Diglyphus isaea
Diglyphus isaea belongs to the family Eulophidae, the order Hymenoptera. The natural geographic range of this organism is Europe, North America, and Asia. Diglyphus isaea has effectively been introduced in many countries. It is a wide-spread ectoparasite of different life-miner flies (Liriomyza bryoniae, L. trifolii, L. huidobrensis, Phytomyza syngenesiae). These small insects are black with dark-green metallic glitter. They have different size of a body. Its length is 0.8–2.8 mm. The female is some bigger than the male and she has a distinctive large strip on hind legs.
After mating the female of Diglyphus moves actively to leaves, following the curvatures of a mine she pierces with her ovipositor the epidermis of the leaves each 3–5 mm. Having found a miner larva she pierces it several times. The afflicted larva of a miner is paralyzed and stops feeding process. The paralyzed larva of the miner as though is conserved for 8–10 days and assumes initially opaque colour then in 5–6 days it assumes brown colour of its body.
Having paralyzed the larva of the miner the female begins to lay eggs. During her life span she can lay about 200–300 eggs. She places them in the mine in groups (2–5 eggs) at a distance of 1.5 cm before, beyond or directly in it. After emergence from the egg a parasite larva moves towards a host. The larva of Diglyphus feeds on the surface of the paralyzed miner assuming blue colour. It pupates directly in the miner. The pupa of the parasite is 1.5 mm in length, initially blue-green. It becomes black for 2 days before its flight. The new formed adult gnaws through the epidermis of the leaf (mine) and climbs on the surface.
The time of development from the egg to the adult at a temperature of 15°C takes 26–27 days, at 25°C lasts 10–11 days. While the species Liriomyza bryoniae develops for 41, 27, and 17 days at temperatures of 15°C, 20°C, and 25°C respectively. This fact shows that the time of Diglyphus isaea ontogenesis under different thermal conditions is considerably less than the development period of pest species.
Application
Diglyphus isaea can be applied for wide assortment of vegetable and ornamental crops (tomato, sweet pepper, melon, gerbera, chrysanthemum and etc.) in the conditions of covered ground. It is an effective component of complex crop protection against leaf-miner flies. Some researchers report that Diglyphus isaea reduces its activity in the winter time. This fact is explained by the deficiency of light (low level of illumination). It is recommended the complex application of Diglyphus isaea together with species Dacnusa sibirica and Opius pallipes.
It is reasonable to release Diglyphus isaea when the availability of food is sufficient. The most effective application of the parasite occurs at the average density of pest population. The terms of releases are determined by means of monitoring (application of colour adhesive traps). The rate of parasite application is 0.25–0.5 individuals per 1 m2. If necessary the releases are made repeatedly.
The optimal conditions for the species Diglyphus isaea are a temperature of 25°C, and a relative air humidity of 40–60%.
Advantages
- wide crop assortment for application;
- the affliction of the most harmful species Liriomyza and Phytomyza;
- the high activity of population development and the suppression of harmful species;
- pest larva paralyzing that allows to reduce the harmfulness of a phytophage.
Storage and transportation:
- keep out the biomaterial of direct sunlight;
- use within 18 hours since the moment of reception;
- store in dark place at a temperature of 10–15°C.
