Ecology and Management of Plum Curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae) in Alabama Peaches by Clement Akotsen-Mensah A dissertation submitted to the Graduate Faculty of Auburn University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Auburn, Alabama August 9, 2010 Key words: Conotrachelus nenuphar, grandisoic acid, benzaldehyde, plum essence, thiamethoxam, degree-day Copyright by Clement Akotsen-Mensah Approved by Henry Fadamiro, Chair, Associate Professor of Entomology Arthur Appel, Alumni Professor of Entomology and Plant Pathology Wheeler Foshee, Professor of Horticulture Louis Jackai, Professor of Entomology, North Carolina A & T State University Robert Boozer, Regional Research and Extension Horticulturist Abstract Peach production is a major industry in Alabama and many other southeastern states of the United States. Over 40,000 acres of fresh and processed peaches worth $65 million are produced annually in Alabama, Georgia, and South Carolina. In Alabama alone, approximately 22 million pounds of peaches were produced in 2001 with a market value of about $12 million. The plum curculio, Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae) is the most serious economic pest of peaches in Alabama and other parts of the southeastern U.S. This study was conducted to develop and implement cost-effective and environmentally friendly pest management practices for plum curculio. Specific objectives are: (1) Field evaluation of traps and lures for monitoring plum curculio in Alabama peaches, (2) Laboratory evaluation of behavioral response of plum curculio to synthetic host plant volatiles and male-produced aggregation pheromone (grandisoic acid); (3) Seasonal occurrence and development of a degree- day model for forecasting spring emergence of plum curculio in Alabama peaches; (4) Field evaluation of targeted insecticide sprays against plum curculio in Alabama peaches and (5) Evaluation of the effects of soil and weed management practices on plum curculio pupal development and adult emergence in Alabama peaches. In chapter II, the effectiveness of two widely used trap types (pyramid versus Circle traps) and commercially available synthetic lures for monitoring plum curculio was evaluated in two peach orchards in Alabama during 2008 and 2009. The lures evaluated alone or in combinations included benzaldehyde or BZ (a component of fruit odor), plum essence or PE ii (mixture of fruit odor extracted from food grade plum), and grandisoic acid or GA (male- produced aggregation pheromone of plum curculio). The results showed that pyramid traps captured more plum curculio adults than Circle traps, particularly, during the first generation. Trap performance was improved numerically by the addition of BZ, PE or GA alone (single lures), and was significantly enhanced by the addition of the combined BZ + PE lure. A follow- up study was conducted in the laboratory (Chapter III) to determine the influence of physiological factors (sex, age, diet and mating) on the response of plum curculio to the commercial lures (BZ, PE and GA) in four-choice olfactometer bioassays. The results showed that the physiological state of the weevils did not affect their response to the lures. In Chapter IV a degree-day model was developed for forecasting spring migration of plum curculio in peaches using historical temperature and trap capture data. The degree-day model predicted well the first and peak trap captures of plum curculio adults occurred in peach orchard. January 1 at a lower temperature threshold (LTT) of 10°C were found to be a better combination for accumulation of degree-days in peach orchards in Alabama. A six-order polynomial function fitted best to seasonal trap captures and cumulative degree-days, and revealed three overall seasonal peaks with the first (spring generation), second (summer generation), and third (summer generation) peaks occurring at cumulative degree-days of ca 220, 1122 and 1932 (base 10°C, biofix of January 1), respectively. The three-parameter Weibull model predicted the first trap and first peak (spring generation) trap captures to occur at mean cumulative degree-days of 108.02 ± 9 and 220.07 ± 16, respectively. In chapter V, studies were conducted in a peach orchard in Alabama during 2007 to 2009 to compare the conventional calendar-based insecticide spray program involving weekly applications of phosmet (Imidan®) to three different reduced spray programs using three targeted (well-timed) insecticide sprays (TIS) of phosmet, permethrin iii (Arctic®), or thiamethoxam (Actara® ) applied in an alternated fashion. All the three TIS programs significantly reduced plum curculio damage at harvest compared to the untreated control in two of the three years (2008 and 2009). Fruit damage due to stink bugs, which are emerging pests of peaches in the region, was also significantly reduced in the TIS programs in both years. In chapter VI the effects of soil and weed management practices on development and emergence of plum curculio was investigated in both field and greenhouse studies. Significantly fewer plum curculio adults emerged from centipede grass understory treatment than from other soil and weed management treatments. The results have identified promising tactics for the development of an IPM program for plum curculio in the southeastern United States. iv Acknowledgements This dissertation would not have been possible without the assistance and encouragement of many people. Primarily, I am thankful to Dr. Henry Fadamiro, my major advisor, whose tireless efforts initiated and provided funding on a consistent and sustained basis for this project through the EPA and Alabama IPM mini-grant. Apart from serving as my academic advisor, Dr. Fadamiro nurtured, mentored and instilled in me a sense of discipline and work ethics that has inspired me to achieve the unimaginable no matter the obstacles. I am highly indebted to the rest of my committee members, namely Drs. Arthur Appel, Louis Jackai, Foshee Wheeler, Mr. Robert Boozer and the outside reader of my dissertation Dr. Floyd Woods. I am particularly, grateful to Mr. Robert Boozer; Research and Extension Horticulturist at Chilton Research and Extension Centre (CREC), Clanton, AL., who has been a great source of motivation and his immense contribution and expertise which he made available to me can not go without my recognition. The head, Dr. Arthur Appel and staff of the Entomology and Plant Pathology Department, Auburn University are worthy of mentioning for their enormous support in many diverse ways. I am personally grateful to the Superintendent, Mr. James Pitts and all the staff of CREC for the opportunity and assistance to work at the Centre. The contributions of Drs Li Chen and Kavita Sharma, both postdoctoral fellows in our laboratory and my lab colleagues namely, Yingfang Xiao, Rammohan Balusu, Prithwiraj Das, Esther Ngumbi, Timothy Nafziger and Kate Nangle are also acknowledged. Finally, I owe much gratitude to my family and Ameyaw family for contributing to this achievement. v Dedication This work is dedicated to my dear father, Mr. Ebenezer Kwesi Akotsen vi Table of Contents Abstract ......................................................................................................................................... ii Acknowledgements ...................................................................................................................... v Dedication .................................................................................................................................... vi List of Tables .............................................................................................................................. xii List of Figures ............................................................................................................................ xiv Chapter 1 Introduction and Literature Review ............................................................................ 1 1.1 History, Production and Uses of Peaches ................................................................... 1 1.2 Economic Importance and Production Constraints ..................................................... 2 1.3 Plum Curculio, Contrachelus nenuphar Herbst (Coleoptera: Curculionidae)............ 3 1.3.1 Description, Biology and Life Cycle ................................................................. 3 1.3.2 Distribution and Host Range .............................................................................. 6 1.3.3 Strains of Plum Curculio .................................................................................... 7 1.3.4 Factors Affecting Plum Curculio Abundance and Activity ............................... 8 1.3.5 Plum Curculio Behavior .................................................................................... 9 1.3.5.1 Flight Behavior ......................................................................................... 9 1.3.5.2 Sound Production .................................................................................... 11 1.3.5.3 Orientation Behavior ............................................................................... 11 1.4 Integrated Management of Plum Curculio ................................................................. 12 1.4.1 Monitoring (sampling) ..................................................................................... 13 vii 1.4.2 Cultural Control ..............................................................................................