STUDIES ON THE INSECT FAUNA ON SCOTCH BROOM
167
The peak of adult A8ci&ma w m reached in t h m generations (in
1960) and more rapidly than in the other broom Miridas. The peak in
nymphal numbers followed a year later, in 1961. The population then
dmlined for 4 mcoeeeive years and showed only a slight recovery
in 1966.
1967-68
1968-59
19110-60
1960-61
1962-83
1963-64
1964-66
1961-62
-
96.00
4.67
1.66
0.09
2.60
1-02
2.26
-
32.60
2.78
0.80
0.32
0.37
0.92
2 a 0 0
-
60.00
12.13
2.87
0.67
0.96
1.11
0.62
9 *o
2.68
9.47
0-79
1.62
0.48
0.17
0.8%
-
30.00
13.66
1-80
1 a72
0.34
0.71
1.41
The peak of 0. ademcarpi population W&B reaohed in four generations
in 1961, i.e. in the same year aa that of Heterocordylw. The numbers
were maintained at a high level for 4 successive yeam but dropped to a
lower level in 1966. Qrthtylw &nocurpi was the most abundant mirid
species and as such, the most successful.
The numbers of the adult population of 0. vireecene were second only
to 0. czdenomrpi. This species colonised the plantation in 1967, but
reached its peak more slowly than the other Miridae, i.e. in its sixth
generation, 1962. Since then, the population haa steadily declined.
The population of 0. concolor waa relatively small. It reached its peak
in 1962, in its fifth generation, then it declined for two successive years
and recovered slightly in 1966.
Although the adult populations of three mirid species have shown
signs of recovery in 1965, locally they are doomed to a low level by the
nature of the habitat, i.e. by a plantation of uniform age in which many
bushes are at the end of their life span and dying. Natural growths of
broom are usually more heterogeneous in their age struoture and would
support insect populations for longer periods of time, but it is arguable
whether they would support the mme ttbsolute high densities in peak
years.
167
The peak of adult A8ci&ma w m reached in t h m generations (in
1960) and more rapidly than in the other broom Miridas. The peak in
nymphal numbers followed a year later, in 1961. The population then
dmlined for 4 mcoeeeive years and showed only a slight recovery
in 1966.
1967-68
1968-59
19110-60
1960-61
1962-83
1963-64
1964-66
1961-62
-
96.00
4.67
1.66
0.09
2.60
1-02
2.26
-
32.60
2.78
0.80
0.32
0.37
0.92
2 a 0 0
-
60.00
12.13
2.87
0.67
0.96
1.11
0.62
9 *o
2.68
9.47
0-79
1.62
0.48
0.17
0.8%
-
30.00
13.66
1-80
1 a72
0.34
0.71
1.41
The peak of 0. ademcarpi population W&B reaohed in four generations
in 1961, i.e. in the same year aa that of Heterocordylw. The numbers
were maintained at a high level for 4 successive yeam but dropped to a
lower level in 1966. Qrthtylw &nocurpi was the most abundant mirid
species and as such, the most successful.
The numbers of the adult population of 0. vireecene were second only
to 0. czdenomrpi. This species colonised the plantation in 1967, but
reached its peak more slowly than the other Miridae, i.e. in its sixth
generation, 1962. Since then, the population haa steadily declined.
The population of 0. concolor waa relatively small. It reached its peak
in 1962, in its fifth generation, then it declined for two successive years
and recovered slightly in 1966.
Although the adult populations of three mirid species have shown
signs of recovery in 1965, locally they are doomed to a low level by the
nature of the habitat, i.e. by a plantation of uniform age in which many
bushes are at the end of their life span and dying. Natural growths of
broom are usually more heterogeneous in their age struoture and would
support insect populations for longer periods of time, but it is arguable
whether they would support the mme ttbsolute high densities in peak
years.