Bva 2 Mosquito Larvicide-A New Surface Oil Larvicide for Mosqutto Control

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Journal of the American Mosquito Control Association, 14(2):196-199,1998 Copyright O 1998 by the American Mosquito Control Association, Inc.

BVA 2 MOSQUITO LARVICIDE-A NEW SURFACE OIL LARVICIDE FOR MOSQUTTO CONTROL

T, G. FLOORE,' J. C. DUKES.T J. P. CUDA., E. T SCHREIBER' AND M. J. cREERt

ABSTRACT. BVA 2 mosquito larvicide was evaluated in laboratory pan tests against 3rd-instar Aedes taeniorhynchus (Wied.), Culex quinquefosciatus Say, and Culex nigripalpus Theobald larvae. BVA 2 was as effective as the standard, GB-1111, at 14 liters/ha (>99.lVo vs.99.8Vo). In small field plot tests BVA 2 mosquito larvicide applied at 28 liters/ha was as effective as GB- 1 1 I I (99 .OVovs. 99 .87o) 24 h posttreatment. Operation- ally, applied by helicopter at 46.8 liters/ha, BVA 2 mosquito larvicide was more effective (>9OV") in the slightly less vegetated site than in the heavily vegetated site. As a pupicide applied at 14 liters/ha in laboratory pan tests, no significant differences were noted between BVA 2 mosquito larvicide and GB-llll against Ae. tae- niorhynchu,s, Cx. quinquefasciatus, and Cx. nigripalpus pupae.

KEY WORDS Operational field laboratory, Diptera, Culicidae, Aedes taeniorhynchus, Culex, pupicide

INTRODUCTION mulations were evaluated (unpublished data). Less than 2Vo differences in mortality The use of petroleum oils as mosquito larvicides separated the 3 formulations from in the United States dates to 1793 in Philadelphia one another and less than 57o separatedthem from the (Howard 1928). Early petroleum-based larvicides standard,GB-1111. B-V (Wixom, such as diesel oil, kerosene,or tar oils were odor- Associates MI) chose the BVA 2 formulation reported iferous and often discolored the water's surface for on here for further study based on the several days (Headlee 192I, Lowry 1929, Howard initial study. 1932, lI0'4,aJJ1933, King et al. t944). Current products, although derivatives of petroleum distillates, MATERIALS AND METHODS are nearly odorless and clear (Anonymous 1990, Laboratory Floore et al. 1992). Phytotoxicity and other detri- studies: Laboratory bioassay tests mental effects some petroleum oils have on certain were conducted in 61 X 6l X 10-cm pans filled nontarget aquatic organismshave lead to the elim- with 16 liters of well water. The proceduresfor the laboratory and plot ination of all of these products except Golden small studieswere describedby Floore (1991). Bear@-1111(Golden Bear Oil Specialties,Oildale, et al. One hundred 3rd-instar mosquito CA) (GB-1111) and Bonide@(Bonide Products, larvae were placed in each pan before treat- Inc., Yorkville, NY) (Gjullin 1968, Mulla et al. ment. [n the Ae. taeniorhynchrs tests, 60 g of re- 1969,Schmidt et ^1. 1973,Levy et al. 1980,Mulla agent grade NaCl (Fisher Scientific, Inc., Atlanta, and Darwazeh 1981).Currently, these2 surfaceoils GA) was added to the water prior to adding the (5Voa are labeled as larvicides/pupicides. Pupicidal ef- larvae salinity). The 14 liters/ha application (1.5 fects of larvicide oils had been documented by rate gallons per acre, GPA) was basedon 0.37 Howard (1917), Lowry (1929>, and Micks et al. m2 of water surface area.Five tests were conducted (1e68). againsteach speciesin the laboratory with eachtest For several years studies evaluating candidate consisting of 2 pans of BVA 2 mosquito larvicide surface oils as mosquito larvicides have been con- formulation, I pan of GB-llll, and L untreated ducted by the John A. Mulrennan, Sr. Arthropod control. Larvae were considered dead if they did Research Laboratory, Panama City, FL (JAM- not move when touched by a glass probe. Larvae SARL). This paper reports the results of a study treatedwith GB- I I 1I sank to the bottom of the pan comparing BVA 2 mosquito larvicide with GB- when dead. Larvae treated with BVA 2 mosquito 1111 against 3rd-instar Aedes taeniorhynchus larvicide floated on the surface when dead. Water + (Wied.), Culex quinquefasciatusSay, and Culex ni- temperature during the laboratory tests was 26 gripalpus Theobald larvae and pupae in laboratory 1"C. pupae and small plot field tests. Also, results of an oper- In the tests,4 testswere conductedagainst lN Ae. ational study conductedby the Hillsborough Coun- taeniorhynchus,Cx. quinquefosciatus,and pupae ty Mosquito and Aquatic Weed Control Department Cx. nigripalprr in laboratory pans. Mortality (HCMCD), Tampa, FL, is presented.In initial lab- was assessedby determining the emergenceinhi- (EI) (Floore oratory pan bioassaytests 3 candidateBVA oil for- bition et al. 1991): CS_DA VoEl: t* - x roo). IJohn A. Mulrennan, Sr. Artbropod Research Labora- (CS+PE+DP tory Florida A. & M. University, 40OO Frankford Avenue Panama City, FL 32405-1933. where CS is cast skin, DA is dead adults, PE is 2 Department of Entomology and Nematology, Univer- partially emerged adults, and DP is dead pupae. sity of Florida PO. Box 110620, Gainesville, FL 32611- Water temperature during the pupae laboratory tests -{- 0620. was 26 1'C.

