During the exploration phase of the Oriental fruit fly program, and using the genus name
Opius, several of the opiines from Kenya were variously identified as either
perproxima or as color varieties of
concolor (
Clausen et al. 1965). Material from the same localities had been identified as either
humilis or
perproxima during an earlier sampling program (
Bianchi and Krauss, 1936). Difficulty in identification of these three nominal species is still a problem (
Kimani-Njogu et al. 2001,
Rugman-Jones et al. 2009), and uncertainty over whether or not they are distinct makes it difficult to correctly associate previously published host records.
Psyttalia concolor was originally described from Tunisia,
P. humilis from Western Cape Province of South Africa, and
P. perproxima from Benin, Ghana, and Nigeria in West Africa. In some of the more recent studies, populations from Kenya have been tentatively identified as
P. concolor because of reproductive compatibility with populations from Italy (
Kimani-Njogu et al. 2001,
Wharton et al. 2000). Because the two populations are genetically distinct, however, the name
humilis can be used for subsaharan populations and the name
concolor for populations from the Mediterranean Region when it is useful to do so, such as in some biological control programs (
Rugman-Jones et al. 2009). Laboratory studies need to be expanded to determine reproductive compatibility under field conditions to further address this problem.
Similarly, two decades after the purposeful introduction of P. concolor to Italy to control olive fly, Bactrocera oleae (Rossi), Monastero (1931) described Psyttalia siculus from Sicily as a parasitoid of B. oleae. Considerable debate ensued over whether P. siculus was actually distinct from P. concolor (Monastero, 1934; Delucchi, 1957). Fischer (1963, 1971, 1972) treated P. siculus as a subspecies of P. concolor with slightly longer ovipositor, and retained P. humilis as distinct from P. concolor “because of differences in morphology of developmental stages.”
Three other species from Africa are also difficult to distinguish from Psyttalia concolor: Psyttalia dacicida (Silvestri) reared from Bactrocera oleae in Eritrea, Psyttalia dexter (Silvestri) reared from Dacus longistylus in Senegal, and Psyttalia inconsueta (Silvestri) reared from Carpophthoromyia tritea in southern Nigeria. Almost nothing is known of these three species other than the information provided by Silvestri from his original collections made prior to 1914. Psyttalia lounsburyi (Silvestri) is also similar to concolor and the other species mentioned here but is much darker in coloration. It has been reared from olive fly infesting wild and cultivated olives in South Africa and wild olives in Kenya.