Web Spinning Spider Mites

Transcription

1 Published by Utah State Univesity Extension and Utah Plant Pest Diagnostic Laboatoy ENT Octobe 2011 Do You Know? Web Spinning Spide Mites Twospotted Spide Mite (Tetanychus uticae) McDaniel Spide Mite (Tetanychus mcdanieli) Diane G. Alston, Entomologist Michael E. Reding, Entomologist 1 Spide mites feed on a wide ange of plants, including fuit tees, field and foage cops, onamentals, and weeds Adult and immatue mites feed on leaves causing white stippling, bonzing, and defoliation Tee vigo and fuit colo, size, and poduction can be educed Spide mite populations can incease apidly duing hot summe months Pesence of the westen pedatoy mite, avoidance of non-selective pesticides, and pope gound cove management ae essential fo good biological contol Use of miticides is only ecommended when infestations ae sevee and pedatoy mite numbes ae low Mite monitoing is essential to management; pesence-absence sampling is ecommended Two spotted spide mite adult, immatue and egg (Utah State Univesity Extension). Mites ae small athopods that ae moe closely elated to spides and ticks than to insects. Mites in this goup ae web spinnes, hence the name spide mites. They ae an impotant and destuctive goup of pests to agicultual cops woldwide. Howeve, the spide mite s status as a pest is often ceated by poo pest management pactices, such as boad spectum pesticide applications and impope management of ochad gound coves. These pactices shift the balance towad high spide mite densities and low natual enemy densities. Duing hot summe months, the spide mite s high epoductive ate can cause population explosions in only 1 to 2 weeks. In addition, its small size makes detection, identification, and monitoing paticulaly difficult. Twospotted and McDaniel ae the two most impotant web spinning species of spide mites (Ode Acai, Family Tetanychidae) to attack Utah fuit ochads. Howeve, twospotted spide mite tends to have a highe epoductive ate duing hot summe conditions. Fo that eason, when both species occu togethe, twospotted spide mite often out competes McDaniel spide mite. Although 1 USDA ARS, Wooste, OH Spide mite injuy to a tat chey leaf; note stippling and debis caught in webbing on the leaf suface (Utah State Univesity Extension). Spide mite injuy to pea can cause apid and sevee leaf bun (E. Bees, Washington State Univesity).

2 they ae diffeent species, thei life histoies, monitoing methods, and management techniques ae simila enough to discuss togethe. Ap May Jun Jul Aug Sept Adults Monitoing time Eggs Immatues PLANT HOSTS LIFE HISTORY Ovewinteing Females Aow indicates time when monitoing should occu. Count the numbe of mite-infested leaves evey 1-2 weeks (see Pesence-Absence Sampling Method, page 3). Twospotted spide mite attack hundeds of plants including many field and foage cops, hoticultual cops, onamentals, and weeds. The host ange of McDaniel spide mite is not as boad as that of twospotted spide mite, although it does attack most deciduous fuit tees, some field and foage cops, and many weeds. The following is a list of fuit hosts: apple plum pea pune chey stawbey peach/nectaine apicot cane and bamble beies Adult Ovewinteing and Damaging Stage Size and shape: female 1/60 inch (0.42 mm) long and oval; male slightly smalle with a tapeed hind end Colo: ovewintes as oange female without spots; tuns fom oange to geen once feeding begins in the sping; summe adult has two distinct dak spots on the back behind the eyes (twospotted spide mite) o multiple dak spots on the back (McDaniel spide mite), and is yellow to geen tuning bown with age; has two ed eyes Whee: winte-fom female esides unde bak at the base of tees, and unde oganic matte (duff) on the soil suface When: emeges when the weathe begins to wam in ealy sping Begins feeding on gound cove host plants (see Table 1); moves up into tees as the ochad floo vegetation dies out in ealy to mid summe o following a majo distubance to the cove, such as hebicide application, mowing, o cultivation Egg laying stats a few days afte feeding