196 Jur,rB1998 A Nr,w Sunracs On Lenvrcron t97

Laboratory small field plot studies: Small plot Table 1. Laboratory tests of BVA mosquito larvicide field study application rates (28 liters/ha, 3 GPA) compared to GB-1111 against 3rd-instar Aedes were based on 0.93 m2 of water surface area. These taeniorhynchus, C ulex quinquefasciatus, and Culex nigripalpus lanae 24 h posttreatment.r-l tests were conducted in a screened enclosure at the JAMSARL in concrete cattle watering tanks (J. B. BVA mosauito larvicide oil GB-l111 Hill Contractor, Inc., Leesburg, FL) that measured Formu- X 1.7-m long X 0.6-m wide 0.6-m deep. The Cx. lation 7a control + SE Ea colrfiol + SE quinquefascialus and Cx. nigripalpus bioassays were conducted in freshwater and tlre Ae. taenio- Aedes taeniorhynchus^ rhynchus bioassays were conducted in tanks filled 95.91' r.43 100.00, 0.00 with salt water pumped from a saltwater canal de- Culer quinquefasciatus^ scribed by Rathburn and Boike (1975). Pretreat- 97-92, t.t2 99.88" O.1l ment assessments and posttreatment mortality were Culex nigripalpus^ determined by dipping larvae using a standard mos- 99.33" 0.67 100.00, 0.00 quito larval dipper at 8 stations located at each cor- ner of the tank (4), the middle of each long wall 'Application rates: BVA oil and GB-1111 at 14 liter/ha (1.5 axis (2), and 2 areas along the center axis of each gallons per acre). 'Species followed by different uppercase letter represent signif- tank approximately 30.5 cm from each end. Water (P : -r icant differences 0.05) between species using least significant temperature during the tests was 29 3"C and the differences (LSD) multiple comprison test. salinity in the saltwater plots was +l8Voo at treat- 3 Means followed by different lowercase letter represent signifi- (P : ment. cant differences 0.05) between treatments usins LSD multiple comparison test. Analysis: Larval mortality was assessed by counting the number of larvae in each pan or plot 24 h posttreatment. All the larvae were counted in Percentreduction was assessedas percentreduction the pans and in the plots only those actually dipped using the following formula (Mulla et al. 1971): were counted. Treatment means were separated by Toreduction analysis of variance (ANOVA) PROC GLM and : - least significant differences (LSD) multiple com- 100 [(no. larvae control pretreat- parison tests (SAS Institute l99O). Differences were ment X no. larvae treatment considered significant at P : 0.05. Pupicidal data were assessed and analyzed in a manner similar to postreatment) the larval data described above. + (no. larvae treatmentpretreat- Operational study: In the operational study, conducted at the Seaboard sewage effluent sprinkler ment X no. larvae control field in Hillsborough County, Florida, BVA 2 mos- postreatment)l X 100. quito larvicide was applied at 46.8 liter/ha (5 GPA) by a Bell 47 helicopter equipped with 20 disc core This formula assumedthat changes in the mosquito nozzles (TeeJet DIO/45, Spraying Systems Co., larval population were occruring at the same level Wheaton, IL) attached to a 9.8-m boom. Applica- and rate in both treated and untreatedcontrol sites. tion was from a height of 3.3 m at an airspeed of Comparisons within and among sample sites, and among sampling 74 kilometers/hr and a swath width of 21.3 m. The times to assesslarval abundance procedures treatments were initiated at O8O0 h. were made by ANOVA PROC GLM and LSD multiple comparison tests after arcsin Ditching characteristics of the 28.3-ha study sites transformation of the data (SAS Institute 1990). allowed for a portion of each cell (A, B, and C cells) to be utilized as either a treated or untreated control site. The initial test was conducted in April RESULTS AND DISCUSSION 1993 when the vegetation (various grasses and Laboratory: In the laboratory pan test no signif- woody shrubs) in the study site was 18-61 cm in icant mortality differences existed between species height. In October when the last test was conduct- (P : 0.2018) (Table 1). The treatments were sig- ed, the majority of the vegetation exceeded 1 m. niflcantly different from the control (P : O.OOO1). The mosquito species complement at the sprin- No differences were noted in the treatmentby spe- kler field was Aedes sollicitans (Walker), Anopheles cies interaction (P : 0.1054), or between larvicide crucians Wied, Anopheles quadrimaculatus Say, oils (P : O.O272). Cx. nigripalpus, Cx. quinquefasciatus, Psorophora In the laboratory bioassay test the BVA 2 mos- ciliata (Fabricus), and Psorophora columbiae quito larvicide was as effective as the GB- I 1I 1 for- (Dyar & Knab) throughout the season. mulation in controlling Ae. taeniorhynchus(95.97o Operational data analysis.' Twenty larval sam- vs. lOO.OVo),Cx. quinquefasciatus, (97.9Vo vs. ples at HCMCD predetermined dipping stations 99.9Vo)and Cx. nigripalpus (99.3Vovs. 100.0%) were taken at each site (treated and untreated) prior larvae (Table l). BVA 2 was more effective against to application and again 24 and 48 h posttreatment. t}aeCulex speciesthan againstAe. taeniorhynchus. 198 Joun-t.telop rse Auenrc,lN Mosgurro Corrnol Assocrlrron VoL. 14. No. 2

