ARTHROPOD MANAGEMENT

Transcription

1 The Journal of Cotton Siene 13: (2009) The Cotton Foundation ARTHROPOD MANAGEMENT Comparative Effiay of Seleted Insetiide Alternatives for Boll Weevil (Coleoptera: Curulionidae) Control Using Laboratory Bioassays Boris A. Castro* and J. Sott Armstrong ABSTRACT B. A. Castro, 7521 W. California Ave., Fresno, CA 93706; J. S. Armstrong, USDA, ARS, BIRU, KDLG-SARC, 2413 East Highway 83, Weslao, TX *Corresponding author: The boll weevil, Anthonomus grandis grandis (Boheman), is a major pest of otton (Gossypium hirsutum L.), and responsible for an estimated $300 million in annual losses (National Cotton Counil of Ameria 2009, Texas Boll Weevil Eradiation Foundation, In. 2009). Current boll weevil eradiation programs depend on malathion ULV to ahieve and maintain eradiation status. Should this effetive and eonomial insetiide beome unavailable, eradiation efforts ould be jeopardied. The objetive of this projet was to evaluate the effiay of seleted insetiides as alternatives to malathion ULV on field olleted boll weevils. The study was onduted in the Lower Rio Grande Valley of Texas in Insetiides inluded malathion ULV, endosulfan, bifenthrin, enapsulated methyl parathion, oxamyl, arbaryl and yfluthrin. Malathion ULV was applied using an ULV, ontrolled-droplet appliator. Other insetiides were applied with a hand-held, CO2-harged sprayer. Leaf disks were removed from treated otton, plaed in ulture plates and infested with individual adult boll weevils. Boll weevil mortality in the malathion ULV, endosulfan, enapsulated methyl parathion and bifenthrin treatments was at or near 100%. Mortality with yfluthrin and arbaryl was low and inonsistent. Mortality in the oxamyl treatment was intermediate between the two above groups. Highest mortality after 24 h was observed with malathion ULV (97.9%), endosulfan (86.6%) and bifenthrin (80.2%). After 48 h, mortality reahed 100% with malathion ULV but was not signifiantly different from those of enapsulated methyl parathion (96.1%), bifenthrin (95%) and endosulfan (94.9%). Results indiate that malathion ULV is a highly effetive material for boll weevil ontrol and that enapsulated methyl parathion, bifenthrin and endosulfan also ause high mortality. The boll weevil, Anthonomus grandis grandis (Boheman), is a major otton pest, responsible for an estimated $300 million in otton rop losses every year inluding $70 million spent annually on ontrol efforts (National Cotton Counil of Ameria 2009, Texas Boll Weevil Eradiation Foundation, In. 2009). Malathion ULV is urrently the only insetiide being used to ontrol the boll weevil in ative boll weevil eradiation programs. While substantial areas of the otton belt have been delared either boll weevil-free or funtionally-eradiated, most prodution regions of Texas and Mexio remain in ative eradiation programs. The Lower Rio Grande Valley of Texas (LRGV) ompleted its third full season in 2008 under the Texas Boll Weevil Eradiation Program, and is not projeted to attain funtionally-eradiated status for a few years. The ontinued availability of malathion ULV is ritial to boll weevil eradiation programs to both ahieve and maintain eradiation. Should this effetive and eonomial insetiide beome unavailable, efforts toward eradiation status ould be jeopardied. There has been limited progress in identifying replaements for malathion ULV that meet the riteria of urrent registration, low environmental impat, low ost, and high level of effiay against the boll weevil. Beause all otton areas in the United States are now engaged in eradiation or maintenane efforts, opportunities to ondut effiay studies on field olleted boll weevils are limited. Previous studies provided important information on the effiay of seleted insetiide alternatives on boll weevil infestations (Sparks et al. 1997, Parker and Huffman 1997, Raulston et al. 1998). Although they do not report diret boll weevil mortality over time aused by insetiides, they inreased knowledge on boll weevil management by reording the perentage of oviposition-puntured squares and by measuring impat on yields (Sparks et al. 1997, Parker and Huffman 1997, Raulston et al. 1998). Field experiments

