Op-jeen150272 1.8Journal of Economic Entomology Advance Access published September 5, 2015
Spray Toxicity and Risk Potential of 42 Commonly Used Formulations of Row Crop Pesticides to Adult Honey Bees (Hymenoptera: Apidae) YU CHENG ZHU,1,2 JOHN ADAMCZYK,3 THOMAS RINDERER,4 JIANXIU YAO,1 ROBERT DANKA,4 RANDALL LUTTRELL,1 AND JEFF GORE5 J. Econ. Entomol. 1–8 (2015); DOI: 10.1093/jee/tov269 ABSTRACT To combat an increasing abundance of sucking insect pests, >40 pesticides are currentlyrecommended and frequently used as foliar sprays on row crops, especially cotton. Foraging honey beesmay be killed when they are directly exposed to foliar sprays, or they may take contaminated pollen backto hives that maybe toxic to other adult bees and larvae. To assess acute toxicity against the honey bee, weused a modified spray tower to simulate field spray conditions to include direct whole-body exposure,inhalation, and continuing tarsal contact and oral licking after a field spray. A total of 42 formulated pesti-cides, including one herbicide and one fungicide, were assayed for acute spray toxicity to 4–6-d-oldworkers. Results showed significantly variable toxicities among pesticides, with LC50s ranging from 25 tothousands of mg/liter. Further risk assessment using the field application concentration to LC1 or LC99ratios revealed the risk potential of the 42 pesticides. Three pesticides killed less than 1% of the workerbees, including the herbicide, a miticide, and a neonicotinoid. Twenty-six insecticides killed more than99% of the bees, including commonly used organophosphates and neonicotinoids. The remainder of the13 chemicals killed from 1–99% of the bees at field application rates. This study reveals a realistic acutetoxicity of 42 commonly used foliar pesticides. The information is valuable for guiding insecticideselection to minimize direct killing of foraging honey bees, while maintaining effective control of fieldcrop pests.
KEY WORDS insecticide, spray, toxicity, honey bee, risk assessment Honey bees (Apis mellifera L.) play a vital role in global such as the tarnished plant bug (Lygus lineolaris [Pali- crop production. In addition to honey production, com- sot de Beauvois]) and stink bugs (Acrosternum hilare mercial beekeepers provide millions of honey bee hives [Say], Nezara viridula [Linnaeus], and Euschitus servus for pollinating fruit, nut, seed, oil, and fiber crops [Say]), having a wide range of host plant species ). The annual enhanced (, This pest status crop value from pollination in the United States is esti- shift, coupled with the development of insecticide resis- mated at US$16 billion, with 75% of that being attrib- tance in target insects ), has re- uted to honey bees sulted in increased foliar sprays of insecticides to Honey bee populations are threatened by control the sucking insects. This also increase the risk numerous pests, parasites, and pathogens, including of foraging honey bees coming into direct contact with the idiopathic colony collapse disorder ( insecticides. Currently, a variety of insecticides from at least four insecticide classes are available for pest con- Additionally, changing agricultural practices have added trol, including pyrethroids, organophosphates, carba- obstacles to maintaining healthy populations of honey mates, neonicotinoids, and other novel insecticides.
bees (U.S. Department of Agriculture ).
More than 40 pesticides (including acephate, dicroto- During the past few years, the widespread implementa- phos, thimethoxam, clothianidin, imidacloprid, etc.) are tion of transgenic plants has caused a pest status shift currently recommended by extension specialists for the from chewing insects to sucking insects on row crops, chemical control of row crop (mainly cotton, soybean,rice, and corn) insects ,, particularly avariety of insects (e.g., tarnish plant bug and stink Mention of a proprietary product does not constitute a recommen- dation or endorsement by the USDA.
1 USDA-ARS, Stoneville, MS 38776.
Residues of >150 pesticides were detected at various 2 Corresponding author, e-mail: [email protected].
levels in wax, pollen, bee, or honey 3 USDA-ARS, Poplarville, MS 39470.
The possible relationships be- 4 USDA-ARS, Honey Bee Breeding, Genetics and Physiology Labo- tween honey bee colony losses and sublethal effects of ratory, 1157 Ben Hur Rd., Baton Rouge, LA 70820.
