Hosts or Prey
Elm leaf beetle and tamarisk beetles
Identification
The most easily recognized evidence this parasitoid is present is its cylindrical puparium (covering of the pupae) that are dark reddish, but appear black if they remain covered with the dead host's skin. During spring and summer puparium can be observed at the base of elms or tamarisk and in bark crevices among the orange to yellowish pupae of their host leaf beetles.
Adults of E. antennata are black, robust flies about 1/6 inch (4 mm) long. They resemble the common house fly, except they have stout bristles covering the body including at the tip of the abdomen.
Erynniopsis antennata eggs are about 1/60 inch (0.4 mm) long, oval, and transparent to whitish. Eggs occur glued on late instar (larval) hosts. Larvae of E. antennata are pale maggots that occur hidden inside host leaf beetles. The first instar has distinct, hooked mouthparts it uses to chew into the host and to chew holes in its covering through which the parasitoid larva inserts its breathing tubes (spiracles). Mature larvae of E. antennata occupy the entire body of the host and are up to 1/5 inch (5 mm) long.
Life Cycle
Tachinidae develop through four life stages: egg, larva, pupa, and adult. The parasitoid spends the winter as young larvae inside adult leaf beetles that overwinter in sheltered places, such as debris on the ground and in buildings and woodpiles. In the late winter or spring when adult leaf beetles become active the parasitoid larva matures, pupates inside the host, and emerges, killing the leaf beetle.
Erynniopsis antennata then seeks mates and the adult females deposit one egg per host on late-instar beetle larvae. The egg hatches almost immediately after being laid. The fly larva chews into the beetle larva and feeds inside. During spring and early summer, the parasitized, mature larvae (prepupae) of leaf beetle hosts are killed by the parasitoid. Erynniopsis then develops into oblong, black to reddish puparium in bark crevices and on the ground around host plants.
As the season progresses an increasing proportion of the parasitoid population enters diapause (a resting stage). Each overwintering Erynniopsis remains as an immature parasitoid within its host during the beetle's pupal through adult stages. In the late winter or spring the E. antennata matures and the adult fly emerges from an adult beetle, although this is not readily observed. Erynniopsis antennata has two or more generations per year.
Habitat
Erynniopsis antennata occurs in most of California where elm trees and elm leaf beetle are found. In California it is the most important parasitoid of elm leaf beetle. However, its effectiveness is limited by a secondary parasitoid (hyperparasitoid), Baryscapus (=Tetrastichus) erynniae. Evidence that this secondary parasitoid is present includes one or more small emergence holes in the puparia of Erynniopsis antennata. To improve biological control
- Control ants because they attack natural enemies of various pests.
- Grow flowering insectary plants to provide nectar to nourish adult parasitoids and predators.
- Reduce dustiness that disrupts the activities of natural enemies (e.g., periodically hose off small plants).
- Avoid the application of broad-spectrum, persistent insecticides for all pests because they are toxic to natural enemies.
See Protecting Natural Enemies and Pollinators for more information.
In addition to elm leaf beetle that is a pest, E. antennata can parasitize Diorhabda species tamarisk leaf beetles. Tamarisk beetles are beneficial species that were deliberately introduced to control invasive Tamarix species that are riparian weeds. The extent to which these introduced Diorhabda species are parasitized by E. antennata in California is unknown.
Species
Over 400 Tachinidae species are known in California. Varying by species their hosts include beetles, caterpillars, grasshoppers, and true bugs. Erynniopsis antennata is the only Erynniopsis species in North America.
More Information
- Distribution and Abundance of Erynniopsis antennata [Dipt.: Tachinidae] and Tetrastichus brevistigma [Hym.: Eulophidae], Two Introduced Elm Leaf Beetle Parasitoids in Northern California, UC Berkeley, Entomophaga
- The Elm Leaf Beetle, Pyrrhalta luteola, in Southern California: Its Pattern of Increase and Its Control by Introduced Parasitoids, UC Riverside, Environmental Entomology
- Elm Leaf Beetle (Xanthogaleruca luteola [Muller]) (Coleoptera: Chrysomelidae) (PDF), In The Use of Classical Biological Control to Preserve Forests in North America, U.S. Department of Agriculture Forest Service
- Elm Leaf Beetle, Xanthogaleruca (=Pyrrhalta) luteola (Muller) (Coleoptera: Chrysomelidae), Encyclopedia of Entomology, Second Edition
- Pest Notes: Elm Leaf Beetle, UC Integrated Pest Management Program
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Diptera
- Family: Tachinidae
