Browsing by Author "Antwi, Frank B."

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Comparative evaluation and economic potential of ecorational versus chemical insecticides for crucifer flea beetle (Coleoptera: Chrysomelidae) management in canola
(2007-06) Antwi, Frank B.; Olson, D. L.; Carey, D. R.
From 2001 to 2004, field studies were conducted to evaluate the effect of the ecorational insecticides SpinTor (spinosad), BotaniGard ( Beauveria bassiana ), Neemix (azadirachtin), and Surround (kaolin) against crucifer flea beetle on canola, Brassica napus L., at the cotyledon stage. The ecorational treatments were compared with a standard foliar chemical insecticide, Capture (bifenthrin), and the chemical seed treatment insecticide Helix XTra (thiamethoxam). This study indicated that flea beetle injury was lower for Helix XTra, Capture, and the ecorational insecticide SpinTor. SpinTor was less effective when flea beetle populations were relatively high (200–300 per trap-week). Yields for chemical insecticide treatments were always greater than SpinTor, with differences being the smallest (68–374 kg/ha) at low levels of flea beetle feeding injury. Differences were greatest when canola seedling injury was high (775–1,364 kg/ha). Yield differences between the conventional insecticides and BotaniGard, Neemix, and Surround were 119–439 and 61–2,248 kg/ha at low and high flea beetle feeding injury, respectively. Although yield differences between SpinTor and chemical insecticides were relatively small at lower levels of flea beetle injury, net losses ranged from 03047 to 030151/ha when SpinTor was used as an alternative to a standard chemical seed treatment, Helix XTra. This suggests that SpinTor would not be a viable alternative to the chemical insecticide. Net losses ranged from 03030 to 030266/ha when BotaniGard, Neemix, and Surround were used as alternatives to the seed treatment.
Comparisons of ecorational and chemical insecticides against crucifer flea beetle (Coleoptera: Chrysomelidae) on canola
(2007-08) Antwi, Frank B.; Olson, D. L.; Carey, D. R.
Studies were done comparing the insecticides SpinTor (spinosad), BotaniGard ( Beauveria bassiana ), Neemix (azadirachtin), and Surround (kaolin, a clay) with conventional chemical insecticides Capture (bifenthrin) and Helix XTra (thiamethoxam), all applied at seven rates in a 7-d assay to assess their impact on adult crucifer flea beetle, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae). Lethal time (LT) required for 25, 50, and 75% mortality (LT 25 , LT 50 , and LT 75 ) and relative potencies for the insecticide concentration groupings (0, 1X–1.5X, and 2X–4X) were estimated for each treatment by using survival functions. P. cruciferae mortality increased in response to increasing concentrations, especially for Helix XTra, Capture and SpinTor. After 2 d of exposure in 2002, mortality ranged from 54 to 78% for Helix XTra, from 60 to 94% for Capture, and from 66 to 92% for SpinTor across concentrations. In 2003, flea beetle mortality ranged from 37 to 60%, from 29 to 63%, and from 23 to 52% on exposure to Helix XTra, Capture, and SpinTor, respectively, for 2 d. The LT 50 and relative potencies of the insecticides were in the order of Helix XTra, Capture, and SpinTor > BotaniGard, Neemix, and Surround. In 2002, LT 50 values were 1 and 2 d for Capture and SpinTor, 2 d for BotaniGard, and 3 d for Neemix and Surround. In 2003, LT 50 values occurred between 2 and 4 d after exposure to Helix XTra, Capture, and SpinTor, with LT 50 values of 5–7 d on exposure to BotaniGard, Neemix, and Surround. SpinTor seems to be a suitable ecorational insecticide in canola, Brassica napus L., for P. cruciferae management.
Efficacy of Entomopathogenic Nematodes and Sprayable Polymer Gel Against Crucifer Flea Beetle (Coleoptera: Chrysomelidae) on Canola
(2016-06) Antwi, Frank B.; Reddy, Gadi V. P.
The crucifer flea beetle, Phyllotreta cruciferae (Goeze), is a key pest of canola ( Brassica napus L.) in the northern Great Plains of North America. The efficacies of entomopathogenic nematodes ( Steinernema spp. and Heterorhabditis spp.), a sprayable polymer gel, and a combination of both were assessed on canola for flea beetle management. Plots were treated soon after colonization by adult flea beetles, when canola was in the cotyledon to one-leaf stage. Ten plants along a 3.6-m section of row were selected and rated at pre-treatment and 7 and 14 d post treatment using the damage-rating scheme advanced by the European Plant Protection Organization, where 1 = 0%, 2 = 2%, 3 = 5%, 4 = 10%, and 5 = 25% leaf area injury. Under moderate flea beetle feeding pressure (1–3.3% leaf area damaged), seeds treated with Gaucho 600 (Bayer CropScience LP Raleigh, NC) (imidacloprid) produced the highest yield (843.2 kg/ha). Meanwhile, Barricade (Barricade International, Inc. Hobe Sound, FL) (polymer gel; 1%) + Scanmask (BioLogic Company Inc, Willow Hill, PA) ( Steinernema feltiae ) resulted in the highest yields: 1020.8 kg/ha under high (2.0–5.3% leaf area damaged), and 670.2 kg/ha at extremely high (4.3–8.6 % leaf area damaged) feeding pressure. Our results suggest that Barricade (1%) + Scanmask ( S. feltiae ) can serve as an alternative to the conventional chemical seed treatment. Moreover, Scanmask ( S. feltiae ) can be used to complement the effects of seed treatment after its protection has run out.