5 Mississippi State University Delta Research and Extension Center, pesticide residues have received considerable attention, Stoneville, MS 38776.
and published data indicated that pesticide residues Published by Oxford University Press [on behalf of Entomological Society of America] 2015.
This work is written by US Government employees and is in the public domain in the US.
JOURNAL OF ECONOMIC ENTOMOLOGY may pose either serious adverse impact When multiple formulations made by different compa- nies were marketed, the selection of a formulation for or very low to no risk testing was based exclusively on availability without preference. All chemicals were stored at approximately bees. While the collective data from these studies has 10C in a refrigerator.
generally provided inconclusive results, however, many Honey Bees and Cage Design. Colonies and pesticides used in mid-south agriculture, such as dicro- brood were supplied by local beekeepers in Arkansas.
tophos and acephate, have high acute toxicity to honey Hives were inspected and certified to be apparently bees. Yet, they have received relatively less experimen- disease free by the Arkansas State Plant Board. Combs tal examination. In addition, when farmers come to se- with >50% coverage of healthy brood were transferred lect insecticides for insect pest control, it is difficult to to an incubator (33 6 0.5C; 65% 6 3 RH) with no determine which are relatively more or less toxic for light. Twenty-five newly emerged bees were transferred honey bees, because very limited bee-toxicity warning to a cage and maintained at 33C in an incubator for at is provided in pesticide use recommendation, or a simi- least 4 d before being used for bioassays. The cage was lar or even identical warning is marked in pesticide la- made of a 500-ml round wide-mouth polypropylene jar beling for most chemicals. Therefore, honey bees and (D by H: 9.3 by 10 cm). The lid of the jar was cut to other pollinators may be indiscriminately exposed to a make an 8.9-cm-diameter (d) hole and covered with 8- variety of pesticides in row crops.
mesh metal screen to facilitate spray applications. Four Previous assessments of pesticide acute toxicity to holes were made at the bottom of the jar: two 1.27 cm honey bees have mostly been made from topical applica- (d) holes for bee entry and ventilation and two 2.54 cm tion or using an artificial feeder with pesticides incorpo- (d) holes for holding sugar solution and water vials. A rated into sugar solution , piece of plastic comb foundation (3.81 by 8.9 cm) was , ). Insecticides can ex- glued to the bottom and side of the jar for bees to con- hibit contact toxicity, systemic toxicity, and/or both toxic- gregate and reach the feeding vials. Each cage, contain- ing 25 workers (4–6 d old), was supplied with a piece (1 One-time topical treatment with technical grade pesti- by 1 by 2 cm3) of Global Patties (purchased from Bet- cide excludes continuous exposure via tarsal contact and terbee Inc., Greenwich, NY), and 20 ml each of sugar oral licking after spray and ignores potential synergistic syrup (50%, V/V) and d-H2O in scintillation vials.
toxicity from formulating materials ( Modified Spray Tower. The Potter-Precision Lab- ). Such tests may not provide adequate oratory Spray Tower was purchased from Burkard Sci- information about formulated pesticides for growers to entific (Uxbridge, Middx, United Kingdom). For choose that may be both effective to target pests and laboratory safety and working efficiency purposes, the less harmful to honey bees if such products are available.
spray tower was reconstructed with Plexiglas to fit into Recent study evaluated the risk of a neonicotinoid insec- a fume hood. The modified spray tower, containing the ticide to bumble bees and found clothianidin was haz- original spray nozzle and nearly the same pressure air ardous to bumble bees after spraying delivering and regulating systems as those in Potter ) because foraging bees took the contaminated pol- Spray Tower, significantly reduces the time for sample len. Thus, research is promptly needed to simulate foliar handling and cleaning between chemicals. With the sprays to better understand the potential risk of pesticide spray settings at volume ¼ 0.5 ml, air pressure ¼ 69 kpa exposure in the field because foraging honey bees are (10 psi), and spray distance ¼ 22 cm, the sprayer deliv- not only directly exposed to spraying pesticides, but also ers a stream of mist into the cage which forms a thin through multiple routes simultaneously including direct layer that uniformly covers all inner sides of the cage contact, inhalation, and ingestion ). To without forming visible droplets.
