Sucrose Octanoate Research Articles

European starling feeding activity on repellent treated crops and pellets

The varied diet of European starlings (Sturnus vulgaris L.) can present challenges when working with starlings in experimental testing and holding situations and should be taken into account when testing repellents applied to food. Our purpose was to evaluate an anthraquinone-based repellent (Arkion Life Sciences, New Castle, DE, USA; active ingredient 50% 9,10-anthraquinone; hereafter anthraquinone) and SucraShield™ (Natural Forces, Davidson, NC, USA; active ingredient 40% sucrose octanoate esters) repellent for non-lethal protection of specialty crops (i.e., fruit, sweet corn) and grains. Our objectives were to evaluate (1) laboratory efficacy of anthraquinone applied topically to blueberries and sweet corn, (2) laboratory efficacy of anthraquinone applied to two pellet matrices, and (3) laboratory efficacy of SucraShield™ as a chemical repellent for European starlings. We found that anthraquinone was not an effective repellent for blueberries or sweet corn, although consumption of each matrix varied potentially due to sucrose content. Anthraquinone was an effective repellent on CU Bird Carrier pellets with 6275 ppm needed to achieve 80% repellency, whereas up to 35,000 ppm anthraquinone was not effective when the anthraquinone was not topically applied. SucraShield was not an effective repellent for starlings and in fact increased consumption of CU Bird Carrier as concentration increased.

Formulating essential oil microemulsions as washing solutions for organic fresh produce production

Applications of plant-derived organic essential oils (EOs) as antimicrobials for post-harvest produce operations are limited by their low water solubility. To dissolve EOs in water, microemulsions were studied using two surfactants permitted for organic production, sucrose octanoate ester (SOE) and soy lecithin that were mixed at various mass ratios before dilution with water to 40% w/w. EOs were then mixed with the surfactant solution by hand shaking. Based on visual transparency, intermediate lecithin:SOE mass ratios favoured the formation of microemulsions, e.g., up to 4.0% clove bud oil at ratios of 2:8 and 3:7, and 4.0% cinnamon bark oil and 3.0% thyme oil at ratios of 2:8 and 1:9, respectively. Microemulsions with intermediate lecithin:SOE mass ratios had a relatively low viscosity and better ability to wet fresh produce surfaces. The microemulsions established in this work may be used as washing solutions to enhance the microbial safety of organic fresh produce.

Biorational glycol diesters as dietary toxins versus bioefficacy of sucrose octanoate against lepidopteran larvae

A series of biorational glycol diesters were prepared which have similar characteristics as sugar esters. From 62 glycol diesters prepared, 35 compounds were active in the range of 1–10mg/ml concentration in diet that inhibited larval growth of second instars of Spodoptera litura and Helicoverpa armigera. The most inhibitory compounds to growth were ethylene, diethylene and triethylene glycol dialkanoates with EC50 range of 1–5mg/ml for S. litura and 2–6.5mg/ml for H. armigera. Comparatively, sucrose octanoate, the known insecticidal sugar ester, was least active (EC50=10.76 and 9.02mg/ml for S. litura and H. armigera, respectively). Toxicity induced by glycol diesters is not mediated through feeding inhibition as relative consumption rate was never significantly reduced but the relative growth rate was reduced by 25–54% in S. litura and 26–44% in H. armigera. Efficiency of conversion of ingested food (ECI) was also significantly reduced. Obviously, these results do not implicate any absolute antifeedant effect, but a toxicity effect due to a reduced ECI. This was surprisingly opposite to sucrose octanoate action, where a significant effect on consumption and not the ECI was observed after oral administration, which suggests an antifeedant effect. From structure/activity point of view, increasing the chain length of molecules decreased the activity. This is obvious from least activity obtained in molecules like propane, methyl propane and pentane derivatives. Second, the deviation from open chain compounds to cyclohexyl alkanoates also reduced the activity substantially. Therefore, an open chain glycol diester of C-8 carbon length is required for the said activity against lepidopterans.