Table 2. Laboratory tests of BVA 2 mosquito larvicide Table 3. Small plot field tests of BVA 2 mosquito compared to GB-lll1 against Aedes taeniorhynchus, larvicide compared with GB-lll1 against 3rd-instar Culex quinquefosciatus, and Culex nigripalpus plpae 24 A ede s tae ni o rhync hus, C ule x q uinq uefo sc iat us, and ' h posttreatment.r Culex nigripalpus larvae 24 h posttreatment.r3

BVA 2 mosquito larvicide" BVA 2 mosquito larvicide, GB-l1l l +SE Vo control Vo control +SE Va control +SE Vo control + SE Aedes taeniorhynchusA Aedes taeniorhynchus^ 99.50 0.7| 100.00 0.00 100.00, 0.00 100.00 0.00 C u Ie x q u i n quefa sc i at u s^ C ulex quinquefas ciatus^ 96.50 o.71 100.00 0.00 97.00" 1.00 99.50" o.50 Culex nigripalpus^ Culex nigripalpus^ 94.50 4.50 100.00 0.00 r00.00" 0.00 100.00" 0.00 rApplication rApplication rates: BVA oil and GB-llll ar 14 liter/ha (1.5 rates: BVA 2 oil and GB-l111 applied at 28 liter/ gallons per acre). h (3.0 gallons per acre). ' Larvicides followed by dif't'erent lowercase letter represent srg- ' Species followed by different uppercase letter represent signif- - nilicant differences (P 0.05) between treatments usinq least sis- icant differences (P : 0.05) between species using least significant nificant differences (LSD) multiple comparison rest. differences (LSD) multiple comparison test. r Species tbllowed by different uppercase letter represent signif- 3 Means followed by different lowercase letter represent signifi- : icant differences (P 0.05) between species using LSD multiple cant differences (P = 0.05) between treatments usins LSD mut- comptrison test. tiple comparison test.

