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How to Manage Pests:
Pest Management and Identification
Aphytis spp.
Scientific name: Aphytis melinus and other Aphytis species
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Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Aphelinidae
Common Hosts: Parasite of California red scale (Aonidiella
aurantii) in citrus and floriculture and
San Jose scale (Diaspidiotus {=Quadraspidiotus} perniciosus) in plum and
prune and many other fruit and nut trees .
Commercially available: Yes
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Aphytis melinus is an important parasite of several species
of armored scales including California red scale, latania scale,
San Jose scale, and oleander scale. Several other closely related
(and difficult to distinguish) Aphytis species attack various
armored scales in California. Aphytis feeds on and oviposits
in immature scales, preferring virgin adult female scales. Adult Aphytis are
tiny wasps, measuring approximately 2 mm (1/16 in) long, are yellow
and have short knobby antennae. Aphytis melinus adults can
be confused with the adult male California red scale; however, the
male scale has long antennae, a dark band around its back, and only
one pair of wings.
The female Aphytis deposits a single egg beneath the scale
cover and upon hatching, the Aphytis larva feeds on the
scale. Because its feeding is external to the scale body, Aphytis is
considered an ectoparasite. After reaching adulthood, the tiny
adult wasp chews a small round hole in the scale cover and leaves.
In citrus, the round hole distinguishes scales parasitized by this
species from ones parasitized by Comperiella bifasciata, which
leaves a larger, more irregularly shaped exit hole. If a parasitized
scale cover is flipped over, the dead scale will be flat and dehydrated,
and the parasite's cast skin and fecal pellets will be evident.
A. melinus are commercially available and often used in
citrus groves for California red scale control. One reason for
its effectiveness as a natural enemy is that A. melinus has
two or three generations for each scale generation. Ant control
is also important where Aphytis are present because ants
will disrupt the ability of the parasites to oviposit. Aphytis are
sensitive to many pesticides and it is important to check for pesticide
residues before releasing the parasites. Be sure to consider secondary
effects of a pesticide before using them in any crop where Aphytis is
present.
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