1999. The Journal of Arachnology 27:531-538

ABUNDANCE OF AND PREDATORS ON GRAPES IN CENTRAL CALIFORNIA

Michael J. Costello!:Costello1: University of California Cooperative Extension, 1720 South Maple Ave., Fresno, California 93702 USA

Kent M. Daane: Center for Biological Control, Division of Insect Biology, Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720 USA

ABSTRACT We compared the abundance of spiders and predaceous in five central California vineyards. Spiders constituted 98.1 98.1%% of all predators collected. More than 90% of all spiders collected were from eight species of spiders, representing six families. Two theridiids ( dilutum and T. melanurum) were the most abundant, followed by a miturgid (Cheiracanthium inclusum) and an agelinid (Hololena nedra). Predaceous insects comprised 1.6% of all predators collected, and were represented by six genera in five families. Nabis americoferis (Heteroptera, Nabidae) was the most common predaceous insect, with its densities highest late in the growing season. Chrysoperla camea,carnea, Chrysoperla comanche and Chrysopa oculata (Neuroptera, Chrysopidae) and Hippodamia convergens (Coleoptera, Coccinellidae) were most abundant early in the season. The dominance of spiders may be due to their more stable position in the vineyard predator community compared to predaceous insects. We also suggest that the low per?per­ centage of predaceous insects (e.g., lacewings) may reflect the lack of preferred prey (e.g., aphids) on grapevines.grape vines.

Spiders are important predators in agroe­agroe? ported population densities of the most cosystems (reviews in Nyfeller & Benz 1987; abundant spiders (Misumenops spp.) found on Nyfeller et al. 1994). Many researchers have Arizona cotton,eotton, presenting predaceous insects provided descriptions of species abun­abun? as overall percentages but not itemizing for dance or composition in a variety of agroe­agroe? different taxonomic groups. In these publica?publica­ cosystems (e.g., Bishop 1980; Dean et al. tions, the amount of detail presented reflects 1982; Agnew & Smith 1989; Bardwell & Av­ Av- the focus of the research, depending in part erill 1997; Wisniewska & Prokopy 1997). upon the breadth of the predator taxon being Other researchers have provided qualitative studied. More commonly, researchers present observations on the abundance of spiders more detailed descriptions of the predaceous (Carroll & Hoyt 1984) or recorded spider pre?pre­ insect fauna, while spiders are grouped to­to? dation events (Reichert & Bishop 1990; Ny?Ny­ gether and data presented as an overall mean, feller et al. 1992). However, it is less common numerical rank or percentage of the number for researchers to compare spider abundance collected (e.g., Roach 1980; Knutson & Gil­ Gil- to that of to that of predaceous insects. Those studies strap 1989; Royer & Walgenbach 1991; Bra­Bra- that have analyzed the relative abundance of analyzed man & Pendley 1993). Few studies have pro?pro­ all predaceous vary considerably predaceous arthropods vary considerably vided equivalent comparisons of spiders and in the presentation of the data. For example, presentation example, predaceous insects at the or species lev­lev? MacLellan (1973) reported on predaceous ar­ar? (1973) reported predaceous el (but see Breene et al. 1989). thropods collected on apples in southeastern thropods apples In vineyards, several researchers have cat­ cat- Australia, presenting numbers of spiders col­col? presenting spiders aloged the abundance of predaceous arthro­arthro? lected by size and numbers of predaceous in­in? by predaceous pods on grapevines. In southern Germany, sects collected by family. Plagens (1983) re- by family. Plagens (1983) Buchholz & Schmft Schruft (1994) presented num­num? bers of predaceous insects by family, identi­identi- 1 fying salticids to species and thomisids to ge­ 1 Current address: Costello Agricultural Research & fying species ge? Consulting, PO.