provide spray toxicity data and potential risk of field ex- Dose Response Bioassay. To obtain the median posures, we simulated field spray and assessed toxicities lethal concentration (LC50) data, each chemical was of 42 commonly used formulated pesticides diluted in d-H2O to 6–7 concentrations, plus a water , to honey bees, using a (d-H2O) only as control. Bees at 4–6 d old were used modified Potter Spray Tower.
for dose-response bioassays. Each cage (containing 25bees) was treated as a replication, and three replica-tions were used for each concentration. Dead bees Materials and Methods were recorded before treatment, and cages with more Pesticides. A total of 42 formulated pesticides were than three dead bees were not used for bioassays. The examined for spray toxicity to honey bee workers, modified spray tower at the setting described above including 40 insecticides and miticides, one herbicide, was used to spray bees with 500 ml of pesticide solution.
and one fungicide. These studied were chosen from After spraying, bees were maintained at 33C and 48-h recommended crop protection chemicals listed in mortality was recorded. For some slow action and/or extension bulletins low-toxicity pesticides, the incubation was extended to 7 d to ensure the 48-h mortality is truly representative.
tions from extension entomologists and pathologists, Data Processing and Statistical Analysis. SAS and direct information from cotton farmers. Pesticides (version 9.2) probit analysis ) used for these bioassays were provided by the manufac- was conducted to calculate LC50 (lethal concentration turers or purchased from local agro-chemical suppliers.
that kill 50% honey bee workers) values and 95% ZHU ET AL.: SPRAY TOXICITY AND RISK POTENTIAL OF 42 PESTICIDES fiducial limits. Chi-square tests were applied to ensure values ). Five insecticides had an LC50 value the goodness-of-fit of the models. If a given bioassay below 100 mg/liter, suggesting higher toxicity to bees failed the goodness-of-fit chi-square test, the experi- than those with higher LC50 values. Thirteen insecti- ment was repeated. Some pesticides have low toxicity cides had an LC50 range from 100 to 300 mg/liter. Thir- to honey bees, and their 95% fiducial limits could not teen insecticides had an LC50 range from 300 to be calculated. The assays for these chemicals were 7,000 mg/liter and the remaining 11 chemicals had repeated until similar mortality patterns were reached LC50 values greater than 7,000 mg/liter. All 42 pesti- over a similar dose range.
cides were sorted into ascending order according to Risk Assessment. LC50 values are often used as a their LC50 value, while their toxicities to bees were in toxic parameter for revealing the comparative toxicity descending order in because more toxic pesti- of chemicals tested. In field, pesticides are used at dif- cides need less amount of the chemical to kill the same ferent rates or concentrations. Therefore, two chemi- percentage (50%) of bees. The slope of the dose cals having the same LC50s may pose different risks to response curve indicates the sensitivity of honey bees foraging bees if they are used at different field concen- to chemicals. The higher slopes indicate the greater trations. To correctly assess the risk of all 42 pesticides, sensitivity. Twenty-five pesticides had slopes between 1 we obtained the field use rates from extension recom- and 2. Nine chemicals had slopes below 1, while eight pesticides, including all four organophosphorus insecti- A field use (or applica- cides, had slopes greater than 2.
tion) concentration (mg/liter) was calculated by dividing the field use rate by average use volume (e.g., 10 gallon Parameters. The average fresh body weight for 16-d- per acre; ) for each pesticide. The old worker bees was 0.125 g. The average volume of toxic risk of each pesticide to bees was assessed by pesticide solution deposited on each bee was 1.575 ml using the ratio calculated by dividing the field use con- or mg per bee. By using these two numbers, lethal con- centration by toxic parameter (LC1, LC50, or LC99 to centration (LC50: mg/liter) and lethal dose (LD50: mg/ bees). If their ratios of field use concentration to LC1 bee) of formulation and active ingredient were are less than 1, these pesticides are relatively safe to obtained (). The toxicity ranks of 42 pesticides bees. If their ratios of field use concentration to LC99 were sorted by LC50s of formulations from 1, the most are greater than 1, those pesticides are highly toxic.
