Sabadilla Alkaloids Research Articles

Evaluation of non‐target effects of OMRI‐listed insecticides for management of Drosophila suzukii Matsumura in berry crops

AbstractThe spotted wing drosophila, Drosophila suzukii Matsumura, is an invasive pest of many fruit crops throughout North America, South America and Europe. The presence of this destructive pest has led to an increase in the number of insecticide applications. While conventional growers have an arsenal of different insecticides at their disposal, organic growers have a limited selection of effective options and rely heavily on applications of Entrust®, the organic formulation of spinosad. An important part of research is to develop more tools for organic growers and evaluate the effects of insecticides intended to target D. suzukii on natural enemies in the system. The effects of six organic pesticides alone and in combination with three adjuvants and two phagostimulants were tested in laboratory bioassays on three common natural enemies in berry production systems including two predators, Chrysoperla rufilabris and Orius insidiosus, and a parasitoid wasp, Aphidius colemani. Under the IOBC toxicity rating scale, spinosad was rated consistently from slightly harmful to harmful across natural enemy species and residue age (the effects of pesticides over time). Sabadilla alkaloids caused mortality to O. insidiosus equal to that of spinosad. All tested pesticides were at least slightly harmful to A. colemani, and the adjuvant polyether‐polymethylsiloxane‐copolymer polyether caused mortality that was not significantly different from spinosad. In general, neither the addition of adjuvants nor phagostimulants increased the mortality of the insecticides tested. The exception was polyether‐polymethylsiloxane‐copolymer polyether, but it is unclear whether it increased the toxicity of the pesticides or was simply toxic itself since it caused high mortality to A. colemani when applied alone. Sublethal effects were measured for two predatory species by measuring eggs laid and % egg hatch. Minimal sublethal effects were observed in C. rufilabris. In contrast, all tested insecticides caused reduced egg hatch in O. insidiosus compared with the control.

Evaluation of adjuvants to improve control of spotted‐wing drosophila in organic fruit production

AbstractSpotted‐wing drosophila, Drosophila suzukii (Matsumura), is a key pest of berry crops in the United States. It is managed intensively using insecticides, but organic fruit growers have few effective chemical control options. Spinosad is the most effective organically approved product for control of D. suzukii, while other organic options have not shown high levels of control. Adjuvants are products added to pesticides to improve effectiveness, and these may function as stickers, spreaders or surfactants improving the spray coverage of insecticides on surfaces and thereby increasing the likelihood that pests will contact residues. We conducted experiments evaluating organically approved biopesticides in combination with three adjuvants including poly‐1‐p‐menthene, alcohol ethoxylate and polyether‐polymethylsiloxane‐copolymer polyether to determine whether addition of adjuvants improved efficacy and residual activity of these products. Alcohol ethoxylate and poly‐1‐p‐menthene showed some inherent insecticidal activity against D. suzukii in laboratory assays. Adjuvants increased mortality of some insecticides but not to a level that would provide adequate fruit protection. Poly‐1‐p‐menthene had a negative effect when combined with hydrogen peroxide + PAA and sabadilla alkaloids. Mortality in semi‐field bioassays was quite low except for spinosad. Polyether‐polymethylsiloxane‐copolymer polyether had a negative effect on the efficacy of spinosad. The adjuvants did not extend residual activity of the insecticides. Adjuvants did not provide the expected benefits of increased performance against D. suzukii when combined with organic biopesticides. Other methods for enhancing these insecticides will need to be explored to provide organic growers with more effective chemical control options for this invasive pest.

Evaluation of organic insecticides for management of spotted‐wing drosophila (Drosophila suzukii) in berry crops

AbstractSpotted‐wing drosophila, Drosophila suzukii (Matsumura), is an invasive pest affecting fruit production in many regions of the world. Insecticides are the primary tactic for controlling D. suzukii in organic as well as conventional production systems. Organic growers have a greater challenge because fewer insecticides are approved for use in organic agriculture. The most effective organically approved product is spinosad, but alternatives are needed because of label restrictions limiting the number of applications per year, toxicity to beneficial arthropods and the risk of developing resistance. We evaluated several organically approved insecticides against D. suzukii in laboratory assays and field trials conducted on organic blueberry and raspberry farms. Spinosad was consistently the most effective insecticide, but a few other insecticides such as azadirachtin + pyrethrins, Chromobacterium subtsugae and sabadilla alkaloids showed moderate activity. None of the treatments had long residual activity. Mortality started to decline by 3 days after treatment, and by 5 days after application, the treatments were not different from the controls. These products may be useful in rotation programmes, necessary for reducing reliance on spinosad and mitigating resistance. Cultural and biological control approaches are needed in fruit production for D. suzukii management, but insecticides will likely continue to be the dominant management tactic while these other approaches are being optimized and adopted.