~O. Box 165, Tollhouse, California nus, but leaving most spiders unidentified. In 93667 USA. California vineyards, spider species composi- 531 532 THE JOURNAL OF ARACHNOLOGY tion, relative abundance and seasonal occur­ occur? date, samples were taken between 0700-1200 rence were described by Costello & Daane h PDT. Samples from the .replicatedreplicated cover (1995) and Roltsch et a1. al. (1998), but neither crop studies were pooled across treatments study included data on .predaceouspredaceous insects.insects. and sample dates. A total.oftotal of 100 samples was Here, we present data that compare the rela­ rela? taken from the Reedley vineyard, 180 from tive abundance of spiders to predaceous in­in? the Del Rey vineyard and 120 from the Parlier sects on grapevines in California's central val­ val- vineyard (one season each). A total of 243 ley. samples was taken from the Ripperdan vine­vine? yard and 360 from the Woodbridge vineyard METHODS (two seasons each). Voucher specimens were Study sites.-sites.?TheThe data presented are from deposited at the Essig Museum at the Univer­ Univer? five central valley vineyards that were sam­ sam? sity of California at Berkeley. pled from 1995-1997. Grapevine cultivar and For each vineyard and sampling method, cultural practices varied among the sites. In means were transformed to numbers of pred?pred­ 1995, three vineyards in Fresno County were ators per vine. Seasonal abundance of spiders sampled: a raisin vineyard (cultivar "Thomp­"Thomp? and predaceous insects were plotted against son Seedless" near Del Rey, California)CaHfornia) a ta­ ta? cumulative degree days above 10°C 10 ?C (the low­low? ble grape vineyard (cultivar "Ruby Seedless" er developmental threshold for grapevines) near Reedley, California) and a juice vineyard from 1 January, for each sample year. (cv "Thompson Seedless" near Parlier, Cali­CaH? RESULTS fornia). In 1995 and 1996, a winegrape vine­vine? yard in San Joaquin County (cv "Cabemet"Cabernet We collected a total of 13,348 spiders (2781 Sauvignon" near Woodbridge, California) at Del Rey, 6468 at Woodbridge, 1273 at Rip­Rip? and, in 1996 and 1997, a juice vineyard in perdan, 679 at Parlier and 2147 at Reedley) Madera County were sampled (cv "Thompson and 219 predaceous insects (36 at Del Rey, Seedless" near Ripperdan, California). These 122 at Woodbridge, 6 at Ripperdan, 43 at Par­ Par? sites were part of studies designed to deter­deter? lier and 12 at Reedley). Over all sites, spiders mine the impact of cover crops on vineyard constituted 98.1 98.1%% of all predators collected, insect pests and their natural enemies (see whereas the insect predators comprised just Costello & Daane 1998b; Daane & Costello 1.6% of total predators. At individual sites, 1998). All of the study sites were bordered by spiders comprised at least 94% of predators cultivated vineyards or orchards. collected, with the highest percentage at Rip­Rip? In each year, all vineyards received multiple perdan (99.5%) and the lowest at Parlier applications of sulfur for control of powdery (94.0%) (Table 1). Predaceous insects com­ com? mildew, Uncinula necator Burrill, and one or prised 6.0% or less of all predators at each two applications of cryolite (sodium alumi­alumi- site, the highest percentage found at Parlier nofluoride) for control of omnivorous leaf­leaf- (5.9%) and the lowest at Ripperdan and Reed­ Reed? roller, Platynota stultanastultanaWalshingham Walshingham 1884 ley (0.5%) (Table 1). The only other (, Tortricidae), and grapeleaffold­grapeleaf fold- predator collected was Anystis agilis (Banks er, funeralis (Hubner(Hiibner 1796) (Lepidop­(Lepidop? 1915) (Acari, Anystidae), a predaceous mite tera, Pyralidae). that feeds on insects as opposed to spider SampUng.