Effects of Brassica oleracea waxblooms on predation and attachment by Hippodamia convergens

Four mutations that reduce waxbloom in Brassica oleraceaL. were examined for their effects on predation, mobility, and adhesion to the plant surface by the general predator Hippodamia convergens (Guérin-Menéville) (Coleoptera: Coccinellidae). The mutations reduce waxbloom to different degrees, but all produce a ‘glossy’ phenotype. Plants tested were inbred lines, near isogenic lines, or segregating F 2 populations, depending on the mutation. In an experiment on caged leaves, predation of Plutella xylostellaL. larvae byH. convergensadult females was significantly greater on glossy types as compared with ‘normal-wax’ or wild-type counterparts. Although the trend was the same for each mutation, individual comparisons between glossy and normal-wax lines or segregants were only significant for two of them, those producing mutant alleles g a andgld . IndividualH. convergenswere observed to spend more time walking on leaf edges and less time walking on leaf surfaces of normal-wax plants than glossy plants. Hippodamia convergens also obtained better adhesion to the surfaces of glossy plants than to normal-wax plants when tested using a centrifugal device. Two of the mutations produced similarly strong effects on predation, behaviour, and adhesion by H. convergens . These two are the same previously determined by us to provide the strongest similar effects on another generalist predator, Chrysoperla plorabunda(Fitch). The results indicate that waxbloom variation in nature could affect herbivore populations through its effects on generalist predators.

[1]  R. Bodnaryk Leaf epicuticular wax, an antixenotic factor in Brassicaceae that affects the rate and pattern of feeding of flea beetles, Phyllotreta cruciferae (Goeze) , 1992 .

[2]  S. Eigenbrode,et al.  Predators mediate host plant resistance to a phytophagous pest in cabbage with glossy leaf wax , 1995 .

[3]  Sanford D. Eigenbrode,et al.  Predation, behavior, and attachment by Chrysoperla plorabunda larvae on Brassica oleracea with different surface waxblooms , 1999 .

[4]  H. N. Barber,et al.  Chemical genetics of wax formation on leaves of Brassica oleracea , 1970 .

[5]  K. A. Stoner,et al.  Glossy Leaf Wax and Plant Resistance to Insects in Brassica oleracea Under Natural Infestation , 1990 .

[6]  Nigel E. Stork,et al.  ROLE OF WAXBLOOMS IN PREVENTING ATTACHMENT TO BRASSICAS BY THE MUSTARD BEETLE, PHAEDON COCHLEARIAE , 1980 .

[7]  W. S. Abbott,et al.  A method of computing the effectiveness of an insecticide. 1925. , 1925, Journal of the American Mosquito Control Association.

[8]  C. Eckenrode,et al.  Breeding for Resistance in Cabbage and Cauliflower to Cabbage Looper, Imported Cabbageworm, and Diamondback Moth1 , 1980, Journal of the American Society for Horticultural Science.

[9]  C. Eckenrode,et al.  Variation in Brassica oleracea Resistance to Cabbage Looper and Imported Cabbage Worm in the Greenhouse and Field , 1975 .

[10]  Richard J. Harris A primer of multivariate statistics , 1975 .

[11]  S. Eigenbrode,et al.  Mobility of three generalist predators is greater on cabbage with glossy leaf wax than on cabbage with a wax bloom , 1996 .