toxic, to 42, the least toxic pesticides. The toxicity ranks The remaining pesticides may have intermediate toxic- were also sorted by LC50s of active ingredient (column ity to bees if their ratios don't fall into the low range or 5, Re-calculating LC50s to active ingredient high range. The greater the ratio is the greater the risk changed toxicity ranks substantially for some pesticides, to honey bees. In addition, each LC50 value of all 42 and the toxicity of the chemical, different percentages formulations was converted to amount of active ingre- of active ingredient in formulations, and other potential dient. Relative toxicity of the active ingredient to honey factors may account for the discrepancy (please see dis- bees was ranked and compared to the toxicity rank of cussions). LC50s were converted to LD50s based on average weight of pesticide solution deposited on each Conversion of LC50 to LD50. Honey bee workers bee and average fresh weight of bee body. Comparison (16 d old) were immobilized by placing bees in freezer of 12 LD50s from this study with corresponding 12 (20C) until all bees fell to the bottom of cage (some LD50s from indicated that bees with barely moving legs). Five bees (as a group) four insecticides had similar range of LD50s and other were weighed immediately before and after being eight insecticides had different LD50s between our sprayed with of d-H2O using spray tower. The spray data and the data from .
volume, distance, and pressure were set the same as Among the eight insecticides, five insecticides from this describe above. The sprays were repeated eight times study had lower LD50s or higher toxicity and three with different bees. Average spray weight per bee was insecticides had lower toxicity than the same insecti- calculated by assuming 1 ml of d-H2O is equal 1 gram.
In order to compare relative toxicity in term of active Risk Assessment. The field-use rates recom- ingredient among 42 pesticides, the percentage of mended by the Delta Agricultural Digest active ingredient from pesticide label was used to cal- ) are different for different target culate LC50 in active ingredient. LD50 for either for- pests, and have a range for one specific target. We mulation or active ingredient was estimated by using used a median rate as the field use rate (oz./acre in average weight of spray solution deposited on each for each pesticide. Ratios of field use con- centration to LC1 or LC99 were used as an indicationof the toxicity risk of the various chemicals to honeybees. Results in indicated that three chemi- cals (Acetamiprid, Etoxazole, and Glyphosate) had Acute Spray Toxicity (LC50). A total of 142 dose ratios of field use concentration to LC1 less than 1, response assays were conducted. The assay was suggesting these chemicals are relatively safe to for- repeated at least twice for each pesticide to obtain aging bees because they may kill less 1% bees at the overlapped 95% fiducial limits. LC50 values and statisti- field use rate. When the field use concentrations cal analyses for all 42 pesticides are summarized in were compared with corresponding LC99 values, 26 . These chemicals showed a wide range of LC50 chemicals (with gray background in ) have a JOURNAL OF ECONOMIC ENTOMOLOGY Table 1. Spray toxicity of 42 commonly used pesticides to honey bees, measured with formulated pesticides and spray tower Toxicity to bees LC50 mg/liter 95% Fiducial limitsb Emamectin Benzoate Thiamethoxam þ l-cyhalothrin Bifenthrin þ avermectin Imidacloprid þ b-cyfluthrin Bifenthrin þ Zeta-cypermethrin Methoxyfenozide þ spinetoram l-cyhalothrin þ chlorantraniliprole a Commercial name (formulation) and Manufacturer: 1. Bidrin 8 EC by AMVAC Chemical Co.; 2. Centric 40 WG by Syngenta; 3. Denim 0.16 EC by Syngenta; 4. Belay 50 WDG by Valent; 5. Epi-Mek (Agri-Mek 0.15EC) by Syngenta; 6. Endigo 2.06ZC by Syngenta; 7. Bracket97 byWinfield Solutions LLC; 8. Mustang Max/Respect by FMC; 9. Lorsban 4E by Dow AgroSciences; 10. Dimethoate 4 E by Cheminova; 11. Lan-nate 2.4 LV by DuPont; 12. Tombstone 2 EC by Loveland; 13. Athena by FMC; 14. Arctic 3.2EC by Winfield Solutions LLC; 15. Leverage360EC by Bayer CropScience; 16. Vydate 3.77 CLV by DuPont; 17. Transform 5G by Dow AgroSciences; 18. Brigade 2 EC by Agrisolutions; 19.