-CostelloSampling.?Costello & Daane (1997) pro?pro­ mites. Only 17 Anystis agilis. agilis were collected, vide a detailed description of sampling meth­meth? all at the Reedley site, comprising 1.5% ofofthethe ods. In brief, the Del Rey,Ripperdan,Rey, Ripperdan, Parlier predators collected there. and Woodbridge vineyards were sampled by Spiders.-EightSpiders.?Eight species from six families 2 shaking a 0.89 mm2 section of vine foliage into constituted >90% of all spiders collected. By a funnel shaped collector, and the Reedley family, these were: (1) Miturgidae: Cheira­Cheira- vineyard was sampled by shaking the foliage canthium inclusum (Hentz 1847); (2) Corin­Corin- of two grapevines onto a drop clothcloth and col­ col? nidae: Trachelas pacificus (Chamberlin & Ivie lecting all predators ·withwith small battery-pow­battery-pow- 1935); (3) : Theridion dilutum ered vacuums. Samples were taken monthly, Levi 1957 and Theridion melanurum Hahn from May to September, except for the Rip­Rip? 1831; (4) Oxyopidae: Oxyopes scalaris Hentz perdan vineyard in 1996,.1996, which·.which was.was sampled 1845 and Oxyopes salticus Hentz 1845; (5) from July to September. On each sampling Agelinidae: Hololena nedra Chamberlin & ~ ~ f<:o 0 0 CIl CIl () ~ tT1 > Z 0 0 ~ ~ tT1 r > g; 0 CIl CIl 8 ~ ~ > < Z Z 0 CIl tT1 () CIl ~ .-< W > W lJl O O oo

years t % 5.22 5.63 3.73 0.97 4.70 0 0.55 0.41 0.41 0.55 0 5.92 0.27

19.22 O 14.66 22.13 94.08 Table 1.?Mean season-wide density and population21.87 percentage of predatory arthropods in five central valley vineyards, 1995-97, data pooled across years for each site. Superscript "1" indicates Theridion dilutum and Theridion melanurum. "2" indicates scalaris and salticus. across Superscript Oxyopes Oxyopes salticus. (0.62) (0.19) (0.59) (1.92) (0.24) (0.74) (0.20) (0.06) (0.09) (0.69) (0.06) (0.05) (0.07) (0.29) (0.06) (0.33) (±SE) pooled Parlier 1.04 1.17 1.26 1.32 3.26 4.27 4.92 0 0.12 0.21 4.89 0.83 0.09 0.09 0.06 0.12 0 Oxyopes 20.90 Mean data and % 1.54 2.96 2.27 7.61 4.05 0.09 0.32 0 0 0.09 0.05 0.56 0 16.87 12.17 10.66 97.90 41.35 1995-97, scalaris (0.005) (±SE) (0.19) (0.47) (0.06) (0.67) (0.01) (0.08) (0.10) (0.01) (0.09) (0.20) (0.05) (0.02) (0.02) Oxyopes vineyards, Reedley 1.24 1.85 1.33 0.45 0.32 4.53 0.84 0.17 0.01 0.25 0 0.03 0.01 0.005 0 0.06 Mean 10.73 valley indicates % 1.24 1.24 1.28 7.38 7.49 2.94 5.95 0 0.39 0.42 0.42 0 0 0.03 0 0 31.23 central "2" 98.72 41.28 five in (1.24) (3.54) (0.45) (0.40) (2.37) (0.12) (0.06) (0.13) (0.27) (0.56) (0.06) (0.02) (0.09) (0.13) Rey (±SE) Superscript Del 1.59 3.23 4.00 4.06 0.21 0.67 0.23 0.67 0 0.02 0.23 0 0.69 0 16.95 22.40 53.57 Mean arthropods % 1.09 1.09 3.65 0.40 3.65 0 9.28 0 0 0.44 0.38 2.27 0.02 0.13 0.09 0.09 melanurum. 22.41 97.72 57.20 predatory of (0.06) (2.74) (0.75) (2.24) (0.15) (0.09) (0.24) (0.61) (0.08) (0.59) (0.04) (0.01) (0.02) (0.02) (0.02) (0.12) (±SE) Theridion 1.84 1.84 1.14 0.20 0.55 0 4.66 0.22 0.01 0.06 0.19 0.55 0.04 0.04 and 11.27 28.76 49.14 Woodbridge Mean percentage % dilutum 7.11 2.34 0 4.22 0 0 0.55 0.08 0.08 0.08 0.08 0.16 0.47 0 0 36.20 22.04 99.53 26.50 population Theridion and (0.016) (0.016) (0.016) (0.016) (0.023) (0.040) (±SE) (0.28) (0.34) (1.06) (0.41) (1.48) (0.09) (0.18) (0.04) Ripperdan 1.54 7.85 5.75 0 4.79 0.39 0.92 0.12 0 0.017 0.017 0.017 0.017 0 0.034 0 0.101 density Mean 21.62 indicates "1" season-wide total convergens Superscript Spp.l pacijicus aridifolea nedra spp. Spp.2 dentosa agilis site. I.-Mean americoferus spiders spp. renardii total Predator predator inclusum each sinensis Table Theridion Trachelas Cheiracanthium Oxyopes Hololena Erigone Other Orius Tenodera Chrysopidae Afetaphidippus Geocoris Nabis Hippodamia Zelus Anystis Araneae for Spider Acari Insecta Insect 534 THE JOURNAL OF ARACHNOLOGY