begins Ovewinteing females lay 30 to 50 eggs in a 25-day aveage life span Summe-fom female lays up to 100 to 150 eggs in a 4- to 6-week peiod In fuit tees, mites ae fist found on oot suckes, UPPDL, 5305 Old Main Hill, Logan UT 84322, utahpests.usu.edu Oct Table 1. Occuence of spide mites on gound cove plants in Utah ochads (Alston 1994). Plant Common Name Alfalfa Apple oot sucke Bittesweet nightshade Cheatgass Common budock Common dandelion Common lambsquatte Common mallow Culy dock Field bindweed Geen foxtail Hoay cess (whitetop) Knotweed Moning Gloy Ochadgass Pickly lettuce Punctue vine Red fescue Mite Host Status * x indicates that only adult mites wee found; indicates that the plant was a epoductive host on which mite eggs, immatues, and adults wee found; blank indicates that no mites wee obseved wate spouts, o on leaves in the lowe cente o at the top of the tee canopy, speading to the canopy peiphey Utah ochads can have eight o moe geneations a yea; summe geneations ovelap A geneation may be completed in as few as days duing hot summe peiods When leaf quality begins to decline fom excessive mite feeding o when conditions change to coole tempeatues and shote days in the fall, oange ovewinteing females once again begin to accumulate in potected sites Egg Size, shape, and colo: 1/150 inch (0.2 mm) in diamete, spheical, and tanslucent when fist deposited, becoming opaque Whee: pimaily on the undesides of leaves Red eye spots of the lava appea just befoe hatching Fist geneation eggs laid in the sping may take 3 weeks to hatch, depending on tempeatues Egg hatch in the summe may take only 1 to 2 days Immatue Damaging Stage Thee ae thee stages of immatues: lava, potonymph, and deutonymph. Each immatue stage goes though thee phases including active feeding, a esting peiod when the oute skin of the body takes on a silvey colo, and a molt when the skin is shed. Immatue stages con- x x x Page 2

3 gegate on the undesides of leaves on fuit tees, gound cove, and weed hosts, but can also be found on uppe sufaces when population densities ae high o mites ae migating to new sites. Lava Size: about the same size as the egg Colo: tanslucent when fist hatched, tuning pale geen to staw colo with chaacteistic black spots foming on the back Shape: ound with thee pais of legs Potonymph Size: lage and moe oval shaped than the lava Colo: deepe geen Shape: oval with fou pais of legs Two dak spots ae moe ponounced Deutonymph Size: slightly lage than the potonymph Shape: male can be distinguished fom the female by its smalle size and moe pointed abdomen Dispesal Mites pimaily move fom ovewinteing to feeding sites in the sping and among host plants by cawling. Howeve, mites ae able to balloon on ai cuents by holding onto a thin thead of silk (webbing) poduced by thei spinneets, o without the aid of silk by just eaing up on thei head o back and into the ai. HOST INJURY Peak injuy to tees typically occus in late June though mid Septembe when weathe conditions ae hot and dy. Mite infestations often begin as hot spots within an ochad that spead to neighboing tees if weathe conditions ae favoable and pedatoy mites ae unable to suppess the infestation. The following ae the common chaacteistics of mite feeding and injuy: Mites feed by piecing leaf tissue with thei mouthpats and sucking up plant fluids Photosynthetic activity of tees is educed Light to modeate feeding causes white speckling o stippling of leaves Heavy feeding causes leaves to bonze o tun bown, dy up, and dop pematuely (peas ae especially sensitive to mite injuy; even low to modeate infestations can esult in apid leaf bun and defoliation) Mite feeding on the suface of pea fuit can cause usseting Mite webbing and feeding on the suface of tat cheies can cause scaing and shiveling of fuit Infested leaves and twigs may be coveed with fine webbing Tee vigo and fuit colo, size, and poduction can be educed If injuy occus ealy enough in the season, thee may be insufficient eseves fo nomal fuit set and poduction the following yea High mite populations in the summe