Science and a bit of art is practiced from a set of unassuming buildings in a Santa Paula, Calif. neighborhood.

Each year over 500 million beneficial insects are reared from facilities constructed nearly 100 years ago to beat back citrus mealybug infestations that threatened to wipe out the local citrus industry. The work that goes with these predators and tiny parasites has helped sustain commercial citrus in the region.

Associates Insectary is a grower-owned cooperative that provides insects and pest control advisors to assist growers with integrated pest management strategies in the coastal systems. Insects are also shipped globally for similar IPM strategies.

Brett Chandler, president, and general manager of Associates Insectary, says the cooperative has been successful in rearing Cryptolaemus montrouzieri beetles, a generalist predatory beetle, to help control the citrus mealybug and other insects in coastal lemons and avocados for about a century.

Since then additional predators and parasites have been discovered and reared at the facility to give growers a leg up on insect control without the need for costly or overly toxic insecticides. Other beneficial insects reared at the facility include Anagyrus vladimiri, a parasitic wasp that specifically targets vine mealybug and compliments Cryptolaeumus releases, and a predatory mite called Neoseiulus californicus, that helps avocado growers.

Citrus growers struggling with California red scale can also benefit from Aphytis melinus wasps reared by the facility.

Science meets art

Rearing the tiny insects requires a bit of science and art. Chandler says an understanding of insect biology that includes how the "good" bugs and "bad" bugs interact and the agricultural systems nearby are critical. Though care is taken to contain both sets of insects in the 90-year-old facilities, these are not the same kinds of quarantine containment facilities used by government and private researchers to study critical insects like the Asian citrus psyllid.

The ACP is a worrisome pest for citrus growers because of the disease it vectors in lemons, oranges, limes and other Rutaceae plants. In Santa Paula and nearby communities where lemons are grown, this is of particular concern for Associates Board Chairman Chris Sayer, a Ventura County, Calif., lemon and avocado grower.

Controlling the ACP through IPM methods alone will not work, according to University of California researchers. That is because the Tamarixia radiata, a tiny parasitic wasp that the State of California is rearing, and Associates once reared until it became too cost prohibitive, only feeds on the ACP. Because the citrus industry has a zero-tolerance for the ACP, and because without the ACP, Tamarixia cannot survive, Chandler says other methods of controlling the ACP are necessary.

Adding to the difficulties in controlling ACP through enough Tamarixia wasps is the Argentine ant, a predator that actively and effectively protects ACP from the Tamarixia because of the sugary excretions of ACP nymphs.

"You can get 60-70% parasitism in the fall, as long as ants aren't present, but ants are active in most locations, reducing parasitism to 3-5%" Chandler said of efforts to control ACP with Tamarixia.

Insect nursery

Creating a habitat for the insects to reproduce and grow requires potato plants raised in the dark. The intended mealybugs reared on the blanched potato plants with no chlorophyll will not reproduce well otherwise, Chandler says.

Rearing the mealybugs are necessary to start the process of raising the "Mealybug Destroyer," or Cryptolaemus beetle. It takes about 45 days of raising mealybugs before the destroyer beetle is introduced. The object is to give the Cryptolaemus an opportunity to feed and reproduce. From there the offspring of those beetles are collected about 35 days after combining the two insects. The whole cycle, start to finish, takes about 90 days.

The Aphytis wasp is likewise carefully reared on scale insects grown on butternut squash. This tiny insect helps IPM efforts to control the California red scale in citrus. Organic butternut squash is used as a host food source to grow the Oleander scale host and ultimately allow the Aphytis to lay her eggs and reproduce. From there the tiny Aphytis wasps are collected.

The process of rearing "good" and "bad" pests near each other requires some forethought. Chandler said the selection of "alternate" hosts to allow the "good" bugs to flourish are chosen based on the understanding of nearby agricultural systems and the knowledge that if some of the target pests escape into the environment, these tend to be an insect of "minor importance," meaning growers would not suffer crop losses or damage from those minor pests.

Rooms full of organic butternut squash and greenhouses with lima beans used in the process to rear beneficial insects and their target hosts are carefully managed. The host plants and gourdes are eventually recycled for livestock feed.

"The hogs and cattle love these things," Chandler said of the butternut squash. "We've got locals who come in daily and buy these things from us."

The benefits to growers like Sayer are evident.

For instance, controlling the avocado thrips through IPM methods has reduced Sayer's need to treat avocados because of the high presence of generalist predators in his orchards that will feed opportunistically on a host of troublesome pests.

Even with the necessity of timed insecticide sprays for ACP control, Sayer says having neighbors who also are insectary members helps coordinate spray timing and make management decisions beneficial to growers in a larger area.