Ivie 1942; and (6) Salticidae: Metaphidippus 40 Theridion spp. vitis (Cockerell 1895). Overall spider abundance varied among 30 sites, ranging from a high of 49.1 spiders per vine (Woodbridge site) to a low of 10.7 10.7 spi­ (Woodbridge site) spi? 20 ders per vine (Reedley site) (Table 1). Species composition also varied among sites and may composition among may 10 have contributed to differences in spider abun­abun? dance. For example, overall spider abundance o ~----r----~-----,.----, was highest at the Del Rey and Woodbridge 20 sites, where the dominant spiders were the ~ 15 Cheiracanthium inclusum small, web-building theridiids, T. dilutum and T. melanurum. In contrast, overall spider :> 10 abundance was more than 50% lower at the ~ 5 other sites, where larger spiders, such as the CD sites, larger spiders, .0.-C Ot------r------,.-----r------, nocturnal hunters C. inclusum and T. pacifi-pacifi­ c Hololena nedra cus, dominated the spider community (Table en 10 J spider community ~ ~.:?-?-+-? 1). . There were also differences in spider sea­sea? sonal abundance (Fig. 1). Theridion spp. was ^Erigonedentosa the most abundant spiderspider group, with the . highest overall spider density in both the ear­ ear- • ly-season (---17(?17 per vine) and late-season ("""34(?34 5g ]I Trachelas pacificus per vine) samples, but equivalent with C. in­ in? o0 ! ~ •• =====- clusum in mid-season samples (---7.5(?7.5 per 5 J, Metaphidippus vitis vine). Cheiracanthium inclusum was the next o0 1·!? ,••f- ...... most abundant spider, with densities relatively 5 1Oxyopes spp. j ~. low early in the season ((?2...... 2 per vine) and o0 1•l??--??r= ::::=== • --. 500 1000 1500 2000 2500 peaking late in the season (---18(?18 per vine). The May June July AugustAugust' September agelinid, Hololena nedra, maintained a rela­rela? Mean Cumulative·DegreeCumulative Degree Days (OOtO)(D 10) tively steady population density of ~4.7 ?4.7 spi­spi? Figure 1.--Mean1.?Mean seasonal abundance of the most ders per vine throughout the season. The sea­ sea? Figure abundant spider species on grapevines, plotted sonal abundance patterns reported here are against cumulative seasonal degree days above 10 consistent with those reported in Costello & reported °C?C (since January 1), all vineyards and years com­com? Daane (1995). bined. Insects.-PredaceousInsects.?Predaceous insects collected in­ in? clude Hippodamia convergens Guerin-Mene­Guerin-Mene- ville 1842 (Coleoptera, Coccinellidae); Chry­Chry- species composition. At the Woodbridge site, soperla comanche Banks 1938,.1938, Chrysoperla the most abundant insect predators were the cameacarnea (Stephens 1836), and Chrysopa ocu­ocu- chrysopids (O.5per(0.5 per vine), whereas at the Par­ Par? lata Say 1839 (Neuroptera, Chrysopidae);Na­ Chrysopidae); Na- lier site,.site, N.N.americoferus americoferus was most frequentlyfrequently hisbis americoferus Carayon 1961 (Heteroptera, collected (0.8 per vine) (Table 1). Nabidae); Orius spp. (Heteroptera, Anthocor­Anthocor- Predaceous insect seasonal. seasonal patterns showshow idae); Geocoris spp. (Heteroptera, (Heteroptera, Lygaeidae); that N. americoferus was the most abundant Zelus renardii Kolenati 1856 (Heteroptera, insect.insect predator overall (Fig.(Fig. 2)2). .. Its population Reduviidae); and Tenodera aridifolia sinensis rose from near zero in early-season samples Saussure 1871 (Mantodea, Mantidae). to ~O.6?0.6 per vine in late..;late-seasonseason samples. Chry­ Chry? Overall, predaceous insect density was low­low? sopsopidsids were the most abundant predaceous in­in? est at the Reedley and Ripperdan sites, with sects inin early-season samples, with densities seasonal means of 0.06 and 0.10 predators per of ---0.6?0.6 per vine, but thereafter were quite rare vine, respectively, and most abundant at thethe (Fig. 2). Coccinellidae were also relatively Woodbridge and Parlier sites, averaging 1.1 abundant in·in early.-seasonearly-season samples (0.35 per and 1.3 predators per vine, respectively (Table vine at the first sampling period) and their 1). There were also differences among sites in density also steadily dropped in later later samples. COSTELLO & DAANE?SPIDERSDAANE~SPIDERS AND INSECT PREDATORS IN VINEYARDS 535