can cause ealy senescence (leaf colo change and dop); stessed tees ae moe susceptible to winte injuy and motality TIMING CONTROL In most situations, spide mites in Utah fuit ochads can be managed without the use of miticides. Some exceptions include mites on pea o on all tee types duing exteme hot and dy peiods when mites have a tendency to epoduce apidly and each outbeak levels within 1 to 2 weeks. Because biological and cultual contols play a dominant ole in integated mite management and because mite infestations often begin as hot spots, the use of a eliable sampling method is citical to the success of an integated pogam. A faily eliable and easy-to-use sampling method fo mites is called pesence-absence, o binomial, sampling. Rathe than counting the numbe of mites on leaves, which is difficult because of thei small size, pesenceabsence sampling equies only that the scout detemine whethe o not pest o pedato mites ae pesent on each leaf sampled. The following ae easons to use pesence-absence sampling: Detemines mite densities quickly and easily Eliminates unnecessay miticide teatments Conseves beneficial pedatoy mite populations, which can povide adequate biological contol of spide mites Allows identification of mite hot spots that can be tageted with chemical contol when necessay Ensues pope timing of miticide teatments when necessay Reduces the likelihood of mite populations developing esistance to miticides Pesence-Absense Sampling Method Scouting fo mites can be done at the same time as fo westen tentifom leafmine in apples and cheies. Select epesentative ochad blocks of each fuit type to include in the scouting pogam. Sampling all ochad blocks will impove you ability to make specific mite management ecommendations. How to Sample: Randomly select 10 tees scatteed thoughout a 2- to 5-ace block to sample. If the ochad block is lage than 5 aces, divide it into two 5 ace sub-blocks fo sampling puposes. Scout designated ochad blocks evey 1 to 2 weeks fom mid-june though mid-septembe; duing hot peiods, sample evey week On each sampling date, collect 10 leaves fom each of the 10 tees (100 leaves total); because spide mites ae found in the lowe cente and at the top of tee canopies fist, speading to the peiphey ove time, leaves should be selected fom inside the canopy as well as fom the edges Leaves fom each tee should be kept sepaate fom leaves of othe tees, which will enable you to identify hot spots; eithe place leaves fom each tee in a sepaate bag to count at the end of collection, o count infested leaves fom each tee immediately afte collecting Using a 10 20X hand lens, count the numbe of leaves fom each tee infested with each type of mite (spide and pedatoy); it is not necessay to count the numbe of mites on each leaf UPPDL, 5305 Old Main Hill, Logan UT 84322, utahpests.usu.edu Page 3

4 Table 2: Web spinning spide and pedatoy mite pesense-absense sampling method look-up tables (Jones 1990). Twospotted and McDaniel Spide Mites Tetanychus uitcae and T. mcdanieli Numbe of leaves out of 10 with at least one mite pesent* Estimated numbe of mites pe leaf Pedatoy Mite Typhlodomus occidentalis Numbe of leaves out of 10 with at least one mite pesent* Estimated numbe of mites pe leaf * Note: fo each tee sampled, detemine the numbe of leaves out of 10 with at least one mite pesent Recod the numbe of mite-infested leaves pe tee on the sampling fom (See the Spide and Pedatoy Mites Sampling Fom) Use the look-up table (Table 2) to estimate the numbe of mites pe leaf fo both spide mites and pedatoy mites Total the estimated mite densities fo all 10 tees and divide by 10 to obtain an aveage fo the tees sampled in the block, note any tees with substantially highe spide mite densities than the block aveage as these may indicate hot spots The same leaves can be used to monito fo westen tentifom leafmine in apple and chey MANAGEMENT Relying pimaily on biological and cultual contol fo spide mite management should be the goal of evey ochad pest manage. In many situations, chemical contol is unnecessay and may