News and Reviews

The Status of Biological Control for Insect and Mite Control in the U. S. Greenhouse and Nursery Industry

Recently a national survey of the greenhouse and nursery industry was conducted to determine the current status of pest management practices and pesticide use, as well as factors that affect adoption of nonchemical control measures. Although the industry used an estimated 2.8 million pounds of active ingredients to control insect and mite pests, numerous alternatives to chemicals are used, including cultural, physical, and biological methods.

Unfortunately biological control is not widely utilized in this industry. Of almost 650 respondents, only 9.7% reported using predatory mites and 8.7% utilized parasitic wasps. Two-thirds of those that did use these natural enemies felt they were effective. Fewer than 10% considered them impractical to use in their operations, despite problems with obtaining predators or parasites and the necessary adjustments in other management practices.

In this report Bacillus thuringiensis was considered a "pesticide-like" control alternative, along with insect growth regulators, horticultural oils and insecticidal soaps. Bt was used by nearly half of the respondents, with most viewing Bt as effective. The authors suggest the higher use of pesticide-like products are the result of easy integration into a system accustomed to applying chemical pesticides.

Nematode products were used by about half the respondents, with 75% reporting them as effective. The low number of people reporting nematodes as effective but impractical (3-7%) indicates the potential for this control tactic to fit well into the normal operations of an ornamental production facility.

Regional use of natural enemies varied dramatically. Parasitic wasps were used by less than 10% of the respondents in the northeastern, southeastern, and north-central regions, but by just over 50% of the respondents in the western region. Predatory mites were used more or less equally by all four regions, as was Bt, but nematodes were used more in the western region than in the other regions. The authors suggest that this apparent higher acceptance of biocontrol agents in the western region may be related to the climate and cultural conditions in California where a large portion of the western region respondents are located. Two important underlying factors in that state are the impact of the University of California system historically in identifying and developing protocols for the use of biocontrol agents, and the regulatory climate in California which encourages and even requires the use of such alternatives.

The focus in the section titled "Implications for University Research and Extension Programs" is on reducing the amount of active ingredient applied in this industry. They indicate that mites are a major problem for producers, so attempts to change pesticide use patterns in the industry should focus on mite control as one of its major target areas. Mites are often easily controlled using predatory mites, so perhaps our challenge should be to increase the acceptance and utilization of these natural enemies in this industry, especially here in the north-central region.

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