Upwind flight by the cabbage root fly, Delia radicum

Abstract

In fourteen releases, most female D.radicum (L.) (Diptera, Anthomyiidae) flew upwind or at an angle to it of less than 77q regardless of the presence of host-plant odour. Females ready to lay eggs flew upwind without prior stimulation by odours from either a host crop or a trap releasing up to 3ml/day of the attractant allylisothiocyanate. Upwind flight was more pronounced in flies from a diapause than from a continuous, non-diapause culture. Males from the nondiapause culture dispersed upwind and downwind in more or less equal numbers; old males flew mainly downwind. But, like the females, most males from the diapause culture flew upwind. Long-distance, odour-modulated anemotaxis did not appear to be used to locate distant host crops by either sex. It is concluded that the distances of insect orientation to plant odours recorded to date are only of intermediate range, and that long-range orientation to the odours of a host-plant still has to be proven. It is suggested that host-plant volatiles are involved not only in the final stage of host location but also in the first, and probably most important stage of host selection whilst the insect is still in flight.

Response by Specialist and Generalist Natural Enemies to Agroecosystem Diversification: A Selective Review

“…Plants provide visual, olfactory, and tactile stimuli that may be used as long-range attractants or as short-range arrestants by enemies in habitat or patch location (reviewed by Vinson [1976Vinson [ , 1984; see Drost et al 1986). However, evidence for distant (> 10 m) olfactory orientation to plants is controversial for herbivores (Finch & Skinner 1982), and is entirely lacking for enemies. Specialist herbivores appear to use more specific chemical and visual cues than generalists in orienting to host plants (Stadler 1977, Prokopy & Owens 1978; this may be true for enemies as well (Vinson 1976).…”

Effects of Canola-Wheat Intercrops on <I>Delia</I> spp. (Diptera: Anthomyiidae) Oviposition, Larval Feeding Damage, and Adult Abundance

“…would be greater in monocultures than intercrops. However, Finch and Skinner (1982) found that the direction of Table 5 long-range movements of D. radicum females was little mediated by host plant odors but substantially inßuenced by wind direction. Rather than indicating the direction of host plants, volatile host plant chemicals signal passing crucivores such as D. radicum that suitable host plants are nearby (Finch and Collier 2000).…”

From where are insects recruited? A new model to interpret catches of attractive traps

“…Flight direction in relation to wind direction was studied in gypsy moth males Lymantria dispar and the moths did not preferentially fly across the direction of the wind, upwind or downwind (Elkinton & Carde , 1983). In contrast, the cabbage root fly Delia radicum flew upwind before intercepting the host odour plume (Finch & Skinner, 1982), and Agrotis segetum moths typically flew across the direction of the wind when outside the range of a pheromone plume (Riley et al, 1998). Both these studies were performed in open habitats (e.g.…”