Comparative bioefficacy of biorational ethylene glycol diesters and sucrose octanoate against Lipaphis erysimi (Homoptera: Aphididae)

AbstractWe report the toxicological effects of new series of biorational glycol esters and compare the efficacy with the known commercial sugar ester, sucrose octanoate. Ethylene glycol diesters were easy to prepare without any isomeric constraints and very safe compounds that were applied as sprays or as residues. The compounds were equally toxic to mustard aphid, Lipaphis erysimi nymphs and adults and the activity was significantly comparable with sucrose octanoate activity. In spray assays LC50 of various compounds ranged from 1.32 to 11.5 mg/ml and in residual assay the range was 20.3–51.4 μg/cm2. In residual assay, ethylene glycol di‐2‐ethylhexanoate (5) and dioctanoate (6) were as effective as sucrose octanoate. Structure activity relationship suggested that higher number of carbon chains in these two compounds may be playing a role in the stability of compounds under residual operation of the insecticide. Based on these results, glycol esters would be useful and easy to prepare biorational compounds in integrated pest management.

Mortality of Bemisia tabaci biotype B (sternorrhyncha: aleyrodidae) adults by aliphatic and aromatic synthetic sucrose esters

The B-strain of Bemisia tabaci Gennadius is a key pest of several crops and chemical control is the main control method used by growers, although reduction in efficacy due to insecticide resistance has already been reported. The aim of this work was to investigate the insecticidal effect of an array of synthetic sucrose esters with the aliphatic and aromatic groups on whitefly adults. Sucrose butyrate, caprate, octanoate, palmitate, oleate, octaacetate, phthalate, benzoate, and sucrose diacetate hexaisobutyrate were tested. The solutions were prepared and applied on the adults caught on yellow sticky traps using the Potter spray tower. Long-chains sucrose aliphatic esters were more effective against the silverleaf whiteflies and the highest mortality was obtained with sucrose oleate and sucrose octanoate. Since these compounds were tensoactive, sodium dodecylsulphate was also tested for the comparison but no effect was observed. Sucrose butyrate and other aliphatic and aromatic sucrose polyesters showed negligible effect on the silverleaf whiteflies.

Characterization and insecticidal activity of sucrose octanoates

Sucrose esters, a new class of biopesticides related to the Nicotiana family, were synthesized efficiently under vacuum and isolated by column chromatography (CC). The isolations were characterized with mass spectrometry (MS) and nuclear magnetic resonance (NMR). Their insecticidal activities against Lymantria dispar grubs were determined. Thin-layer chromatography ultraviolet (TLC-UV) spectrophotometric analyses showed that the ratio of the monoesters to others in the reaction product was 1.48:1. After isolation by CC., three groups, which had polarity from weak to strong, were obtained in high purity. Both electrospray ionization (ESI)-MS and 1H NMR analyses proved that these groups were triesters, diesters and monoesters, respectively. According to their peak areas of gas chromatographic (GC) analyses, the monoester content was 61.72%. Among these esters, the reaction product and monoesters presented the highest insecticidal activities. The Lymantria dispar grub mortality reached 79.2% after being treated for 5 days with 12 mg/mL of the reaction products. The results indicate the synthesized sucrose octanoate product under vacuum is a good insecticide candidate.

Synthesis of insecticidal sucrose esters

Some synthetic sucrose esters (SE) are a relatively new class of insecticidal compounds produced by reacting sugars with fatty acids, which are safe for the environment. Especially, sucrose esters composed of C6–C12 fatty acids have desirable insecticidal properties against many soft-bodied arthropod pests. In our study, sucrose octanoate which has the highest activity against a range of arthropod species was synthesized by a trans-esterification method and proved its insecticidal property. Under the condition of a homogeneous liquid, sucrose octanoate was prepared by reacting ethyl octanoate with sucrose at reduced pressure; the yield was 79.11%. Sucrose octanoate synthesized was identified and its property analyzed by IR, TLC and spectrophotometric analysis. It was shown that the ratio of monoester to polyester in sucrose octanoate was 1.48:1. The insecticidal activity of the synthetic sucrose octanoate was evaluated at a concentration of 4 and 8 mg·mL−1. The mortality of first-instar larvae of Lymantria dispar from its contact toxicity was 72.5% after 36 hours, the revision insect reduced rate of Aphis glycines reached above 80% at 4 and 8 mg·mL−1 after being treated for 5 days. Since the SE products are nontoxic to humans and higher animals, fully biodegradable and hydrolyzed to readily metabolizable sucrose and fatty acid, they are not harmful to crops and appear to be good insecticide candidates.

