Amblyseius andersoni - From Pollen to Pests

Just like the Very Hungry Caterpillar, Amblyseius andersoni will eat and eat and eat with a variety of items on its menu. Native to the Northern Hemisphere, in early spring it will feast on pollen from conifers until pest populations become the main food source. It then turns its attention to hunting down two-spotted spider mites, broad mites, russet mites, cyclamen mites, gall mites and more. It also will attack thrips and eats pollen, honeydew and fungus in the absence of prey. This makes them an ideal predator for prevention as they can survive on a variety of foods until pest populations arrive. 

They remain active over a very wide temperature range and are effective between 43° to 104°F, allowing them to be introduced much earlier in the growing season as well as in very hot conditions. However, in cooler temperatures and diminishing light (less than 10 hours of daylight) they will seek out shelter in cracks and crevices and enter diapause. This period of dormancy allows them to survive harsh environmental conditions in the northern hemisphere. 

Andersoni mites feed on all life stages of pests, from eggs to adults. They generally live 3-4 weeks. Females can lay 2-3 eggs per day and these are deposited individually on leaf hairs, often near the veins. Andersoni eggs are small oval white spheres, approximately 0.14 mm in diameter. Adults often congregate in the axils of leaf veins when resting but otherwise are very active on the undersides of leaves and will disperse rapidly. 

These versatile predators are used on many crops including fruit orchards, ornamental plants, soft fruits, hemp/cannabis and in tree nurseries. They persist best with relative humidity between 40-60%. For more details on this proficient predator, see our Andersoni Tech Sheet.

How does andersoni compare to other generalist mites? Swirskii also feeds on a variety of pests and pollen, but it is most effective in warmer temperatures (77-82°F) with high humidity. Stratiolaelaps is another predatory mite that feeds on many things, but it lives in the soil, not on the foliage. Finally we have Amblydromalus limonicus which is active down to 55°F and does not diapause in the winter as it is native to subtropical regions of the world. Limonicus has a very high reproductive capacity, but the downside is that it will attack other predatory mites as well as aphidoletes (intraguild predation). 

 Amblyseius andersoni are available in tubes mixed with a bran carrier as well as in slow-release sachets. Upon receipt, lay tubes horizontally to allow all the mites to disperse throughout the carrier.  Do not store predator mites, they will start to die if left in the tube for too long and do not refrigerate predatory mites. Best to release same day as delivery and sprinkle onto the foliage and tops of plants.

For slow-release sachets, hang in the interior of plant foliage and replace every 4 weeks. These tiny packets are breeding sachets and andersoni will continue to multiply and exit the sachets over a period of 3-4 weeks, depending on humidity in the greenhouse. Place sachets in sheltered locations, out of direct sunlight if possible. Introduce early in the crop cycle to prevent pest build-up and for best results.

 

Rates

2-5 andersoni mites/sq. ft.

125 ct. sachets use 1 sachet /5-7 sq. ft.

250 ct. sachets use 1 sachet per 10-14 sq. ft., 1 sachet/ 6-13 ft. row, 1 sachet /tree

Orders for Amblyseius andersoni must be received by Wednesday at 10:00 pst for delivery the following week, so plan accordingly. 

For an in depth look at using andersoni as a predator against pests mites on conifers, review this in depth article: A Preliminary Assessment of Amblyseius Andersoni as a Potential Biocontrol Agent against Phytophagous Mites Occurring on Coniferous Plants. It’s interesting that this North American and European predator utilizes pollen on conifers in early spring to sustain itself until pest populations build.  

Consider Amblyseius andersoni for early season or high summer control and watch as it eats its way through all your pests.