2 Castro and Armstrong: Insetiide ALTERNATIVES for Boll Weevil Control 190 indiated that ainphosmethyl (Guthion ), fipronil (Regent ), oxamyl (Vydate ), endosulfan (Phaser and Thiodan ), lambda-yhalothrin (Karate ), yfluthrin (Baythroid ), and miro enapsulated methyl parathion (Pennap-M ) redued boll weevil damage and inreased otton lint yields (Parker and Huffman 1997). Some researh on field effiay of seleted insetiides to manage boll weevil damage often was onfounded by multiple field and other environmental variables (England et al. 1997, Raulston et al. 1998). Field evaluations by Raulston et al. (1998) revealed that weekly appliations of fipronil resulted in higher number of puntured squares than did weekly appliations of ainphosmethyl. However, fipronil-treated plots also had higher number of total squares. This aused the atual perentage of infested squares to be lower in fipronil-treated plots than in ainphosmethyl-treated plots. The authors onluded that the higher numbers of total squares in fipronil-treated plots probably resulted from produt effiay. They added that the higher numbers of puntured squares likely resulted from a ombination of inter-plot movement of boll weevils towards fipronil-treated plots whih ontained higher number of squares. It was onluded that fipronil-treated plots offered inreased opportunities for boll weevil population reruitment and inreased attrativeness relative to adjaent plots. Similar results were observed by Sparks et al. (1997) while evaluating fipronil and ainphosmethyl. Fipronil provided the highest residual ativity in leaf-disk exposure bioassays. More oviposition-puntured squares were observed in fipronil-treated plants in small repliated plots. Despite this valuable information, fipronil and ainphosmethyl are no longer available as alternatives to malathion ULV. Previous researh inreased our understanding of insetiide options for improved boll weevil management and yield protetion. They not only illustrate diffiulties in ontrolling field and other environmental variables but also the ontinued trend for redution in insetiidal options on whih previous effiay work was onduted. Moreover, information ontinues to be limited on the ability of urrently available insetiides to ause diret and swift mortality, whih is the ultimate objetive of the boll weevil eradiation program. Therefore, there is still a ritial need for diret assessment of effiay orresponding to materials urrently labeled for otton. The objetive of these experiments was to diretly evaluate effiaies of seleted insetiides as alternatives to malathion ULV on native, field olleted adult boll weevils using a simple and repeatable laboratory bioassay. MATERIALS AND METHODS Insetiides. Seleted insetiides evaluated in this study inluded oxamyl (Vydate C-LV, DuPont Crop Protetion, Wilmington, DE), arbaryl (Sevin XLR Plus, Bayer CropSiene, Researh Triangle Park, NC), enapsulated methyl parathion (Pennap M, United Phosphorus, In., King of Prussia, PA), malathion ULV (Fyfanon ULV AG, Cheminova, Wayne, NJ), bifenthrin (Capture 2EC, FMC Corporation, Philadelphia, PA), endosulfan (Thionex 3EC, Makhteshim Agan of North Ameria, In., New York, NY) and yfluthrin (Baythroid 1.0L, Bayer CropSiene, Researh Triangle Park, NC). The insetiide rates were applied in aordane with the label and are inluded in Tables 1 through 6. Table 1. Effiay of seleted insetiides on adult boll weevils using a sprayed leaf-disk bioassay, Lower Rio Grande Valley of Texas, 6 April 2007 (bioassay 1). Enap. methyl parathion 560 g ai ha -1 (0.5 lb a.i./are) a a a Endosulfan 560 g ai ha -1 (0.5 lb a.i./are) a a a Bifenthrin 112 g ai ha -1 (0.10 lb a.i./are) 97.2 a 97.2 a 97.2 a Oxamyl 280 g ai ha -1 (0.25 lb a.i./are) 36.1 b b Cyfluthrin 23 g ai ha -1 ( lb a.i./are) b Carbaryl 280 g ai ha -1 (0.25 lb a.i./are) Adult boll weevils olleted from pheromone traps in the LRGV prior to otton squaring.

