Tip Top Bio-Control Technical Bulletin

Aphytis melinus
The Golden Chalcid Armored Scale Parasite

Target pests:
California red scale, Aonidiella auranti, on citrus, roses and ornamentals.
Ivy or oleander scale, Aspidiotus nerii, on a wide range of hosts including cycads and palms, San Jose scale, Quadraspidiotus perniciosus, Walnut scale, Q. juglanregiae, Dyctyospermum scale, Chrysomphalus dictyospermi, on a wide range of hosts.

Description:
Aphytis melinus is a small light yellow parasitic wasp about 1mm in size. The wasp parasitizes various types of armored scale. The wasp lays eggs under the waxy scale covering, created by the scale. The parasite larvae develop under the scale covering. The window for female control is during the second and third instars of development while she is a virgin. The male's window is during the second instar and pre-pupae development. It is during these developmental stages that the scale is not affixed to host plant thus allowing the parasites to get under the scale. In some cases the scale is killed by adult hosts feeding on them. Once the scale is parasitized it looks dried out and when examined closely may have dark spots.

Life Cycle:
At 80° F Aphytis take 13-18 days to develop from egg to adult. Adults live for approximately 10-16 days (up to 25) and deposit 6-8 eggs daily.

Product Information:
Aphytis melinus are shipped in cups.

Introduction Rates:
General:
It is best to release Aphytis melinus in 1-3 week intervals upon detection of scale until low scale numbers are observed. Scale mergence usually occurs in spring. Optimal release conditions are between 60°-88° F.

Orchards:
The optimum time for augmentative releases would be the seven-week period from mid-March through the first week in May. During this time the scale population is still at an ebb after coming through the winter and yet weather conditions are generally warm enough to be conducive to releases of our insectary-reared parasites. In addition, at this time of year the Aphytis should be able to produce three generations during one generation of scale development. 1-2 cups per acre is for moderate infestations. Release on shaded side of tree during temperatures below 90° F. Release parasites every fifth to sixth tree every fifth to sixth row starting at a different row each release. An open cup may be left in a tree or applicator may walk through the rows releasing at will for rapid dispersal. The use of a summer oil spray to reduce high number of scale 2-3 weeks prior to parasite release is also helpful.

Interiorscapes:
On established scale sites it can take up to 2-3 months for complete control. Release Aphytis at 1-3 week intervals until scale levels are low. Once low levels are achieved 1-3 releases per year should maintain control. The release rates depend on the host plants. A simple guideline is 5-10 wasps per infested plant. Parasites should be released by waiving cup around infested plants 2-3 times. Release at dusk or when windows are covered so that the Aphytis will find infested plants quicker. If infestation levels are high apply insecticidal soap 2-3 weeks prior to release. Wash off Honeydew from plants just before release.

Ant control is of paramount importance in all applications!

For Best Results:
Use wasps within 1 day of receiving your order. If necessary store in a cool dark place (60°F.) until use. Do not refrigerate. Aphytis viability decreases rapidly with prolonged storage.

Using Pesticides:
Insecticidal soaps are harmful to all stages of Aphytis, but have no residual effect. Oil sprays Bacillus thuringiensis and Sabadilla are compatible. If harsh toxic pesticides must be used, Aphytis should be re introduced in 4 weeks after application.