Trapping Cabbage Root Flies in Traps Baited With Plant Extracts and With Natural and Synthetic Isothiocyanates

Abstract

Yellow water traps were more effective than yellow sticky traps in capturing female cabbage root flies, Delia brassicae (Wied.). The water vapour from the traps preferentially attracted 9 9.Experiments showed that the cabbage root fly can locate sources of the cruciferous plant chemical, allylisothiocyanate (ANCS) solely by olfactory cues.Attempts to make yellow traps more effective by adding different amounts of synthetic and naturally occuring isothiocyanates were unsuccessful. There was no synergistic/coalitive effect when effective isothiocyanates were released from the traps as mixtures. Complex mixtures of mg amounts of volatiles extracted from six cuitivars of swede, a favoured host plant of the cabbage root fly, were as effective in traps as 7 ml of ANCS. It is possible that ANCS has to be released at this high rate because the fly normally responds only to mixtures of volatile cruciferous chemicals rather than to individual components of brassica odours. An extract from the swede cv. Wilheimsburger was ineffective, correlating with its partia ! resistance to this pest in the field.None of the traps tested caught 5 to 10 x more <2 9 than the standard ANCS trap and so they would not be able to control this pest.

Chemical characterization of fruit and fungal volatiles attractive to dried-fruit beetle,Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae)

“…Likewise, it is also important in determining the activity of a synthetic odor that the components be presented at quantitative levels corresponding to those of the natural source. For example, although Finch and Skinner (1982) found allylisothiocyanate to be as attractive as host-plant extracts in trapping Delia brassicae, the cabbage root fly, the concentration necessary for this response was far greater than that released from a plant. Similarly, Alm et al (1986) found either propyl propionate or butyl acetate to be effective for trapping the nitidulid G. quadrisignatus; however, since a release rate of > 1 g/day was needed for this response, we do not know what role this compound plays in host-finding for the species.…”

Oviposition behavior of the cabbage root fly,Delia radicum (L.), influenced by host plant extracts

“…This method does destroy the enzymes which may degrade compounds in the extract, such as glucosinolates. Due to this method, the isothiocyanates, which have been shown to be attractive (Finch and Skinner, 1982;Tuttle et al, 1988), probably were eliminated or were present in the extract at a much lower concentration. Second, the more volatile constituents were lost during the evaporation of the solvent from the extract.…”

Volatile compounds from crabapple (Malus spp.) cultivars differing in susceptibility to the Japanese beetle (Popillia japonica Newman)

“…More specialized herbivores such as the Colorado potato beetle [Leptinotarsa decemlineata (Say)], in contrast, would be attracted to a blend of compounds in a more definite ratio (May and Ahmad, 1983;Bernays and Chapman, 1994). It should be noted, however, that specialist herbivores often exhibit attraction to single test compounds of either common or restricted occurrence (Finch and Skinner, 1982;Ko~[~il, 1992). The present study supports the hypothesis for generalist herbivores in that linalool seems to be more important in Japanese beetle attraction than any of the other compounds identified from crabapple leaves.…”