Field Guide for Integrated Pest Management in Hops

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Mite FeedersMite-Eating Lady BeetlesStethorus picipes, S. punctillumDescriptionMite-eating lady beetles are black,tiny (1/25 to 1/16 inch), oval, convex, andshiny, covered with sparse, fine, yellowishto-whitehairs (Fig. 110). Emerging adultsare reddish-orange for a few hours beforeturning black. The white, oval eggs are lessthan 1/50 inch long, and turn dark justbefore the larvae emerge (Fig. 111). Eggs arelaid singly, usually on the underside of leavesnear the primary vein, and adhere tightlyto the leaf. The newly hatched larva is grayto blackish and has many long-branchedhairs and black patches (Fig. 112). Thelarvae grow from 1/25 to 1/16 inch long,becoming reddish as they mature, at first onthe edges of the body. Just prior to pupationthe entire larva turns reddish. The pupaeare black and flattened, somewhat pointedon the posterior end, with the entire bodycovered with yellow hairs (Fig. 113).Mite-Feeding Lady BeetlesMonitoring, Importancein IPM and Compatibilitywith PesticidesMite-eating lady beetlesare critical to good biologicalcontrol of spider mites. One ortwo Stethorus beetles are usuallysufficient to control an early-seasonmite “hot spot,” preventing it fromspreading into a larger outbreak.In combination with predatorymites, Stethorus may maintain nondamaginglevels of spider mitesduring July and August. Monitoringcan be conducted by examiningleaves in the field or a laboratoryby looking for tiny alligator-likelarvae or mobile pinhead-sized blackdots. The beetles also can be shakenfrom bines and collected onto atray. Stethorus spp. are susceptibleto broad-spectrum insecticidesand miticides such as abamectin.However, many narrow-spectrumpesticides are compatible with thesurvival of these important predators.TOP: Figure 110. Adult mite-eating lady beetlesare 1/25 to 1/16 inch long. MIDDLE: Figure111. White, oval eggs are less than 1/50 inchlong. BOTTOM: Figure 112. Newly hatchedS. picipes larva is dark and hairy, with blackpatches. (3 photos, D. G. James)Biology and Life HistoryStethorus picipes (a native species) ismost commonly found in hop yards butS. punctillum (exotic) also occurs. Bothspecies are found in hop yards not exposedto broad-spectrum pesticides and arevoracious spider mite feeders, consuming 50to 75 mites per day. Overwintering occursas non-reproductive adults in protectedhabitats (e.g., in ground debris, under bark)away from hop yards. Adults emerge fromhibernation sites in late March and April, andseek out spider mite colonies in hop yards,which they are able to do extraordinarilywell. Once prey is found, female Stethorusfeed and lay eggs (approximately 15 eggs perday), rapidly exterminating small colonies ofmites. Larvae develop through four instars,pupating after 12 days. Development fromegg to adult takes approximately three weeksand three to four generations are producedduring spring-summer. Adults live for fourto eight weeks during summer and thrive attemperatures between 68 and 95 °F.At-A-GlanceMite-FeedingLady Beetles◆◆Monitor formite-eating ladybeetles.◆◆Learn torecognize “blackdot” adults andalligator-typeblack larvae.◆◆Thesevoracious spidermite feedersconsume 50 to75 mites per day.◆◆Spider mite“hot spots” canbe suppressedby 1 or 2 miteeatingladybeetles.◆◆Use onlyinsecticides andmiticides safe tomite-eating ladybeetles.17 57Figure 113. Pupae of the miteeatinglady beetle S. picipes.Notice the pointed posteriorend and yellow hairs coveringthe body (D. G. James)
58 Predatory BugsThe predatory bugs described here are true bugs, belonging to the insect orderAt-A-GlancePredatoryBugsHemiptera. Predatory bugs have shield-like, thickened forewings and suck out the bodycontents of their prey through tubular, stylet-like mouthparts. All of the predatory bugsfound on hop feed on more than one type of prey, consuming the eggs, immatures, andadults of a wide variety of prey including mites, aphids, caterpillars, and thrips.◆◆Recognizeand identifypredatory bugs.◆◆Predatorybugs areimportant inearly seasonsuppressionof mites andaphids.◆◆Predatorybugs alsofeed on eggs,immature andadult thrips,loopers andother soft-bodiedarthropods.◆◆Monitorpredatorybugs by shakesampling ordirect counts onfoliage.