Tracer 4 SC by Dow AgroSciences; 20. Baythroid XL 1 EC by Bayer; 21. Holster by Agrisolutions; Loveland; 22. Hero 1.24 by FMC; 23. Advise2 F (Couraze 1.6 F) by Winfield Solutions, LLC; 24. Declare by Cheminova; 25. Karate Z 2.08 CS by Syngenta; 26. Intrepid Edge by Dow Agro-Sciences; 27. Sevin XLR Plus by Bayer CropScience; 28. Steward EC by DuPont; 29. Asana XL 0.66 EC by Bayer; 30. Larvin 3.2 F by Bayer; 31.
Besiege by Syngenta; 32. Domark 230 ME by Valent; 33. Portal 0.4 EC by Nichino America Inc; 34. Intruder 70 WP by Gowan; 35. Carbine 50WG by FMC; 36. Zeal by Valent; 37. Diamond 0.83 EC by Mana/Chemtura; 38. Comite II by Chemtura; 39. Belt 4SC by Bayer; 40. Prevathon0.43 SC by DuPont; 41. Oberon 2 SC by Bayer; 42. Roundup PowerMAX by Monsanto.
b Because the chi-square is small (P > 0.1000), some fiducial limits were not calculated by SAS.
high risk of acute toxicity to foraging bees because from July to early September to control a com- these chemicals may kill more than 99% of bees at plex of sucking insects and a few lepidopterans. Ace- the field use rate. The remaining 13 chemicals may phate and neonicotinoids are often used to control be considered to have intermediate toxicity risk to sucking insects because these insecticides may have bees. They may kill 1 to 99% foraging honey bees at both contact and systemic toxicities. To better protect field use rate, and more bees are expected to be honey bees and other pollinators, it is important to killed by chemicals that have higher ratios of field- understand that 1) field sprays of pesticides may inevi- used concentration to LC99 ).
tably pose a risk to foraging honey bees and 2) the riskto honey bees could be minimized through the carefulselection of pesticides having lower toxicity. To achieve this goal, one strategy is to screen commonly used pes- Southern row crops, especially the cotton with longer ticides and to determine which pesticides have low tox- blooming period, are frequently sprayed icity to honey bees.
ZHU ET AL.: SPRAY TOXICITY AND RISK POTENTIAL OF 42 PESTICIDES Table 2. Toxicity of 42 pesticides, expressed as lethal concentration (LC50: mg/liter) and lethal dose (LD50: mg/bee) of formulation (F) and active ingredient (AI) 0.26 1.72(0.41–3.05) Emamectin Benzoate 0.85 0.847(0.59–1.14) 0.78 1.62(1–2.47) 0.92 1.18(0.172–2.03) 1.68 0.402(0.025–0.78) 1.28 1.18(0.2–3.7) 1.49 0.403(0.128–0.75 Methoxyfenozide þ 2.51E þ 05 1.76E þ 05 9.76E þ 05 4.88E þ 05 1.30E þ 06 9.33E þ 05 4.03E þ 07 3.75E þ 06 8.06E þ 07 5.61E þ 07 5.96E þ 08 2.32E þ 08 2.93E þ 17 1.46E þ 16 2.3046E þ 13 1.8437E þ 14 2.75E þ 19 6.36E þ 18 1.0009E þ 16 8.0076E þ 16 4.62E þ 34 2.25E þ 34 3.5474E þ 31 2.8380E þ 32 a Percentage of the active ingredient was obtained from pesticide label.
b The active ingredient and toxicity rank in five insecticide mixtures were calculated based on one component with higher percentage.
c LD50 mg/bee was calculated by multiplying LC50 value by the volume of pesticide solution deposited on each worker bee (1.575 ml/bee).
d LD50 mg/g (or LD50 mg/kg) is the lethal dose (mg) at per gram bee weight base, calculated by dividing LD50 mg/bee by average weight of worker bee (0.125 g/bee).
e Data were from .
In this study, we evaluated formulated pesticides with through tarsal contact and oral licking, a real situation a spray tower application, to realistically simulate field present in fields after they are sprayed. In addition, spray situations rather than using a topical application of spray tower application takes advantage of the ability to technical grade pesticides to measure contact toxicity. At generate pesticide vapor that may enter respiratory a constant spray pressure and standard spray distance tracts to incur inhalation toxicity The sec- and spray volume, the spray tower delivers a stream of ond novelty of the techniques used in this study was the pesticide mist uniformly which covers the whole bodies selection of commercially formulated pesticides instead of target honey bees and all the inner sides of the cage.
of technical grade (relatively pure) active ingredients.