only make the mite poblem wose. Use of miticides will eliminate the beneficial pedatoy mites, which ae capable of keeping spide mite populations below economically damaging levels. Anothe eason to avoid chemical contol is that populations of twospotted and McDaniel spide mites have developed esistance to miticides. The following sections will descibe the vaious components of a good mite management pogam. Teatment Thesholds Using the pesence-absence sampling method descibed on page 3, the following ae the steps to follow to detemine if economic thesholds fo spide mites have been exceeded (Jones 1990): Apple and Stone Fuits: If the aveage numbe of spide mites pe leaf is less than 5 and no pedatos ae pesent, esample in 1 week. If the pedato to pest atio is at least 1:5, wait 2 weeks to esample If the aveage numbe of spide mites pe leaf is 5 to 10 and thee is less than 1 pedato pe leaf, esample in 2 to 5 days; if the pedato to pest atio is at least 1:10, esample in 1 week If the aveage numbe of spide mites pe leaf is moe than 10 and thee is less than 1 pedato pe leaf, conside applying a miticide teatment (see Chemical Contol below) Pea: If the aveage numbe of spide mites pe leaf is less than 5 and less than 1 pedato pe leaf is pesent, esample in 2 to 5 days; if the pedato to pest atio is at least 1:5, esample in 1 to 2 weeks If the aveage numbe of spide mites pe leaf is 5 o geate and pedato to pest atio is at least 1:5, esample in 1 week. If pedato to pest atio is less than 1:5, conside applying a miticide teatment (See Chemical Contol below) Biological Contol Mite Pedatos The westen pedatoy mite, Typhlodomus occidentalis (Family Phytoseiidae), is common and the most impotant mite pedato in Utah fuit ochads. Seveal othe species of pedatoy phytoseiid mites do occu, but thei ole in biological contol of spide mites is usually minimal. The westen pedatoy mite is teadop-shaped (naowe at the head), tanslucent to yellow in colo, and can move quickly. It pimaily eats the eggs and immatue stages of spide mites, but can be cannibalistic if spide mite pey is scace. Zetzellia mali (Family Stigmaeidae), a smalle yellow to oange pedatoy mite, can often be found in unspayed ochads o in those ochads that eceive fewe insecticides. Howeve, Z. mali pedominantly attacks Euopean ed mite and apple ust mite. Othe pedatos that feed on spide mites include a small black lady beetle, Stethous picipes; some pedatoy bugs; thips; and lacewings. But in Utah ochads, Typhlodomus occidentalis povides the most consistent and highest level of mite biological contol. UPPDL, 5305 Old Main Hill, Logan UT 84322, utahpests.usu.edu Page 4

5 Avoid using the following chemicals afte bloom as they can significantly educe pedato numbes: bifenthin (Bigade, Captue) cabayl (Sevin) dicofol (Kelthane) esfenvaleate (Asana) fenebutatin-oxide (Vendex) fomentanate hydochloide (Cazol) lambda-cyhalothin (Waio) lime-sulfu methidathion (Supacide) oxamyl (Vydate) pemethin (Ambush and Pounce) sulfu zeta-cypemethin (Mustang Max) The westen pedatoy mite is the most impotant pedato in Utah ochads; it is teadopped-shaped and moves quickly (Utah State Univesity Extension). Zetzellia mali is a seconday pedato, mostly of Euopean ed mite and ust mites, but will also feed on spide mite eggs (TFREC, Washington State Univesity). In ode to encouage the suvival of pedatoy mites in sufficient numbes, it is cucial to adopt sound, biologically-based pest management pactices. The following ae ecommendations fo encouaging pedatoy mites: When applying domant, delayed domant, and pe-bloom teatments fo contol of othe pests, do not diect spays at the lowe tunk and suounding gound cove whee pedatos ovewinte In most situations, do not contol populations of eiophyid mites, such as ust mites and leaf bliste mites, because they seve as an ealy season food souce fo pedatos; the exception is pea tees and ochads whee lage populations of eiophyid mites ae pesent and significant injuy occued the pevious season Avoid Nonselective Chemicals To maintain adequate pedato populations, chemicals