| Summary: | The bedbugs Cimex lectularius and C. hemipterus (Hemiptera:
Cimicidae) have been identified from a study area in
northern Natal and KwaZulu. South Africa, between 26° 45' S
and 28° 45' S, and 32° 00 ' E and 32° 52' E. Morphological
behavioural data suggest that the pigeon bug, C.
columbarius, which closely resembles C. lectularius, is not
present in Zulu huts. Two characters are suggested to
supplement Usinger's (1966) key for distinguishing the
nymphal stages of C. lectularius, and a key is presented for
the case of G. hemipterus. Distinguishing features between
the nymphal stages of the two species are also given. The
two species were found to be sympatric over most of the
study area, with C. hemipterus the more plentiful species in
the north and apparently still in the process of invading
the study area. Evidence was found that C. hemipterus
replaces C. lectularius in huts where initially both species
were found, and this agrees with laboratory findings that
interspecific mating tends to shorten the life span and
reduce the egg production of female C. lectularius females.
Interspecifically mated female C. lectularius can be
recognised by an easily visible morphological change in the
reproductive system (Walpole, 1988b) and this character was
used to prove that interspecific mating takes place in the
wild.
The size and life-stage composition of bedbug infestations
were investigated together with factors likely to affect
their growth. Cimex hemipterus was found not to be at a disadvantage as regards rate of egg production despite low
temperatures in the wild, which suggested that such
interspecific differences apparent in the laboratory may be
an artifact. The specific status of C. lectularius and C.
hemipterus are discussed, with particular reference to their
cross-mating in the wild and the production of a hybrid. The
acceptability of the Recognition Concept of species
(Paterson, 1985) is
considered
in detail. The
susceptibilities of wild bedbugs of both species to DDT,
dieldrin and fenitrothion were tested in comparison with a
susceptible strain of C. lectularius. Field trials of
bendiocarb, deltamethrin and fenitrothion were carried out
involving monitoring by bioassay and insecticidal knockdown.
Subsequent to successful bedbug control operations,
reinfestation rates and rates of replastering of mud walls
of huts (an indigenous method of attempted bedbug control
inimicable to malaria control operations) are assessed. === Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1989.
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