The morphology and ecology of the Carob moth (Ectomyelois ceratoniae) (Zeller) in citrus orchards of the Western Cape, South Africa

Morland, Gail (2015-03)

Thesis (MScConsEcol)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: The Carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae: Phyticitinae) became known initially as a Mediterranean pest of stored commodities such as pods of the Carob tree (Ceratonia siliqua) and dates, but became a pest of phytosanitary concern in South Africa when recorded in 1974 as a pest of citrus in the Citrusdal area in the Western Cape. Since then it has been a pest of questionable concern to the citrus industry. In its larval stage the Carob moth is often confused with that of the False Codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), presenting a problem when contaminated fruit exports are intercepted at ports of entry. The aim of this study was thus to establish some guidelines for the development of an integrated pest management programme, which will enable growers to more effectively manage Carob moth infestations as well as to present morphological detail to facilitate definite identification of the Carob moth in all of its life stages. This was achieved by collating and screening all available literature, ranging from obscure historical to modern texts, to arrive at a clear understanding of key morphological features of use to classify the Carob moth from ordinal to the species level. These features were then used and supplemented to produce a detailed morphological study of the Carob moth’s life cycle. Morphological detail was then condensed into a user-friendly key based on and restricted to the most distinguishing characteristics to aid the identification of the Carob moth and the False Codling moth and to point out morphological characteristics separating the two species. A field study was also carried out in the Western Cape to determine the Carob moth’s seasonal cycle within local citrus orchards. This was determined by using a pheromone based trapping system and a set protocol for damage assessment by actively monitoring for two growing seasons. A pheromone lure preference trial was conducted in all areas of study to assess two commercially available lures. The outcomes of this study aim towards a better understanding of the nomenclatorial and morphological history of the Carob moth, as well as serving as a user friendly morphological identification key. The field results showed a clear seasonal cycle history of the Carob moth within citrus orchards of the Western Cape, closely following the phenology of the citrus tree. A lure preference was recorded for only one of the study areas. The Carob moth was found to be a minor pest, compared to False Codling moth, and presented more of an economic threat in certain areas with suitable hosts. A longer study should be undertaken to ascertain factors affecting the sporadic nature of the pest.

AFRIKAANSE OPSOMMING: Die Karobmot, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae: Phycitinae), was aanvanklik bekend as ‘n Mediterreense plaag van gestoorde produkte, soos, byvoorbeeld, die peule van die Johannesbroodboom (Ceratonia siliqua) en dadels, maar het ‘n plaag van fitosanitêre belang in Suid-Afrika geword toe dit in 1974 as ‘n plaag van sitrus in die Citrusdal gebied in die Wes-Kaap bekend geword het. Sedertdien is dit ‘n plaag van groot belang vir die sitrusbedryf. In sy larwale stadium word die Karobmot dikwels verwar met dié van die Valskodlingmot, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), wat op sy beurt ‘n probleem veroorsaak wanneer besmette uitvoervrugte by invoerhawens onderskep word. Die doel van hierdie studie was dus gemik om sekere gidslyne daar te stel vir die ontwikkeling van ‘n geïntegreerde plaagbestuurprogram wat produsente in staat sal stel om besmettings van die Karobmot beter te bestuur, asook om morfologiese besonderhede wat die juiste identifikasie van die Karobmot in al sy stadia bevorder beskikbaar te stel. Dit is bereik deur die samestelling en nagaan van alle beskikbare literatuur, wisselend van skaars histories tot modern, om sodoende ‘n duidelike begrip van sleutel morfologiese kenmerke van nut om die Karobmot van ordinale tot spesiesvlak te klassifiseer, te verkry. Hierdie kenmerke is dan gebruik en aangevul om ‘n gedetailleerde morfologiese van die lewenssiklus van die Karobmot daar te stel. Morfologiese besonderhede is dan gekondenseer tot ‘n gebruikersvriendelike sleutel gebaseer op, en beperk tot, die mees onderskeidende kenmerke as hulp by die identifikasie van die Karobmot en die Valskodlingmot om morfologiese kenmerke wat die twee spesies skei, uit te wys. ‘n Veldstudie is in die Wes-Kaap bykomend uitgevoer om die Karobmot se seisoenale siklus in sitrusboorde te bepaal. Dit is bereik deur die gebruik van ‘n feromoon-gebaseerde vangsisteem and ‘n gestelde protokol vir skadebepaling deur aktiewe monitoring gedurende twee groeiseisoene. ‘n Feromoon voorkeurproef is ook in alle studiegebiede uitgevoer. Die uitkomste van hierdie studie poog om ‘n beter begrip van die nomenklatoriese en morfologiese geskiedenis van die Karobmot daar te stel, maar ook om as ‘n gebruikersvriendelike morfologiese identifikasie sleutel te dien. Die veldresultate toon ‘n duidelike seisoenale siklus geskiedenis van die Karobmot, in ooreenstemming met die fenologie van sitrus in sitrusboorde van die Wes-Kaap. ‘n Lokvoorkeur is vir net een van die studiegebiede aangeteken. Die Karob mot was gevind as ‘n plaag van minder belang, in vergelyking met die False Codling mot. Dit was ook gevind dat die Karob mot meer ekonomies skadelik is in areas waar daar meer toepaslike gashere is. ‘n Langer studie is nodig om al die faktore in te reken.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/96606
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