FOREST ENTOMOLOGY Efficacy of Systemic Insecticides for Protection of Loblolly Pine Against Southern Pine Engraver Beetles (Coleoptera: Curculionidae: Scolytinae) and Wood Borers (Coleoptera: Cerambycidae) DONALD M. GROSMAN AND WILLIAM W. UPTON Texas Forest Service, Forest Pest Management, P.O. Box 310, Lufkin, TX 75902Ð0310 J. Econ. Entomol. 99(1): 94Ð101 (2006) ABSTRACT We evaluated the efÞcacy of the systemic insecticides dinotefuran, emamectin ben- zoate, Þpronil, and imidacloprid for preventing attacks and brood production of southern pine engraver beetles (Coleoptera: Curculionidae: Scolytinae) and wood borers (Coleoptera: Ceramby- cidae) on standing, stressed trees and bolt sections of loblolly pine, Pinus taeda L., in eastern Texas. Emamectin benzoate signiÞcantly reduced the colonization success of engraver beetles and associated wood borers in both stressed trees and pine bolt sections. Fipronil was nearly as effective as emamectin benzoate in reducing insect colonization of bolts 3 and 5 mo after injection but only moderately effective 1 mo after injection. Fipronil also signiÞcantly reduced bark beetle-caused mortality of stressed trees. Imidacloprid and dinotefuran were ineffective in preventing bark beetle and wood borer colonization of bolts or standing, stressed trees. The injected formulation of emamectin benzoate was found to cause long vertical lesions in the sapwoodÐphloem interface at each injection point. KEY WORDS southern pine engraver beetle, systemic insecticide, single-tree protection THREE SPECIES OF Ips engraver beetles (Coleoptera: Protection of individual trees from conifer bark Curculionidae: Scolytinae) infest pines in the south- beetles has historically involved topical applications ern United States: the sixspined ips, Ips calligraphus of chemical insecticides to the entire bole of the tree (Germar); eastern Þvespined ips, Ips grandicollis (Ei- by using hydraulic sprayers. Several products had choff); and small southern pine engraver, Ips avulsus been registered with the Environmental Protection (Eichoff). These beetles tend to be secondary pests, Agency (EPA) for this use, including benzene hexa- normally attacking trees stressed by drought, lighten- chloride, lindane, fenitrothion (Pestroy), and chlor- ing strikes, root disturbances, and other factors. Local pyrifos (Dursban), but these insecticides are no and regional outbreaks of Ips spp., often coinciding longer available for use against bark beetles. Car- with regionwide drought, can cause severe pine mor- baryl is currently registered and is effective against tality. For example, losses in 1999 were estimated at western bark beetle species (Haverty et al. 1998) $13 million U.S. dollars, second only to southern pine but ineffective against southern pine bark beetles beetle, Dendroctonus frontalis Zimmermann, in value (Zhong et al. 1994). Permethrin (Astro, Dragnet and lost from insect-caused mortality (reports on losses Permethrin Pro) and bifenthrin (Onyx) are effec- caused by forest insects, Southern Forest Insect Work tive against several species of bark beetles, including Conference 2000). Ips engraver beetles do not just Ips engraver beetles, but it is not registered for use affect the timber industry; they also have a signiÞcant in forests. Even when available, insecticide spray impact on recreation, water, and wildlife resources as applications have limitations. They are expensive, well as residential property. The urbanÐwildland in- time-consuming, present a high risk for worker ex- terface around metropolitan centers is continuing to posure and drift, and are detrimental to natural expand, thus placing more high-valued residential enemies (Billings 1980). trees at risk to Ips attack. Systemic insecticides have been suggested as a po- Several species of wood borers also are known to tentially useful tool for protection of individual trees attack and colonize recently dead or felled conifers in or forested areas. One of the Þrst to be tested, ace- this region. They include species in the genera phate (Orthene), was applied to foliage at two differ- Monochamus, Acanthocinus, and Stenocorus (Coulson ent rates (C. E. Crisp, C. E. Richmond, and P. J. Shea, and Witter 1984). The females lay eggs on host ma- unpublished data in Billings 1980). The treatments terial, and larvae of these species quickly begin feed- were reported to reduce southern pine beetle larval ing in the phloem before mining into the xylem tissue. survival, but they had no effect on eggs, pupae, callow, The result of this feeding and boring is the quick or parent adults. A more recent study evaluated feni- degredation of wood and its value. trothion (Pestroy) and a combination treatment of 0022-0493/06/0094Ð0101$04.00/0 ᭧ 2006 Entomological Society of