Toxicity of Sucrose Octanoate to Egg, Nymphal, and Adult <I>Bemisia tabaci</I> (Hemiptera: Aleyrodidae) Using a Novel Plant-Based Bioassay

The sweetpotato whitefly, Bemisia tabaci (Gennadius), B biotype, presents a unique problem for vegetable growers by serving as a vector of plant viruses and by inducing physiological disorders of leaves and fruit. An action threshold of a single whitefly is necessary because of the threat of disease in many areas and growers rely heavily on a single class of insecticides (neonicotinoids) for whitefly control. Additional control methods are needed to manage this pest in commercial vegetables. Extracts of wild tobacco contain natural sugar esters that have previously been shown effective in controlling many soft-bodied insects. We developed a novel tomato leaf bioassay system to assess a synthetic sugar ester derivative, sucrose octanoate, for insecticidal activity against the eggs, nymphs, and adults of B. tabaci. The LC50 values for sucrose octanoate against adults, second instars, and fourth instars of the whitefly were 880, 686, and 1,571 ppm, respectively. The LC50 against whitefly eggs was higher (11,446 ppm) but indicated that some egg mortality occurred at the recommended application rate of 0.8-1.2% (3,200-4,800 ppm [Al]). Toxicity of sugar esters to whitefly eggs has not been reported previously. The tomato leaf bioassay produced reliable and repeatable results for whitefly toxicity studies and predicted that effective nymph and adult whitefly control can be achieved with sucrose octanoate at application rates < or = 1% (4,000 ppm [AI]). Field efficacy studies are warranted to determine whether this biorational pesticide has application in commercial tomato production.

PFGSE–NMR study of the self-diffusion of sucrose fatty acid monoesters in water

The micellization of pure monosubstituted sucrose fatty acid esters in water, namely sucrose octanoate, sucrose decanoate, sucrose laurate, sucrose dodec-5- cis-enoate, sucrose myristate, and sucrose palmitate, has been investigated by means of two NMR methods, pulsed field gradient spin-echo NMR (PFGSE–NMR), giving access to the self-diffusion coefficients of free molecules and micelles in solution, and the ERETIC method (electronic reference to access in vivo concentrations) for the measurement of concentrations by external calibration of a synthetic NMR signal. The early micellar regions and, when possible, the premicellar regions were investigated. By this method, we obtained the hydrodynamic radii of micelles, displaying a linear progression in relation to the chain length and an accurate determination of critical micellar concentration (CMC) for each sucrose ester. The effect of the regiochemistry of fatty chain grafting has been investigated, showing special behavior for 1 ′ - O-sucrose palmitate.

Sucrose octanoate toxicity to brown citrus aphid (Homoptera: Aphididae) and the parasitoid Lysiphlebus testaceipes (Hymenoptera: Aphidiidae).

We report the toxicological effects of a new biorational, synthetic sucrose octanoate (AVA Chemical Ventures L.L.C., Portsmouth, NH), on brown citrus aphid, Toxoptera citricida (Kirkaldy), nymphs and adults and to its native parasitoid Lysiphlebus testaceipes (Cresson). Sucrose octanoate topically applied was equally toxic to brown citrus aphid adults and nymphs with LC50 and LC90 values ranging from 356 to 514 and 1029 to 1420 ppm, respectively. Mortalities of both stages did not differ significantly over time during the 3-24-h sampling period. Dry residues of sucrose octanoate exhibited similar levels of toxicity to both nymphs and adults. Mortality ranged from 60 to 70% at 6,000 ppm 4 h after exposure. L. testaceipes was not harmed by treatments as high as 4,000 ppm of sucrose octanoate as long as the parasitoid had mummified before treatment. Based on these results, sucrose octanoate would be a useful biorational in citrus integrated pest management programs.

Effect of sucrose octanoate on survival of nymphal and adult Diaphorina citri (Homoptera: Psyllidae).

Asian citrus psylla, Diaphorina citri Kuwayama (Homoptera: Psyllidae) was detected for the first time in the United States near Delray Beach, FL, on 2 June 1998 and is continuing to spread and multiply throughout southern Florida. This psyllid is the vector of Liberobacter asiaticum, a phloem-limited bacterium that causes citrus greening disease. This pathogen has not been found in the Western Hemisphere to date. Furthermore, high infestation levels of D. citri can impact citrus plant health, fruit quality, or yield. Replicated laboratory and spray booth bioassays were conducted to determine the insecticidal activity of a synthetic analog of natural sugar esters found in leaf trichomes of wild tobacco, Nicotiatna gossei Domin, to nymphal and adult D. citri. Field trials were initiated in Fort Pierce, FL, in 2000 to determine activity of the sugar ester formulation (sucrose octanoate) on D. citri and other citrus pests, including immature Asian citrus leafminer, Phyllocnistis citrella Stainton and mites. Sucrose octanoate rates tested ranged from 400 to 8000 ppm (0.1-2% formulated product). Our data suggest that both nymphal and adult D. citri as well as the mite complex tested would be equally controlled to levels of >90% at the higher concentrations of sucrose octanoate and that good coverage is key to efficacy.