that ae toxic to beneficial pedatos should be avoided. If cabayl (Sevin) is used fo fuit thinning, use minimum egisteed dosages and confine the spay to the peiphey of tees. Use post-bloom miticides only when absolutely necessay to pevent economic injuy (see Teatment Thesholds above). Impotant Role of Rust Mites To successfully maintain pedato mite populations in ochad tees and on gound cove vegetation, a pey souce must be available. Rust mites on apple, pea, chey, and plum play an impotant ole as an altenate food souce fo pedato mites in tees. Altenate pey can be citical in maintaining pedatos when spide mite densities ae low. In fact, minimal spide mite numbes and modeate to high pedato mite numbes have been obseved in Utah ochads thoughout the summe season because of the altenate ust mite pey. Fo that eason, ust mites should not be contolled on tees unless they ae causing significant injuy. Keep in mind that pea ust mites can cause substantial fuit usseting if populations ae high enough. Theefoe, thei populations should be monitoed caefully and consideed in the oveall mite management pogam. Re-establishing Pedato Mites The most impotant pedato mite, Typhlodomus occidentalis, occus natually in Utah ochads. If Typhlodomus populations ae eliminated though the use of nonselective chemicals (see list above), it may be possible to hasten thei e-establishment athe than waiting fo natual colonization. Howeve, as long as nonselective chemical use is continued, Typholodomus populations will not thive and povide mite contol. To successfully e-establish Typhlodomus, a souce of pey, such as ust mites o spide mites, must be available in the ochad. The following ae some suggestions fo e-establishing Typhlodomus in the ochad: Cut shoots containing both Typhlodomus and a pey souce fom one ochad tee and place them in tees of anothe ochad To facilitate mite dispesal into the tees, position shoots so that thee is leaf-to-leaf contact; because the movement of Typhlodomus between tees is limited, at least one shoot should be placed in each tee Typhlodomus occidentalis can also be puchased fom commecial supplies and eleased into tees; eseaches have developed stains of Typhlodomus with toleance to some of the common ochad insecticides; make sue to choose a eliable supplie and select a stain that is appopiate fo you aea Gound Cove Management The type and density of vegetation gowing on the ochad floo can play an impotant ole in ochad mite UPPDL, 5305 Old Main Hill, Logan UT 84322, utahpests.usu.edu Page 5

6 management. Studies in Utah ochads found that cetain boad leaf weeds and apple oot suckes enhanced the movement of spide mites fom gound cove plants into tees (see Table 1). Establishing a healthy gass gound cove has poven successful in displacing most boad leaf weeds that seve as epoductive hosts fo spide mites and peventing build up of poblem spide mite densities. Because gound cove plants ae an impotant souce of food fo spide mites in sping and ealy summe, they can also assist with building up pedato mite populations that feed on the spide mites. Theefoe, allowing a low level of weeds may impove the availability of ealy season spide mite pey fo pedato mites, and thus impove the synchony of pedato and pey as they move into tees late in the season. Howeve, the availability of ust mites in tees as an enticement fo pedato mites to move into tees ealy in the season can pevent the need fo ealy season spide mite populations on gound cove (see Impotant Role of Rust Mites). Keep in mind that aggessive weed and gound cove suppession should be maintained in ochads less than 3 yeas old to pevent competition fo wate and nutients until the ochad is well established. Gound cove management pactices such as mowing, hebicide application, cultivation, and iigation can also stongly influence the movement of mites. When thee ae abundant spide mites on gound vegetation, especially duing mid-june to Septembe, minimize mowing, cultivation, and hebicide teatments because lage numbes of spide mites may be diven up into ochad