3 JOURNAL OF COTTON SCIENCE, Volume 13, Issue 3, Table 2. Effiay of seleted insetiides on adult boll weevils using a sprayed leaf-disk bioassay, Lower Rio Grande Valley of Texas, 20 June 2007 (bioassay 2). Endosulfan 560 g ai ha -1 (0.5 lb a.i./are) a a a Malathion ULV 1035 g ai ha -1 (12 fl o/are) 92.0 ab a a Bifenthrin 112 g ai ha -1 (0.10 lb a.i./are) 88.0 ab a a Enap. methyl parathion 560 g ai ha -1 (0.5 lb a.i./are) 76.0 b 96.0 a a Oxamyl 280 g ai ha -1 (0.25 lb a.i./are) b 66.0 b Carbaryl 560 g ai ha -1 (0.5 lb a.i./are) 8.0 d 16.0 d 16.0 d Adult boll weevils reared out from infested squares olleted from ommerial otton fields in the LRGV. Table 3. Effiay of seleted insetiides on adult boll weevils using a sprayed leaf-disk bioassay, Lower Rio Grande Valley of Texas, 25 June 2007 (bioassay 3). Endosulfan 560 g ai ha -1 (0.5 lb a.i./are) a a a Malathion ULV 1035 g ai ha -1 (12 fl o/are) a a a Bifenthrin 112 g ai ha -1 (0.10 lb a.i./are) 64.2 b 90.0 ab a Enap. methyl parathion 560 g ai ha -1 (0.5 lb a.i./are) 61.7 b 96.7 a 96.7 a Oxamyl 280 g ai ha -1 (0.25 lb a.i./are) 16.7 d-g f 50.0 d Carbaryl 1120 g ai ha -1 (1.0 lb a.i./are) 6.7 efg 16.7 d-g 36.7 de Cyfluthrin 23 g ai ha -1 ( lb a.i./are) 3.3 fg 10.0 efg 24.1 d-g Carbaryl 560 g ai ha -1 (0.5 lb a.i./are) 0.0 g 3.3 fg 10.8 efg Adult boll weevils reared out from infested squares olleted from ommerial otton fields in the LRGV. Table 4. Effiay of seleted insetiides on adult boll weevils using a sprayed leaf-disk bioassay, Lower Rio Grande Valley of Texas, 30 June 2007 (bioassay 4). Malathion ULV 1035 g ai ha -1 (12 fl o/are) a a a Enap. methyl parathion 560 g ai ha -1 (0.5 lb a.i./are) 50.0 b-e 75.0 ab a Bifenthrin 112 g ai ha -1 (0.10 lb a.i./are) f 70.0 a-d 85.0 ab Cyfluthrin 23 g ai ha -1 ( lb a.i./are) 45.0 b-e 65.0 a-d 75.0 a-d Endosulfan 560 g ai ha -1 (0.5 lb a.i./are) 50.0 b-e 60.0 a-d 70.0 a-d Oxamyl 280 g ai ha -1 (0.25 lb a.i./are) 20.0 def 25.0 def f Carbaryl 1120 g ai ha -1 (1.0 lb a.i./are) 0.0 f 5.0 ef 5.0 ef Adult boll weevils reared out from infested squares olleted from ommerial otton fields in the LRGV.

4 Castro and Armstrong: Insetiide ALTERNATIVES for Boll Weevil Control 192 Table 5. Effiay of seleted insetiides on adult boll weevils using a sprayed leaf-disk bioassay, Lower Rio Grande Valley of Texas, 17 July 2007 (bioassay 5). Malathion ULV 1035 g ai ha -1 (12 fl o/are) a a a Bifenthrin 112 g ai ha -1 (0.10 lb a.i./are) 86.1 ab a a Enap. methyl parathion 560 g ai ha -1 (0.5 lb a.i./are) 60.0 bd a a Endosulfan 560 g ai ha -1 (0.5 lb a.i./are) 57.2 d 93.9 ab 93.9 ab Cyfluthrin 23 g ai ha -1 ( lb a.i./are) 33.3 def 50.0 de 64.4 a-d Oxamyl 280 g ai ha -1 (0.25 lb a.i./are) 34.5 def 46.1 de 62.8 bd Carbaryl 1120 g ai ha -1 (1.0 lb a.i./are) 11.1 ef 53.9 d 65.6 bd Carbaryl 560 g ai ha -1 (0.5 lb a.i./are) 2.8 f 50.0 de 53.3 bd Adult boll weevils reared out from infested squares olleted from ommerial otton fields in the LRGV. Table 6. Effiay of seleted insetiides on adult boll weevils using a sprayed leaf-disk bioassay, Lower Rio Grande Valley of Texas, 20 September 2007 (bioassay 6). Endosulfan 560 g ai ha -1 (0.5 lb a.i./are) ab ab ab Malathion ULV 1035 g ai ha -1 (12 fl o/are) 96.0 ab ab ab Bifenthrin 112 g ai ha -1 (0.10 lb a.i./are) 92.0 ab ab ab Enap. methyl parathion 560 g ai ha -1 (0.5 lb a.i./are) 72.0 b 92.0 ab ab Oxamyl 280 g ai ha -1 (0.25 lb a.i./are) 76.0 ab 80.0 ab 80.0 ab Carbaryl 1120 g ai ha -1 (1.0 lb a.i./are) 12.0 d 21.0 d 37.0 d Cyfluthrin 23 g ai ha -1 ( lb a.i./are) 4.0 d 8.0 d 17.0 d Adult boll weevils olleted from pheromone traps in the LRGV during otton post-harvest season. Boll weevil soure. The first and sixth bioassays (on 6 April 2007 and 20 September 2007, respetively) were onduted using adult boll weevils from pheromone traps beause ommerial