Hylobius pales, the pales weevil, and Pachylobius picivorus, the pitch-eating weevil, comprise part of a weevil complex which affects plantation pine production in the Lake States. Common control practices on Christmas tree farms include calendar applications of persistent insecticides. The resulting environmental risks could be minimized by repeating applications only when needed. A sampling method using ethanol-and turpentine-baited pitfall traps was used here to assess the efficacy and monitor persistence of chemical sprays. Trap catch in lindane-treated field plots and untreated controls were compared over two years. Unsprayed controls had significantly higher weevil populations than treated plots. Spray efficacy continued for three years following tion. Weevil population growth in relation to insecticide efficacy and degradation is discussed

Raffa, Kenneth F

Rieske, Lynne K

English

ValpoScholar

Use of a Monitoring System to Evaluate Pesticide Efficacy and Residual Activity Against Two Pine Root Weevils, \u3ci\u3eHylobius Pales\u3c/i\u3e and \u3ci\u3ePachylobius Picivorus\u3c/i\u3e (Coleoptera: Curculionidae), in Christmas Tree Farms

Valparaiso University

The Great Lakes Entomologist Volume 23 Number 4 - Winter 1990 Number 4 - Winter 1990 Article 2 December 1990 Use of a Monitoring System to Evaluate Pesticide Efficacy and Residual Activity Against Two Pine Root Weevils, Hylobius Pales and Pachylobius Picivorus (Coleoptera: Curculionidae), in Christmas Tree Farms Lynne K. Rieske University of Wisconsin Kenneth F. Raffa University of Wisconsin Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Rieske, Lynne K. and Raffa, Kenneth F. 1990. "Use of a Monitoring System to Evaluate Pesticide Efficacy and Residual Activity Against Two Pine Root Weevils, Hylobius Pales and Pachylobius Picivorus (Coleoptera: Curculionidae), in Christmas Tree Farms," The Great Lakes Entomologist, vol 23 (4) Available at: https://scholar.valpo.edu/tgle/vol23/iss4/2 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. 1990 THE GREAT LAKES ENTOMOLOGIST 189 USE OF A MONITORING SYSTEM TO EVALUATE PESTICIDE EFFICACY AND RESIDUAL ACTIVITY AGAINST TWO PINE ROOT WEEVILS, HYLOB US PALES AND PACHYLOBIUS PICIVORUS (COLEOPTERA: CURCULIONIDAE), IN CHRISTMAS TREE FARMS Lynne K. Rieske and Kenneth F. Raffa! ABSTRACT Hylobius pales, the pales weevil, and Pachylobius picivorus, the pitch-eating weevil, comprise part of a weevil complex which affects plantation pine production in the Lake States. Common control practices on Christmas tree farms include calendar applications f persistent insecticides. The resulting environmental risks could be minimized by repeating applications only when needed. A sampling method using ethanol-and turpentine-baited pitfall traps was used here to assess the efficacy and monitor persistence of chemical sprays. Trap catch in lindane-treated field plots and untreated controls were compared over two years. Unsprayed con­trols had significantly higher weevil populations than treated plots. Spray efficacy continued for three years following tion. Weevil population growth in rela­tion to insecticide efficacy and degra tion is discussed. The pales weevil, Hy obius pales (Herbst), and pitch-eating weevil, Pachylobius picivorus (Germar) are important pests of pines in the eastern United States. Larvae of both species develop in highly stressed hosts or recently cut stumps. Adult feeding on branches and twigs can disfigure mature trees and cause heavy seedling mortality (KearbyI965, Davis & Lund 1966, Wilson 1968). With the increasing production of plantation pines in the Lake States, the importance of these two species and the pine root collar weevil, Hylobius radicis Buchanan, is increasing (Hunt & Raffa 1989, Rieske 1990, Rieske & Raffa in press). The even-aged plantations used for Christmas trees, timber, and pulp provide ideal habitat. Insecticide usage on Christmas trees in particular is often high (Benyus 1983). A major proble  in managing these weevil species is that infestations may not be detected until damage is irreversible. Subterranean larval development and noc­turnal adult activity make direct detection difficult. Common practice dictates pre­plant dipping of seedlings to prevent feeding injury, or stump applications of lin­dane to prevent brood development (Benyus 1983, Lynch 1984). Lindane poses severe environmental problems (Newton & Knight 1981), however, and is banned from all commercial uses in Wisconsin except against pine root weevils in Christmas trees. This exception is allowed because other insecticides do not provide the desired long-term control. tDept. of Entomology, University of Wisconsin, Madison, WI 53706. 