No significant differences (P : O.3149) were heavily vegetated (95Vo surface obstruction). In noted between BVA 2 mosquito larvicide and GB- sites B and C, which were SOVo vegetated, larval 1111 in the laboratory pan tests against pupae; reduction was approximately 94Vo anLd6OVo, re- however, signiflcant differences were noted be- spectively, at 24 h posttreatment and 95Vo and 63Vo tween treatments and control (P : 0.0001) (Table at 48 h posttreatment. Site A differed significantly 2). No significant differences were observed be- (P = 0.0010) from the less vegetated sites B and tween Ae. taeniorhynchas and the Culex species (P C (807o) in percent larval mortality (Thble 4). No : O.7993) or between tbe Culex species (P : significant treatment by site interaction (P : 0.6634). BVA 2 was most effective against Ae. tae- 0.5609) was noted between the sites with similar niorhynchus (99.57o vs. 100.07o) and least effective vegetation properties (B and C). Significant differ- against Cx. nigripalpus (94.5Vo vs. l0O.O7o). ences existed between pretreatment a/nd 24 and 48 Small plot field tests: In the small plot field study h posttreatment assessment times (P : 0.0002 and no significant statistical differences were noted be- P : 0.0017, respectively), but not between 24 and tween the oils (P : 0.0255) (Table 3). Significant 48 h posttreatment (P : 0.2897). differences were noted between the treatments and In the operational study, BVA 2 mosquito lar- controls (P : 0.0001). No significant differences vicide applied aerially controlled the larval mos- were noted between the 2 larvicides and the tests quito population in a sewage effluent sprinkler field with Cr. quinquefasciatus and those with Ae. tae- site where mosquito breeding was a problem. Lar- niorlrynchus and Cx. nigripalpus larvae (P : val control ranged from less that 6OVo to greater 0.0971). Actual Cx. quinquefasciatus larval mor- than 93Vo. This variation was presumed to be di- tality was 97.OVo with BVA 2 mosquito larvicide rectly related to the amount of surface or emergent and 99.5Vo with GB-1111, whereas Ae. taeniorhyn- vegetation in the target habitat. No reduction was chus and Cx. nigripalpzs mortality was lo07o with noted in the more densely vegetated site (A) where both surface oils (Table 3). the mosquito rearing areas were covered with grass Small plot field bioassay tests under identical canopies, making aerial larvicide application diffi- outdoor conditions showed BVA 2 mosquito lar- cult. The sites with good (C) to excellent (B) con- vicide to be as effective as GB-l111 in controlling trol were more accessible to aerial larvicide appli- Ae. taeniorhynchus, Cx. quinquefasciatus, arrd Cx. cation because the larval rearing sites were more nigripalpus larvae. Emergent vegetation, rainfall exposed. events, mixed larval instars, and fluctuating water temperatures were no more detrimental to BVA 2 SUMMARY mosquito larvicide than to GB-llll. Operational study: Because significant treatment BVA 2 mosquito larvicide oil successfully con- by site interaction (P : 0.0023) occurred in the trolled Ae. taeniorhynchus, Cx. quinquefasciatus, study, sample sites were considered separately (Ta- alad Cx. nigripalpus larvae and pupae in laboratory ble 4). Based on the larval reduction formula (Mul- tests and small plot field studies. BVA 2 was most la et al. 1971) no differences were noted between effective against Ae. taeniorhynchus and Cx. nigri- treatment and control areas in site A. which was palpus and least effective against Cx. quinquefas- JuNn1998 A Nsw SunpA.cBOrL Llnvrcroe 199

Table 4. BVA 2 mosquito larvicide operational study at Seaboard Sprinkler Field, Tampa, FL, March 30-October 21, tgg3.r3

Total no. larvae/2O dips Percent reductiona Pretreatment 24 h posttreatment4S h posttreatment 24h 48h A----control 131 4l 46 A-treafinentB 94^ 3gb 55b NR5 NR5 B----control 1,389 1,648 1,881 B-treatmentA ) 1)1a l68b l42b 93.62 95.28 C-control 465 166 180 C-treatmentB 35" 5b 5b 59.98 63.l