tees. This can also occu when the gound cove dies out duing the hot summe months. Adding a miticide to an hebicide fo contol of weeds and mites on the ochad floo is an expensive option that is not usually cost effective. In addition, if cultivation is used to educe weeds on the ochad floo o a well-taveled dit oad is neaby, the dust poduced may incease populations of spide mites and lowe populations of pedato mites. Chemical Contol Miticides and nonselective ochad chemicals should be avoided in favo of biological and cultual pactices that allow pedatos to maintain spide mite populations below economically damaging levels. But if summe applications ae equied fo contol of twospotted o McDaniel spide mites, the following mateials ae ecommended: abamectin (Agi-Mek) acequinocyl (Kanemite) - apple and pea only bifenazate (Acamite) clofentezine (Apollo) dicofol (Kelthane) - apple and pea only etoxazole (Zeal) fenbutatin-oxide (Vendex) R - not on apicot fenpyoximate (FujiMite) - apple and pea only hexythiazox (Onage, Savey) insecticidal soap (M-Pede, Safe s, othes) O,H popagite (Omite) R - nectaine only pyidaben (Nexte) spiodiclofen (Envido) sucose octanoate estes (SucaShield) o summe-weight oil (hoticultual mineal oil, canola oil, soybean oil, othes) O,H O Oganic (OMRI-appoved) poducts available. H Homeowne poducts available. R Resticted use insecticide; a pesticide applicato license is equied to puchase and apply All bands ae egisteed tademaks. Examples of bands may not be all-inclusive, but ae meant to povide examples of poducts egisteed in Utah. The availability of pesticides may change. Always ead the label fo egisteed uses, application and safety infomation, and potection and pe-havest intevals. Use lowe label ates if pedatos ae pesent. To avoid selecting fo esistance, otate diffeent types of miticides. Once a miticide is applied, mite densities should be monitoed 1 week late. A second application may be equied in 7 to 10 days following the fist application if a lage numbe of eggs and hatching lavae ae pesent. ADDITIONAL RESOURCES Alston, D. G Effect of apple ochad floo vegetation on density and dispesal of phytophagous and pedaceous mites in Utah. Agicultue, Ecosystems and Envionment 50: Jones, V. P Sampling and dispesion of the twospotted spide mite (Acai: Tetanychidae) and the westen ochad pedatoy mite (Acai: Phytoseiidae) on tat chey. Jounal of Economic Entomology 83: Pecautionay Statement: Utah State Univesity Extension and its employees ae not esponsible fo the use, misuse, o damage caused by application o misapplication of poducts o infomation mentioned in this document. All pesticides ae labeled with active ingedients, diections fo use, and hazads, and not all ae egisteed fo edible cops. Resticted use pesticides may only be applied by a licensed applicato. The pesticide applicato is legally esponsible fo pope use. USU makes no endosement of the poducts listed heein. Utah State Univesity is committed to poviding an envionment fee fom haassment and othe foms of illegal discimination based on ace, colo, eligion, sex, national oigin, age (40 and olde), disability, and vetean s status. USU s policy also pohibits discimination on the basis of sexual oientation in employment and academic elated pactices and decisions. Utah State Univesity employees and students cannot, because of ace, colo, eligion, sex, national oigin, age, disability, o vetean s status, efuse to hie; dischage; pomote; demote; teminate; disciminate in compensation; o disciminate egading tems, pivileges, o conditions of employment, against any peson othewise qualified. Employees and students also cannot disciminate in the classoom, esidence halls, o in on/off campus, USU-sponsoed events and activities. This publication is issued in futheance of Coopeative Extension wok, acts of May 8 and June 30, 1914, in coopeation with the U.S. Dept. of Ag., Noelle E. Cockett, Vice Pesident fo Extension and Agicultue, Utah State Univesity. Fact Sheet Seies: Insects-Tee Fuit UPPDL, 5305 Old Main Hill, Logan UT 84322, utahpests.usu.edu T: F: Page 6