1Rieske and Raffa: Use of a Monitoring System to Evaluate Pesticide Efficacy and ResPublished by ValpoScholar, 1990190 THE GREAT LAKES ENTOMOLOGIST Vol. 23, No.4 A method of detecting and monitoring pine root weevils prior to yield losses and quality grade reduction, could potentially reduce insecticide usage to situations where damage was imminent. Ethanol and turpentine baited pitfall traps are effec­tive in capturing these weevils (Raffa & Hunt 1988, Hunt & Raffa 1989). The objective of this study was to use this trapping system for monitoring resurgence of weevil populations following insecticide treatments. MATERIALS & METHODS The study was conducted in the summers of 1988 and 1989, in Waushara and Portage counties, in the "central sands" region of Wisconsin. Plots were established in the spring of 1988 in 4-112 and 5- 12 year old Scots pine, Pinus sylvestris, Christmas tree farms. The trees were planted in rows 1.8 m apart, and with 1.8 m between trees in a given row, with the exception of one site, where this spacing was 1.68 m. Plots were established on six farms which exhibited a range of foliar discol­oration indicative of root weevil infestation. The pitfall traps used were modified from those developed by Tilles et al. (l986a,b), and consisted of 17 cm sections of 10 cm diameter plastic PVC drainpipe. Eleven cm from one end, eight 7 mm diameter holes were drilled about the perime­ter. The trap interior was coated with liquid teflon Fluon to prevent weevil escape. The traps were capped at each end and inserted into the ground so that the holes were flush with ground level. Two 2 mm holes were drilled in the bottom to allow for drainage. The exposed 6 cm of the trap was painted flat black (New York Bronze Powder Co. Inc., Elizabeth, NJ) to simulate a tree trunk image. Baits were dispensed from two 2 ml glass vials (0.5 dram, 12 mm x 35 mm) and were suspended by thin aluminum wire to a stiff 14 guage wire that passed through two 2 mm holes in the trap wall. The vials were suspended 4 cm below ground level. Baits consisted of 95070 ethanol (Worum Chemical Co., St. Paul, MN) and turpen­tine (Mautz Paint Co., Madison, WI). The turpentine consisted of 46% alpha­pinene, 42% beta-pinene, 2% beta-phellandrene, 1 % limonene, 0.88% camphene, 0.77% myrcene, and less than 1 % unknown compounds, as determined by gas liquid chromatography using the method of Raffa & Stef eck (1988). The volatiliza­tion rates from the 2 ml vials at 23 0 C were 200 mg/ 24 h of et anol and 40 mg/ 24 h of turpentine. Each treatment consisted of 6 traps/ 432 m2, equivalent to the I trap/72m2 used by Hunt & Raffa (1989). Within each treatment, traps were arranged 7 m apart on two transects within the interior of the plot. Two treatments were compared for total trap catch: (I) Standard insecticide application, and (2) control. Standard insecticide treatment consisted of a liquid formulation f lindane applied at a rate of 0.95 I of active ingredient per ac e. The lindane was mixed with water at the rate of 0.95 I lindane: 473 I water. 0.48 I of mixture was applied to the collar region of each tree in June, 1987. There were 15 replicates for the insecticide treatment and 30 replicates of the unsprayed control, located on farms with a wide array of symptoms indicative of pine root weevil damage. Traps were monitored on 6 to 10 day intervals throughout the 1988 and 1989 growing seasons. At each monitoring interval, the weevils were removed and the baits replenished. Weevils were identified to species and their gender determined using available keys (Warner 1966, Wilson et al. 1966, Franklin & Tay or 1970). Data were analyzed from each year and from both years combined by the General Linear Model and Duncan's Multiple Range Test (SAS 1982). A square root + 0.5 transformation normalized the data prior to analysis. 