1 0 2
N . WAI.OFF
This change probnbly led to intcrspccific competition between Apicm
and Ih~chulius larvae since Apion hatrh first and have “the first choice
of seeds”. 111 Uruchidius parasitism reduced the population inside the
pods to about half in both year8 and predation of the exposed eggs of
the species must also have been considerable. Finally, dispersal of
Uruchidius adult8 to overwintering sites and the earlier dispersal to
other flowering plants, in search of pollen, causes the heaviest loss in
that stage.
The populations of Apion fuscirostre were smaller and causes of
changes within them could not be adequately analysed but it is clear
that parasitism of the larvae can be very important and again, as in
Bruchidius, dispersal of adults contribut>es greatsly to the diminution of
the populations.
B. S P E C I E S LIVING WITHIN T H E B R O O M POD CAVITY
1. Three species of Cecidomyidae
Three species of Cecidomyidae (Diptern) occupy this ecological niche.
The occurrence of several genera of Cecidomyidae in the same microhabitat has previously been recorded by a number of authors (Milne,
1960; Otter, 1938; Barnes, 1916, 1918, 1951). The cecid larvae within
the pods have different habits. Contarinia pulchripes (Kieffer) are found
early in the year in green arid unripe pods and are phytophagous. They
reduce thc insides of the pods, including the seeds, to a brown mass.
The larvae of C‘lindiplosis sarothanini Kieffer are fungus feeders and
are found later in t,he year, when the broom pods have hardened.
Lestaliplosis species are 1)redatory and appear about two weeks after
Clinodiplosis.
Within the broom pod each specie6 has its set of parasites, the biology
of which is closely linked with that of the hosts.
2. Outline of life histories
(a) Contarinia. The fly oviposits through the hole left by a feeding
Apion fuscinostre and lays batches of up to 200 eggs. As the larvae
complete feeding, the pod disintegrates and hardens. Cracks uppear
through which the third instar larvae escape. They arc capable of
jumping and leave the pods to overwinter in cocoons in broom litter.
The adults emerge in the following May or June.
The percentages of pods infested by this species in 1960 and 1961 were
3.4 and 6.1 in Area 1 and 0.2 and 1.4 in Area 4.
Three hymenopterons sperics pnrai4tise C‘ontnrinia larvae. The first,
Aprostocetus sp. nr. aethiops (Zetterstedt) (Eulophidae) is an ectoparasite which requires 8- 10 host larvac to complete its development.
Aproatocetux larvac HINO kill any o t h e r Iarvatc and pupae in their vicinity,
N . WAI.OFF
This change probnbly led to intcrspccific competition between Apicm
and Ih~chulius larvae since Apion hatrh first and have “the first choice
of seeds”. 111 Uruchidius parasitism reduced the population inside the
pods to about half in both year8 and predation of the exposed eggs of
the species must also have been considerable. Finally, dispersal of
Uruchidius adult8 to overwintering sites and the earlier dispersal to
other flowering plants, in search of pollen, causes the heaviest loss in
that stage.
The populations of Apion fuscirostre were smaller and causes of
changes within them could not be adequately analysed but it is clear
that parasitism of the larvae can be very important and again, as in
Bruchidius, dispersal of adults contribut>es greatsly to the diminution of
the populations.
B. S P E C I E S LIVING WITHIN T H E B R O O M POD CAVITY
1. Three species of Cecidomyidae
Three species of Cecidomyidae (Diptern) occupy this ecological niche.
The occurrence of several genera of Cecidomyidae in the same microhabitat has previously been recorded by a number of authors (Milne,
1960; Otter, 1938; Barnes, 1916, 1918, 1951). The cecid larvae within
the pods have different habits. Contarinia pulchripes (Kieffer) are found
early in the year in green arid unripe pods and are phytophagous. They
reduce thc insides of the pods, including the seeds, to a brown mass.
The larvae of C‘lindiplosis sarothanini Kieffer are fungus feeders and
are found later in t,he year, when the broom pods have hardened.
Lestaliplosis species are 1)redatory and appear about two weeks after
Clinodiplosis.
Within the broom pod each specie6 has its set of parasites, the biology
of which is closely linked with that of the hosts.
2. Outline of life histories
(a) Contarinia. The fly oviposits through the hole left by a feeding
Apion fuscinostre and lays batches of up to 200 eggs. As the larvae
complete feeding, the pod disintegrates and hardens. Cracks uppear
through which the third instar larvae escape. They arc capable of
jumping and leave the pods to overwinter in cocoons in broom litter.
The adults emerge in the following May or June.
The percentages of pods infested by this species in 1960 and 1961 were
3.4 and 6.1 in Area 1 and 0.2 and 1.4 in Area 4.
Three hymenopterons sperics pnrai4tise C‘ontnrinia larvae. The first,
Aprostocetus sp. nr. aethiops (Zetterstedt) (Eulophidae) is an ectoparasite which requires 8- 10 host larvac to complete its development.
Aproatocetux larvac HINO kill any o t h e r Iarvatc and pupae in their vicinity,