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Title: Systematics of whiteflies (Aleyrodidae: Aleurodicinae) : their distribution, phylogeny and relationship with parasitoids
Author: Charles, Elroy
ISNI:       0000 0004 2684 3604
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2010
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The whitefly subfamily Aleurodicinae (Hemiptera: Sternorrhyncha: Aleyrodidae) comprises 20 genera consisting of 138 described species. They are plant feeders and have six developmental stages. The sessile puparia stage is used to identify whiteflies and can provide useful host-plant identity. The general aim of this study is to re-define the subfamily Aleurodicinae by addressing its distribution and phylogenetic relationships. Approximately 88% of Aleurodicinae species are neotropical, though six genera, Aleuroctarthrus, Palaealeurodicus, Nipaleyrodes, Pseudosyaleurodicus, Synaleurodicus and Stenaleyrodes, are mostly distributed in the Australasian region. The separation of Australia from the Southern Gondwanan land mass may explain the Australasian distribution. Twentyseven percent of species are polyphagous but few species are recorded in three or more regions. Aleurodicus dispersus, Paraleyrodes minei and P. bondari are considered invasive pests. Regional proximity coupled with the anthropogenic effects are the main factors responsible for the shared species. In general, polyphagous species are more likely to suffer parasitism and are generally the subject of biological control. Dirphys, a neotropical genus of aleurodicinae, has potential as a bio-control agent. Phylogenetic relationships were assessed using 65 DNA sequences derived from members of nine aleurodicine genera and from 30 adult whitefly species, and puparial morphological characters were derived from 76% of described aleurodicine species and an additional nine out-groups. From morphological data, the strict consensus (length 182, CI=0.189 and RI=0.649) of unweighted most parsimonious trees, Aleurodicinae was recovered as non-monophyletic with some, mainly Australasian genera, being placed among the out-group taxa. Under the implied weighting algorithm and with the concavity factor K > 6, Aleurodicinae was, however, monophyletic. A similar relationship occurred with the molecular analysis in the absence of those Australasian genera. Twelve valid monophyletic genera were recognized, with Dialeurodicus forming the sister group to the remaining genera. Three pairs of sister genera were indicated and one pair, Bakerius plus Leornadius was synonymized. Some intrageneric relationships were supported while some species formed sibling relationships, for example Aleurodicus pulvinatus, A. cocois and A. juleikae form a subclade within the genus. Some generic groups need restructuring, for example, Metaleurodicus.
Supervisor: Leather, Simon ; Quicke, Donald Sponsor: Commonwealth Association of Universities ; University of Guyana
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral