Greenhouse - Thrips Control with Conserve Insecticide

Thrips were a very difficult insect to control in greenhouses for a period of time. Then Conserve insecticide was introduced giving a good control option. The following is some information on this insecticide and how it is best used.

Conserve

Most greenhouse managers are using spinosad (Conserve) for controlling thrips in the greenhouse. This material continues to do a bang-up job in controlling thrips. The origin of this material is rather interesting. Back in 1982 a microbiologist who worked for Dow AgroScience Company was visiting a Caribbean island and took a soil sample from an abandoned rum distillery. The microbes from the soil sample were grown in a fermentation broth that provided a bacterium that was an actinomycete called Saccharopolyspora spinosa. The Latin name is very descriptive with "Saccharopolyspora" translating to "sugar loving with multiple spores". The species name "spinosa" refers to the spiny structure of the sheath. The word "spinosad" is derived from spinos A and D. When grown aerobically in water based medium it produces metabolites called spinosyns. The product that is sold as an insecticide is approximately 85 % Spinosyn A and 15% spinosyn D.

The Scientist from Dow AgroScience who found this original material realized this was a unique material that was very effective in controlling several species of insects. It was labeled by Dow AgroScience and submitted to EPA for approval in 1997. The spinosad is effective in controlling immature stages of Lepidoptera (moth and butterfly larvae), thrips, leafminers, and Diptera species such as apple maggot and fruit flies.

This Spinosad material works well in IPM programs because it is selective in what it kills and tends to spare beneficial organisms. In field trials, spinosad was found to be non-harmful to most predators. In lab trials it has had a very negative impact on parasitoids, especially parasitoids confined to fresh or dried residue in laboratory settings. Outdoor, it is a slightly different story. Outdoors the spinosad breaks down in 3 -7 days, post application, and thus parasitoid exposure is greatly reduced.

Resistance?

Yes, it is time for the lecture part about resistance. Anytime you have a material that works great people tend to use it over and over without switching to another class of chemistry. The good news is that there has been no cross resistance reported between spinosad and organophosphates, pyrethroids, imidacloprid, avermectin or Bt. Continue to use Conserve wisely for thrips control, since it is fairly safe and effective but remember to rotate to other class of chemistry and investigate some of the alternative control methods such as use of microscreening, regular monitoring, and use of beneficial organisms.

Reprinted from the January 20, 2006 Greenhouse TPM/IPM Weekly Report from the University of Maryland Cooperative Extension.