Morphology and taxonomy of tortricid moth pests attacking fruit crops in South Africa

[摘要] ENGLISH ABSTRACT: Cydia pomonella (codling moth), Thaumatotibia leucotreta (False codling moth), Thaumatotibiabatrachopa (Macadamia nut borer), Grapholita molesta (Oriental fruit moth), Cryptophlebia peltastica(Litchi moth), Epichoristodes acerbella (Pear leafroller/Carnation worm) and Lozotaenia capensana (Appleleafroller) are the most economically important tortricids affecting various crops in South Africa. Thecorrect identification of these species, especially of the larval stage, is of great importance in pestmanagement. Using available literature, augmented by additional morphological studies, an interactiveidentification key (Lucid key) for larval and adult stages of the seven species was developed. The colourand markings of the head, characteristics of the prothoracic and anal shields, the position of theprespiracular setae (L-group) relative to the spiracle on the prothoracic segment, the position of the spiracleon the eighth abdominal segment and L-group on the ninth abdominal segment, as well as the presence orabsence of the anal comb are key characteristics for larval identification. For adult identification, wingpattern and genitalia are the most important features. However, the use of genitalia for moth identificationmight be difficult for the lay user, as the dissection and mounting of these structures requires certain skillsand specialized equipment. Thus, genitalia have not been included in the Lucid Key. Differences in themorphological characteristics of most pupae were so minute that this stage was also not included in theLucid key. However, the pupae of E. acerbella and L. capensana are easily distinguished from those of theother species by the presence of acremaster. This study also included the first morphological description ofthe pupa of L. capensana, which can be distinguished from that of E. acerbella by various features of thecremaster, antennae, spiracle shape, number of setae on abdominal segments A5-7, the size of spines onA3-7, and the presence/absence of spines on A9. A previous study by Timm (2005) indicated thatgeographically isolated populations of T. leucotreta tend to be genetically distinct. This raised the questionof whether speciation/subspeciation has occurred or is occurring. Male moth genitalia are thought to evolverapidly and are often the only features that can reliably distinguish similar species. Hence, variation in theshape of the valvae of T. leucotreta was used to determine whether divergence has occurred betweenpopulations of T. leucotreta. Elliptical Fourier analysis was used to analyze the valvar variation in threedifferent populations. Although some variation in valvar shape was detected among mean population valuesfor certain traits, no clear pattern emerged. Principle component analysis also showed no distinct clusteringof valvae shape among populations, providing no evidence for divergence in male genitalia and thereforeno morphological evidence of incipient speciation.

[发布机构] Stellenbosch University