Ecological Studies of Lygus Lineolaris and Phytophagous Thrips in Iowa Strawberry Fields
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1-1-2001 Ecological studies of Lygus lineolaris and phytophagous thrips in Iowa strawberry fields Bethzayda Matos Carrion Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Recommended Citation Matos Carrion, Bethzayda, "Ecological studies of Lygus lineolaris and phytophagous thrips in Iowa strawberry fields" (2001). Retrospective Theses and Dissertations. 21443. https://lib.dr.iastate.edu/rtd/21443 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Ecological studies of Lygus lineolaris and phytophagous thrips in Iowa strawberry fields by Bethzayda Matos Carrion A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Entomology Program of Study Committee: John J. Obrycki (Major Professor) Gail R. Nonnecke Mark L. Gleason Leslie C. Lewis Iowa State University Ames, Iowa 2001 Copyright © Bethzayda Matos Carrion, 2001. All rights reserved. ii Graduate College Iowa State University This is to certify that the Master's thesis of Bethzayda Matos Carrion has met the thesis requirements oflowa State University Signatures have been redacted for privacy iii TABLE OF CONTENTS CHAPTER 1. GENERAL INTRODUCTION AND LITERATURE REVIEW 1 Thesis Organization 1 Literature Review 1 References Cited 13 CHAPTER 2. ASSESSMENT OF PARASITISM AND FUNGAL INFECTIONS OF LYGUS LINEOLARIS ADULT AND NYMPHS IN ALFAF A AND STRAWBERRY FIELDS 19 Abstract 19 Introduction 19 Materials & Methods 21 Results 23 Discussion 25 Acknowledgements 28 References Cited 28 CHAPTER 3. FRANKLIN/ELLA TRITICI INFESTATIONS OF STRAWBERRIES IN IOWA Abstract 41 Introduction 41 Materials & Methods 43 Results 48 Discussion 50 Acknowledgements 54 References Cited 54 lV CHAPTER 4. POTENTIAL SOURCES OF FRANKLIN/ELLA SPECIES IN IOWA STRAWBERRY FIELDS 66 Abstract 66 Introduction 66 Materials & Methods 68 Results 70 Discussion 70 Acknowledgements 73 References Cited 73 CHAPTER 5. GENERAL CONCLUSIONS 82 ACKNOWLEDGEMENTS 85 1 CHAPTER 1. INTRODUCTION AND LITERATORE REVIEW Thesis Organization Three individual papers and general conclusions follow a literature review. The first paper covers the assessment of parasitism of Lygus lineolaris in strawberry and alfalfa fields in Iowa. The second paper identifies the thrips species, which causes damage to strawberries and assesses the damage caused by Frankliniella tritici to strawberries. The third paper examines the overwintering biology ofthrips in strawberry fields in Iowa and how sticky card colors affect attraction of thrips. Strawberry Production In most of the United States, strawberries are produced and consumed as fresh fruits; the production of processed strawberries is concentrated to California (Evans 1999). Relative to other fresh market fruits produced in the United States strawberries are fourth in value behind apples, grapes and oranges (over $1 billion) (Evans 1999). In 1996, the value of strawberry production for the approximately 300 growers in Iowa was over $3 million (Nonnecke, G. Iowa State University, Dept. of Horticulture, personal communication). Most farms in the Midwestern U.S. are 'u-pick' operations; consumers go directly to the farm and harvest their own strawberries. Consumers are concerned about the agricultural chemicals used in the strawberry fields they are hand harvesting. Farmers are concerned about producing marketable fruit; insecticides have been their primary method for insect pest management. The strawberry (Fragaria x ananassa Duchenese) is a hybridized plant produced from two species, Fragaria virginiana from North America and Fragaria chiloensis from South America (Maas 1998). This herbaceous perennial plant produces a tasty fruit, which is 2 the enlarged receptacle of the flower. The strawberry is an aggregate fruit comprised of achenes (seeds) on an enlarged receptacle (Handley 1991). These achenes supply auxins for receptacle enlargement (Handley 1991, Nitsch 1950). Short stems, runners, and loose roots are important agronomic characteristics that make the strawberry plant more viable and productive. Flower bud development is induced by short days and low temperatures, thus temperate and subtropical climatic zones are suitable for strawberry production (Maas 1998, Simmonds 1976). Two types of strawberries are commonly planted in Iowa, June-bearing and day- neutral. June-bearing cultivars are short-day plants and begin to produce fruit in the second spring after the flower buds differentiation in the short-days of the previous autumn whereas, day-neutral