Entomopathogens in conjunction with imidacloprid could be used to manage wireworms (Coleoptera: Elateridae) on spring wheat
(2018-02) Antwi, Frank B.; Shrestha, Govinda; Reddy, Gadi V. P.; Jaronski, Stefan T.
We examined the effect of biopesticides used alone, mixed with other biopesticides, or in conjunction with an imidacloprid against wireworms (Coleoptera: Elateridae) in spring wheat Triticum aestivum Linnaeus (Poaceae) (variety: Duclair). The study was conducted at Ledger and Valier, Montana, United States of America in 2015 and 2016. Ten biopesticides (spinosad, azadirachtin, pyrethrin, Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Fungi: Clavicipitaceae) GHA (Mycotrol), B. bassiana ANT-03 (BioCeres), Chromobacterium subtsugae Martin et al. (Bacteria: Neisseriaceae), Burkholderia Yabuuchi et al. (Burkholderiaceae) species, Metarhizium brunneum Petch (Fungi: Clavicipitaceae) ESC1 (MbESC1), and M. brunneum F52 (MetF52) as microsclerotial and corn grit-based granules) were tested in addition to thimet and imidacloprid. Treatment efficacy was based on plant stand protection, wireworm populations, and yield. In 2015, there was considerable variation between sites in treatment efficacy. Mycotrol, BioCeres, MetF52+spinosad, and MetF52+imidacloprid applications protected seedlings from wireworm damage better than the control at Ledger, while only MetF52 at Valier. Wireworm populations were significantly higher with Mycotrol, spinosad, MetF52+spinosad, MbESC1 (25 g/L), and MetF52 treatments, compared with control, at 14 and 28 days post application at Ledger, but without effect at Valier, 2015. We found significantly higher yield in plots treated with imidacloprid+MetF52 and Mycotrol+azadirachtin (Xpulse) compared with control at Ledger. In 2016, no significant treatment effects were observed at either site. In summary, this study provides insight on what treatments should be explored in more detail despite variable results.
Evaluation of toxicity of biorational insecticides against larvae of the alfalfa weevil
(2016-05) Reddy, Gadi V. P.; Antwi, Frank B.; Shrestha, Govinda; Kuriwada, Takashi
The alfalfa weevil, Hypera postica (Coleoptera: Curculionidae), is a major pest of alfalfa Medicago sativa L. (Fabaceae). While H. postica usually causes the most damage before the first cutting, in summer of 2015 damaging levels of the pest persisted in Montana well after the first harvest of alfalfa. Although conventional insecticides can control H. postica, these chemicals have adverse effects on non-target organisms including pollinators and natural enemy insects. In this context, use of biorational insecticides would be the best alternative options, as they are known to pose less risk to non-target organisms. We therefore examined the six commercially available biorational insecticides against H. postica under the laboratory condition: Mycotrol ^Â® ESO (Beauveria bassiana GHA), Aza-Direct ^Â® (Azadirachtin), Met52 ^Â® EC (Metarhizium brunneum F52), Xpectro OD ^Â® (Beauveria bassiana GHA+pyrethrins), Xpulse OD ^Â® (Beauveria bassiana GHA+Azadirachtin) and Entrust WP ^Â® (spinosad 80%). Concentrations of 0.1, 0.5, 1.0, and 2.0 times the lowest labelled rates were tested for all products. However, in the case of Entrust WP, additional concentrations of 0.001 and 0.01 times the lowest label rate were also assessed. Mortality rates were determined at 1 to 9days post treatment. Based on lethal concentrations and relative potencies, this study clearly showed that Entrust was the most effective, causing 100% mortality within 3days after the treatment among all the tested materials. With regard to other biorational, Xpectro was the second most effective insecticide followed by Xpulse, Aza-Direct, Met52, and Mycotrol. Our results strongly suggested that these biorational insecticides could potentially be applied for H. postica control.
Risk assessments for the insect repellents DEET and Picaridin
(2008-06) Antwi, Frank B.; Shama, Leslie M.; Peterson, Robert K. D.