1.0 Nabis americoferus mid-July and early September. Leafhopper densities which reach 10-15 nymphs per leaf 0.5 nymphs per may require insecticide treatment to prevent 0.0 economic damage. In comparison, there were low densities of other potential arthropod 1.0 Chrysopa spp. & Chrysoperla spp. prey, such as lepidopteran larvae (Platynota 0.5 stultana and ), mealybugs (I) (Pseudococcus maritimus Ehrhorn 1900) and c: :> 0.0 spider mitesrnites (Tetranychus pacificus McGregor 1919 and Eotetranychus willametti [Mc­[Mc? CI)(0 1.0 Eotetranychus 1.0-j Hippodamia covergens ....,0o Gregor 1917]). Prey such as aphids and white­white- COca "0"O 0.50.5- flies are only occasionally found on grape­grape? (I)0) Q: vines, and atat relatively low densities. ...., 0.0 0o Insect predators such as coccinellids and (I)0) CI) 1.0 chrysopids will feed on.on a variety of soft bod-bod­ ..s Orius spp. c:c 1.0 J ied insects, including Erythroneura spp.; how­how? co (I) 0.5 ever, they are better known as predators of ~5 aphids and mealybugs (Daane et al. 1998)1998). . 0.0 ,. .--. • • • The lack of preferred prey likely affects the 1.01.0-1 dispersal habits of adult coccinellids and chry­ Geocoris spp. dispersal chry? sopids, and their density on grapevines. For 0.50.5- example, migration of Hippodamia conver­conver- gens from overwintering sites in the Sierra 0.0 J--4.--~i.a---~.~i==-==::;::,==~""~---, gens overwintering 500 1000 1500 2000 2500 Nevada foothills to the San Joaquin Valley is May June JwyJuly August September o arrested when adult beetles find aphids and Mean C'umulativeCumulative Degree Days (0(D 10) their honeydew (Hagen 1962). Similarly, Figure 2.-Mean2.?Mean seasonal abundance abundance of ofthethe most Chrysopa cameacarnea responds to aphid honeydew abundant·abundant predaceous insect groups on grapevines~grapevines, (Hagen 1950). It is well known that cover plotted against cumulative seasonal degree days crops such as vetches and cereals support high above .10 10 °C ?C (since January 1), all vineyards and populations of aphids (Bugg et al. 1991), and years combined. years we suspect that the relatively high early sea­sea? son populations of H. convergens and chry­chry? sopids we found on the grapevines were due Orius spp. and Geocoris spp. were not col­ col? to the presence of aphids on cover crops and lected until the third sampling period (mid­(mid- weeds in and around the study vineyards at summer), and peaked in late-season samples that time. The decline of these predators, dur­dur? at 0.11 and 0.06 per vine, respectively. ing the season, followed the decline of their preferred prey on the cover crops. DISCUSSION Although spiders are polyphagous, we These results show that spiders overwhelm­overwhelm- found differences among vineyard species in ingly outnumber predaceous insects on grape­grape? prey preference. For example, Metaphidippus vines in California's central valley. The expla­expla? vitis does not feed on leafhoppers in the lab­ lab? nation for this may partly lie in the type and oratory; and, in this study, its numbers were abundance of prey species: the low number of relatively low compared with other spider spe­ spe? predaceous insects may reflect the lack of pre?pre­ cies. In contrast, field observations suggest ferred prey on grapevines. At all of our study that Theridion spp. feed primarily on leafhop­leafhop? sites, the most abundant insects on grape·grape fo­fo? pers, with high populations of Theridion pos?pos­ liage are various Diptera, which are most itively correlated with high leafhopper densi­densi? abundant in the spring and early summer, and ties (Costello & Daane 1995). In this study, the leafhoppers Erythroneura elegantula Os­Os- Theridion spp. reached the highest density of born 1928 and E. variabilis Beamer 1929 any spider group. Theridion spp. numbers (Homoptera, Cicadellidae). Erythroneura spp. were highest at the Woodbridge and Del Rey have three generations in the central valley, sites, where there were also high population with nymphal peaks occuring in late May, levels of leafhoppers (Daane & Costello 536 THE JOURNAL OF ARACHNOLOGY

