Effects of Host Plant and Temperature on the Biology ofToxoptera citricida(Homoptera: Aphididae)

Abstract

Development reproduction, and population growth parameters of the brown citrus aphid. Toxoptera citricida (Kirkaldy), were evaluated at 25 degrees C on 5 citrus-related host plants ('Carizo','sour orange'. 'Duncan grapefruit', 'Pineapple sweet orange', and 'Mexican lime'), and at 3 temperatures (20, 25, and 30 degrees C ) on 'sour orange'. Brown citrus aphids had faster nymphal developmental times on 'Carrizo' and 'sweet orange' (6.7 d) compared with the other host plants (7.5-7.6 d). Aphids reared on 'Carrizo' had the highest fecundity (67.5 offspring/aphid) and daily reproduction (3.8 offspring/aphid/d). The net reproductive rate (62.6 offspring/aphid/generation) on 'Carrizo' was 21%, 49%, 53%, and 77% higher and the population doubling time (1.8 d) was 2%, 13%, 14%, and 20% faster compared with on 'sweet orange', 'sour orange', grapefruit, and 'Mexican lime', respectively. Development of nymphs was completed in either 4 or 5 instars. The brown citrus aphid had longer nymphal developmental times and adult reproductive periods at 20 degrees C (9.0 and 22.2 d, respectively) compared with at 25 degrees C (7.5 and 15.2 d) and 30 degrees C (6.3 and 11.2 d). The moderate temperature (25 degrees C) was optimal for the brown citrus aphid population growth and intrinsic rate of increase (0.33) was highest. Fecundity of brown citrus aphids reared at 30 degrees C in Florida (our data) was approximately equal to 10 times greater, and r(m) was twice as large as those reared under similar conditions in Japan (data from Komazaki 1982). It was concluded that brown citrus aphid populations in Florida could tolerate higher temperatures than the populations in Japan, and that different populations of brown citrus aphids may have greater genetic variation than was previously thought.