The predatory mite Neoseiulus californicus (McGregor) has characteristics of both type II specialist predatory mites and type III generalist predatory mites. N. californicus prefers Tetranychid mites as food, but will also consume other mite species, small insects, such as thrips, and even pollen when the primary prey is unavailable.
N. californicus is often used to control the twospotted spider mite, Tetranychus urticae Koch, and other phytophagous mites on various crops in temperate and subtropical regions around the world.
N. californicus has a very complex taxonomic history. It was first described by McGregor in 1954 from lemon in California as Typhlodromus californicus. After 1954, it was moved to the genus Amblyseius and later to the genus Neoseiulus or Cydnodromus, and now Neoseiulus chilenensis (Dosse) is considered a synonym of N. californicus.
Natural populations of N. californicus, are found in Argentina, California, Chile, Florida, Japan, South Africa, Texas, parts of southern Europe, and all along the border of the Mediterranean Sea. N. californicus has been found on many crops including avocado, citrus and other fruit trees. They are also found on cassava, corn, grapes, strawberries, and several vegetable crops and ornamental plants. They prefer warm 10°C–33°C (50°F–91°F) temperatures, but they can tolerate much colder temperatures for short periods of time. For example, they can survive the winters in north Florida where temperatures can fall below freezing at night. They can tolerate a wide range of humidity (40%–80% relative humidity), but prefer humidity at the upper end of this range.
N. californicus eggs are football shaped, approximately 0.04 mm (0.00016 in) in length, and are pale whitish in color. Larvae have only six legs and are translucent in color. Both nymphal stages, the protonymph and the deutonymph, resemble the adults except that they are smaller and cannot reproduce. Adult females are approximately 0.1 mm (0.00039 in) in length and oval in shape. Males are slightly smaller than females. Both males and females are translucent and can be pale orange, peach, or pink in color.
N. californicus females can lay up to four eggs a day. However, two eggs per day is the average. Eggs take from 1.5 to 4.0 days to hatch depending on the temperature. Eggs hatch into six-legged larvae, which can progress to the protonymphal stage without feeding. The larval stage can last from 0.5 to 1.0 day. N. californicus then passes through two nymphal stages: protonymph and deutonymph. Both stages (protonymph and deutonymph) are active feeders. Each nymphal stage can last from 1.0 to 3.0 days. Total developmental time can be as short as 4.0 days or as long as 12.0 days depending on the temperature. N. californicus develops more quickly at higher temperatures. Adults live for approximately 20 days.
N. californicus develops faster when consuming the twospotted spider mite, Tetranychus urticae Kotch, than when consuming other prey sources. However, it will also successfully develop and reproduce when consuming other mite species including Aculus schlenchtendali (Nalepa), Oligonychus pratensis (Banks), O. perseae Tuttle, O. ilicis (McGregor), Panonychus ulmi (Koch), Phytonemus pallidus (Banks), Polyphagotarsonemus (Stenotarsonemus) latus Banks (the broad mite), and Phytonemus pallidus L. (the cyclamen mite). Many of these mites are crop pests. It can also survive and reproduce by consuming thrips and other small insects, but reproduction is very low. N. californicus can even survive for a short period of time by consuming only pollen.
N. californicus is used commercially around the world to control the twospotted spider mite and several other economically important mites on avocado, citrus, dwarf hops, grapes, raspberries, roses and other ornamentals, strawberries, and several vegetable crops. It has been shown to effectively control the twospotted spider mite and P. pallidus on strawberries in glasshouses in the UK and in greenhouses in Argentina. In the United States, N. californicus has been used successfully to control twospotted spider mites on field grown strawberries in southern California and Florida. N. californicus has also been used to control the twospotted spider mite on dwarf hops and to control O. perseae on avocado, to mention a few examples.
The recommended release rate depends on pest species, pest density, and crop. In strawberry, a release rate of one female N. californicus per 10 twospotted spider mites is recommended once mites are present. A predator in first technique, where N. californicus is released at a low rate before twospotted spider mites infestations appear, has become popular in California strawberries. If twospotted spider mire populations are already high, it may be necessary to spray a miticide before releasing N. californicus. The predatory mite can tolerate applications of some miticides.
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