1998). Theridion dilutum and T. melanurum 35% with the funnel shake method. The D­ D- are small (adults are ---0.5 ?0.5 em),cm), have low food vac also biased samples toward·toward smaller and requirements, occupy very little territory com­com? more mobile spiders compared to beating or pared to larger spiders such as Cheiracan­Cheiracan- shaking methods. In addition, foliage shaking thium inclusum and Hololena nedra, and methods do not collect flying predators. This Theridion spp. populations increase consider­ consider? is most important for the tiger fly, Coenosia ably from mid- to late-summer. Therefore, humilis Meigen 1826 (Diptera, Muscidae), Theridion spp. densities may be highest be?be­ which can be quite common in San Joaquin cause they readily feed on leatbopperleafhopper nymphs Valley vineyards. The adult captures its prey and because grapevines can support more of on the wing .and has been observed feeding these spiders per given area compared with on leafhopper adults (immature Coenosia feed other spider species. on earthworms in the soil and, therefore, are That nabids increased over the course of the not collected). We have collected this fly with season may reflect their ability to use leafhop­leafhop- the D-vac and have usually found the mean pers as food. NabidsNabids are good predators of density to be less than 5 per vine (unpubl. leafhoppers (Martinez & Pienkowski 1982; data). In addition, very small predators such Flinn et al. 1985). Other insect predators, such as A. agilis may never be sampled with the as Orius spp., prefer thrips and spiderspider mites. D-vac, and are probably more efficiently sam­sam? Geocoris spp. feed on lepidopteran and he­ he- pled with the drop cloth method than the fun­ fun? mipteran eggs and nymphs, spider mites, nel method. This may partly explain why an aphids and whiteflies (Hagler & Cohen 1991). additional small insect predator, Leptothrips The low densities of these prey items on vines mali, was observed at the Woodbridge site but may explain the low density of Orius and was never found in the samples. Geocoris species we found. This is the·the first report that spiders comprise Spiders may also comprise the majority of such a high percentage of a predator com­com? the predator community because most species munity in vineyards. The.The great number of spi­spi? overwinter in the vineyard and are therefore ders in comparison to other predators reveal, permanent residents. They are a more stable empirically, why so much research has fo­ fo? part of the predator community than .insect insect cused on spiders as vineyard predators (Zalom predators because of their broader diet breadth et al. 1993; Costello & Daane 1998; Roltsch and their ability to subsist for long periods of et al. 1998). These results suggest that pre?pre­ time without food. Insect predators such as daceous insects play a minor role in suppress­suppress- Hippodamia convergens and chrysopids are ing insect pest populations in California vine­vine? more migratory, and often follow migratory yards. We note that leafhoppers were the pest populations. All but one of the spiders primary prey species in our study sites. In mentioned in this study have been found over­over? vineyards with high mealybug or lepidopteran wintering in cardboard bands placed around populations, the natural densities of preda?preda­ the vine trunks, the exception being Erigone ceous insects may be higher. More work is dentosa (M.J. Costello & K.M. Daane unpubl. needed in determining the role of spiders on data). None of the predaceous insects has been economically important vineyard insects such