The extent intraspecific variation among 42 morphological characters within Neoseiulus californicus (McGregor) (Acari : Phytoseiidae) is examined. Neoseiulus californicus is an important biological control agent used commercially worldwide to control pest mites in many crops. The correct diagnosis of this species is thus of prime importance for successful biological control and agricultural development. Incorrect interpretation of intraspecific variation could lead to misidentification and potentially to the description of new species that may be invalid. Three hundred female N. californicus representing ten populations collected from all over the world were measured and compared with the types of two morphologically close species: Neoseiulus marinus (Willmann) and Neoseiulus ornatus (Athias-Henriot). Significant differences between the populations were observed for almost all of the characters considered. However, these differences were small and low within-population standard errors in measurement data were observed. The mites collected in Chile were very different from the specimens of the other populations of N. californicus considered. The level of intraspecific morphological variation found within N. californicus indicates that caution must be applied to correctly determine species boundaries within this genus and morphological variation needs to be considered more in species' descriptions. Based on our morphological analysis we conclude that N. ornatus, N. marinus and N. californicus are valid species. Redescriptions of these three species are given in this paper.
This paper focuses on the differentiation of specimens, identified as Phytoseiulus longipes, collected in four countries: Argentina, Brazil, Chile and South Africa. Two of these populations are known to feed and develop on Tetranychus evansi, whereas the two others do not. As morphologically similar specimens can sometimes belong to different species and because differences in predatory behaviours exist among the four populations considered, we tested for the presence of cryptic species. Morphological and molecular experiments (12S rDNA) were carried out. The four studied populations of P. longipes could be morphologically differentiated thanks to a combination of characters. However, these morphological differences are very small. The two populations that feed and develop on T. evansi (from Argentina and Brazil) are morphologically closer to each other than to the two other populations. Genetic distances among the four populations of P. longipes were very low, suggesting that despite their different feeding habits, all specimens belong to the same species. However, the populations associated with T. evansi showed some genetic differentiation from those that do not use this pest. This is the first time that this type of differentiation has been reported for the family Phytoseiidae. These results are of primary importance to ensure the success of biological control programs and to develop strains adapted to both crops and prey species.
Neoseiulus californicus (McGregor) is a natural enemy of pest mites used worldwide in many crops. Its correct identification is thus essential to ensure biological control success. The present study aimed to characterize molecular and morphological intraspecific variations for assisting in the diagnosis of the species and to build baseline information about expected variations within a commercially important phytoseiid species. Morphological and molecular [12S rRNA, cytochrome b mitochondrial (mt)DNA, and internal transcribed spacer] analyses were carried out on fourteen populations collected worldwide and on one mass-reared strain. The genetic distances between the specimens of N. californicus and another related species were high and no overlap was observed, sustaining the reliability of such molecular methods for assisting a specific diagnosis. Furthermore, the genetic distances between populations of N. californicus were very low and overlap between intra-and interpopulations distances was observed, except for two populations collected in France (Marsillargues and Midi-Pyrénées). The high mitochondrial differentiation between these two latter populations and the others questions their specific status: do they belong to the species N. californicus or to another cryptic species? However, using nuclear DNA marker analyses, no distinct differences were observed. Furthermore, even if significant morphological differences were observed between the populations, these differences were very small and the standard errors within each population were very low. We thus concluded that all the populations studied belong to the species N. californicus, despite unexpected high mitochondrial variations. The present study thus displays the importance of an integrative taxonomic approach for avoiding misidentifications. A discussion on morphological and mtDNA variations in relation to diagnostic reliability is developped.
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