insecticides may be successfully integrated with the use of Eretmocerus. Where the insecticide used affects the development of whitefly larvae, there will inevitably be an indirect effect on Eretmocerus populations due to the death of hosts. Thus young parasite larvae may die because of the death of the host, but in most cases mature larvae and pupae will survive, and the population will recover rapidly.