Forest & Disease Leaflet 183 March 2015

U.S. Department of Agriculture • Forest Service Goldspotted Oak Borer T.W. Coleman1, M.I. Jones2, S.L. Smith3, R.C. Venette4, M.L. Flint5, and S.J. Seybold 6 The goldspotted oak borer (GSOB), New Mexico, and southwestern Texas. auroguttatus Schaeffer Specimens of GSOB have only been (Coleoptera: ) (Figure collected from Arizona, California, 1), is a flatheaded phloem- and wood and Mexico. In southeastern Arizona, borer that infests and kills several GSOB feeds primarily on Q. emoryi, species of oak (Fagaceae: Quercus) in and silverleaf oak, Q. hypoleucoides A. California. One or more populations Camus (both Section Lobatae). Larval of GSOB were likely introduced via feeding injures the phloem and outer infested firewood into San Diego xylem of these red oak species, with County, California from the native most feeding activity and occasional range in southeastern Arizona. Since cases of tree mortality noted in large- its introduction to California, GSOB has expanded its range and has killed red oaks (Quercus Section Lobatae) nearly continuously across public and private lands (Figure 2).

Distribution and Hosts The native distribution of GSOB likely coincides with that of Emory oak, Q. emoryi Torrey, including the Coronado Figure 1. Adult goldspotted oak borer, Agrilus National Forest in southeastern auroguttatus, an exotic insect threatening red Arizona and floristically related oaks in California (Adults are approximately regions in northern Mexico, southern 0.35 inches long by 0.08 inches wide).

1Entomologist, USDA Forest Service, Forest Health Protection, San Bernardino, CA; 2Entomologist, Dept. of Environmental Science and Forestry, Syracuse University, Syracuse, NY; 3Entomologist, USDA Forest Service, Forest Health Protection, Susanville, CA; 4Research Biologist, USDA Forest Service, Northern Research Station, St. Paul, MN; 5Entomologist, Dept. of Entomology and Nematology and Statewide Integrated Pest Management Program, University of California, Davis, CA; 6Research Entomologist, USDA Forest Service, Pacific Southwest Research Station, Davis, CA. Figure 2. Aerially mapped oak mortality (red stippling) associated with the goldspotted oak borer in San Diego County in southern California (2002-2013). Disjunct infested areas (satellite populations indicated by ●) occur in San Diego County (San Diego); Riverside County (Idyllwild) and Orange County (Orange). diameter trees [>17 inches in diameter facilitated the dispersal of GSOB in at breast height (dbh)]. A sibling southern California and will likely species, the Mexican goldspotted oak continue to play a role in its future borer, A. coxalis Waterhouse, is native dispersal in California and beyond. to central and southern Mexico and Guatemala, and was once synonymized In California, GSOB preferentially with A. auroguttatus. Surveys have attacks and kills large-diameter coast shown that Mexican GSOB feeds on live oaks, Q. agrifolia Née, and both red oaks and white oaks (Section California black oaks, Q. kelloggii Quercus) in southern Mexico. Newberry (>18 and 20 inches dbh, respectively). Interior live oak, Q. In 2004, GSOB was first detected in wislizeni A. DC., another red oak survey traps in southern California (San species, was susceptible to GSOB larval Diego Co.), but it was not linked to tree feeding in laboratory tests, but GSOB injury or mortality until 2008. In 2012, has not been observed to infest this oak GSOB was detected in Riverside Co. species in the field. Goldspotted oak and was likely introduced to this new borer can also attack a taxonomically county in infested firewood (Figure 2). intermediate oak species, canyon live The movement of infested firewood oak, Q. chrysolepis Liebm. (Section was also most likely responsible Protobalanus), and, on rare occasions, for additional satellite infestations a white oak species, Engelmann oak, of GSOB that have been detected Q. engelmannii Greene, in California. elsewhere within San Diego Co., and Goldspotted oak borer has killed in Orange Co. Unregulated movement canyon live oak at low levels (<25% of infested oak wood has presumably of surveyed trees) in San Diego Co. 2 Dead Engelmann oak trees have been then to northern California along observed with signs of GSOB injury the Coastal Mountain Range (Figure (e.g., larval galleries and D-shaped 3). It also extends south into Baja emergence holes, see below), but tree California Norte, Mexico. California mortality in these cases was likely a black oak occurs on Mt. Laguna and result of a complex of factors (e.g., Palomar Mountain in San Diego Co., drought and root disease). Several the Transverse Mountain Range, ornamental oak species, including Coastal Mountain Range, and along holly oak, Q. ilex (Section Quercus), the Sierra Nevada Mountain Range and cork oak, Q. suber (Section to southern Oregon. Goldspotted oak Cerris), are planted frequently in the borer-caused mortality has occurred urban areas of southern California and in coast live oak at sea level as well as may be at risk. In laboratory studies, in California black oak at elevations GSOB larvae fed on cork oak logs but up to approximately 6,000 feet in were unable to complete development. San Diego Co.; in laboratory tests, However, it has been hypothesized that prepupae (mature larvae in a hair-pin species in the Sections Quercus and configuration) have shown a cold- Cerris are not favored by GSOB and tolerance of approximately -0.4° F likely not susceptible to the extensive during the winter months. The ’s injury needed to cause tree mortality. distribution will likely expand from San Diego, Riverside, and Orange Cos. In California, the range of coast live to mirror the range of its primary hosts oak extends north from San Diego and conducive climatic conditions in Co. along the Santa Anita Mountains California and into Oregon and Mexico and Transverse Mountain Range and (Figure 3).

