The larvae of some Lepidopteran (moths), Coleopteran (beetles), Hymenopteran (sawflies) and Dipteran (flies) insects generally feed within a leaves by producing large blotches or meandering tunnels that are called mines. Because of this mining and feeding behavior of these insects are called leafminers. These leafminers can cause a significant health and aesthetic damage to many plant species.
Although there are several kinds of natural enemies that can keep the populations of leafminers under control, it has been proved that the release of the warm weather wasp parasitoids, Diglyphus isaea as biological control agent have a potential to control different species of leafminers that cause a serious damage to many crops including beans, celery, cucumbers, eggplants, lettuce, onions, pepper, potatoes squashes, tomatoes and watermelons whether they are grown in the greenhouses, fields, orchards or gardens.
Parasitic Diglyphus isaea are called mini wasps because they are very small about 1.5-3 mm long. These mini wasps are black in color with a yellow stripe on their hind legs and possess short segmented antennae. The females are slightly bigger than males and like other species; these wasps also grow through four developmental stages such as eggs, larvae, pupae and adults. Wasp larvae start feeding on the leafminer larvae immediately after hatching from eggs and develop thorough 3 larval stages (instars). Eventually the mature wasp larva pupates in the mines on the upper surface of the leaf. After 6-9 days of pupation, adult wasp emerges from pupa and lifecycle continues. Under optimal conditions i.e. temperatures between 75-90°F and about 80% relative humidity, egg to egg life cycle of mini wasp Diglyphus isaea is completed within 2 weeks.
- +Effective against the following pests
- Chrysanthemum/Serpentine leafminer,Liriomyza trifolii
- Pea leafminer, Liriomyza huidobrensis
- The tomato leafminer, Liriomyza bryoniae
- Common ornamental and Vegetable crop leafminer, Liriomyza sativae
- + How Parasitic Diglyphus isaea kill leafminers?
Diglyphus isaea are shipped as adults that are ready for fast oviposition or egg-laying.
- Females of mini wasps use their antennae to locate second or third stage larvae of leafminers in the mines.
- After locating leafminer larvae, Diglyphus isaea wasp females use their ovipositors to puncture and inject paralyzing toxins in the body of leafminer larvae.
- Unlike other parasitic wasps, the females of this mini wasp lay 1-5 oval shaped eggs next to (not inside) the body of paralyzed larva.
- Each female wasp generally lay about 50 eggs during its life span of 2 weeks and temperature is above 20°C (68°F).
- Immediately after hatching from eggs the larvae of mini wasps start feeding externally on the larvae of leafminers.
- Because of this external feeding habit, Diglyphus isaea wasp larvae are considered as ectoparasitic wasps.
- Females of Diglyphus isaea wasp are also parasitic in nature and known to kill and feed on several leafminer larvae during their life-span.
- + How many Diglyphus isaea wasps should be released?
Diglyphus isaea wasps are commercially available and easy to apply in the greenhouses or fields
- Generally rate of Diglyphus isaea wasps will depend on the size of leafminer infested areas to be treated.
- Also, mini wasp released during summer will have better impact on the control of leafminer insects than those released early in the spring or late in the fall.
- As a preventive control of leafminers, release 1- 2 wasps per 9.0 square foot area at every three week interval as needed.
- As a curative strategy, release bi-weekly about 2-4 mini wasps per 9.0 square foot area.
- + Why you need Diglyphus isaea
- they can reduce the crop damage by feeding on leafminers responsible for the damage
- they can munch on different stages including larvae of leafminers
- they are able to actively search for their hosts and feed on them
- they can reproduce and continue their life cycle in the garden after first application
- they are commercially available and easy to apply in the greenhouses or fields
- + Why predatory Diglyphus isaea are safer than traditional pesticides
- they do not damage plants
- do not cause any harm to the personnel involved in their production and application
- food products are safe to handle and eat when they are treated with wasps
- they do not harm humans, animals and pollute the environment
- + Research Papers
- Boot, W.J., Minkenberg, O. P. J. M., Rabbinge, R., De Moed, G. H. 1992. Biological control of the leafminer Liriomyza bryoniae by seasonal inoculative releases of Diglyphus isaea: simulation of a parasitoid-host system. Netherlands Journal of Plant Pathology. 98: 203-212.
- Haghani, M., Fathipour, Y., Talebi, A.A. and Baniameri, V. 2007. Temperature-dependent development of Diglyphus isaea (Hymenoptera : Eulophidae) on Liriomyza sativae (Diptera : Agromyzidae) on cucumber. Journal of Pest Science 80: 71-77.
- Musundire, R., Chabi-Olaye, A., Salifu, D. and Kruger, K. 2012. Host Plant-Related Parasitism and Host Feeding Activities of Diglyphus isaea (Hymenoptera: Eulophidae) on Liriomyza huidobrensis, Liriomyza sativae , and Liriomyza trifolii (Diptera: Agromyzidae). Journal of Economic Entomology 105: 161-168.