2The Great Lakes Entomologist, Vol. 23, No. 4 [1990], Art. 2https://scholar.valpo.edu/tgle/vol23/iss4/21990 THE GREAT-LAKES ENTOMOLOGIST 191 TOTAL NUMBER OF WEEVILS TRAPPED IN SPRAYED VERSUS UNSPRAYED PLOTS 1988 & 1989 800 u.C o~ a:: Il.. 600 Wo:( III a: ::ill­=> Z ~ 400 ...,J­0:(> I- W ~~ 200 o III 0+------1....-­Treated Control Figure 1. Comparison of Hylobius pales and Pachylobius picivorus pitfall trap catches in lindane versus untreated control plots, 1988 and 1989. P < 0.05. Means within years followed by the same letter are not significantly different, Duncan's Multiple Range Test. RESULTS There was a 580/0 increase in the number of insects trapped from 1988 to 1989(Fig. 1). In both years, P. picivorus comprised 59% of the total trap catch; H. pales comprised 40%. Hylobius radicis comprised less than 1 % of the total in both 1988 and 1989, even though this species is attracted to the ethanol-turpentine bait (Hunt & Raffa 1989). The 1988 drought appears to have impacted root collar weevil more severely than either pales or pitch-eating weevil populations (Rieske 1990). Because so few H. radicis were trapped, this species was not included in the analysis. The insecticide application had a strong effect on trap catch. Plots with stan­dard insecticide spray caught significantly fewer weevils of both species than the unsprayed controls (p < 0.009, Table 1) in both 1988 and 1989. Differences between treatments were similar for both genders. However, the proportion of total insects trapped in sprayed plots increased from 6.7% in 1988 to 11 % in 1989. This includes a 1.56x increase in H. pal s, and a 1.63x increase in P. picivorus. No significant difference emerged in the total trap catch between farms in either year. There was no significant treatment/farm interaction in either year individually or pooled (P > 0.05). 3Rieske and Raffa: Use of a Monitoring System to Evaluate Pesticide Efficacy and ResPublished by ValpoScholar, 1990192 THE GREAT LAKES ENTOMOLOGIST Vol. 23, No.4 Table I.-Mean number (+I-s.d.) of H. pales and P. picivorustrapped per replicate under standard insecticide spray and unsprayed controls. (P < 0.05, Means within columns within years followed by the same letter are not significantly different, Duncan's Multiple Range Test). 1988 Treatment N H. pales P. picivorus TOTAL Standard spray 15 (1.28) a 1.75 (1.71) a 2.93 (2.19) a Unsprayed control 30 6.45 (5.06) b 10.17 (7.03) b 16.42 (9.72) b 1989 Standard spray 15 4.26 (4.12) a 3.81 (1.92) a 6.70 (5.59) a Unsprayed control 30 10.99 (8.83) b 16.34 (4.19) b 27.33 (9.43) b 1988 & 1989 Standard spray 30 3.03 (1.97) a 2.66 (3.36) a 4.82 (4.82) a Unsprayed control 60 8.57 (5.03) b 13.10 (8.53) b 21.57(10.87) b DISCUSSION The strong treatment effect among all locations in both 1988 and 1989 confirms the efficacy of lindane and the potential of baited traps in monitoring residual control. While total weevil catch increased by 58070 in 1989, weevil catch in sprayed plots increased three-fold. This suggests that traditional chemical applications are an effective means of controlling the pine root weevil complex for up to three growing seasons after application (Fig. I). The population resurgence in treated plots sug­gests that residual activity begins to break down in its second season. This trapping method may allow growers to monitor weevil populations follow­ing sprays, so that repeat applications are applied only where necessary. By assuring growers that weevil population resurgence can be detected before grade reduction or yield loss occurs, this method may also allow use of less persistent insecticides. This approach could also be used against other species such as H. radicis, Hylobius rhizophagus Millers, Benjamin, and Warner, and Hylobius abietis L., against which ethanol! turpentine combinations are known attractants (Tilles et al. 1986a, 1986b, Hunt & Raffa 1989). ACKNOWLEDGMENTS We thank the Kirk Company of Wautoma, Wisconsin for the study sites and assistance with trap installation, and Lorin Zastoupil of the Kirk Company