Figure 3. Potential range of goldspotted oak borer in Arizona, California, New Mexico, Oregon, and Baja California Norte, Mexico based on host distributions and climatic suitability. On the map, areas with hosts are colored, and climatically suitable areas within the distribution of hosts appear as shades of yellow (moderately suitable), orange, and red (highly suitable). 3 Impacts the main stem is girdled and the oaks sustain significant injury and, eventually, mortality (Figure 4B). This Neither GSOB nor Mexican GSOB is process appears to be gradual, taking considered a significant pest or threat from 3 to 5 years. However, oaks to forest health in its native range. predisposed by other injury agents Instead, they have caused minor levels (e.g., drought and root disease) may of injury to oaks (4% infestation succumb more quickly to the effects of rates) and have been associated with GSOB larval feeding. background levels of tree mortality in Arizona (2%) and Mexico (1%). As In coast live oak woodlands in eastern a consequence, virtually no research San Diego Co. where trees have related to the biology and ecology of suffered at least a decade of infestation these species occurred prior to 2008 from GSOB, oak mortality levels have when GSOB-caused oak mortality was approached 45%. Infestation rates have discovered in California. been high (>90%) on large-diameter oaks at the hypothetical origin of the The death of large-diameter coast beetle’s introduction near Descanso live oaks and California black oaks in and Guatay in San Diego Co., but the California results from several years of rates are lower (<10%) at the edges of extensive larval feeding at the interface the advancing infestation. of the phloem and xylem (Figure 4). This feeding kills large sections of The expansion of the core area infested live tissue (Figure 4A), including the by GSOB has progressed slowly in vascular cambium. As a consequence, San Diego Co. despite a maximum adult flight distance of approximately A 0.9 miles in tethered flight mill assays in the laboratory. Moderately and severely infested trees (known as brood trees) represent <7% of the oaks in forest stands in areas that have

B

Figure 4. Typical goldspotted oak borer larval feeding galleries under recently removed bark of a living coast live oak tree (A) and etched on the xylem (wood) surface of a dead coast live oak tree (B). The meandering dark-colored galleries in living phloem and xylem (A) are characteristic of goldspotted oak borer larval feeding. 4 been infested for longer than a decade. longevity has not been recorded in the Coast live oak brood trees were field and is likely shorter in duration. also found at low densities in newly Adults feed on oak foliage to survive, infested sites and, based on inferred and females require approximately 10 population density from emergence days of feeding to become sexually hole records, they contain 66 to 93% mature and likely mate in the crown or of the GSOB population at these on the bark surface of the main stem sites. The contrast between the rate of or larger branches. In the laboratory, spread of the core population and the a single female can lay approximately appearance of satellite populations in 200-500 eggs. Females lay eggs in Orange, Riverside, and San Diego Cos. fissures and crevices on the bark surface suggests that GSOB will spread slowly of the main stem and larger branches, via natural dispersal or quickly via either singly or in clusters (Figure 5). human-assisted dispersal (Figure 2). The eggs are oval, approximately 0.01 inches wide, tan-colored, and very Life History difficult to find on the bark surface. The goldspotted oak borer typically Eggs develop in approximately 12 days completes one generation in a year. and first instar larvae bore through the However, anecdotal evidence suggests bark into the phloem. that populations may require more than one year to complete development in healthier hosts. In southern California, adults fly from mid-May to early October with peak flight occurring in late-June to early July (Table 1A). The majority of adult flight occurs from June to September. Adults can live for Figure 5. Goldspotted oak borer eggs laid on several months in the laboratory, but the bark surface of coast live oak.

