AN ABSTRACT OF THE THESIS OF Alice M. Kelly for the degree of Master of Science in Entomology presented on April 30, 1987. Title: Oviposition Behavior and Thermal Constants for Egg Development of the Filbertworm, Cydia latiferreana (Lepidoptera: Tortricidae) Redacted for privacy Abstract approved: M. T. AliNiazee' Cydia latiferreana Wlshm. is recognizedas the key insect pest of cultivated filbert (hazelnut) inOregon. The purpose of this studywas to obtain information on mating and oviposition behavior of theadult insect, to calculate the lower temperature threshold anddegree-days required for egg development, and to developan ovipositional model basedon the information derived in this study. Field studies showed significant differencesbetween the number of eggs depositedon the foliage of filbert varieties Daviana and Barcelona. Data showed that Daviana trees were preferred for ovipositionover Barcelona. On both varieties, significantly greater numbers ofeggs were deposited on leaves located within 15cm. of a nut or nut cluster than on those located farther than 15cm. No significant differences were found between numbers ofeggs collected from two canopy heights. Oviposition was observed in the field at dusk, and mating was observed at night. The role of climatic conditions, particularly temperature, and time of dayas major influences on initiation and frequency of oviposition was discussed. Laboratory studies using field-collected eggs indicated that ca. 77.8 degree-daysare required for egg hatch above a threshold of 10.3° C. Oviposition Behavior and Thermal Constants for Egg Development of the Filbertworm Cydia latiferreana (Lepidoptera: Tortricidae) by Alice M. Kelly A THESIS submitted to Oregon State University in partial fulfillment of the requirement for the degree of Master of Science Completed April 30, 1987 Commencement June 1987 APPROVED: Redacted for privacy Professor of Entomology in charge of major Redacted for privacy liekd of ,epartment of,r4mology Redacted for privacy Dean of G ate Schll Date thesis is presented April 30, 1987 Typed by A. Kelly for Alice M. Kelly ACKNOWLEDGEMENTS I would like to express my appreciation tomy major professor, Dr. AliNiazee, for his support andpatience during this project; and to theOregon Filbert Commission for providing the funds for research. In addition, my committee members, Drs. Maxine Thompsonand Jeff Miller, supplied helpful advice. Many thanks to Dr. Ali's research assistants,Steve Booth and Mark Shelton; and to fellowgraduate students for moral support and inspiration, namelyLarry Gut, Steve Stark, and Diane Henneberger. TABLE OF CONTENTS INTRODUCTION 1 LITERATURE REVIEW 4 METHODS AND MATERIALS 10 OVIPOSITION STUDIES 11 Egg Distribution Sampling 11 Phenology 13 Oviposition Behavior 13 Greenhouse Studies 14 EGG DEVELOPMENT STUDIES 15 Low Temperature Threshold for Egg Development 16 Degree-Days for Egg Development 17 Development of an Oviposition Model 17 RESULTS AND DISCUSSION 19 OVIPOSITION STUDIES 19 Egg Distribution on Varieties 19 Egg Distribution Within a Tree 25 Egg Distribution in Relation to Nuts 28 Phenology of Oviposition 35 Observation of Mating and Oviposition 39 Greenhouse Studies 42 Factors Affecting Oviposition 43 EGG DEVELOPMENT STUDIES 48 Lower Temperature Threshold 48 Degree-Days Required for Egg Development 50 A Model for Oviposition and Egg Hatch 52 SUMMARY 58 LITERATURE CITED 60 LIST OF FIGURES Figure Page 1. Abundance of filbertworm eggs on foliage 21 of two varieties of filberts 2. Abundance of filbertworm eggs at two 26 canopy heights: Daviana 3. Abundance of filbertworm eggs at two 27 canopy heights: Barcelona 4. Abundance of filbertworm eggs at two 29 distances from the nut cluster: Daviana 5. Abundance of filbertworm eggs at two 30 distances from the nut cluster: Barcelona 6. Scatterplot of number of filbertworm eggs 32 within 15 cm. of a nut cluster v.s. number of eggs farther than 15 cm. 7. Relation of 8 P.M. temperature to weekly 36 egg counts and light trap catches 8. Relation of 8 P.M. temperature to light 37 trap catch: average of previous evening temperature v.s. average number of moths per day 9. Observations of oviposition and mating of 41 filbertworm on two dates 10. Scheme showing major behavioral components 46 of oviposition behavior of M. sexta adult 11. Effect of temperature on filbertworm egg 51 development at four constant temperatures in laboratory 12. A functional model of filbertworm emergence, 56 oviposition, and egg hatch LIST OF TABLES Table Page 1. Oviposition of C. latiferreana on filbert 20 nut and husk 2. Number of days to C. latiferreana egg 49 hatch at four constant temperatures in the laboratory OVIPOSITION BEHAVIOR AND THERMAL CONSTANTS FOR EGG DEVELOPMENT OF THE FILBERTWORM, CYDIA LATIFERREANA (LEPIDOPTERA: TORTRICIDAE) INTRODUCTION The filbertworm, Cydia latiferreana (Walsingham), (Lepidoptera: Tortricidae) has beena serious pest of filbert (hazelnut), Corvlus avellana L., in the Pacific Northwest for more than fifty years (AliNiazee and Kelly, 1981). This insect causes direct damage to the nut kernel, and in unsprayed orchards, crop loss has averaged 20% (AliNiazee, 1983a). However, in commercial orchards which apply insecticide on a preventive basis, thecrop loss is generally less than 1.0%. The sprays applied for control of this insect generally cause the disruption of biological control of other pests, including the filbert aphid, Myzocallis coryli (Goetze), and the filbert leafroller, Archips rosanus L. Consequently, reduction of sprays applied to control the filbertworm by improved monitoring of pest emergence and density is essential for an efficient filbert pest management program. There are currently two methods for deciding the time to apply control measures for filbertworm. The traditional calendar method involves the application of twocover sprays, the first occurring around July 4th, and the second 2 3 weeks later (AliNiazee, 1977). The second method involves the utilization of sex attractant traps to determine moth emergence and timing of sprays to coincide with emergence levels. Although the first method is usually effective, the advent of the filbertworm pheromone in the last five years makes it possible to monitor adult flight activity within an individual orchard witha high degree of accuracy (AliNiazee, 1983b). By using pheromone traps, spray decisions can be made based on knowledge of population emergence and density. In some orchards, by using the latter method, the total number ofsprays has been reduced (J. Calkin, pers. comm). In order for sprays or other control methods to be effective, they must coincide with theoccurrence of the vulnerable stage in the life cycle ofan insect species. This is particularly important in thecase of the filbertworm, because once the larva has penetrated thenut, it is so well protected that it is essentially impervious to any means of control, chemicalor biological. Consequently, the period of time between emergence of adults from overwintering sites and penetration of nuts by the neonate larvae is the only interval during which damage can be prevented. Unfortunately, relatively little information is available on adult mating and oviposition behavior, egg placement and hatch, larval movement, and nut penetration under field conditions. 3 The purpose of this study was to obtain informationon oviposition and egg development of C. latiferreanaunder field conditions, and to developan understanding of adult behavior during this critical period. In addition, the phenology of these events in the fieldwas studied. 4 LITERATURE REVIEW Cydia latiferreana was first described byLord Walsingham in 1879 from specimens collected inCalifornia and southern Oregon in 1871-1872 which henamed Carpocapsa latiferreana (Bacon, 1948; Brown, 1983). In 1881, Riley described Melissopus and differentiated Melissopusfrom Carpocapsa. In 1926, Heinrich also described this species in a revision of the North American Mothsof the Subfamilies Laspeyresiinae and Olethreutinae(Heinrich, 1926). He divided the species intoseven varieties; variety A occurs in Oregon, Californiaand Washington, and is the variety which he called"the typical latiferreanus." The other varieties are from different localitiesin the U.S., the eastern form being varietyG. The latest taxonomic reclassification occurredwhen Brown (1983) examined thegenus Melissopus and synonymized it with Cvdia. He placed Cvdia in the subfamily Olethreutinae, tribe Grapholitini. Most members of this tribe, of which over 500 specieshave been described worldwide, feed on fruits and seeds, includingsuch pest species as C. pomonella (L.), codlingmoth; C. strobilella (L.), spruce seed moth; and C. molesta (Busck), oriental fruit moth (Roelofs and Brown, 1982). Brown considered C. latiferreana to be closely related to C.caryana (Fitch), hickory shuckworm, and C. candana (Forbes),based on 5 similarities in morphology, feeding behavior,allozymes, and pheromones. More than one species may be included in C. latiferreana, since intraspecific variation insize, color, and genitalia appears to begreater than in any other species of North American Olethreutinae(Brown, 1983). This indigenous species has beenreported on a wide variety of host plant material.The following hosts have been recorded: cultivated filbert,Corylus avellana L.; wild hazelnut, C. americanaand C. cornuta; acorns, Quercus spp.; galls formed by Andricus californicus (Basset)on the branches and twigs of Ouercusgarryana Dougi.; galls formed on the leaves of O. garryana by Cvnips maculipennis