Eretmocerus eremicus

Eretmocerus eremicus is a small parasitoid wasp (0.8-1 mm in length) used to control populations of greenhouse and tobacco whitefly. If it is necessary to control the pest population, Eretmocerus eremicus is used for preventive purposes or at a low level of infection. In the case of an average level of pest infestation of the site, this entomophage will be effective, provided that the period of population formation has been successful. In the case of a mass attack of plants by phytophages, Eretmocerus eremicus is used in combination with Encarsia formosa. Also, under the condition of an established population of Eretmocerus eremicus and its combination with Encarsia formosa, entomophages are able to qualitatively protect the crop throughout the season.

Description

Eretmocerus eremicus females have a pale lemon-yellow body colour, green eyes and clavate antennae on the head. The name Eretmocerus in Latin means ”paddle-like”, and is characterized by the shape of the antennae of the females. The antennae of the male parasitoid wasp are longer and darker. Pupae of whitefly infected with Eretmocerus acquire a beige colour, unlike non-infected white or light yellow. After pupation, the entomophage, feeding on the whitefly, eats a round hole in its body and comes out into the light.

Life cycle

Both males and females of Eretmocerus eremicus develop as primary parasitoids of whitefly. In mass commercial cultivation using greenhouse whitefly as a host, the sex ratio of this wasp is 1:1 (female: male), however, in the field, the sex ratio may be in favour of females. Females of Eretmocerus eremicus find the whitefly partly by sense of smell and lay eggs between the nymph of the whitefly and the surface of the leaf. Females lay eggs at all the younger stages of the whitefly, except eggs, but the 2nd stage of development is preferred.

The egg stage of Eretmocerus eremicus lasts about 4 days after laying (the exact time depends on the temperature). After that, a wasp larva appears, which develops as an external-internal parasitoid. The newly emerged larva attaches itself to the underside of the white-winged nymph with its hook-shaped mouthpart and chews a small hole in it. After 3-4 days of such feeding, the larva of the parasitoid enters the host, where it remains dormant until the pupation of the whitefly. Upon reaching the pupal stage of the whitefly, the wasp larva releases digestive enzymes and begins to absorb the soft tissues of the pupa.

The wasp larva goes through three ages, and it takes about 12 days for it to fully develop. Upon reaching the final stage of development, the parasitoid wasp chews his way out of the corpse of the whitefly. Adult female wasps live for 6-12 days at a temperature of 27 °C. Life expectancy depends on the temperature and availability of food. Females lay 3-5 eggs per day. Adult female wasps also kill whitefly nymphs by repeatedly probing their ovipositors and feeding on hemolymph (blood) that is released from the wound. An adult female Eretmocerus eremicus is a potential killer of about 100 whiteflies in its short life.

Relative efficiency

Eretmocerus eremicus is a parasitoid wasp who actively searches for offspring and nutrition. On some plants, the speed of movement of the parasitic wasp reaches 1.3 mm / s. Females of Eretmocerus eremicus probe all stages of the whitefly with their ovipositor as often as they meet them on the way. About 74% of the nymphs of the whitefly will be infected with parasites, during the life of the parasitoid. The optimal temperature, which promotes rapid development and egg production, is 25-29 °C. In the greenhouse, it is necessary to regulate the temperature so that the Eretmocerus develops faster than its owner. On poinsettia grown in a greenhouse in the northeastern United States, the release rate of 3 females of Eretmocerus eremicus per 1 plant per week provided a mortality rate of more than 98% of the tobacco whitefly in the first 6-8 weeks of cultivation.

Sensitivity to pesticides

It is assumed that Eretmocerus eremicus is sensitive to pesticide residues and fumigants. Parasitoid wasp releases will be most effective in areas that are not sprayed for 10-14 days.

Application

Usually Eretmocerus is used proactively through several introductions with an interval of 1 week for 2-3 individuals / m2, it is desirable to dose Eretmocerus in portions into special boxes of 50-100 pupae and hang these boxes every 10-15 meters on plants. The introduction of Eretmocerus into the foci of whitefly in a ratio of 1:5  justifies itself. Each crop and each specific pest requires an individual approach, our specialists are always ready to give professional advice on these issues.