Ips paraconfusus, LANIER, 1970

Murray, Todd A., Kohler, Glenn R. & Willhite, Elizabeth A., 2013, Ips paraconfususLanier (Coleoptera: Curculionidae): New Records of the California Fivespined Ips from Washington State and the Columbia River Gorge in Oregon, The Coleopterists Bulletin 67 (1), pp. 27-31 : 28-30

IPS PARACONFUSUS LANIER ( COLEOPTERA : CURCULIONIDAE ): NEW RECORDS OF THE CALIFORNIA FIVESPINED IPS FROM WASHINGTON STATE AND THE COLUMBIA RIVER GORGE IN OREGON

TODD A. MURRAY Washington State University Extension, PO Box 790 Stevenson, WA 98648, U.S.A. [e-mail]

GLENN R. KOHLER Washington State Department of Natural Resources, PO Box 47037 Olympia, WA 98504, U.S.A. [e-mail]

AND

ELIZABETH A. WILLHITE Forest Health Protection, Westside Forest Insect and Disease Service Center USDA Forest Service, 16400 Champion Way Sandy, OR 97055, U.S.A. [e-mail]

California fivespined ips (CFI), Ips paraconfusus Lanier ( Coleoptera : Curculionidae ), is an engraver beetle that feeds on multiple species of pine hosts. Prior to 1945, CFI was considered an insignificant pest of pines. Harvest practices of ponderosa pine stands ( Pinus ponderosa Douglas ex Lawson ; Pinaceae ) that significantly increased availability of host material is attributed to increasing the significance of CFI as a pest of ponderosa pines in California (Schultz and Bedard 1987). In western Oregon, CFI is considered the most important pest in managed pine stands (Flowers 2007). Damage by CFI in young managed plantations of the Willamette Valley biotype of ponderosa pine was first reported in 1999 ( Overhulser 2000), following increases in abundance and more intensive management of the biotype throughout the region since the late 1980s. Since then, localized outbreaks have been observed regularly. Flowers and Willhite (2010) documented the significance of CFI in the Willamette Valley of Oregon in a three-year study.

California fivespined ips has multiple generations per year and in favorable conditions can occur in large populations. Its populations can rapidly increase in small diameter (> 7 cm), recently broken, or cut pine material created by storms, fires, logging, or thinning. In spring, overwintering adult males initiate attacks on suitable host material by tunneling into the inner bark (phloem). Each male constructs a nuptial chamber in the phloem and attracts multiple females, typically three. Females tunnel egg galleries branching out from the nuptial chamber, forming the “Y” gallery pattern characteristic of CFI. Fifty percent of the initially attacking CFI can re-emerge and initiate a second brood in neighboring fresh host material (Schultz and Bedard 1987). Within two weeks after oviposition, larvae hatch and begin consuming phloem tissue. New adults emerge three to seven weeks after hatching. The numerous individuals produced in these spring/summer generations can then successfully mass attack and overwhelm nearby live trees. Two to five spring/ summer generations (depending on temperature and latitude) increase the potential for rapid population eruption. Bark thickness has been associated with susceptibility of trees to attack (DeGomez et al. 2008). Bark thicker than 2.5 cm is attacked less frequently than thinner bark on pine trees (Struble and Hall 1955). High numbers of CFI can overwhelm mature trees over 61 cm in diameter at breast height when trees are stressed by drought or weakened by other environmental factors. Evidence of attack on larger trees is seen when trees are “top-killed” or their entire crown fades to reddish brown (Goheen and Willhite 2006).

Ips paraconfusus has a somewhat muddled distribution record due to its taxonomic history and various distribution descriptions in the literature. Originally undifferentiated from Ips confusus by LeConte in 1876, I. paraconfusus was not named a separate species until 1970 by G. N. Lanier (1970) . Thus, early distribution descriptions represent both taxa, I. confusus (not found in the Pacific Northwest) and I. paraconfusus (occurring in the Pacific Northwest). In 1958, W. J. Chamberlin described the distribution of I. confusus to include California, Oregon, Washington, and Idaho. However, no other references to the distribution of I. confusus or I. paraconfusus in the literature are described as such. Lanier (1970) describes the range of I. paraconfusus to only include California and Oregon (northern Oregon to southern California west of the crests of the Sierra Nevada and Cascade Mountains). He states it is not known from the desert-facing “Great Basin” timber type even though P. ponderosa , its principal host, is present ( Lanier 1970 ). While one possibility is that Chamberlin confused Ips confusus with another five-spined Ips that occurs in the Pacific Northwest, Ips montanus (Eichoff) , this is unlikely because Chamberlin (1958) recognized I. confusus and I. montanus as separate species. No voucher specimens or specific references to other collections were listed by Chamberlin (1958). Lanier’ s description is supported by past (Furniss and Johnson 1995) and current species lists of scolytines recorded in Washington, which do not include I. paraconfusus or I. confusus .