Table 1. Approximate timing of the goldspotted oak borer life cycle in southern California (A) and optimal timing of trapping period (B); application of contact (C) and systemic insecticides (D); and timing of mechanical grinding (E) and tarping (F) of infested oak wood. 5 Goldspotted oak borer larvae likely Immediately prior to pupation, larvae complete four instars. Larvae are begin to constrict to adult length in white, legless, and approximately 0.8 the pupal cell (Figure 6D). Pupae inches long by 0.1 inches wide when and teneral (newly formed) adults fully mature. First instar larvae are are present from April to August in <0.05 inches long and difficult to locate the pupal cells. Pupae are the same in the phloem (Figure 6A). Larvae size as adults, but initially are white have C-shaped spiracles (holes where and soft-bodied (Figure 6E). Pupae air exchange occurs) and a pair of transform into teneral adults when spines at the tip of the abdomen, both their exoskeleton begins to sclerotize, of which can be used to identify all or harden, and darken in color. Agrilus larvae (Figure 6B). In southern California, larvae can be found feeding Adults are black to dark green with from July to mid-December in the three dorsal pairs of gold-colored phloem and primarily on the outer pubescent spots on the elytra and one xylem surface (Table 1A). Mature faint pair located dorsolaterally on the larvae migrate to the outer phloem just thorax (Figures 1 and 6F). Additional beneath the bark where they create a gold-colored pubescence is located pupal cell and form a prepupa (Figure laterally on the thorax and abdomen 6C,D). Prepupae have been found in (Figure 1). Males can be differentiated the outer phloem nearly year round, from females by a ventral groove on the but at higher densities during the cooler first male abdominal segment. Adults months (November to May) (Table 1A). chew a D-shaped emergence hole Ground surveys and sampling of trees through the outer bark and are seldom for live GSOB should be conducted at observed in the forest. Adults cause this time of year because mature larvae minor and barely noticeable feeding (prepupae) can be observed easily in damage to oak foliage, which does not the outer phloem (Figure 7). substantially impact tree health.

A B C D E F

Figure 6. A goldspotted oak borer first instar larva (A), fourth instar larva (B), mature larva/ prepupa (C), constricted larva/prepupa (D), pupa (E), and adults (F). The second arrow depicts the location of the ventral longitudinal groove on the abdomen of males.

6 A B

B

Figure 7. Goldspotted oak borer mature larva or prepupa can be found in the phloem adjacent to the bark surface of coast live oak.

