STIJDIEN O N THE INSECT FAUNA O N f3
TABLE XXVIlI
Mortdity of A. spartii n y m p h caused by crowding in Arm 4. Only live, opened
budd are coneidered. Deud OT unopened bud8 were ezclzcdcd from &&icnu
(Watnrough, 1963)
Y W M
No. hatching1
yo mortality
live opened
in opened
bud
buda
1961
4-41
33 -9
1962
0.24
0
1963
0.38
3.6
The field density of A. geni8t.m was always much lower than that of
A. epartii and it is unlikely that intraspecific competition ever had an
appreciable effect.
" " t
7
Initial number A zpcrtr, c A genisfoe per bud
FIG. 7. The effect of denrity in interspecifin competition between A . 8parlii and A .
geniufae nymphs (from Watmough. 1963).
Anot>her set of experiments was designed to see whether interspecific
competition occurred in the two psyllid species. Again, caged expenmental plants were cut down to lengths bearing 6 opened buds and
equal numbers of 1-13 first instar nymphs of both species were introduced on to the plants for a week. Control experiments using one
species at a time were simultaneously rret up. The results (see Figs 6, 7)
indicated R significant difference in mortality in the different sets of
experiments. This waa because the total mortality at low densities wm
lower in the experiment with two species than with A. genistaR alone
TABLE XXVIlI
Mortdity of A. spartii n y m p h caused by crowding in Arm 4. Only live, opened
budd are coneidered. Deud OT unopened bud8 were ezclzcdcd from &&icnu
(Watnrough, 1963)
Y W M
No. hatching1
yo mortality
live opened
in opened
bud
buda
1961
4-41
33 -9
1962
0.24
0
1963
0.38
3.6
The field density of A. geni8t.m was always much lower than that of
A. epartii and it is unlikely that intraspecific competition ever had an
appreciable effect.
" " t
7
Initial number A zpcrtr, c A genisfoe per bud
FIG. 7. The effect of denrity in interspecifin competition between A . 8parlii and A .
geniufae nymphs (from Watmough. 1963).
Anot>her set of experiments was designed to see whether interspecific
competition occurred in the two psyllid species. Again, caged expenmental plants were cut down to lengths bearing 6 opened buds and
equal numbers of 1-13 first instar nymphs of both species were introduced on to the plants for a week. Control experiments using one
species at a time were simultaneously rret up. The results (see Figs 6, 7)
indicated R significant difference in mortality in the different sets of
experiments. This waa because the total mortality at low densities wm
lower in the experiment with two species than with A. genistaR alone