In February 2010, a landowner in Underwood, Washington reported mortality of both small diameter and large diameter ponderosa pines. Underwood sits on the eastern slopes of the Cascade Mountain Range and beside the northern shore of the Columbia River , which forms the respective southern and northern state boundaries of Washington and Oregon. Specimens collected from the trees were identified as I. paraconfusus and confirmed by Jim LaBonte, Oregon State Department of Agriculture. Subsequent aerial surveys of the area conducted by USDA Forest Service and Washington State Department of Natural Resources revealed 40 hectares with killed and top-killed ponderosa pine near the town of White Salmon in Skamania and Klickitat Counties (Dozic et al. 2011). At least 60 mature ponderosa pines were killed from attacks by I. paraconfusus , the western pine beetle, Dendroctonus brevicomis LeConte , or the red turpentine beetle, Dendroctonus valens LeConte. Many of the beetle-killed trees occurred on private home sites where ponderosa pine is often the only shade tree. By the fall of 2011, small localized outbreaks caused additional mortality in adjacent areas of Mosier, Oregon and just west of Lyle, Washington at Catherine Creek trail area of the Columbia River Gorge National Scenic Area. The localized outbreaks are attributed to trees damaged in area fires during 2008 and 2009 and to trees blown down during a January 2011 windstorm.

In 2010, Lindgren funnel traps baited with pheromone of I. paraconfusus were placed in seven locations along the Columbia River Gorge. The pheromone used was ipsdienol [97%(+)], ipsenol [racemic], and cisverbenol [83% − (−)] from Contech Enterprises Inc. (Victoria, British Columbia, Canada). In 2011, Lindgren funnel traps were placed in nine locations in southwestern Washington that expanded north along the western valley separating the Coastal Range and Cascade Mountains and north along the White Salmon River valley on the eastern side of the Cascade Mountains. In 2012, funnel traps were placed in six western Washington locations from the southwestern corner of the state northward to Puget Sound and one eastern slope location (Tampico, WA) of the Cascade Mountain range. Traps were maintained every one to two weeks from late June to September 2010, from mid-April to the end of October 2011, and from early April to the end of October 2012. Pheromone lures were changed at 60-day intervals through the trapping periods. Insects were collected into dry cups at five of seven locations in 2010. Beetles from two of seven locations in 2010 and all locations in 2011 and 2012 were collected into a mixture of propylene glycol, vinegar, and a small drop of soap. Trap contents were filtered and stored at 0°C until trap samples were sorted. The number of CFI individuals was recorded for each trap site and collection date. Voucher specimens of I. paraconfusus were deposited in the M. T. James Collection at Washington State University, Pullman, the W. Barr Collection at the University of Idaho, Moscow, and the Oregon State Arthropod Collection at Oregon State University, Corvallis.

Table 1 lists trap sites where CFI adults were collected during the trapping periods in 2010, 2011, and 2012. The highest trap catches occurred in White Salmon, WA, Rowena Dell, OR, and Hood River, OR. All three trap locations were near a recent significant fire (Underwood bluff fire in 2008, Mosier fire in 2009). California fivespined ips adults were trapped as far north as Fort Lewis, WA.

Regional insect collections were queried for previous records of I. paraconfusus and I. confusus in Washington. The M. T. James Collection (R. Zach, personal communication), the W. Barr Collection (F. Merickel, personal communication), Oregon State Arthropod Collection (C. Marshall, personal communication), Canadian Forest Service Pacific Forestry Centre Arthropod Reference Collection, Victoria, British Columbia (L. Humble, personal communication), and Oregon Department of Agriculture Insect Museum, Salem (J. LaBonte, personal communication) had no specimens of I. paraconfusus collected in Washington. No Washington records of I. paraconfusus are in the Stephen Wood collection materials at the US National Museum of Natural History (J. Prena, personal communication).

Existing range maps for CFI do not include Washington despite frequent and repeated bark beetle surveys. California fivespined ips may have been always present in the region but undetected or perhaps locally extirpated due to logging practices associated with European settlement that reduced availability of suitable hosts and host material. Recent detection of CFI may simply represent re-colonization of the area as pine populations have increased in recent times. In western Washington, I. paraconfusus may have avoided detection due to the scattered and infrequent nature of its primary host, ponderosa pine. Alternatively, these detections could represent range expansion due to changing climate conditions, which may be increasing tree stress or fire occurrence. Documentation of the new record locations is important baseline information for future studies if the range continues to change .