found overwintering on the vines. That E. as leafhoppers and the lepidopteran complex. dentosa was not found overwintering in vine­vine? We are currently working on the development yards and was only found in the early part of of immunochemical assays to.to estimate prey the growing season, suggests that it is more consumption by vineyard spiders. migratory than the other spider species, prob?prob­ ACKNOWLEDGMENTS ably ballooning into vineyards in the spring and leaving for other habitats during the sum­ sum? We are grateful to the Robert Mondavi mer. Winery, Fred Smeds, Kenneth Chooljian, Paul Finally, the sampling methods used will af­ af? Wulf, and the DCUC Kearney Agricultural Cen­Cen? fect the kinds and numbers of predators col­col? ter for the use of their vineyards. Funding was lected. Costello & Daane (1997) compared the provided by the California •Table Grape Com­Com- D-vac to foliage beating in vineyards, and mission, Lodi-Woodbridge Wine Winegrapegrape Com­Com- found that spider density was underestimated mission, DCUC Statewide IPM Project, DCUC Sus­ Sus? by 87% with the D-vac, and overestimated by tainable Agriculture Research and Education COSTELLO & DAANE-SPIDERS DAANE?SPIDERS AND INSECTINSECT PREDATORS IN IN VINEYARDS 537

Program and the USDA National Research crops reduce leatbopperleafhopper abundance in vineyards? California AgricuI., 52(5):27-33. Initiative Competitive Grants Program. California Agricul., 52(5):27-33. Daane, K.M., K.S. Hagen & N.J. Mills. 1998. Pre­ Thanks to Eric Davidian, Glenn Yokota, Ross Daane, K.M., Hagen & NJ. Mills. 1998. Pre? daceous insectsinsects for for insect insect and mite management. Jones, Kimberly Miyasaki and Jose Cantu forfor management. Pp. 62-114. In Mass-reared natural enemies: Ap­Ap? fieldfield and laboratorylaboratory assistance, and to Drs. plication, regulation, and needs (R.L.(R.L. Ridgway, Robert Bugg, Mark Mayse and James Hagler Ridgway, Bugg, Mayse Hagler M.~M.R Hoffmann, M.N. Inscoe & C.S. Glenister, for reviewing an earlier version of the manu­ manu? reviewing eds.). Thomas Say PubI.,Publ., EntomoI.Entomol. Soc. Ameri­ Ameri? script. ca. Dean, D.A., W.L. Sterling & N.V. Homer.Horner. 1982. LITERATURE CITED Spiders inin eastern Texas cotton eotton fields. J. Arach­Arach? nol., 10:251-260. Agnew, C.W. & J.W. Smith, Jr. 1989. Ecology of nol., Flinn, PW., A.A. Hower & R.A. Taylor. 1985. spiders (Araneae) in a peanut agroecosystem. En­En? Flinn, P.W., Taylor. viron. EntomoI.,Entomol., 18:30-42. Preference of Reduvio/usReduviolus americoferus (Hemip­(Hemip- tera: Nabidae) for potato leatbopper nymphs and Bardwell, C.TC.T. & A.L. Averill. 1997. Spiders and Nabidae) potato leafhopper nymphs pea aphids. Canadian EntomoI., 113:365-369. their prey in Massachusetts cranberry bogs. J. pea aphids. Entomol., ArachnoI.,Arachnol., 25:31-41. Hagen, K.S. 1950. Fecundity of Chrysopa califor­califor- nica as affected by synthetic food. J. Econ. En­ En? Bishop, A.L. 1980. The composition and abun­abun? by synthetic tomoI., 43:101-104. dance of the spider fauna in south-east Queens­Queens? tomol., land cotton. Australian J. ZooI.,Zool., 28:699-708. Hagen, K.S. 1962. Biology and ecology of preda­preda? ceous Coccinellidae. Ann. Rev. EntomoI., 7: Breene, R.G., W.L.WL. Sterling & D.A. Dean. 1989. Entomol., 289-326. Predators of the cotton fleahopper on cotton. Southwestern EntomoI.,Entomol., 14: 159-166. Hagler, J.R. & A.C. Cohen. 1991. Prey selection Buchholz, U. & G. Schroft. Schruft. 1994. Rauberische Ar­Ar- by in vitro- and field-reared Geocoris punctipes. EntomoI.Entomol. Exp. AppI., 59:201-205. thropoden auf Bltiten Bliiten und Friichten der Weinrebe Exp. Appl., 59:201-205. Knutson, A.E. & RE. Gilstrap. 1989. Direct eval­ (Vitis vinifera L.) als Antagonisten des einbin­ einbin- Knutson, A.E. & F.E. Gilstrap. 