Hosts or Prey
Purple scale and certain other armored scales
Identification
The most obvious evidence of this tiny parasitic wasp or related species is a rounded hole in the cover of armored scales. If A. lepidosaphes or another external parasitoid is the cause of the hole, if the cover is removed beneath it will be observed the deflated, shriveled skin of the host and several fecal pellets (meconium) excreted by the mature parasitoid larvae (prepupae) before they pupated.
Adults have a golden yellow head and body and clear wings. The bulging eyes are pale green to yellowish. On top the head are 3 dotlike, red, light receptors (ocelli). The adult wasp is about 1/25 inch (1 mm) long.
Eggs, larvae, and pupae of A. lepidosaphes occur externally on the scale body but hidden under the scale cover. The pale eggs are teardrop shaped and about 1/250 inch (0.1 mm) long.
Larvae are legless with distinct segments. First instars are elongate and second and third instars are spherical or saclike. The mature third instar and pupa are about 1/60 inch (0.4 mm) long, but size varies with the size of the host and the number of parasitoid larvae that develop on it. Larvae and initially the pupae are whitish. The pupa is oblong with distinct segments. As it ages it becomes pale yellow and develops appendages folded against the body.
Life Cycle
Aphytis lepidosaphes develops through 4 life stages: egg, larva, pupa, and adult. Adult females lay several eggs on the body of each second and third instar armored scale. Commonly only 2 wasps per host survive to maturity. An adult female on average lays 80 eggs. Unmated females produce male progeny and mated females produce females. Adult longevity is about 2 weeks when temperatures are warm.
In addition to the killing of hosts by parasitizing them, adult female A. lepidosaphes host feed. The female punctures scale covers and bodies with her ovipositor and consumes the exuding body contents. Host feeding increases parasitoid longevity and the abundance of eggs laid and kills scales without any parasitoid eggs being laid on them.
Egg to reproductive adult development time is about 1 month when temperatures are warm. The parasitoid has about 6 generations per year in California.
Habitat
Aphytis lepidosaphes can be found wherever purple scale, Lepidosaphes beckii, occurs. The scale has hosts in at least 56 genera of plants. See ScaleNet from the U.S. Department of Agriculture for a complete list of hosts of L. beckii, which are commonly woody plants, such as certain tree crops, residential fruit trees, and ornamental trees and shrubs.
The parasitoid is native to China and Taiwan. It was collected from there and deliberately introduced into California in 1948. Subsequently A. lepidosaphes has been introduced into Florida, Louisiana, Texas, and various other places.
To improve biological control
- Control ants because they attack natural enemies of purple scale and other pests.
- Grow flowering insectary plants to provide nectar to nourish adult natural enemies.
- 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.
For more information see Protecting Natural Enemies and Pollinators and the table of relative toxicities of insecticides and miticides to natural enemies and honey bees for specific crops.
Species
At least 23 Aphytis species occur in California, each of which parasitizes multiple species of armored scales. Aphytis lepidosaphes parasitizes at least 8 species of armored scales of which the most common host is purple scale.
More Information
- Bionomics of Aphelinidae, Annual Review of Entomology
- Complete Biological Control of Lepidosaphes beckii on Texas Citrus with Aphytis lepidosaphes, Environmental Entomology
- The Introduced Purple Scale Parasitoid, Aphytis lepidosaphes Compere, and a Method of Integrating Chemical with Biological Control, UC Riverside, Hilgardia
- Universal Chalcidoidea Database, Natural History Museum of London
Scientific classification:
- Phylum: Arthropoda
- Class: Insecta
- Order: Hymenoptera
- Family: Aphelinidae