Efficacy of biopesticides on spotted wing drosophila, Drosophila suzukii Matsumura in fall red raspberries

AbstractDrosophila suzukii Matsumura is a significant pest of soft‐skinned fruit. Larvae of D. suzukii develop within the fruit making it unmarketable as fresh berries and increasing the risk of rejection by processors. We evaluated selected biopesticides for control of D. suzukii in fall red raspberries, Rubus idaeus L. The trial results highlight a small number of biopesticides with the potential to reduce infestation of Drosophila larvae in raspberries. In addition to the standard biopesticide spinosad, we found that sabadilla alkaloids and Chromobacterium subtsugae both reduced the number of Drosophila larvae in raspberry fruit. Treatments that included corn syrup as a feeding stimulant showed no significant difference in their infestation levels compared to treatments without the syrup. In the final week of the 5‐week trial, treatments with rotations of either spinosad/C. subtsugae or spinosad/sabadilla alkaloids had a 67% and 57% reduction in infestation when compared to untreated raspberries. Treatments of spinosad alone on a 7 day rotation and C. subtsugae alone on a 3–5 day rotation both had a 62% and 61% reduction in larval infestation when compared to untreated raspberries. Third instar larvae, the largest and most damaging, were significantly reduced in plots treated with spinosad only, a rotation of spinosad/sabadilla alkaloids and the rotation of spinosad/C. subtsugae with corn syrup added when compared to untreated plots. This suggests that either of these biopesticides could be used as effective rotation partners along with spinosad for control of D. suzukii. Our results highlight that biopesticides can provide significant reduction in this devastating pest when used alone or in combination, providing options to support resistance management.

Efficacy of organically approved insecticides against brown marmorated stink bug, Halyomorpha halys and other stink bugs

The brown marmorated stink bug, Halyomorpha halys (Stal), is a serious invasive pest in the USA. Organic growers have limited options to effectively manage this pest. Several organically approved insecticides including pyrethrins, azadirachtin, spinosad, potassium salts of fatty acids, sabadilla, extract from Burkholderia sp., and two combination products were evaluated for toxicity to H. halys nymphs and adults using laboratory bioassays and evaluated in field experiments on tomatoes and peppers using weekly applications of the highest labeled rates of the products. In submersion bioassays, high mortality (>70%) of H. halys nymphs was achieved with pyrethrins, azadirachtin, azadirachtin + pyrethrins, potassium salts + spinosad, and sabadilla alkaloids. Using the same bioassay for adult H. halys, only pyrethrins, azadirachtin + pyrethrins, and potassium salts resulted in high mortality. In bean dip bioassays, only pyrethrins resulted in moderate mortality of nymphs and high mortality of adults. In field experiments, which included weekly insecticide applications, none of the insecticides that were tested significantly reduced stink bug feeding injury (from all species) to tomatoes or peppers with the exception of one harvest date of peppers in 2014, where pyrethrins + azadirachtin had less injury than the control. Our results confirm that several organically approved insecticides may demonstrate a high level of activity on H. halys in laboratory bioassays, but when applied in the field, none of the products that we tested appear to be consistently effective at reducing stink bug injury to peppers or tomatoes.

Purification and Quantitative Analysis of Veratridine and Cevadine by HPLC

As part of a study to determine the variation in the effectiveness of commercial pesticide formulations of ester steroidal alkaloids from sabadilla (Schoenocaulon officinale Grey) seeds in the integrated pest management of citrus, a method to isolate and measure large quantities of alkaloids from natural starting materials was needed. The addition of the solvent modifier sodium dodecyl sulfate (SDS) to a previously published HPLC method greatly improved peak resolution by minimizing peak tailing. The use of the non-ester alkaloid papaverine as an internal standard permitted quantification of sabadilla alkaloids by HPLC, and this modified method was then used to monitor the breakdown of cevadine and veratridine, the two most abundant sabadilla alkaloids, in aqueous solutions as a function of time and pH.