for his valuable advice. S. Gilbert, M. Bleck, J. Graetz, and L. Kellner assisted with data collection. We also thank Daniel K. Young and David B. Hogg for reviewing this manuscript. This research was supported by the Christmas Tree Producers Associa­tions of Wisconsin, Minnesota, Michigan and Illinois, the Wisconsin Department of Agriculture Trade & Consumer Protection Sustainable Agriculture Grant 8825, USDA 86-CRCR-I-2077, USDA 86-FSTY-9-021O, the University of Wisconsin Applied Research Program, and the University of Wisconsin-Madison College of Agricultural and Life Sciences. LITERATURE CITED Benyus, J. M., ed. 1983. Christmas tree pest manual. USDA For. Servo North Central For. Exp. Sta. 108 p. Davis, R. & H. O. Lund. 1%6. Some studies on Hylobius pales (Herbst) and Pachylobius picivorus (Gertnar). J. Georgia Entom l. Soc. 1:25-28. 4The Great Lakes Entomologist, Vol. 23, No. 4 [1990], Art. 2https://scholar.valpo.edu/tgle/vol23/iss4/21990 THE GREAT LAKES ENTOMOLOGIST 193 Franklin. R. T. & J. W. Taylor. Jr. 1970. Biology of Pachylobius picivorus (Coleoptera: Curculionidae) in the Georgia Piedmont. Can. Entomol. 102:%2-%8. Hunt, D. W. & K. F. Raffa. 1989. Attraction of Hylobius radicis and Pachylobius picivorus (Coleoptera: Curculionidae) to ethanol and turpentine in pitfall traps. Environ. Entomol. 18:351-355. Kearby, W. H. 1965. The bionomics of the pine root weevil Hylobius rhizophagus Millers and the weevil complex associated with plantation deterioration. Ph.D. Dissertation, Univ. of Wisconsin, Madison. 147 p. Lynch, A. M. 1984. The pales weevil, Hylobius pales (Herbst): a synthesis of the literature. J. Georgia Entomol. Soc. 19:1-34. Newton, M. & F. B. Knight. 1981. Handbook of weed and insect control chemicals for forest resource managers. Timber Press. Beaverton, OR. Raffa, K. F. & D. W. Hunt. 1988. Use of baited pitfall traps for monitoring pales weevil, Hylobius pales (Coleoptera: Curculionidae). Great Lakes Entomol. 21:123-125. Raffa, K. F. & R. J. Steffeck. 1988. Computation of response factors for quantitative analysis of monoterpenes by gas-liquid chromatography. J. Chem. Ecol. 14:1385-1390. Rieske, L. K. 1990. Use of host volatiles for evaluating population patterns, dispersal, and behavioral responses of the pine root weevil complex, Hylobius pales (Herbst), Pachylobius picivorus (Germar), and Hylobius radicis Millers, Benjamin & Warner, in pine plantations. M.S. Thesis, Univ. of Wisconsin, Madison. 144 p. ; Rieske, L. K. & K. F. Raffa. 1990. Dispersal patterns and mark-recapture estimates of two pine root weevil species, Hylobius pales and Pachylobius picivorus (Coleoptera: Curculioni­dae), in Christmas tree plantations. Environ. Entomol., in press. SAS Institute. 1982. SAS User's Guide: statistics. SAS Institute, Cary, N.C. Tilles, D. A., G. Nordlander, H. Nordenhem, H. H. Eidmann, A. Wassgren & G. Bergstrom. 1986a. Increased release of host volatiles from feeding scars: a major cause of field aggrega­tion in the pine weevil, Hylobius abietis (Coleoptera: Curculionidae). Environ. Entomol. 15:1050-1054. Tilles, D. A., K. Sjodin, G. Nordlander & H. H. Eidmann. 1986b. Synergism between ethanol and conifer host volatiles as attractants for the pine weevil, Hylobius abietis (L.) (Coleop­tera: Curculionidae). J. Econ. Entomol. 70:970-973. Warner, R. E. 1966. A Review of the Hylobius of North America, with a new species injurious to slash pine (Coleoptera: Curculionidae). Coleop. Bull. 20:65-81. Wilson, L. F. 1968. Diel periodicity and survival behavior of pine root collar weevil adults under various light and temperature conditions. Ann. Entomol. Soc. Am. 61:1490-1495. Wilson, L. F., C. D. Waddell & 1. Millers. 1966. A way to distinguish sex of adult Hylobius weevils in the field. Can. Entomol. 98:1118-1119. 5Rieske and Raffa: Use of a Monitoring System to Evaluate Pesticide Efficacy and ResPublished by ValpoScholar, 1990

Use of a Monitoring System to Evaluate Pesticide Efficacy and Residual Activity Against Two Pine Root Weevils, \u3ci\u3eHylobius Pales\u3c/i\u3e and \u3ci\u3ePachylobius Picivorus\u3c/i\u3e (Coleoptera: Curculionidae), in Christmas Tree Farms

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