Abstract
A new distribution map is provided for Delia radicum (L.) (Hylemya brassicae(Bch.)) (Dipt., Anthomyiidae) (Cabbage root fly). Host Plants: Brassica spp. Information is given on the geographical distribution in EUROPE (excl. USSR), Austria, Azores, Belgium, Britain, Bulgaria, Czechoslovakia, Denmark, Finland, France, Germany, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Poland, Romania, Spain, Sweden, Switzerland, Yugoslavia, ASIA (excl. USSR), Israel, Turkey, USSR, AFRICA, Madeira, Morocco, NORTH AMERICA, Canada, USA.
AbstractThe spectral sensitivity of the compound eye of the cabbage root fly, Delia radicum (Linnaeus), was measured using the electroretinogram (ERG) technique, at fifteen selected wavelengths between 340 nm and 670 nm. The form of the ERG was found to be diphasic in nature. A primary peak of spectral sensitivity in the UV (340–350 nm), and a smaller secondary peak in the blue-green region (460–546 nm) were found, together with a shoulder of sensitivity, representing a ‘pseudo-peak’ as reported for other Diptera, in the red region (630 nm). No significant differences were found between the dorsal and ventral regions of the eye. The peak response in the green region (546 nm) agrees well with existing behavioural data on colour attraction and visual discrimination of host plants by the cabbage root fly.
The development of integrated pest management strategies becomes more and more pressing in view of potential harmful effects of synthetic pesticides on the environment and human health. A promising alternative strategy against Delia radicum is the use of trap crops. Chinese cabbage (Brassica rapa subsp. pekinensis and subsp. chinensis) is a highly sensitive Brassicaceae species previously identified as a good candidate to attract the cabbage root fly away from other crops. Here, we carried out multi-choice experiments both in the laboratory and in field conditions to measure the oviposition susceptibilities of different subspecies and cultivars of Chinese cabbages as compared to a broccoli reference. We found large differences among subspecies and cultivars of the Chinese cabbage, which received three to eleven times more eggs than the broccoli reference in field conditions. In laboratory conditions, the chinensis subspecies did not receive more eggs than the broccoli reference. We conclude that D. radicum largely prefers to lay eggs on the pekinensis subspecies of Chinese cabbage compared to the chinensis subspecies or broccoli. Some pekinensis cultivars, which received over ten times more eggs than broccoli in the field, appear especially promising candidates to further develop trap crop strategies against the cabbage root fly.
Abstract
Adult CM were exposed to dry conidia of isolates of Beauvaria bassiana (Bb), Metarhizium anisopilae (Ma) or Paeciomyces fumosoroseus (Pf). Two B. bassiana isolates were from Cornell University (P89, L90) isolated from Musca domestica (Diptera: Muscidae), one was from Mycoteh Corp., Butte, MT (Myc 726) originally isolated from southern corn rootworm, Diabrotica undecimpuntata (Coleoptera: Chrysomelidae), re-isolated from a grasshopper, Melanoplus sp. (Orthoptera:Acrididae), and then re-isolated from silverleaf whitefly, Bemesia argentiflora (Homoptera: Aleyrodidae). The other isolates were from the USDA-ARS Collection of Entomophagous Fungal Cultures. One B. bassiana isolate, 4012, was isolated from Delia radicum (Diptera: Anthomyiidae). The P. fumosoroseus isolates were number 1626 from M. autumnalis (Diptera: Muscidae), 1644, 1645, 1867 and 1868 from M. domestica, 1646 from Calliphora spp. (Diptera: Calliphoridae), and 887 from unidentified Diptera. The M. anisopilae isolates were 2521 from Deois spp. (Homoptera: Cercopidae), 3540 from Gelleria mellonella (Lepidoptera: Pyralidae) and 4862 and 4865 from soil. Flies from rearings at the New York State Agricultural Experiment Station, Geneva, NY, were exposed to the fungi by placing 5 flies in a centrifuge tube containing conidia scraped directly from culture plates. The flies were then released into small screened plastic cages, which were placed in chambers with constant temperature of 21° C and L:D 15: 9. There were 3 replicates. Mortality was assessed after 48, 120 and 160h. Dead flies were placed in petri dishes with moistened filter paper to assess infection.
Oviposition Preference of the Cabbage Root Fly towards Some Chinese Cabbage Cultivars: A Search for Future Trap Crop Candidates
