Investigation of Factors Relating to the Insect Infestation of Chocolate-Based Consumables
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Investigation of factors relating to the insect infestation of chocolate-based consumables. by Terence Graham Bowditch B.Sc. (Hons.) A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Department of Agricultural Science University of Tasmania Australia March 1996 .7 Dedication I dedicate this thesis to my two sons, Zachary Sebastian and Ethan Jack, both born during this study and, themselves, a most enlightening undertaking. II Declaration I hereby declare that this thesis contains no material which has been accepted for the award of any other degree or diploma in any tertiary institution and that, to the best of my knowledge and belief, contains no material previously published or written by another person, except when due reference is made in the text of the thesis. Terence Graham Bowditch Department of Agricultural Science University of Tasmania March 1996 III Authority of Access This thesis may be made available for loan and limited copying in accordance with the Copyright Act 1968. Terence Graham Bowditch IV Publications From research undertaken in this study, the following paper has been published: Bowditch T. G., Madden J. L. and Brassington B. F. (1994) Field evaluation of a cylinder trap design for monitoring Ephestia cautella. In Proc. 6th Int Work. Conf. Stored-Prod Prot. (Edited by Highley E., Wright E. J., Banks H. J. and Champ B. R.), pp. 1233-1234. Canberra, Australia, 1994. A copy of this paper can be found at the rear of this thesis. From other studies undertaken in this research program, which are described in Chapter 4 of this thesis, the following paper has also been accepted for publication: Bowditch T. G. and Madden J. L. (in press) Spatial and temporal distribution of Ephestia cautella (Walker) (Lepidoptera: Pyralidae) in a confectionery factory: causal factors and managment implications../. stored Prod Res. Abstract The aim of this study was to examine the factors relating to insect infestation of produce manufactured at the Cadbury Schweppes' Tasmanian confectionery plant, in order to determine means by which the incidence of product infestation could be minimized. Analysis of the company's infestation-related consumer complaint databases revealed that: assortments (boxed-chocolates) were most likely to be infested; the geographic distribution of complaints was temperature-dependent; 'old' stock and/or produce manufactured during spring was most likely to be infested; infested goods were more likely to be purchased from smaller retail outlets and; the costs associated with infestation were substantial. Phycitine moths were almost exclusively responsible for infestation, and it was estimated that most cases of infestation occurred post-packaging, most likely while stock was in the hands of independent wholesalers and retailers. A small proportion of infestation probably originated at the Hobart plant, caused by a resident population of the almond moth, Ephestia cautella (Walker). This population was traditionally suppressed by the blanket application of synergised pyrethrins throughout the factory, although, an extensive pheromone trapping program indicated that the spraying of pyrethrins affected neither the distribution of E. cautella, nor the capture rate, and the distribution of E. cautella within the factory was primary dependent upon hygiene conditions. A single room within the factory was identified as the primary source of migratory E. cautella, and a control strategy, based on the mass trapping technique, successfully reduced E. cautella numbers in this room to negligible levels. The influence of trap design on E. cautella catch was also evaluated. Aspects of phycitine ecology with regard to the post-packaging infestation of produce were examined, and it was found that both adult and juvenile phycitines responded positively to odours escaping from chocolate boxes. The integrity of packaging significantly influenced the likelihood, and extent, of infestation, while the polyvinyl chloride film used to overwrap assortment boxes was found to be readily penetrated by several stored-product insect species. An alternative polypropylene film offered significantly improved insect barrier properties. A number of measures aimed at minimizing both pre- and post- packaging infestation were recommended. At the factory, it was recommended that an insect pest control strategy relying on advanced insect detection methods and improved sanitary procedures, supported by an appropriate management structure, be adopted in preference to the current chemical-based strategy. With regard to post-packaging infestation, it was recommended that wholesalers and retailers be educated about the dangers that stored-product