The distribution and abundance of phytoseiid mites (Acari: Phytoseiidae) on citrus in southern Africa and their possible value as predators of citrus thrips (Thysanoptera: Thripidae)

On citrus in Zimbabwe, Swaziland and South Africa, predacious mites of the subfamily Amblyseiinae are more common and found in greater numbers than phytoseiids of the subfamily Phytosciinae. The author's survey and other collection data indicated that within the Amblyseiinae the genus Euseius Wainstein is the most widely distributed. Seven Euseius spp. have been recorded on citrus in the above countries but not more than one species has been found at any particular site and time. E. citri (Van der Merwe and Ryke) has the broadest geographical distribution and is capable of suppressing population levels of the citrus thrips Scirtothrips aurantii Faure. However, it is not as effective a biocontrol agent as E. addoensis (Van der Merwe and Ryke) which occurs in higher numbers further south. An orchard comparison of the non-target effects of thripicides showed that E. citri was more susceptible to sabadilla alkaloids (0.0024% AI) plus sugar (0.96%) than to tartar emetic (0.398% AI) plus sugar (0.4%). The author's survey provides the first records of E. orygmus (Ueckermann and Loots) and E. tutsi (Pritchard and Baker) on citrus in Zimbabwe. Typhlodromalus Muma spp. were not widely distributed but where they did occur they were often abundant and sometimes coexisted with Euseius spp. Circumstantial evidence indicated that Typhlodromalus spp. may be effective thrips predators. The combination of Euseius and Typhlodromalus spp. may provide more effective biological control of citrus thrips than either species alone. Amblydromella Muma spp. were the only representatives of the subfamily Phytoseiinac currently found on citrus and they occurred only in the Transvaal and Natal provinces of South Africa. The possibility that Amblydromella spp. compete with Amblyseiinae is discussed.

Sabadilla Alkaloids IX: Isolation of Unreported Minor Constituents and Their Relationship to the Known Sabadilla Alkaloids

Additional minor alkaloidal constituents of sabadilla have been isolated from vera-trine. Four of these were obtained as symmetrical countercurrent distribution peaks. A fifth, sabadene, was obtained in crystalline form. Sabadene possessed no hypotensive properties. The investigation also notes the existence of extremely minor quantities of unresolved constituents. A review of the relationship of all reported sabadilla alkaloids is presented..

Sabadilla Alkaloids VI Separation of Veratridine and Cevadine by CountercurrentDistribution. pH vs. Partition Coefficients

Contrary to previously reported results of partition studies, the plot of the partition coefficient vs. pH for both cevadine and veratridine has been shown to be linear. The two alkaloids were separated from each other in a high state of purity by countercurrent distribution with chloroform and 0.5 M citrate buffer at pH 3.95 with a relatively small number of transfers as well as on a partition column using the same conditions. A much greater number of transfers was required to separate them by countercurrent distribution with benzene and 0.5 M phosphate buffer at pH 5.85. No effective separation could be made on a partition column using the latter conditions. A nonaqueous titration for the alkaloids in benzene or chloroform solution was perfected and an ultraviolet spectral ratio method for detection and analysis of cevadine occurring with veratridine was applied.

A Note on Sabadilla Alkaloids. Cevadine

A Note on Sabadilla Alkaloids. Cevadine

Sabadilla Alkaloids: IV. Separation of Veratridine and Cevadine by Partition Chromatography

Veratridine and cevadine have been separated in a high state of purity from prepared mixtures of the known alkaloids, from commercial veratrine, and from the mixture of alkaloids obtained by Skellysolve® B extraction of sabadilla seed by partition chromatography on a silicic acid column buffered at pH 4.00 and 4.25, using chloroform as the eluting solvent.

Sabadilla Alkaloids. III. Chromatographic Separation of the Water-Soluble Fraction. Isolation of a New Crystalline Alkaloid, Sabatine

By partition chromatography on a buffered silicic acid column, evidence has been obtained for the presence of at least five additional alkaloids in the water-soluble portion, crude fraction D (see paper I in this series) of sabadilla alkaloids. One of the new alkaloids has been obtained in crystalline state and given the name “sabatine.” Upon hydrolysis it gives rise to a new alkanolamine, which has been given the name “sabine.” Some of its properties and the results of preliminary pharmacological tests are reported.

Sabadilla alkaloids. I. Extraction of total alkaloids

A method is described by which the total sabadilla alkaloids were extracted from the seed and by which a partial separation of the crude alkaloidal mixture into four crude fractions was accomplished. Extraction of the seed with Skelly B removed the oil almost completely, in amounts up to 20 per cent, together with alkaloidal Fraction A, which was shaken out of the Skelly extract with acid. Extraction of the defatted seed with alcohol removed the remaining alkaloids. Concentration of this extract to a syrup and pouring into cold water yielded a precipitate of Fraction B which contained a considerable amount of alkaloid along with nonalkaloidal matter, probably resin. The filtrate from Fraction B, upon being made alkaline with ammonia, deposited Fraction C, which was removed by filtration. Chloroform extraction of the filtrate from C yielded Fraction D. From 15.5 Kg. of seed the following approximate amounts of the above fractions were obtained: A, 152 Gm.; B, 800 Gm.; C, 220 Gm.; D, 168 Gm.