Identification of the mealybug Planococcus halli Ezzat & McConnell (Hemiptera: Pseudococcidae) commonly occurring on yams (Dioscorea spp.) in Africa and the West Indies

Abstract

Multivariate analysis was used to demonstrate that specimens of Pianococcus collected from yams (Dioscorea spp.) in both the West Indies and Africa can be differentiated from the similar P. ficus (Signoret) which occurs on figs, grapevines and pomegranates in the Mediterranean Basin, Pakistan, South Africa and Argentina. The specimens from yams are considered here to be a distinct species, to which the name P. halli Ezzat & McConnell is applied. Examination of material of both species reared on potato tubers at various temperatures showed that the differentiation is not a host-induced effect. Independent canonical variates analysis of the field-collected and reared material each showed clear differentiation of the two groups. However, the coefficients obtained for each character differed markedly between the analysis of the field-collected material and that of the reared material, and thus could not be used to assign individuals to groups. This difference in the values of the coefficients is considered to have been due to the peculiarities of individual populations, as the field-collected material included many genotypes while only three genotypes were represented by the reared material. A key and illustrations are provided for the separation of the two species.

Polymerase Chain Reaction-Restriction Fragment Length Polymorphism Method to Distinguish Three Mealybug Groups Within the <I>Planococcus citri</I>–<I>P. minor</I> Species Complex (Hemiptera: Coccoidea: Pseudococcidae)

“…Separating P. citri from P. minor by using only morphological characters has been difÞcult (Cox and Wetton 1988). The standard method, applicable only to adult females, uses six characters that are scored using a point system, often referred to as the "Cox score" (Cox 1989).…”

Genetic diversity of Turkish populations of Planococcus citri Risso, 1813 (Hemiptera: Pseudococcidae)

“…Hap 12 (GenBank accession KU296034) from India was more closely related to the outgroup haplotype from P. minor than it was to P. citri. These two-mealybug species are very difficult to distinguish from each other morphologically (Cox & Wetton, 1988) and, the identification technique to separate these two species is based on Cox Score. Cox score uses point system and if the score less than 35 meaning P. minor, if higher it is P. citri.…”

Sustainable management of the vine mealybug in organic vineyards

“…The citri-group includes the species of main economic importance, such as the sibling species P. citri, P. ficus, P. minor (Maskell) and P. halli Ezzat and McConnell (Hemiptera: Pseudococcidae) (Cox 1989). Planococcus species are not easy to be distinguished due to the lack of discriminant characters in the adult female (1989) and intraspecific morphological variations in the taxonomic characters (Cox and Wetton 1988;Ben-Dov and Matile-Ferrero 1995). Therefore, some species, such as P. citri and P. minor, or P. ficus and P. halli, can only be distinguished morphologically by a matrix to be scored using a point system (Cox 1989), although Rung et al (2008) observed that the score is not 100% reliable, based on molecular characterization of the specimens.…”