Evidence of Infestation Crown thinning and dieback are common indicators of declining oak health and typical of trees that are moderately and severely infested Figure 8. Goldspotted oak borer D-shaped by GSOB. Newly infested trees emergence holes on the bark surface of coast may have healthy, full crowns, but live oak (A). High densities of emergence holes (marked in red paint, B) are observed thinning and dieback become evident frequently on coast live oak killed by following successive years of larval goldspotted oak borer in California. feeding. Crown color of coast live oak trees infested by GSOB or by the Unlike some other wood-boring impact of various stress factors range Agrilus species, GSOB does not from dark green (healthy) to grayish attack the upper branches in the crown green (severely injured). Thinning during the early stages of infestation. crowns can be used to identify The GSOB adult emergence holes potentially infested trees for scrutiny (approximately 0.15 inches in for additional symptoms (see below). diameter) can appear before any However, crown thinning does not other injury symptoms are observed, always indicate GSOB infestation but can be easily overlooked when (e.g., distinct twig or branch mortality they occur at low densities. A high (flagging) in the crown can indicate density of emergence holes (10’s to injury by twig girdlers, bark , or 1,000’s/8 feet of lower stem) on coast scale ). live oak and California black oak is not uncommon when trees have been Goldspotted oak borer is the only infested for several years (Figure 8B). subcortical insect that constructs As the population density increases, D-shaped emergence holes on the main emergence holes can be observed stem and larger branches (>8 inches in easily on the lower part of the main diameter) of oaks in California, making stem (<8 feet) of infested oaks. the presence of these holes a diagnostic Thus, performing a total count of the sign of infestation by this exotic pest emergence holes in this area of the (Figure 8A). stem can provide an estimate of the extent of GSOB injury. 7 Removing the outer bark and phloem exposes larvae and the signs of their feeding at the interface of the phloem and xylem. Larval galleries have a meandering pattern; are dark in color when the fresh bark is recently removed; are about 0.16 inches wide when larvae are mature; and are tightly packed with black boring dust (frass). Following infestation by GSOB, secondary wood borers, including other Figure 9. Dark-colored wet staining or red flatheaded borers, Chrysobothris mali bleeding on the bark is sometimes associated Horn and Chrysobothris wintu Wellso with larval feeding by goldspotted oak borers. and Manley (Coleoptera: Buprestidae), Bark staining does not always indicate goldspotted oak borer injury and may only oak cordwood borers, Xylotrechus appear after extensive injury has occurred. nauticus Mannerheim (Coleoptera: Cerambycidae), oak ambrosia Acorn woodpeckers, Melanerpes beetles, Monarthrum spp. Kirsch and formicivorus Swainson (Piciformes: Gnathotrichus pilosus LeConte (both Picidae), forage for larvae, prepupae, Coleoptera: Scolytidae), and western and pupae just beneath the bark surface oak bark beetles, Pseudopityophthorus in the outer phloem. Woodpecker spp. Swaine (Coleoptera: Scolytidae), foraging occurs frequently from fall to frequently attack these stressed oaks in early summer when larval densities are southern California. Injury symptoms highest in these areas of the tree stem. associated with these secondary insects Woodpeckers chip away the outer oak can be mistaken for GSOB injury; see bark exposing the red phloem (in coast Flint et al. (2013) for a description of live oak) and the dark-colored larval their emergence holes. galleries and pupal cells (Figure 10). The phloem exposed by woodpecker Dark-colored sap stains on the bark foraging turns black with age and thus surface can indicate a GSOB-infested becomes less evident over time. The tree (Figure 9). Sometimes sap exudate degree of woodpecker foraging can over GSOB-infested areas can manifest vary greatly by site, but can be very as a blood-red secretion that hardens extensive on heavily infested trees. as it dries. Bark staining associated with GSOB injury is frequently observed along the main stem and larger branches, and is not associated with invaginations along the stem, at branch junctions, or mechanically and structurally wounded areas. Several secondary fungi can be associated with these dark-stained bark areas, but they are not always present on infested trees Figure 10 Woodpecker foraging for and may only occur after GSOB has goldspotted oak borer prepupae on the main already severely injured the tree. stem can expose larval galleries, pupal cells, and red phloem of coast live oak. 8 Management crowns of oaks on the southern aspect of a tree and hung at 9-10 feet. At sites with low population densities of Monitoring GSOB (<20% infestation), the traps Ground surveys are the most may be ineffective at detecting beetle effective method for detecting GSOB populations. infestations and determining the level of injury caused by GSOB. However, Clear panel sticky traps placed at breast ground surveys are time consuming height on the main stem of declining and GSOB-caused injury symptoms oaks can also be used to capture GSOB are often not obvious during the early adults. Felling live host oaks and stages of infestation. In its native leaving a high stump (approximately 4 range, rates of GSOB infestation and feet tall) can serve as a trap “tree” for tree mortality are low (4% and 2%, GSOB. Girdling live oak trees has not respectively, in a forest stand). These been very effective at attracting GSOB rates have been much higher (90% even at sites with high beetle population and 45%, respectively) in the invaded densities (>50% infestation). These range. Large-diameter red oaks are methods can be useful for detecting the preferred host and should be the GSOB, but are not efficacious tools for focus of ground surveys. Furthermore, preventing or suppressing infestations. oaks along the forest stand edge should Goldspotted oak borer adults have be checked first because there is an responded to host bark and foliage initial preference for GSOB to attack volatiles in electroantennographic trees along the edges of a stand (<150 detection analyses in the laboratory; feet from the forest stand edge). To however, a lure to improve GSOB facilitate detection of GSOB, the outer adult trap catches has not yet been bark of heavily infested trees should be developed. Like most Agrilus spp. chipped away to expose prepupae and studied so far, GSOB does not respond pupae in the outer phloem or the black to ethanol-baited traps. However, meandering larval galleries on the additional research will be necessary xylem surface. Tree injury symptoms to determine whether ethanol may be caused by GSOB, including the degree a semiochemical utilized by GSOB of crown thinning; density of D-shaped in the context of other host- or beetle- emergence holes and bark staining; and produced signals. the presence/absence of woodpecker foraging, have been integrated into a Although the traps described here have system to rank tree health and guide been useful for researchers or managers management decisions (Figure 11). to detect movement of GSOB into new areas, they are not sensitive enough Stickem-coated purple prism panel to guide management decisions. flight-intercept traps are the most Land managers should focus their effective traps for detecting GSOB monitoring efforts on surveying for (Figure 12). Traps should be monitored GSOB emergence holes on oak trees from May to September when most and ground-checking declining and recently killed oaks as indicated from adult flight occurs (Table 1B). Traps aerial survey data. should be positioned adjacent to the 9 1- CROWN RATING (1-5) 1 2