otton fields in the LRGV either had no infested squares to rear the adults (6 April) or were already harvested (20 September). Overwintered boll weevils were used in the first bioassay (6 April). Bioassays onduted on 20 September were performed on adult boll weevils from the post-harvest season of the LRGV. Trapping loation, setup and maintenane for bioassays on 6 April and 20 September followed reommendations outlined in previous studies in the LRGV (Armstrong et al. 2006). Traps were baited with grandlure pheromone and adult boll weevils olleted one day later. Boll weevils were transported to the laboratory and were provided with 10% surose water in moistened otton wiks. Bioassays were onduted one day later after seleting only healthy boll weevil adults. Bioassays onduted on 20 June, 25 June, 30 June, and 17 July were onduted on adult boll weevils reared from infested squares olleted in the LRGV during the otton squaring season. Squares with single boll weevil oviposition puntures were olleted from ommerial otton fields. The squares were olleted from the plant as opposed to infested squares on the ground to prevent pathogen ontamination. Infested squares olleted from plants also inreased uniformity of adult boll weevil emergene. Squares were taken to the laboratory and plaed in a growth hamber at 85

5 JOURNAL OF COTTON SCIENCE, Volume 13, Issue 3, 2009 ºF, 50% RH and 14:10 (L:D) photoperiod regime. After 5 to 6 days, squares were disseted and boll weevils that had pupated were plaed in 15-m-diameter Petri dishes lined with a thin layer of vermiulite moistened with reverse osmosis water. Newly emerged adult boll weevils were plaed in plexiglass ages and provided with pestiide-free otton squares at a rate of one square per boll weevil per day. A 10% surose solution was supplied using moistened otton wiks. Two-day old adult boll weevils were used in bioassays. Cotton leaf soure. Leaves were obtained from greenhouse potted plants from onventional otton ultivar Stoneville 474. Cotton was planted in the greenhouse at different intervals during the study to be used as leaf soure for bioassays. Separate sets of plants were used as square soure to feed emerging adult boll weevils. Inset pests suh as aphids, whiteflies and spider mites on greenhouse plants were kept in hek by washing the plants with water almost on a daily basis. Bioassay proedure. Proedures for leaf-disk bioassays are similar to those used by Spurgeon et al. (1997). Expanded leaves from the upper half of the plant were hosen for bioassays. In the first bioassay (6 April), leaves were exised, sealed in plasti bags and arried to the laboratory. Leaves were plaed horiontally on a spray table in an automated spraying system equipped with a Mirofit ontrolled-droplet appliator alibrated to deliver 140 L ha -1 (15 gpa) and the speified insetiide rate. A malfuntion of the Mirofit ontrolled-droplet appliator prevented the inlusion of the malathion ULV treatment in the first bioassay. In all other bioassays, potted plants were sprayed diretly using a hand-held boom equipped with a CO 2 -harged system alibrated to deliver 140 L ha -1 (15 gpa) at 331 kpa (48 psi) through four Tee Jet 8002VS noles. Malathion ULV was applied at 1035 g ai ha -1 (12 fl o/are) of the ULV formulation using a hand-held Miron ULVA+ ontrolled droplet appliator (Bromyard Industrial Estate, Bromyard, Herefordshire, HR7 4HS, UK). An untreated hek was inluded by spraying water only. Leaves in all insetiide treatments and the untreated (water) hek were allowed to air dry before utting leaf disks. Leaf disks were ut to fit inside Falon 3046 (BD Falon, Billeria, MA) tissue ulture plates equipped with 6, 35 mm diameter wells. The bottom of eah ulture well was lined with a moistened paper filter. Sprayed otton leaf disks were plaed in ulture wells and one adult boll weevil was exposed to the treated surfae in a no-hoie situation. Experimental units onsisted 193 of five or six adult boll weevils per treatment. Culture plates were arranged in a omplete randomied blok design with four to six repliates per trial. Mortality was assessed at 24, 48 and 72 h of ontinued exposure to the treated leaf-disk surfae. The mortality riterion was the absene of response after gently stroking the sides and antennae of the boll weevil for 30 s with a amel s hair brush. Data analysis. Data was orreted for the mortality observed in the untreated heks using Abbott s (1925) formula. Beause mortality data were measured in perentages, they were transformed [arsine (x/100)] for analysis of variane and means separation to normalie the variane distribution. Mortality data were subjeted to ANOVA and analyed using the REPEATED statement within SAS MIXED proedure (SAS Institute In. 2001). Differenes among treatment means were determined by using the Tukey-Kramer s proedure for a onfidene level of α = Results for eah bioassay are presented in Tables 1 through 6 to differentiate adult boll weevil mortality as the otton season progressed. RESULTS AND DISCUSSION Six sprayed leaf-disk bioassays were onduted during the 2007 otton season at the LRGV. These assays were onduted on overwintered adult boll weevils olleted from pheromone traps along otton fields (6 April bioassay, Table 1), from adult boll weevils reared from infested squares (20 June, 25 June, 30 June, and 17 July bioassays, Tables 2-5) and adult boll weevils from pheromone traps during the post-harvest season (20 September bioassay, Table 6). Based on the results from the six bioassays, boll weevil mortality in the malathion ULV, endosulfan, enapsulated methyl parathion and bifenthrin treatments was onsistently at or near 100% at the end of eah bioassay. Effiaies of yfluthrin and different rates of arbaryl were low and inonsistent throughout the bioassays. A season average of boll weevil mortality revealed that suseptibility to oxamyl was intermediate between the two above groups (Fig. 1). An intermittent driling event was experiened during the outdoor plant spraying for the fourth bioassay on 30 June. Despite this event, high mortality (at or near 100%) was onsistently observed in the Malathion ULV and the enapsulated methyl parathion treatments (Fig. 2). Performane of yfluthrin did not seem to be affeted by the driling event. However, overall yfluthrin performane was poor. Conversely, bifenthrin, endosulfan, oxamyl

6 Castro and Armstrong: Insetiide ALTERNATIVES for Boll Weevil Control 194 and arbaryl did not appear to be as rainfast as other materials, as indiated by a deline in boll weevil mortality in the 30 June bioassay (Fig. 2). After removing the 30 June bioassay data, boll weevil suseptibility to eah evaluated insetiide appears to be onstant aross the season (Fig. 2). Malathion ULV was the only treatment to aomplish 100% boll weevil mortality in all bioassays after 48 h of treated leaf-disk exposure (Fig. 1). Signifiantly higher boll weevil mortality after 24 h was observed in the malathion ULV, endosulfan and bifenthrin treatments (97.9%, 86.6% and 80.2%, respetively, see Fig. 1). At 48 h of exposure, boll weevil mortality reahed 100% in the malathion ULV treatment but was not signifiantly different from those of enapsulated methyl parathion (96.1%), bifenthrin (95%) and endosulfan (94.9%). A similar trend of signifiane was observed after 72 h of exposure (Fig. 1). Perent Mortality Fig. 1. Season average adult boll weevil suseptibility to seleted insetiides on treated-leaf bioassays in otton, LRGV, 2007 Perent Mortality Malathion ULV at 12 fl o/a 0 a a a Enap. methyl parathion at 0.5 lb/a Bifenthrin at 0.10 lb/a Malathion