Nursery, Greenhouse, and Landscape News

Green Lacewings for Control of Sweetpotato Whitefly on Greenhouse Hibiscus

Parasitoids are frequently used for biological control of sweetpotato whitefly (SPWF), but a predator might be just as effective. Chyrsoperla rufilabris larvae feed voraciously on SPWF eggs and nymphs. Could this commercially available green lacewing provide an acceptable level of SPWF control on Hibiscus plants in greenhouses?

Experiments in southern Texas showed that inundative releases of C. rufilabris larvae can maintain greenhouse Hibiscus plants in a marketable condition. Lacewings were released at a rate of 5, 25, or 50 per plant at 2 week intervals after SPWF became easily detectable (the normal "threshold" in commercial greenhouses where insecticide applications begin). Most of the plants treated with only 5 larvae remained marketable, whereas all of the plants treated at the higher release rates were marketable. The untreated plants were severely damaged, as evidenced by sooty mold, leaf yellowing, and leaf drop, and were unmarketable at the end of the 4 week experiment.

Two releases of 100 larvae in the center of 12 plants also maintained marketability. The predators provided better control when the plants' leaves were in contact with adjacent plants. Placing the plants so that there is contiguous leaf contact improves lacewing dispersal and perhaps decreases opportunities for cannibalism.

This generalist predator was released with the expectation that it would invade and consume until prey was eliminated and then would die out -- not to survive to reproduce and continue its existence while maintaining low SPWF populations. This seems to be an appropriate strategy in such a short lived system, as are many other greenhouse production systems.

Source:

Breene, R. G., R. L. Meagher, D. A. Nordlund, and Y.-T. Wang. 1992. Biological control of Bemisia tabaci in a greenhouse using Chyrsoperla rufilabris. Biol. Control 2(1): 9-14.


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