3 4

1: Full, healthy crown (0% leaf loss); 2: Minor twig dieback and/or light thinning (10-25% leaf loss); 3: Moderate twig dieback and thinning (25-50% leaf loss); 4:Severe dieback to larger branches (>50% leaf loss); 5: Tree is dead, no living foliage. 2- EMERGENCE HOLE RATING (1-3) 3- BARK STAINING RATING (1-4)

1: Less than ten D-shaped emergence holes on the 1: One to five areas of staining on the lower lower main stem (<8 feet). 2: Ten to 25 emergence main stem (<8 feet). 2: Six to ten stained areas. holes. 3: Greater than 25 emergence holes. 3: Greater than 10 areas stained areas. 4: Bark cracking evident.

4- WOODPECKER FORAGING (+/-)

Present or absent on the main stem or larger branches

Figure 11. A health rating system developed to determine the degree of goldspotted oak borer injury and assist with management decisions (modified from Hishinuma et al. 2011). The health rating system includes the degree of crown thinning and dieback; the density of D-shaped emergence holes and areas of bark staining; and presence/absence of woodpecker foraging. 10 (<8 feet) will likely die in the next few years. Preventive contact sprays of a carbamate (Sevin) or a pyrethroid (bifenthrin and permethrin) insecticide have killed GSOB adults in laboratory assays of treated foliage one month and one year post-application.

Systemic insecticides applied as a trunk injection or a basal spray may kill larvae feeding in the phloem Figure 12. A purple prism panel flight- and outer xylem, but they may also intercept trap hung at 9-10 feet on a metal conduit pole adjacent to the crown of a coast target adults when they feed on the live oak for monitoring the flight of goldspotted foliage. These materials should also oak borer adults. be applied by a certified pesticide applicator. Systemic insecticides such Insecticide Treatments as neonicotinoids (e.g., imidacloprid) A contact insecticide applied to the or emamectin benzoate were effective main stem and to the larger branches at killing adults in laboratory leaf- (>8 inches in diameter) is the best feeding bioassays when leaves were option for preventing GSOB injury to collected from coast live oaks and high-value oaks. To reduce the amount smaller diameter California black oaks of spray drift and the impact to non- that had been injected in December target , treating the entire and/or February and assayed 3 or 5 crown is not suggested and likely not months later. In the field, systemic feasible for ground applications to treatments with imidacloprid or large oaks. Contact spray applications emamectin benzoate slowed the rate of should occur in May prior to the adult growth of GSOB populations on large flight period in southern California and diameter coast live oaks. However, be re-applied annually by a certified studies to evaluate protection of trees pesticide applicator (Table 1C). These from GSOB with systemic insecticides preventive insecticides should only are still in progress. Insecticide be applied after evidence of GSOB uptake was greater in smaller diameter has been found in the immediate area California black oaks than coast live (<½ mile). Contact sprays or systemic oaks with stem-injected applications. insecticides (see below) should not Systemic treatments applied as trunk be applied to GSOB-infested oaks injections to oaks should be applied with a crown injury rating of “3” or from November to February when greater and an emergence hole rating treatment can be followed by seasonal of “3” (>25 emergence holes, see precipitation, which facilitates Figure 11) because they have already translocation of the active ingredient in experienced high levels of injury. In the vascular system (Table 1D). these instances, insecticide treatments may have limited benefit in preventing Basal spray applications of a systemic tree mortality. Trees with >120 GSOB insecticide (dinotefuran) to uninfested emergence holes on the lower stem coast live oak and California black 11 oak trunks resulted in high levels of population density and dispersal, active ingredient in foliage samples grinding wood should occur before the when applied in May just prior to emergence of adults in May, but the adult flight. The active ingredient treatment can be applied year round had declined dramatically when to kill any of the life stages (Table foliage was collected in September. 1E). Grinding wood is only practical Basal trunk applications to coast live for large-scale management projects, and California black oaks yielded due to the specialized equipment the greatest translocation of active required and the cost of the equipment. ingredient in smaller diameter (<12 Chipping infested wood is not inches dbh) trees, but translocation recommended as a management option was also detected in foliage at high because of the difficulty with treating levels one-month post application in large, dense pieces of oak stems with large diameter (>40 inches dbh) trees. a standard chipper. Goldspotted oak Although GSOB adults were not killed borer does not attack the smaller in laboratory leaf-feeding bioassays, stems and branches, which are often the highest label rate was not used in targeted in chipping operations. A these studies. Based on best current more economical and feasible option knowledge, we recommend that basal for landowners with small quantities of trunk applications of dinotefuran wood is to either enclose or debark the be applied annually, whereas trunk- infested wood (Figure 13B,C). injected applications of imidacloprid and emamectin benzoate be applied A once every two years in southern California. Repeated stem injections can cause injury to the trunk, and treated trees should be monitored for bark cracking, staining, and crown thinning. Watering high-value oaks can facilitate insecticide uptake and alleviate drought stress during dry years. For high-value sites or individual trees, a B C combination of topical and systemic insecticide treatments may provide the most effective protection. However, this combined insecticidal approach has not been evaluated sufficiently to support this management action.