insects pose to goods, and methods through which insect apparency can be minimized. It was also recommended that the utility of packaging materials and/or technologies that completely retained odours and provide superior insect barrier qualities be investigated. Also, that quality control procedures be implemented to monitor the integrity of product packaging. VI Acknowledgements I would like to thank my supervisor at the Department of Agricultural Science, University of Tasmania, Australia, Dr John Madden for giving me the opportunity to undertake this research project, and for much knowledgable input into the research. I would also like to thank the department's 'Mr Fix-it', Mr Bill Petersen for invaluable technical assistance. I would like to thank my co-supervisor at Cadbury Schweppes' Claremont factory in Tasmania, Australia, Mr Bryan Brassington for allowing me access to all information, personnel and company facilities I required. I would also like to thank Bryan for sparing much of his valuable time to pass on to me some of his vast knowledge of the confectionery industry. Without the cooperation and assistance of many other personnel at the factory, this research project would have been impossible to undertake. I would like to thank the manager of the Quality Assurance department, Mr John Aston for his interest and encouragement during the course of this project which was much appreciated. I would also like to thank Mr Peter Ralph and Ms Ruby Hodgetts who helped me procure many of the materials and much of the information vital for my research. I would also like to thank Peter and Ruby, and the other members of the Quality Control department, Mr Allan Pryer, Mr Bob Appleby, Mr George D'louhy and Mr Krys Rudzki, for creating a relaxed and enjoyable atmosphere in which to work. I thank Mrs Star King for undertaking on my behalf a mind-numbing package integrity survey, and Mr Jeff Hey for providing me with materials and information necessary to undertake vital packaging experiments. I also thank Mr Richard Berry for providing much useful information concerning the conditions stock is subjected to once it leaves the factory and general sales information (and a constant stream of particularly poor jokes). I would particularly like to thank the factory's Pest Control Officer, Mr Peter Newell. While others in his position might have viewed my presence at the factory with a VII degree of mistrust, Peter was never anything other than completely open and honest, which I believe is of credit to his character. Without Peter's willing assistance and cooperation in imparting his extensive knowledge about the insect pest situation at the factory, this research program would not have proceeded anywhere near as efficiently as it did. I thank Dr Noel Davies of the Central Science Laboratory, University of Tasmania, for undertaking headspace analyses on my behalf, and Mr Michael J. MacQuillan, from Dunlace International, Sydney, Australia, for supplying six black stripe moth traps (AgriSense, UK) for trapping studies. I am indebted to my love and soul-mate Ms Trudi Wharton for looking after me and keeping me relatively sane during the last five years, and mothering our gorgeous sons Zachary Sebastian and Ethan Jack. I am also indebted to my parents David and Jan Bowditch for providing me with a happy and stable upbringing, and my sister Anita Knapp. I also wish to thank Trudi's mother, Joy, for being an excellent mother-in-law to me, and an excellent grandmother to the boys. Finally, I would like to thank our Hobart support crew, Dr's Ann Kitchener and Martin Steinbauer, Kristin Groom, Graham Osler and Jane Giblin, and our interstate cronies David and Andrea Hardcastle. VIII Table of Contents TITLE PAGE DEDICATION II DECLARATION III AUTHORITY OF ACCESS IV PUBLICATIONS V ABSTRACT VI ACKNOWLEDGEMENTS VII TABLE OF CONTENTS IX CHAPTER 1 - GENERAL INTRODUCTION, RESEARCH OBJECTIVES AND LITERATURE REVIEW 1 1.1 GENERAL AIM, COLLABORATIVE PARTNERS AND FUNDING 2 1.2 DESCRIPTION OF THE CONFECTIONERY FACTORY AND PRODUCT RANGE 2 1.3 THE CONSEQUENCES OF INSECT INFESTATION 6 1.4 PREVIOUS STUDIES 10 1.4.1 Methods of controlling stored-product insects in food processing and storage environments 10 (i) Physical control 10 (a) Hygiene 10 (b) Temperature regulation 11 IX (c) Trapping 11 (ii) Chemical control 12 (a) Pesticides 12 (b) Insect growth regulators 13 (c) Mating disruption 13 (iii) Biological control 14 (a) Parasitoids 14 (b) Predators 14 1.4.2 Prevention of infestation of packaged goods by stored-product pests 14 1.4.3 Research undertaken in this study 17 CHAPTER 2- ANALYSIS OF INFESTATION-RELATED CONSUMER COMPLAINT DATABASES 18 2.1 INTRODUCTION 19 2.2 MATERIALS AND METHODS 20 2.2.1 Distribution of infestation complaints between product groups and states 20 2.2.2 The 'age' and date