'Application rates: BVA 2 mosquito larvicide oil and GB-l111 applied at 18.9 liter/hectre (5.O gallons per acre). 'Sites followed by different uppercase letter represent significmt differences (P = 0.05) between treatments using Duncan's multiple compmson rcsl. 3 Means followed by different lowercase letter represent significant differences 1P = 0.05) between time of assessment using Duncan's multiple comparison test. a 70 reduction - l0O - no. larvae control pretreatment x no. larvae treatment posttreatment/no. larvae treatment pretreatment X no. lilvae control posttreatment X 10O. 5 NR, no larvae reduction based on formula. ciatus larvae. However, the actual percentage mor- their control. N.J. Agric. Exp. Stn. Bull. 348. New tality differences were small and probably not im- Brunswick, NJ. portant in an operational program. The BVA 2 mos- Howard, L. O. 1917. Remedies and preventives against quito larvicide was as effective as GB-1111 in mosquitoes. U.S. Dept. Agric. Farm. Bull. 444. Howard, L. O. 1928. The work with mosquitoes around controlling emergenceof pupae. the world in 1928. Proc. N.J. Mosq. Exterm. Assoc. 16: BVA 2 was effective in controlling natural mos- t-22. quito larval populations in an operational study Howard, L. O. 1932. Mosquito remedies and preventives. conducted by the HCMCD in an area accessible to U.S. Dept. Agric. Farm. Bull. 1570. aerial larvicide application. BVA 2 mosquito lar- King, W. V., G. H. Bradley and T E. McNeel. 1944. Tlre vicide should be another reliable tool in the mos- mosquitoes of the southeastern states. U.S. Dept. Agric. quito control arsenalof larvicides. Misc. Pub. 336. Levy, R., J. J. Chizzonite, W. D. Garrett and T, W. Miller, Jr. 1980. Control of immature mosquitoes through ap- ACKNOWLEDGMENTS plied surface chemistry. Proc. Fla. Anti-Mosq. Assoc. 5 I :68-71. This study was funded by B-V Associates,Inc., Lowry, P R. 1929. Mosquitoes of New Hampshire. N.H. Wixom, MI. We thank individuals who assistedin Agric. Exp. Stn. Bull. 243. this study: Dan Gorman, Director (retired), Hills- Mail, G. A. 1933. Mosquito control in Montana. Mont. borough County Mosquito and Aquatic Weed Con- Agric. Exp. Stn. Circ. 143. trol. Cecil Brockinton. Jr.. Fred Boston. and Dennis Micks, D. W., G. Chambers, J. Jennings and K. Barnes. Boone. 1968. Mosquito control agents derived from petroleum hydrocarbons. II. Laboratory evaluation ofa new petroleum, FLIT@ MLO. J. Econ. Entomol.6l:647-65O. REFERB,NCESCITED Mulla, M. S. and H. A. Darwazeh. 1981. Efficacy of Anonymous. 1990. Jacksonville successful with IPM. petroleum oils and their impact on some aquatic non- Pest Control 58:44, 46,82. target organisms. Proc. Calif. Mosq. Control Assoc. 49: Floore, T, G., J. C. Dukes, M. J. Greer and J. S. Coughlin. 84-87. 1992. Bonideo-a surface oil film larvicide: laboratory Mulla. M. S.. H. A. Darwazeh and H. Axelrod. 1969. and small plot efficacy studies against Aedes taenio- Activity of new mosquito larvicides against Culex and rhynchus, Culex quinquefasciatus and Culex nigripal- some nontarget organisms. Proc. Calif. Mosq. Control pus mosquito larvae. J. Fla. Mosq. Control Assoc. 63: Assoc. 37:81-88. 63-67. Mulla. M. S.. R. L. Norland. D. M. Fanara. H. A. Dar- Floore, T G., B. W. Clements, Jr., J. C. Dukes, P R. Sim- wazeh and D. W. McKean. 1971. Control of chiro- monds, A. H. Boike, Jr., M. J. Greer and J. S. Coughlin. nomid midges in recreational lakes. J. Econ. Entomol. I 99 I . Evaluation of a Vectobac- I 2AS/vegetable oil for- 64:300-307. mulation for the control of Aedes taeniorhynchus, Culex Rathburn, C. B., Jr. and A. H. Boike, Jr. 1975. Laboratory quinquefasciatus and Culex nigripalpus larvae com- and small plot field tests of Altosid and Dimilin for the pared with Witco Golden Bear (GB-I111). J. Fla. Mosq. contol of Aedes taeniorhynchus and Culex nigripalpus Control Assoc. 62:41-44. larvae. Mosq. News 35:540-546. Gjullin, C. M. 1968. Insecticides for mosquito control. SAS Institute, Inc. 1990. SAS@ user's guide: statistics, In: D. L. Collins (ed). Ground equipment and insecti- version 6 edition. SAS Institute, Inc., Cary, NC. cides for mosquito control. Am. Mosq. Control Assoc. Schmidt, R., E. Evans and D. J. Sutherland. 1973. A Bull.2:19-22. comparison of oil and FLIT MLO for catch basin treat- Headlee, T. I. 1921. The mosquitoes of New Jersev and ment. Mosq. News 33:585-587.