Mechanical Treatments Grinding GSOB-infested wood to Figure 13. To manage wood infested with a particle size of <3 inches with a goldspotted oak borer, large quantities of wood 3-inch-“minus” grinding screen is the can be ground with a tub grinder (A); small quantities of wood can be enclosed with plastic most effective mechanical method for sheeting (B); or small quantities of wood can eliminating GSOB populations (Figure be debarked by landowners (C). If used for 13A). For greatest impact on GSOB firewood, the wood should be burned locally. 12 Stacks of infested firewood can be sometimes the primary source of enclosed with thick (6 mil), clear, UV heating. To minimize movement or resistant plastic sheeting and placed in introduction of GSOB, the following a sunny location from the first of May simple and effective approaches to September (Table 1F). If the edges for reducing GSOB-associated tree of the tarp are buried in the soil and mortality are available: 1) educate the integrity of the tarp is maintained community members to screen from May to September, emerging incoming firewood for evidence of adults are not capable of escaping and GSOB; 2) allow wood from recently will eventually die. Debarking wood felled trees to season within the requires the manual separation of the infested zone for longer than two years; bark and phloem from the wood prior and 3) keep infested material away to the emergence of GSOB adults. from uninfested trees. Limiting the This option can be very labor intensive movement of firewood <50 miles from and is only feasible for small quantities the location of harvest, (e.g., “Buy it of wood. Goldspotted oak borers where you burn it” approach) is a best can survive in the bark and phloem management practice for limiting the shavings, so this material must be spread of GSOB and other subcortical destroyed (e.g., ground or burned) or invasive insects. tarped to eliminate all live beetles. Natural Enemies Cultural Treatments Three parasitoid wasp species and Removing moderately- and severely- several generalist insect predators infested trees (i.e., “brood” trees) may have been associated with GSOB in slow GSOB population growth at high- Arizona and California. The impact value sites. These infested trees should of these parasitoids and predators on be felled and the wood managed GSOB populations is unknown in by using one of the aforementioned both regions, but low levels of GSOB mechanical treatments. Felling mortality (<15%) have been attributed infested trees and the application to some of these species. Low densities of a preventive insecticide to any of natural enemies and low levels of remaining uninfested or lightly host resistance may have contributed infested (<10 emergence holes) large- to the elevated levels of oak mortality diameter oaks may provide the best by this indigenous exotic species in opportunity for maintaining high-value California. Calosota elongata Gibson sites. However, no experimental data (Hymenoptera: Eupelmidae), a newly are available presently to support these described ectoparasitoid wasp, is combined management steps. only known from GSOB prepupae in Arizona and California (Figure Limiting the movement of GSOB- 14A,B). Calosota elongata was likely infested wood into and within a introduced into California with the community may be the most effective original GSOB population, but its management method for reducing known adventive distribution is limited GSOB-associated tree mortality. In to southeastern San Diego Co. in mountain communities, firewood California. A Trichogramma sp. wasp is often a valuable commodity and (Hymenoptera: Trichogrammatidae) 13 was associated with GSOB eggs in (Coleoptera), moths (Lepidoptera), Arizona, but was only found at low and ants (Hymenoptera). Snakeflies densities there and is believed to be (Raphidioptera) and bark-gnawing a generalist parasitoid (Figure 14C). beetles (Trogossitidae) have also Atanycolus simplex (Hymenoptera: been found feeding on GSOB larvae Braconidae) is a generalist larval or in larval galleries. Though it has parasitoid found in association with appeared to be locally extensive on GSOB, but it also parasitizes other highly infested trees, the impact of wood-boring insects throughout the woodpecker feeding on GSOB has not USA (Figure 14D). The straw itch been quantified. In general, the impact , Lagrèze-Fossat of insect and avian predators on GSOB and Montané (: ), has population density is likely to be limited been found on prepupae, pupae, and in California. Calosota elongata was unemerged GSOB adults from Arizona considered a promising candidate for and California and on Mexican GSOB augmentative biological control in in southern Mexico (Figure 14E). California. However, the difficulty of Pyemotes tritici has a cosmopolitan rearing GSOB populations on cut logs distribution and parasitizes species in and at high densities in a laboratory several insect orders, including beetles setting makes an augmentative biological control program infeasible A B at this time.

