This study explored new possibilities to control whiteflies in greenhouse ornamental crops with omnivorous predatory bugs and volatiles. Besides the well-known Macrolophus pygmaeus, we tested 4 new species of predatory bugs: Dicyphus errans, Dicyphus eckerleini, Dicyphus maroccanus and Dicyphus tamaninii. We assessed both their potential to control whiteflies and their possible plant damaging effects through plant feeding. The best control of whiteflies was achieved by the species M. pygmaeus, D. tamaninii and D. maroccanus. Significant flower damage was only observed for the predator M. pygmaeus. The degree of flower damage depended strongly on the gerbera cultivar, but damage was observed for both large-flowered and small-flowered types. All 5 species of predatory bugs were able to establish in a winter crop of 2 gerbera cultivars and the exotic plant Lantana camara. The most promising candidate predatory bug for biological control in gerbera is D. maroccanus. This species established well on the 2 tested gerbera cultivars, gave in all cases an excellent control of pests and no significant plant damage was observed. The predatory bugs gave, besides whiteflies, a good control of Echinothrips and in some cases a suppression of aphids and western flower thrips. The volatile limonene showed no significant effect on the oviposition of tobacco and greenhouse whiteflies. Neither did they repel adults of these whiteflies. The mixture of (E)-2-hexenal and 3-hexen-1-ol did not induce a significant attraction response of the adult whiteflies.
|Publisher||Wageningen UR Glastuinbouw|
- greenhouse horticulture
- ornamental horticulture
- biological control agents