Therefore, the spray tower application overcomes the Using formulation or active ingredient may substantially disadvantages of the popular topical application which change the toxicity ranking for many pesticides among lacks continuous exposure to pesticide residues by bees the 42 pesticides tested in this study, due to the toxicity JOURNAL OF ECONOMIC ENTOMOLOGY Table 3. Risk assessment of 42 pesticides commonly used for spray treatment of row crop pests, determined using formulated pesti- cides and spray tower Field use concentration Emamectin Benzoate Thiamethoxam þ l-cyhalothrin Bifenthrin þ avermectin Imidacloprid þ b-cyfluthrin a Refer the footnote in for Numbers, Commercial names (formulation), and Manufacturers.
b TPB: tarnished plant bug Lygus lineolaris (Palisot de Beauvois); Thrip: western flower thrip Frankliniella occidentalis (Pergande); BSB: brown stink bug Euschistus servus (Say); GSB: green stink bug Acrosternum hilare (Say); Mite: two spotted spider mite Tetranychus urticaeKoch; WF: whitefly Bemisia tabaci (Gennadius); BW: boll worm Helicoverpa zea (boddie); TBW: tobacco budworm Heliothis virescens (F.),ECB: European corn borer Ostrinia nubilalis (Hu¨bner); CEW: corn earworm Heliothis zea (Boddie); SHB: small hive beetle Aethina tumidaMurray; Aphid: cotton aphid Aphis gossypii Glover; FAW: fall armyworm Spodoptera frugiperda (J.E. Smith); Rust: soybean rust Phakopsorapachyrhizi Sydow; SB: stink bug complex; Many: multiple insect species.
c Field use concentration (FUC) was calculated by dividing field use rate by 10 gallon (field use volume).
d LC1: lethal concentration that incurs 1% mortality in test bees; the ratios, <1 (without background in the column), indicate that those pesti- cides kill <1% of the test bees.
e LC99: lethal concentration that incurs 99% mortality in test bees; the ratios, >1 (with gray background in the column), indicate that those pesticides kill >99% of the test bees.
of chemical itself, concentration in the formulated pesti- Our results make two major contributions to under- cides, and potential interaction between active ingre- standing variable acute toxicity to honey bees. First, the dient and formulating materials. However, formulated spray toxicity data for 42 commonly used pesticides in pesticides, not technical grade chemicals, are the only southern row crop systems help identify comparative choice for farmers to protect their crops when chemical toxicities to honey bees. These data provide valuable control is necessary. When exposure to field sprays information for guiding the selection of chemicals in becomes a serious issue in foraging bees, therefore, crop pest management to minimize risk to honey bees.
measuring comparative toxicity of formulated pesticides The median lethal dose (LD50) and median lethal con- instead of active ingredient would be more important to centration (LC50) are commonly used parameters for include total toxicities from the pesticide itself, the for- measuring the toxicity of a substance (U.S. Environ- mulating agents, and potential additive and synergistic mental Protection Agency ). We chose a spray tower method to treat honey bees to simulate the ZHU ET AL.: SPRAY TOXICITY AND RISK POTENTIAL OF 42 PESTICIDES field exposure of formulated pesticides. Our data risk of these chemicals to honey bees with ratios to ) revealed a wide range of LC50 values among LC99 greater than 1. This is especially true for the 42 commonly used pesticides, suggesting a possibility higher use rate of carbaryl (number 27, and to minimize chemical risk to pollinators by choosing The Gamma-Cyhalothrin (number 24) had relatively lower bee-toxicity pesticides for crop pest control. By higher slope, but its low field use rate (1.67 oz./acre) referring to the classification standard of pesticide still ranked this chemical as an intermediate-risk insec- (World Health Organization formulated ticide, suggesting the possibility to reduce bee mortality dicrotophos may be classified as an extremely toxic by decreasing field use rate.