Assistance If you suspect that you have found signs of GSOB or symptoms of its damage on your property, or on municipal, state, C D or federal lands please contact a Pest Control Advisor, your local University Cooperative Extension Office, the County Agricultural Commissioner’s Office, or your local USDA Forest Service, Forest Health Protection E representative (http://www.fs.fed.us/ foresthealth/). This publication and other Forest Insect and Disease Leaflets are available online (www.fs.usda.gov/ goto/fhp/fidls).

Acknowledgements Figure 14. Natural enemies associated with The authors thank D. Betancourt, A. goldspotted oak borer, include Calosota Cipollone, A.D. Graves, Z. Heath, K. elongata (A: parasitoid larvae feeding on a Koeslag, J. Lydick, J. Moore, and G. GSOB prepupa and B: adult parasitoids); Walter (USDA Forest Service, Forest Trichogramma sp. adult wasp on a GSOB Health Protection); B. Strom (USDA egg (C); Atanycolus simplex adult wasp (D); and the straw itch mite, Pyemotes tritici on a Forest Service, Southern Research GSOB prepua (E). Station); Y. Chen, L. Haavik, S.M. 14 Hishinuma, and A. Poloni (Dept. of Coleman, T.W., and S.J. Seybold. 2011. Entomology, University of California, Collection history and comparison of the interactions of the goldspotted oak borer, Davis); M. Hoddle, V. Lopez, and R. Schaeffer (Coleoptera: Stouthamer (Dept. of Entomology, and Buprestidae), with host oaks in southern Nematology, University of California, California and southeastern Arizona, U.S.A. Riverside); L. Singleton (Dept. of Coleop. Bull. 65: 93–108.

Biological Sciences, California State Coleman, T.W., V. Lopez, P. Rugman-Jones, University, Long Beach), and D. Crook R. Stouthamer, S.J. Seybold, R. Reardon, and (Dept. of Entomology, University M.S. Hoddle. 2012. Can the destruction of of Massachusetts) for contributing California’s oak woodlands be prevented? information and resources to the Potential for biological control of the goldspotted oak borer, Agrilus auroguttatus. information presented in this leaflet. BioControl 57: 211–225. We appreciate critical reviews of this leaflet by Y. Chen, R.A. Haack (USDA Coleman, T.W., A.D. Graves, M. Hoddle, Z. Forest Service, Northern Research Heath, Y. Chen, M.L. Flint, and S.J. Seybold. 2012. Forest stand composition and impacts Station), S.M. Hishinuma, and A.S. associated with Agrilus auroguttatus Schaeffer Munson (USDA Forest Service, Forest (Coleoptera: Buprestidae) and Agrilus coxalis Health Protection). Waterhouse in oak woodlands. For. Ecol. Manage. 276: 104–117.

