Morphological variation and reproductive incompatibility of three coconut-mite-associated populations of predatory mites identified as Neoseiulus paspalivorus (Acari: Phytoseiidae)

Predatory mites identified as Neoseiulus paspalivorus DeLeon (Phytoseiidae)
have been considered as agents for classical biological control of the coconut mite, Aceria
guerreronis Keifer (Eriophyidae), in Africa and elsewhere. Preliminary identification of
geographically distinct populations as belonging to the same species (N. paspalivorus) was
based on their morphological similarity. However, laboratory studies recently conducted
have shown large differences in feeding behaviors and biological characteristics among
individuals collected from three geographic origins: Brazil (South America), Benin and
Ghana (West Africa). As morphologically similar specimens do not necessarily belong to
the same species, we evaluated under laboratory conditions, reproductive compatibility
between the specimens from three geographic locations to ascertain their conspecificity.
Morphological measurements were also made to determine whether there is a means of
discriminating between them. Inter-population crosses showed complete reproductive
isolation between the three geographic populations, but interpopulation discontinuities in
morphometric characters were absent. These results indicate that the tested specimens are
distinct biological entities despite morphological similarity. Further molecular genetic
studies are therefore proposed, including screening for endosymbionts and assessment of
genetic differentiation, to determine the cause of reproductive incompatibility and to
clarify the taxonomic relationship between those populations.