ULV at 1035 g/ha Endosulfan at 560 g/ha Carbaryl at 1120 g/ha a Endosulfan at 0.5 lb/a b Oxamyl at 0.25 lb/a Carbaryl 1.0 lb/a Mortality at 24 hours Mortality at 48 hours Mortality at 72 hours Cyfluthrin at lb/a Enap. methyl parathion at 560 g/ha Oxamyl at 280 g/ha Carbaryl at 560 g/ha Carbaryl 0.5 lb/a Carbaryl 0.25 lb/a Bifenthrin at 112 g/ha Cyfluthrin at 23 g/ha Carbaryl at 280 g/ha 6 APRIL 20 JUNE y 25 JUNE y 30 JUNE y 17 JULY y 20 SEPTEMBER x Fig. 2. Adult boll weevil mortality after 72 h of treated-leaf exposure to seleted insetiides in otton, LRGV, 2007 Pre-squaring season, overwintered boll weevils; y Squaring season; x Post-harvest season Data analysis from these experiments did not reveal effiay problems in the malathion ULV treatment. However, given possible repelleny effets of malathion ULV and other insetiides, additional bioassays using ages will be helpful to further evaluate effiay of insetiides for boll weevil ontrol. Results from this study indiate that, among the materials evaluated, malathion ULV still remains highly effetive for boll weevil ontrol and that enapsulated methyl parathion, bifenthrin and endosulfan also are effetive in ausing high mortality of adult boll weevils. Of the top performing insetiides, bifenthrin at 112 g ha -1 and endosulfan at 560 g ha -1 did not appear to be as rainfast as malathion ULV at 1035 g ha -1 and enapsulated methyl parathion at 560 g ha -1, whih ould be a limiting fator during rainy otton squaring season. However, additional studies are suggested to evaluate rainfastness harateristis in addition to effiay, eonomis and environmental profile of alternative insetiides on boll weevil eradiation programs. Aknowledgements This projet was supported by Cotton Inorporated, Texas AgriLife Extension Servie, Texas AgriLife Researh, USDA-ARS, TBWEF and the Tehnial Advisory Committee for the TBWEF. Dislaimer Mention of trademark, warranty, proprietary produt or vendor does not onstitute a guarantee by the Texas AgriLife Extension Servie, Texas AgriLife Researh, the USDA or any other supporting party of this projet and does not imply approval or reommendation of the produt to the exlusion of others that may be suitable. REFERENCES Abbott W.S A method of omputing the effetiveness of an insetiide. Eon. Entomol. 18: Armstrong, J. S., D. W. Spurgeon, and C. P.-C. Suh Comparison of standard and extended-life boll weevil (Coleoptera: Curulionidae) pheromone lures. J. Eon. Entomol. 99: England, M, R. Minenmayer, C. Sansone Impat of seleted insetiides on boll weevil and natural enemies. p In Pro. Beltwide Cotton Conf., New Olreans, LA Jan Natl. Cotton Coun. Am., Memphis, TN.

7 JOURNAL OF COTTON SCIENCE, Volume 13, Issue 3, National Cotton Counil of Ameria [Online]. Available at: (aessed 3 February 2009). Parker, R.D. and R. L. Huffman Evaluation of Insetiides for boll weevil ontrol and impat on non-target arthropods on non-transgeni and transgeni B.t. otton ultivars. p In Pro. Beltwide Cotton Conf., New Olreans, LA Jan Natl. Cotton Coun. Am., Memphis, TN. Raulston, J. R., D. W. Spurgeon, and A. N. Sparks, Jr., Influene of fruit on sampling and ontrol of adult boll weevils in otton. Southwest. Entomol. 23: SAS Institute In SAS software, release 8.02 TS Level 02M0. Cary, NC. Sparks, Jr., A.N., J. W. Norman., D. W. Spurgeon, and J.R. Raulston Comparative effiay of fipronil and Guthion for boll weevil ontrol. p In Pro. Beltwide Cotton Conf., New Olreans, LA Jan Natl. Cotton Coun. Am., Memphis, TN. Spurgeon, D. W., J.R. Raulston, A. N. Sparks, Jr., J. W. Norman Patterns of effiay of boll weevil insetiides using a leaf disk bioassay. p In Pro. Beltwide Cotton Conf., New Olreans, LA Jan Natl. Cotton Coun. Am., Memphis, TN. Texas Boll Weevil Eradiation Foundation, In [Online]. Available at: (aessed 3 February 2009).