SAFETY OF A NOVEL INSECTICIDE, SUCROSE OCTANOATE, TO BENEFICIAL INSECTS IN FLORIDA CITRUS

Laboratory trials were used to estimate the toxicity of sucrose octanoate to beneficial insects representing four insect orders of importance in biological control in Florida citrus. First instars of the ladybeetles Cycloneda sanguinea L., Curinus coeruleus Mulsant, Harmonia axyridis Pallas and Olla v-nigrum Mulsant (Coleoptera: Coccinellidae) and the lacewing Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) survived topical sprays of sucrose octanoate at 8,000 ppm without significant mortality, a concentration corresponding to twice the recommended field rate required to kill aphids and other soft bodied pests. Similarly, adults of the red scale parasitoid, Aphytis melinus De Bach (Hymenoptera: Aphelinidae) and second instars of the predatory bug Orius insidiosus (Say) (Hemiptera: Anthocoridae) survived 24 h exposures to residues of 8,000 ppm sucrose octanoate on leaf disks without significant mortality. The efficacy of sucrose octanoate as a contact insecticide against various homopteran pests of citrus, combined with its low toxicity to key beneficial insects in the citrus ecosystem, suggest that it may be a valuable material for incorporation into IPM programs for Florida citrus.

Structure-function relationships affecting the insecticidal and miticidal activity of sugar esters.

Synthetic sugar esters are a relatively new class of insecticidal compounds that are produced by reacting sugars with fatty acids. The objective of this research was to determine how systematic alterations in sugar or fatty acid components of sugar ester compounds influenced their insecticidal properties. Sucrose octanoate, sorbitol octanoate, sorbitol decanoate, sorbitol caproate, xylitol octanoate, xylitol decanoate and xylitol dodecanoate were synthesized and evaluated against a range of arthropod pests. Dosage-mortality studies were conducted on pear psylla (Cacopsylla pyricola Foerster) on pear, tobacco aphid (Myzus nicotianae) Blackman and tobacco hornworm (Manduca sexta [Johannson]) on tobacco, and twospotted spider mite (Tetranychus urticae Koch) on apple in laboratory bioassays. These sugar esters were compared with insecticidal soap (M-Pede, Dow AgroSciences L.L.C., San Diego, CA), to determine how toxicologically similar these materials were against the arthropod pests. Substitutions in either the sugar or fatty acid component led to significant changes in the physical properties and insecticidal activity of these compounds. The sugar esters varied in their solubility in water and in emulsion stability, yet, droplet spread upon pear leaves occurred at low concentrations of 80-160 ppm and was strongly correlated with psylla mortalities (R2 = 0.73). Sequentially altering the sugar or fatty acid components from lower to higher numbers of carbon chains, or whether the sugar was a monosaccharide or disaccharide did not follow a predictable relationship to insecticidal activity. Intuitively, changing the hydrophile from sorbitol (C6) to xylitol (C5) would require a decrease in lipophile chain length to maintain hydrophilic-lipophilic balance (HLB) relationships, yet an increase in lipophile chain length was unexpectedly needed for increasing insecticidal activity. Thus, the HLB of these materials did not correlate with pear psylla mortalities. Initial insect bioassays and dosage-mortality data found significant differences among sugar ester compounds' toxicity to the range of arthropod species. Sucrose octanoate high in monoester content had the highest activity against the range of arthropod pests at low concentrations of 1200-2400 ppm. No single chemical structure for the xylitol or sorbitol esters were optimally effective against the range of arthropods we tested and sorbitol octanoate and xylitol decanoate had the highest insecticidal activity of this group. All of the sugar ester materials produced high T. urticae mortalities on apple at very low concentrations of 400 ppm. Overall, most of the sugar esters that were examined had superior insecticidal activity compared with insecticidal soap. Sugar ester chemistry offers a unique opportunity to design an insecticide or miticide specific to certain arthropod pests which would be valuable in crop integrated pest management (IPM) programs. Sucrose esters are currently used as additives in the food industry which makes them especially attractive as safe and effective insecticides.