| Abstrakt: |
During 1972 and 1973, a field study consisting of 5 experiments was conducted to determine the effect of artificial honeydews on insect communities in potato fields. Treatments were based on either yeast hydrolysate or Feed-Wheast® (produced by culturing the yeast, Kluyveromyces fragilis Jorgensen, on cottage cheese whey) combined with honey and molasses. Feed-Wheast® was also used with tryptophan. Freshly extracted aphid juice was used alone and combined with Feed-Wheast® to test its effect on oviposition of syrphid flies. Treatments of artificial honeydews significantly increased the numbers of predatory insects: Chrysopa carnea Stephens, Hippodamia spp., Coccinella transversoguttata richardsoni Brown, Sphaerophoria cylindrica (Say), and Syrphus sp. Fecundity of C. carnea was significantly increased by the treatments. Two predators, Nabis alternatus (Parsh.) and Orius tristicolor White were reduced in treated plots. Neither artificial honeydews nor aphid juice treatments stimulated syrphid flies to lay eggs on sprayed plants. Numbers of Myzus persicae (Sulzer), Lygus hesperus Knight, Leptinotarsa decemlineata (Say) and Autographa californica (Speyer) were significantly reduced in treated areas. |
