Investigations on development, survival and fertility of the cereal aphids Sitobion avenae (F.) and Rhopalosiphum padi (L.) (Hom., Aphididae) at different low temperatures
1994
Sengonca, C. (Bonn Univ. (Germany). Inst. fuer Pflanzenkrankheiten) | Hoffmann, A. | Kleinhenz, B.
The effects of constant (4, 8, 12, 16, 20 degrees C and fluctuating (2/10, 5/10, 10/15, 15/20 degrees C.) temperature regimes on the development, the survival and the fecundity of Sitobion avenae (F.) and Rhopalosiphum padi (L.) were studied in the laboratory. The longest duration of development of S. avenae was at 4 degrees C with 55.4 days and shortest at 15/20 degrees C with 9.3 days. The development times of R. padi were shorter than that one of S. avenae with all temperature regimes. These durations took 49.9 days at 4 degrees C and 6.8 days at 20 degrees C. Fluctuating temperatures till 10/15 degrees C, compared to constant temperatures resulted in faster development of both species. The duration of the fourth instar was significantly longer than the duration of the other three instars, especially at low temperatures. The survival of S. avenae and R. padi was longest at 2/10 degrees C with 76.9 and 39.0 days respectively. Low fluctuating temperatures generally resulted in longer survival of S. avenae compared to R. padi. The number of nymphs/female of R. padi was significantly higher than that one of S. avenae in cases when temperatures were 12 degrees C and higher. The maximum number of nymphs/female was 46.9 at 16 degrees C for R. padi and 18.0 at 2/10 degrees C for S. avenae. In general higher temperatures increase the number of nymphs/female, whereas the number of nymphs/day increases especially at the first days of reproduction. The intrinsic rate of increase r(m) of S. avenae ranges from 0.030 at 4 degrees C to 0.210 at 16 degrees C. The r(m) of R. padi ranges from 0.035 at 2/10 degrees C to 0.0321 at 20 degrees C. Compared to constant temperatures regimes fluctuating regimes temperatures result in high values of r(m)
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