◆◆Always useinsecticides andmiticides safe topredatory bugs.Minute Pirate BugOrius tristicolorDescriptionAdults are 1/12 to 1/5 inch long,oval, and black or purplish with whitemarkings on the forewings (Fig. 114). Thewings extend beyond the tip of the body.The tiny (1/100 inch) eggs are embedded inplant tissue with the “lid” exposed, throughwhich the nymph emerges (Fig. 115).Newly hatched nymphs are transparent witha slight yellow tinge, turning yellow-orangeto brown with maturity (Fig. 116). They arefast-moving, wingless, and teardrop-shaped.Figure 114. Adult minute pirate bug(Orius tristicolor). Adults are 1/12 to 1/5inch in length. (D. G. James)Biology and Life HistoryMinute pirate bugs overwinter asadults in leaf litter or under bark andusually emerge from hibernation in lateMarch or early April. They feed on mites,aphids, thrips, hop loopers, and other softbodiedinsects. Eggs take three to five daysto hatch and development from egg toadult through five nymphal stages takes aminimum of 20 days. Females lay an averageof approximately 130 eggs over a 35-dayperiod and several generations are producedduring spring and summer. When prey isnot available, minute pirate bugs are able tosurvive feeding on pollen and plant juices.Adults and immatures can consume 30 to40 spider mites or aphids per day. Minutepirate bugs are efficient at locating preyand are voracious feeders. They aggregatein areas of high prey density and increasetheir numbers more rapidly when there is anabundance of prey. Minute pirate bugs arecommon predators in low-input hop yardsand contribute significantly to control ofspider mites, aphids, and hop loopers.Figure 115. First-instar nymph and egg ofthe minute pirate bug (Orius tristicolor).Eggs are extremely small (1/100 inch) andembedded within leaves. (D. G. James)Figure 116. Minute pirate bug (Orius tristicolor)nymph. Notice that nymphs are wingless andteardrop-shaped, and older ones are yelloworangeto brown in color. (D. G. James)
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AcknowledgementsFunding for this ha
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Use pesticides with care. Apply the
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Monitoring for Pests, Damage, and T
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Active IngredientTable 1. Signal Wo
Page 13 and 14: 8At-A-Glance:AlternariaCone Disorde
Page 15: 10At-A-Glance:DownyMildew◆◆Sele
Page 18 and 19: 13sporangiophores emergewith sporan
Page 20 and 21: Fusarium CankerDavid H. GentFusariu
Page 22 and 23: Gray MoldDavid H. GentGray mold gen
Page 24 and 25: 17 19to infection, and their develo
Page 26 and 27: PERCENT DISEASED LEAVES100806040200
Page 28 and 29: Sclerotinia Wilt (White Mold)David
Page 30: Verticillium WiltDavid H. Gent and
Page 33 and 34: 28At-A-GlanceCarlavirusComplex◆
Page 35 and 36: 30At-A-GlanceHop stuntviroid◆◆U
Page 37 and 38: 32Other Viruses, Viroids, and Virus
Page 39 and 40: 34 NematodesAt-A-GlanceHop CystNema
Page 41 and 42: 36 Arthropod and Slug Pest Manageme
Page 43 and 44: 38 Hop AphidAmy J. DrevesAt-A-Glanc
Page 45 and 46: 40 Garden SymphylanAmy J. DrevesAt-
Page 47 and 48: 42 Hop Looper and Bertha ArmywormJi
Page 49 and 50: 44ABOVE: Figure 78. Adult black vin
Page 51 and 52: 46 Twospotted Spider MiteJim D. Bar
Page 53 and 54: 481412108642025AVERAGE MITES PER LE
Page 55 and 56: 50 SlugsAmy J. DrevesAt-A-GlanceSlu
Page 57 and 58: 52 Beneficial ArthropodsDavid G. Ja
Page 59 and 60: 54 Predatory Lady BeetlesWashington
Page 61: 56A generalizedsummary ofthe season
Page 65 and 66: 60Assassin BugsReduviidaeDescriptio
Page 67: 62 Parasitic Wasps(Parasitoids)At-A
Page 70: Long-legged FliesThese small to med
Page 73 and 74: 68At-A-GlanceSpiders◆◆Spiderpre
Page 75 and 76: 70 17Planning a WeedManagement Prog
Page 77 and 78: 17 72Figure 161. Redroot pigweedpla
Page 79 and 80: 17 74Figure 177. Common mallow. (R.
Page 81 and 82: 76Calculating Treated Acres versus
Page 83 and 84: 78Figure 198. Severe cupping of lea
Page 85 and 86: 80Figure 210. Yellowing anddeath of
Page 87 and 88: 82HHarmonia axyridis 55Hemerobius s
Page 89: 84TTablesTable 1 5Table 2 12Table 3
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Field Guide for Integrated Pest Management in Hops

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