Photo Credits Coleman, T.W., Y. Chen, A.D. Graves, S.M. Figure 2: J. Moore (USDA Forest Service, Hishinuma, N.E. Grulke, M.L. Flint, and Forest Health Protection); Figure 3: R. Venette S.J. Seybold. 2014. Developing monitoring (USDA Forest Service, Northern Research techniques for the invasive goldspotted oak Station); Figure 14C: R. Lara (University of borer (Coleoptera: Buprestidae) in California. California, Riverside); All other figures by T.W. Environ. Entomol. 43: 729–743. Coleman (USDA Forest Service, Forest Health Protection). Coleman, T.W., M.I. Jones, M.S. Hoddle, L.J. Haavik, J.C. Moser, M.L. Flint, and S.J. Seybold. References 2015. Pyemotes tritici (Acari: Pyemotidae): A parasitoid of Agrilus auroguttatus and Agrilus Chen, Y., M.L Flint, T.W. Coleman, J.J. coxalis (Coleoptera: Buprestidae) in the Doccola, D.M. Grosman, D.L. Wood, and S.J. southwestern United States of America and Seybold. 2015. Impact of the goldspotted oak southern Mexico. Can. Entomol. 147: 244-248. borer, Agrilus auroguttatus, on the health of coast live oak before and after treatment with Coleman, T.W., S.L. Smith, M.I. Jones, A.D. two systemic insecticides. Pest Manage. Sci. Graves, and B. Strom. Insecticide options for Early view: http://onlinelibrary.wiley.com/ protecting high-value oaks from the invasive doi/10.1002/ps.3959/pdf Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae) in southern California. Target Coleman, T.W., and S.J. Seybold. 2008. Journal: J. Econ. Entomol. (In Prep.). Previously unrecorded damage to oak, Quercus spp., in southern California by the goldspotted Flint, M.L., M.I. Jones, T.W. Coleman, and oak borer, Agrilus coxalis Waterhouse S.J. Seybold. 2013. Goldspotted oak borer. (Coleoptera: Buprestidae). Pan-Pac. Entomol. University of California Statewide Integrated 84: 288–300. Pest Management Program, Oakland, California, Agriculture and Natural Resources Pest Notes, Coleman, T.W., and S.J. Seybold. 2010. Pub. 74163, January 2013, 7 pp. http://www. Verification of a useful character for separating ipm.ucdavis.edu/PMG/PESTNOTES/pn74163. the sexes of the goldspotted oak borer, Agrilus html coxalis auroguttatus (Coleoptera: Buprestidae). Pan-Pac. Entomol. 86: 58–62. 15 Haavik, L.J., T.W. Coleman, Y. Chen, M.I. Jones, Jones, M.I., T.W. Coleman, A.D. Graves, R.C. Venette, M.L. Flint, and S.J. Seybold. 2012. M.L. Flint, and S.J. Seybold. 2013. Sanitation First occurrence of the goldspotted oak borer options for managing oak wood infested with parasitoid, Calosota elongata (Hymenoptera: the invasive goldspotted oak borer (Coleoptera: Eupelmidae), in California. Pan-Pac. Entomol. Buprestidae) in southern California. J. Econ. 88: 274–276. Entomol. 106: 235–246.

Haavik, L.J., A.D. Graves, T.W. Coleman, Lopez, V.M., P.F. Rugman-Jones, T.W. M.L. Flint, R.C. Venette, and S.J. Seybold. Coleman, M.S. Hoddle, and R. Stouthamer. 2014. Suitability of native and ornamental oak 2014. Population genetics of goldspotted species in California for Agrilus auroguttatus. oak borer, Agrilus auroguttatus Schaeffer Entomol. Exp. Appl. 150: 86–97. (Coleoptera: Buprestidae): Investigating the origin of an invasive pest of native oaks in Haavik, L.J., M.L. Flint, T.W. Coleman, R.C. California. Biol. Invasions 16: 2393–2402. Venette, and S.J. Seybold. 2015. Goldspotted oak borer effects on tree health and colonization Lopez, V.M., and M.S. Hoddle. 2013. Mortality patterns at six newly-established sites. Agric. For. Entomol. Early view: http://onlinelibrary. factors affecting Agrilus auroguttatus Schaeffer wiley.com/doi/10.1111/afe.12090/epdf (Coleoptera: Buprestidae) eggs in the native and invaded ranges. Biol. Control 67: 143-148. Hishinuma, S., T.W. Coleman, M.L. Flint, and S.J. Seybold. 2011. Goldspotted oak Singleton, L. 2014. Host tree and site borer: Field identification guide. University of characteristics influencing goldspotted California Agriculture and Natural Resources, oak borer, Agrilus auroguttaus Schaefffer Statewide Integrated Pest Management (Coleoptera: Buprestidae), populations in Program, 6 pp., Oakland, California, January southern California. Master of Science Thesis. 13, 2011. http://www.ipm.ucdavis.edu/PDF/ Department of Biological Sciences, California MISC/GSOB_field-identification-guide.pdf State University, Long Beach. 74 pp.

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Published by USDA Forest Service, Pacific Northwest Region (R6), Portland, Oregon FS/R6/RO/FIDL#183-15/001 16