For the use of topical insect repellents, DEET and picaridin, human health risk assessments were conducted for various population subgroups. Acute, subchronic, and chronic dermal exposures were examined. No-observed-effect-levels (NOELs) of 200, 300, and 100 mg/kg body weight (BW) were used as endpoints for DEET for acute, subchronic, and chronic exposures, respectively. For picaridin, a NOEL of 2000 mg/kg BW/day for acute exposure and a NOEL of 200 mg/kg BW/day for subchronic and chronic exposures were used. Daily exposures to several population subgroups were estimated. Risks were characterized using the Margin of Exposure (MOE) method (NOEL divided by the estimated exposure), whereby estimated MOEs were compared to an MOE of 100. Estimates of daily exposures ranged from 2 to 59 mg/kg BW/day for DEET and 2 to 22 mg/kg BW/day for picaridin. Children had the lowest MOEs. However, none of the estimated exposures exceeded NOELs for either repellent. At 40% DEET for acute exposure, children ⩽12 years had MOEs below 100. For subchronic and chronic exposures children at ⩾25% DEET and at 15% picaridin had MOEs below 100. Therefore, we found no significant toxicological risks from typical usage of these topical insect repellents.
Toxicity of natural insecticides on the larvae of wheat head armyworm, Dargida diffusa (Lepidoptera: Noctuidae)
(2016-03) Reddy, Gadi V. P.; Antwi, Frank B.
The wheat head armyworm, Dargida (previously Faronta) diffusa (Walker) (Lepidoptera: Noctuidae), is widely distributed in North American grasslands and is most common on the Great Plains, where it is often a serious pest of corn and cereal crops. Six commercially available botanical or microbial insecticides used against D. diffusa were tested in the laboratory: Entrust® WP (spinosad 80%), Mycotrol® ESO (Beauveria bassiana GHA), Aza-Direct® (azadirachtin), Met52® EC (Metarhizium brunneum F52), Xpectro® OD (Beauveria bassiana GHA + pyrethrins), and Xpulse® OD (Beauveria bassiana GHA + azadirachtin). Concentrations of 0.1, 0.5, 1.0 and 2.0 fold the lowest labelled rates of formulated products were tested for all products, while for Entrust WP additional concentrations of 0.001 and 0.01 fold the label rates were also assessed. Survival rates were determined from larval mortality at 1–9 days post treatment application. We found that among the tested chemicals, Entrust® (spinosad) was the most effective, causing 83–100% mortality (0–17% survival rate) at day 3 across all concentrations. The others, in order of efficacy from most to least, were Xpectro® (B. bassiana GHA + pyrethrins), Xpulse®OD (B. bassiana GHA + azadirachtin), Aza-Direct®(azadirachtin), Met52® EC (M. brunneum F52), and Mycotrol® ESO (B. bassiana GHA). These products and entomopathogenic fungi caused 70–100% mortality (0–30% survivability) from days 7 to 9. The tested products and entomopathogenic fungi can be used in management of D. diffusa.
Toxicity of δ- phenothrin and resmethrin to non-target insects
(2009-03) Antwi, Frank B.; Petterson, Robert K. D.
BACKGROUND: The susceptibility of adult house cricket, Acheta domesticus (L.), adult convergent lady beetle, Hippodamia convergens (Guérin-Méneville), and larval fall armyworm, Spodoptera frugiperda (JE Smith), to resmethrin and δ-phenothrin synergized with piperonyl butoxide (PBO) was evaluated in a laboratory bioassay procedure. RESULTS: The 1 day LC50 values for resmethrin + PBO were 23.2, 32.08 and 307.18 ng cm−2 for A. domesticus, H. convergens and S. frugiperda respectively. The 1 day LC50 values for δ-phenothrin + PBO were 26.9, 74.91 and 228.57 ng cm−2 for A. domesticus, H. convergens and S. frugiperdarespectively. The regression relationship between species mortality and concentration explained 51–81% of the variation for resmethrin + PBO and 72–97% of the variation for δ-phenothrin + PBO. The LC50 values decreased with time for these insecticides for all surrogate species. In terms of sensitivities among the insects to resmethrin + PBO and δ-phenothrin + PBO, A. domesticus was most sensitive, followed by H. convergens and then S. frugiperda. CONCLUSION: The results indicate that resmethrin + PBO was generally more toxic than δ-phenothrin + PBO. Based on the results, A. domesticus seems to be a good surrogate species for estimating potential non-target terrestrial insect impacts from exposure to pyrethroids used in public health applications.
Toxicological effects of pyrethroids on non-target aquatic insects
(2015-11) Antwi, Frank B.; Reddy, Gadi V. P.
The toxicological effects of pyrethroids on non-target aquatic insects are mediated by several modes of entry of pyrethroids into aquatic ecosystems, as well as the toxicological characteristics of particular pyrethroids under field conditions. Toxicokinetics, movement across the integument of aquatic insects, and the toxicodynamics of pyrethroids are discussed, and their physiological, symptomatic and ecological effects evaluated. The relationship between pyrethroid toxicity and insecticide uptake is not fully defined. Based on laboratory and field data, it is likely that the susceptibility of aquatic insects (vector and non-vector) is related to biochemical and physiological constraints associated with life in aquatic ecosystems. Understanding factors that influence aquatic insects susceptibility to pyrethroids is critical for the effective and safe use of these compounds in areas adjacent to aquatic environments.