Current knowledge Ceratitis FAR complex (July 2013)
The Ceratitis FAR complex comprises three described entities:
C. rosa Karsch, 1887
C. rosa var. fasciventris (Bezzi, 1920)
C. anonae Graham, 1908
C. rosa var. fasciventris was given specific status by De Meyer (2001). All three entities are thus
currently recognized as separate species. Males can be easily differentiated, based on secondary
male characters (pilosity of the mid leg. See De Meyer & Freidberg, 2006). Females cannot be easily
differentiated. There are some minute differences in leg and anepisternal pilosity between C. anonae
and the other two species (cf De Meyer & Freidberg, 2006).
However, no mitochondrial or nuclear markers were found so far to serve as unambiguous
differentiating character between the three entities (Barr & McPheron, 2006; Virgilio et al, 2008; Barr
& Wiegmann, 2009). Also in laboratory conditions, C. rosa and C. fasciventris can interbreed (G.
Franz, pers. communication) although the hybrids show a higher fluctuating asymmetry which might
indicate a decrease in developmental stability (Erbout et al, 2008). Therefore, it is not clear whether
the three entities correspond to true biological species.
Pheromone and cuticular hydrocarbon analyses showed that the three entities are clearly separable,
based on these methodologies (2nd RCM meeting report and presentations; Vacinkova et al, subm.).
Morphology of immature stages also showed differences specimens of C. rosa (2nd RCM meeting
report and presentation by G. Steck), while the use of morphological characters to separate the three
entities needs further examination. Recent morphometric research, based on wing landmarking, also
allows separation of the three entities (3rd RCM meeting presentation De Meyer).
Using microsatellite markers, it was shown that the three entities could be recognized but that both
C. rosa and C. fasciventris each consist of two separate genotypes (R1-R2 and F1-F2) resulting in five
different entities within the complex.
Recent work has focused on re-analyzing existing data and extending previously used methodologies
recognizing the five entities.
C. anonae is a single entity and is not further investigated. Both males and (albeit to a lesser degree)
females can be differentiated from the other four entities. It shows a clear geographic pattern unlike
that of the other entities (although with some considerable overlap).
Research on C. fasciventris is restricted to re-analyzing the adult morphology, host plant and
geographic data. Male adults can be differentiated by characters of the mid tibia. Wing landmarking
gives an indication of separation for both sexes but not significantly. The data on host plants are too
limited to make draw any conclusions on possible differences in host spectrum. The distributional
data show two largely separated geographical occurrences with one type (F2) restricted to eastern
Africa, while the other type (F1) mainly found in western and central Africa (this separations was also
confirmed by the markers used in Virgilio et al., 2008). However the latter type is also found in some
isolated areas in Angola, Malawi, Tanzania and Zambia. No clear geographical or other pattern could
be detected. The lack of an established colony of both types has prevented providing material for
some of the other studies (like larval morphology or pheromones) and did not allow to check on
mating incompatibility and physiological differences. Currently there is an established colony of F2
type (from eastern Africa) at ICIPE (Kenya). Contacts have been made with researchers in western
Africa but establishment of live colony of F1 has been unsuccessful so far.
Most research has been focusing on the two C. rosa types, also because C. rosa is considered
economically the most important species within the complex. Adult males can be differentiated,
based on characters of the male mid tibia. Wing landmarking gives an indication of separation for
both sexes but not significantly. There is conflicting information in the literature regarding
developmental physiology and climatic niche for C. rosa (De Meyer et al, 2008; Duyck et al , 2002,
Grout & Stoltz, 2007). Re-analysis of distributional data indicate that this might be because of failure
to recognize the two types that were indicated by the microsatellite study. One type, R2, appears to
occur at lower latitudes on the African continent and at higher altitudes. It might be more cold
resistant than R1 type that is absent from the colder parts (lower latitudes, higher altitudes) within
the geographic range of C. rosa. In order to corroborate this with experimental data, physiological
development experiments are set up by different teams throughout the range of the species (South
Africa, Tanzania, Kenya). So far live colonies of both types have be established only in Kenya by ICIPE.
South African and Tanzanian teams are currently setting up live colonies. Preliminary results on the
Kenyan experiments will be presented at the 3rd CRM. In addition, material from the colonies at
ICIPE has been made available to other teams for study of larval morphology and cuticular
hydrocarbons. Preliminary investigation of larval morphology between R1 and R2 from Kenya has not
shown any differences (but there is marked difference with earlier studied material of C. rosa (type
unknown) from South Africa. Further results will be presented a the 3rd CRM. Mating compatibility
experiments have been conducted between the two C. rosa (R1-R2) and the C. fasciventris (F2)
populations at ICIPE. These results will also be presented at the 3rd CRM.
Conclusions
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All evidence so far points towards the fact that the three recognized species within the FAR
complex are indeed three separate species
Further evidence indicate that C. rosa and C. fasciventris might each comprise two different
entities, while C. anonae remains a single entity
For the two C. fasciventris types, there is only the indication of some adult morphological
differences and different biogeographic patterns. The latter are not completely understood
so far. Further investigation in the status of the two entities will require the establishment of
live colonies.
For the two C. rosa types, there is some evidence that these are indeed two separate species.
Results presented at the 3rd CRM and further research that is planned in the forthcoming
months might further reveal the exact status of these two entities.