1989. Direct eval? uation of natural enemies of the southwestern digen Traubenwicklers (Eupoecilia ambiguella uation natural enemies of the southwestern com borer (Lepidoptera: Pyralidae) in Texas Hbn.) (Lep., Cochylidae). J. App. EntomoI.,Entomol., 118: corn borer (Lepidoptera: Pyralidae) in Texas 31-37. com.corn. Environ. Entomol., 18:732-739. Bugg, R.L., J.D. Dutcher & ~ P. McNeill. 1991. Martinez, D.G. & R.L. Pienkowski. 1982. Labo­ Labo? Cool-season cover crops in the pecan orchard un-un­ ratory studies on insect predators of potato leaf­leaf? derstory: Effects on Coccinellidae (Coleoptera) hopper eggs, nymphs, and adults. Environ. En­ En? and pecan aphids (Homoptera: Aphididae). Biol.BioI. tomol.,tomoI., 1111:361-362.:361-362. Cont.,Cont, 11:8-15.:8-15. MacLellan, C.R. 1973. Natural enemies of ofthethe light Carroll, D.P.D.~ & S.C. Hoyt. 1984. Natural enemies brown apple , Epiphyas postvittana, in the and their effects on apple aphid Aphis pomi Australian capital territory. Canadian Entomol., DeGeer (Homptera: Aphididae), colonies on 105:681-700. young apple trees in central Washington. Envi?Envi­ Nyfeller, M. & G. Benz. 1987. Spiders in natural ron. Entomol.,EntomoI., 13:469-481. pest control: A review. J. Appl.AppI. Entomol.,EntomoI., 103: Costello, M.J. & K.M. Daane. 1995. Spider species 321-339. composition and seasonal abundance in San Joa-Joa­ Nyfeller, M., W.L. Sterling & D.A. Dean. 1992. quin Valley grape vineyards. Environ. Entomol.,EntomoI., Impact of the striped lynx spider (Araneae: Oxy-Oxy­ 24:823-831. opidae) and other natural enemies on the eottoncotton Costello, M.J. & K.M. Daane. 1997. Comparison fleahopper (Hemiptera: Miridae) in Texas eotton.cotton. of sampling methods used to estimate spider (Ar?(Ar­ Environ. Entomol., 21:1178-1188. aneae) species abundance and composition in Nyfeller, M., W.L.WL. Sterling & D.A. Dean. 1994. grape vineyards. Environ. Entomol.,EntomoI., 26:142-149. Insectivorous activities of spiders in United Costello, M.J. & K.M. Daane. 1998a. Influence of States field crops. J. Appl.AppI. Entomol., 118:113-118: 113­ ground cover on spiders in a table grape vine?vine­ 128. yard. Ecol.EcoI. Entomol.EntomoI. 23:33-40. Plagens, M.J. 1983. Populations of Misumenops Costello, M.J. & K.M. Daane. 1998b. Role of cov?cov­ (Araneidae: Thomisidae) in two Arizona eottoncotton er crops on pest and beneficial arthropods in fields. Environ. Entomol., 12:572-575. vineyards. Pp. 93-106. In Cover Cropping in Reichert, S.E. & L. Bishop. 1990. Prey control by Vineyards: A Growers Handbook (CA.(C.A. Ingels, an assemblage of generalist predators: Spiders in R.L. Bugg, G. McGourty & L.P.L.~ Christensen, garden test systems. Ecology, 71:1441-1450. eds.). Univ. of California Division of Agriculture Roach, S.H. 1980. Arthropod predators on eotton,cotton, and Natural Resources Publication No. 3338, corn,com, tobacco, and soybeans in South Carolina. Oakland, California. J. Georgia Entomol.EntomoI. Soc,Soc., 15:131-138. Daane, K.M. & M.J. Costello. 1998. Can cover Roltsch, W.R., R. Hanna, H. Shorey, M. Mayse & 538 THE JOURNAL OF ARACHNOLOGY

RF. Zalom. 1998. Spiders and vineyard habitat re­re? fectfeet on faunal composition, abundance, and body lationships in central California. Pp.pp. 311-338. In length of spiders (Araneae) in apple orchards. Enhancing Biological Control: Habitat Manage­Manage? Environ. Entomol., 26:763-776. ment to Promote Natural Enemies of Agricultural Zalom, RG., F.G., R. Hanna, C.C Elmore & EP. Christensen. Pests (C.H.(CH. Pickett & R.L. Bugg, eds.). Univ. of 1993. A cover crop for vineyard pest, weed, and California Press, Berkeley, California. nutrition management. 1992-93 Research Report Royer, T.A. & D.O.D.D. Walgenbach. 1991. Predaceous for California Table Grapes, California Table arthropods of cultivated sunflower in eastern Grape Commission, Fresno. South Dakota. J. Kansas Entomol. Soc.,Soc, 64:112­64:112- 116. Manuscript received 6 January 1998, revised 21 Wisniewska, J. & R.J. Prokopy. 1997. Pesticide ef- July 1998.