insecticide to honey bees. Twenty insecticides (num- In summary, an increased abundance of sucking bers 2 to 21 in ) are highly toxic chemicals, insects, particularly on cotton, may trigger frequent including thiamethoxam, clothianidin, three organo- foliar sprays that may pose a risk to foraging honey phosphates (acephate, chlorpyrifos, and dimethoate), bees in the field and negatively impact developing and most pyrethroids tested. Ten pesticides (numbers brood in hives through contaminated pollen. This study 22 to 31) are moderately toxic, including imidacloprid was initiated to realistically simulate field sprays to and a few carbamate insecticides. The remaining 11 assess the toxicity of 42 commonly used pesticides for pesticides (numbers 32 to 42) are slightly toxic chemi- row crop pest control. Our data, particularly the ratios cals to honey bees, including acetamiprid, spiromesifan of field application rates to lethal concentrations of and novaluron. If LD50s (mg/g of active ingredient) are each pesticide provide a quantifying scale to help used for the classification, 33 pesticides would fall into extension specialists and farmers with pesticide selec- extremely toxic category. From this study, it is clear tion to maintain effective control of target pests and that tetraconazole (a fungicide), etoxazole (miticide), minimize the risk to foraging honey bees as well. In and glyphosate (a popular herbicide) have very minor addition, this study established a baseline and founda- or no acute toxicity to honey bees based on 48-h mor- tion for our future studies on the impact of sublethal tality data, with the results being supported by an addi- doses of major concerning insecticides on honey bee tional week-long observation.
physiology, including defense-, immunity-, stress-, and The second major contribution of this study is the metabolic-related enzyme activities and gene regula- risk assessment of the 42 pesticides to honey bees.
tions. This study will also facilitate our continuing Although the LC50 is an important parameter which research to understand whether pre-mixtures and tank- reflects the acute toxicity of a chemical, different insec- mixtures of major insecticides with other insecticide ticides may be used at different rates. The recom- classes, fungicides, and herbicides synergize toxicity mended field use rates for row crop insect control are to honey bees and negatively interact with other significantly different from 0.83 to 125 oz./acre Therefore, the risk of an insecticide to honeybees depends both on how toxic the chemical is andhow much is used in field spray. Our risk assessmentconsidered both acute spray toxicity (LC each pesticide to honey bee workers and recommended We are grateful to Dr. Don Cook of Delta Research and field use rate. The ratios of field application concentra- Extension Center (Stoneville, MS), visiting professor Dr. Ales tion to LC1 or LC99 values ) gave clear indica- Gregorc of USDA-ARS (Poplarville, MS), and many anony- tion of low-risk pesticide to bees if the ratio to LC1 is mous journal reviewers and editors for valuable comments less than 1, or high-risk pesticides if the ratio to LC99 is and suggestions that improved an early version of this manu- greater than 1. If the ratios were not included in these script. We also appreciate Sandy West, Xiaofen Fanny Liu, two categories, those pesticides are intermediate toxic Robert Cox, Les Price, Michael Everett, Richard Underhill, to bees. Furthermore, our data provided a scale to Jeremy Bemis, Gaila Oliver, Owen Houston, Faizan Tahir, measure the risk of each insecticide within each Austin Henderson, Dr. Tom Allen of Mississippi State Univer-sity Delta Research and Extension Center (Stoneville, MS), category, because the higher the ratio is, the higher risk Dr. Lilia De Guzman of USDA-ARS (Baton Rouge, LA), Dr.
Nathan Schiff of USDA Forest Service Southern Research The risk is influenced by two factors, the field appli- Station (Stoneville, MS), and Dr. Zachary Huang of Michigan cation concentration and the dose-response curve State University (East Lasing, MI) for their assistance and slope. In , 42 pesticides are listed from 1 to 42 advices in this study.
according to their LC50 toxicity from the highest (num-ber 1) to the lowest (number 42), whereas the corre- sponding risk (ratio to LC99) did not follow the sameorder. While the first 22 pesticides (number 1-22) Brandon, H., and E. Robinson, 2014. Delta Agricultural remained to be high-risk chemicals (killed >99% of Digest. Farm Press, Clarksdale, MS.
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Received 12 April 2015; accepted 20 August 2015.
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Róbert Torontáli: Intensive Krav-Maga I. Zsuzsa Fritz: Hevruta Tradition Community November 07. Friday, 17:00 - 18:30 November 08. Saturday, 11:30 - 12:45 Robert Torontáli, technical director of Intensive Krav-Maga Europe is running a very useful Experience the ancient method of text study. In pairs or in small groups juxtapose texts from the