Preference and performance responses of California grape phylloxera to different Vitis rootstocks

Laboratory experiments on host preference and performance were simultaneous ly conducted with Cabernet Sauvignon, AXR#1, and 5C Vitis rootstocks for th e California biotypes A and B grape phylloxera. Preference bioassays record ed over a 3-day period indicated that phylloxera exhibit differential host choice. AXR#1 is antixenotic to biotype A, and 5C is antixenotic to both ph ylloxera biotypes. Preferences observed with biotype B for Cabernet Sauvign on and AXR#1 were not statistically different, whereas biotype A had shown a significant preference for Cabernet Sauvignon. On 5C the preferences scor ed were significantly lower than on either of the other two rootstocks, and there was no significant difference beetween biotypes. Performance bioassa ys recorded over a 29-day period indicated that survival, development, and reproduction of both biotypes were affected by Vitis rootstock. Both biotyp es were unable to survive or develop on 5C suggesting the presence of antib iotic resistance in 5C against these phylloxera biotypes. The antibiotic ef fects observed with AXR#1 against biotype A were expressed as significant r eductions in survival, development, and reproduction. Performance of biotyp e B on AXR#1 was similar to its performance on Cabernet Sauvignon. For both AXR#1 and 5C rootstocks and both phylloxera biotypes A and B the antibioti c mechanism was considerably stronger than the antixenotic mechanism. This research indicated that host preference and performance are positively corr elated in grape phylloxera with the rootstocks and phylloxera biotypes test ed.