strawberries are not affected by day-length (Galletta and Himelrick 1990). In the eastern U.S., strawberries are infested by several insect species including the strawberry bud weevil (Anthonomus signatus) (Coleoptera: Curculionidae) that attacks the flowers (Mailloux and Bostonian 1993), the strawberry leaf roller (Ancy/is comptana fragariae) (Lepidoptera: Tortricidae), whose larvae feed on leaves (Gabriel 1989); the tarnished plant bug (Lygus lineolaris) (Heteroptera: Miridae) attacks the developing fruit (Allen and Gaede 1963, Schaefers 1980); root weevil larvae (Otiorhynchus spp. and Nemocestes incomptus) (Coleoptera: Curculionidae) attack the roots (Strand 1994); and the flower thrips (Frankliniella tritici) (Thysanoptera: Thripidae) causes bronzing of the strawberry fruit (Lynch and Tremblay 1995). In this thesis, I focus on the ecology and management of L. lineolaris and thrips in the genus Frankliniella that infest strawberry flowers and fruits. Both pests may have an economic impact on strawberry production in Iowa. 3 Lygus lineolaris In a recent thesis, Rose (1996) examined the management of Lygus lineolaris in Iowa strawberries and reviewed the L. lineolaris literature. As a result, in my literature review of L. lineolaris, I primarily focus on literature published after 1996; however, I will discuss key references published before 1996. Much of the literature is focused on cotton, because Lygus spp. are the third most important group of insect pests attacking cotton (Carder et al. 2000). Selected species in the family Miridae (Order: Heteroptera), commonly referred to as plant bugs, cause yield reductions in grains, vegetables, and fruit crops (Young 1986). Lygus lineolaris (Palisot de Beauvois) adults are about 6 mm long, flat and oval with a clear-yellow triangular cunneus (small triangle at the end of the differentiated part of the forewing in some Heteroptera) on the posterior dorsal side (Metcalf and Metcalf 1993). Lygus lineolaris feed on the growing parts and buds of plants (Goodell 1998). In alfalfa, the most serious damage is in alfalfa grown for seed production, in which Lygus spp. damage the buds producing sterile seeds (Metcalf and Metcalf 1993 ). Lygus lineolaris has a wide host range that includes over 300 plant hosts, including twenty-one of the major crops in the U.S e.g., cotton, beans, strawberries, alfalfa, and apple (Goodell 1998, Young 1986). Lygus hesperus, the western tarnished plant bug, is found west of the Rocky Mountains in ecological niches similar to those of L. lineolaris (Kuhlmann et al. 1998). Udayagiri et al. (2000) concluded that strawberries do not appear to be a preferred host for L. hesperus, because pests densities tend to be relatively low in strawberry. In Iowa, L. lineolaris is considered the principal insect pest of strawberries (Gleason and Lewis 1992). In a 1992 survey conducted in Iowa, more than 60% of the insecticide sprays used in strawberries were for control of L. lineolaris (Domoto et al. 1995). Depending 4 upon environmental conditions, L. lineolaris completes development during the summer in about 4 weeks in Iowa (Gleason and Lewis 1992). Both adults and nymphs have been observed feeding on strawberry achenes (Handley and Pollard 1993). Before achenes lignify, nymphs and adults cause the most significant damage to strawberries (Handley and Pollard 1993). Nonviable achenes are produced and deformities of the fruit usually occur at the tip of the fruit caused by the failure of injured cells to enlarge (Handley and Pollard 1993). Management tactics used against L. lineolaris include insecticides (Bordelon et al. 1999, Cooley et al. 1996), tolerant cultivars (Handley et al. 1991), cultural controls including timing of the mowing of adjacent alternative plant hosts (Gleason and Lewis 1992, Strand 1994), and biological control (Norton et al. 1992). If cutting of alfalfa near strawberry fields is required, then strip mowing at 2-week intervals should be considered because this preserves populations of natural enemies and inhibits Lygus migration (Strand 1994). Nordlund (2000) introduced the possibility of area-wide management for Lygus spp. in cotton and other field crops. Lygus species are secondary pests in crops such as cotton. However, with the boll weevil area-wide management program, Lygus spp. are becoming primary pests, therefore pesticides have to be used against them, thus, negatively affecting the boll weevil's management program (Ehler et al. 1973). Other characteristics of Lygus spp. that make them amenable for an area-wide management program are