America February 2006 GROSMAN AND UPTON:SYSTEMICS FOR PROTECTION OF PINE FROM BEETLEs95 sodium N-methyldithiocarbamate (Vapam) plus di- northwest of Lufkin (Angelina County), TX. Fifteen methyl sulfoxide (DMSO) applied to bark hacks and trees in one plantation were injected with one of four dicrotophos (Bidrin) applied by Mauget injectors (In- systemic insecticides for use in a bolt (log section) ject-a-icide-B) to trees at the leading edge of southern study (trial 1) (31Њ 27.95Ј N, 94Њ 56.48Ј W). Six trees per pine beetle infestations (Dalusky et al. 1990). insecticide were injected in a 0.2-ha section of the Although none of the treatments prevented tree second plantation as part of a single-tree protection mortality, dicrotophos signiÞcantly reduced both egg study (trial 2) (31Њ 27.67Ј N, 94Њ 56.68Ј W). The treat- gallery length and subsequent brood production. Be- ments included the following: 1) Emamectin benzoate cause dicrotophos has a relatively high mammalian (Denim 0.15 EC, 1.92% [AI], Syngenta Crop Protec- toxicity, it is not available to the general public. Ox- tion). Denim was mixed 1:1 with methanol (histolog- dydementon methyl (Metasystox-R) applied by ical, Ͼ99% pure, Fisher, Pittsburgh, PA) and applied Mauget injectors (Inject-a-cide) is registered for use at 7.3 ml of solution per centimeter of tree diameter at against several Dendroctonus and Ips species, but it is breast height (dbh) (ϭ0.08 g active per cm dbh); 2) not effective against western pine beetle, Dendrocto- Imidacloprid (IMA-jet, 5% [AI], Arborjet, Inc.). IMA- nus brevicomis LeConte (Haverty et al. 1996). In ad- jet was mixed 1:3 with AAD-jet (Arborjet, Inc.) and dition, according to R. Billings (personal communica- applied at 6.3 ml solution per centimeter of tree dbh tion), Mauget injectors do not function well on pines (ϭ0.08 g active per cm dbh); 3) Fipronil (300 g [AI] because the pressure produced when the injector is per liter emulsiÞable concentrate, BASF Corpora- primed after installation is often insufÞcient to over- tion). The Þpronil formulation was mixed 1:2.8:7.5 come the treeÕs resin pressure. with methanol and distilled water and applied at 3.1 ml Emamectin benzoate (Syngenta Crop Protection), solution per centimeter of tree dbh (ϭ0.08 g active per an avermectin derivative, has shown systemic activity cm DBH); 4) Dinotefuran (10% [AI], Valent USA). in pine and is highly effective against pine wood nem- Dinotefuran was mixed 1:3 with distilled water and atode, Bursaphelenchus xylophilis (Steiner & Buhrer) applied at 3.1 ml solution per cm of tree dbh (ϭ0.08 Nickle (Takai et al. 2000, 2001, 2003a, b), and cone- g active per cm dbh); and 5) Check (untreated). A worm, Dioryctria spp. (Grosman et al. 2002), with staging area also was set up in the second plantation protection from a single injection lasting Ͼ3 yr. Pre- where bolts from the Þrst plantation were exposed to liminary trials also suggest that this chemical has in- bark beetles and wood borers. secticidal activity against coleopteran pests, including Trial 1. Seventy-Þve loblolly pine trees, with pales weevil, Hylobius pales (Herbst) (Jeff Fidgen, mean Ϯ SE dbh of 19.0 Ϯ 0.2 cm and height of 16.7 Ϯ unpublished data) and Anoplophora glabripennis 0.2 m, were selected in March 2004. Each treatment (Motschulsky) (Poland et al. 2006). Denim 0.15 EC consisted of a single insecticide formulation injected (emamectin benzoate) is registered for use as a into four cardinal points, Ϸ7 cm in depth and 0.3 m foliar spray on cotton against lepidopteran pests. Imi- above the ground, on each tree 16Ð23 April by using dacloprid is a neonicotinoid insecticide with known the new Arborjet Tree IV microinfusion system (Ar- systemic activity against several coleopteran pests, borjet, Inc.). including Japanese beetle, Popillia japonica Newman, After 1 (24 May), 3 (19 July), and 5 (2 September) and bronze birch borer, Agrilus anxius Gory (Dotson mo postinjection, Þve trees of each treatment were 1994). Arborjet, Inc. (Woburn, MA) has recently felled, and two 1.5-m-long bolts were removed from registered IMA-jet for use in its injection systems for the 3- and 8-m heights of the bole. The bolts were protection of trees against several forest pest species. transported to a nearby plantation that was recently Fipronil (BASF Corporation), a new pheny pyrazole thinned and contained fresh slash material. Bolts were insecticide shown to have systemic activity in pine, randomly placed Ϸ1 m from other bolts on discarded, is highly effective in reducing damage from Nan- dry pine bolts to maximize surface area available for tucket pine tip moth, Rhyacionia frustrana (Com- colonization as well as to discourage predation by stock), on young seedlings for Ͼ12 mo (D.M.G., un- ground and litter-inhabiting