Attached
The effect of temperature on aspects of survival fecundity
morph determination, rate of development and relative growth rate
of the bluegreen lucerne aphid (Acyrthosiphon kondoi Shinji)
(BGLA) is discussed. Age specific life tables for BGLA under
different temperatures have been developed. S~gnificant regressions were obtained with rate of developm~nt of life stages
and the temperature.tTemperature thresholds were deduced and a
base temperature of 2.630
C was considered to be of most significance ~n ecological work. Adult apterae are 1.86 times heavier
than alatae. Colour polymorphism of BGLA is apparent at constant
low temperatures. Survival and performance of BGLA on lucerne
cultivars 'Saranac', 'Wairau' and 'Washoe' under different temperatures have been discussed. The cultivars did not affect the
survival of BGLA. 'Washoe' is generally more resistant to aphids
under variable temperature than the other two cultivars. A
laboratory assessment study of BGLA damage on 'Wairau' is
described. The number and the density of leaves produced, and
the number of side branches are positively influenc~d by infestations. Total length in side branches and the number of secondary
stems remain the same under the attack. Plant height, length of
aerial shoots, total leaf area, mean length of secondary stems,
diameter and dry matter of roots and plant dry weight are
significantly affected by the aphids' feeding. A comparative
sampling study for three stages during the year is discussed.
Whole stems, suction and total removal of circular areas were
compared. Aphid population dynamics and the field damage reflected in agronomic features in 'insecticide' and 'noinsecticide' treated lucerne is discussed. Population dynamics
studies of BGLA under two hay cutting practices indicated that
harvesting after the spring flight lS advantageous. Pea aphid
population fluctuations during the 1977-78 season are presented. Peak pea aphid populations occurred in summer. Grazing
in early autumn, mid autumn and early winter as a means of
regulating the spring aphid buildup is investigated. Early
winter grazing after the autumn flights have ceased reduces
BGLA buildup markedly in spring. An aerial sampling study of
BGLA ~s discussed an& the flight pattern of BGLA and natural
enemies in two years is presented. Two major flight peaks per
growing season are apparent. Diurnal density changes of BGLA
O~
convential aphid flight
~
and natural enemies are given. Four
traps are compared using correlation analysis and the influence
of the climatic factors on aphid catch in traps is discussed.
Threshold analysis of BGLA flight for climatic factors is
described. The occurrence of the spring and autumn peaks of
BGLA with respect to physiological time is discussed. Autumn
and spring median flight days are 1625 DO or 11.2 generations
apart. Ninety percent of the spring flight peak lasts for 2.5
generations. Four Fortran computer programmes utilized in the
thesis for (1) obtaining the heat units accumulated over a
