How Effective Is Conservation Biological Control in Regulating Insect Pest Populations in Organic Crop Production Systems?

Organic crop production systems are designed to enhance or preserve the presence of natural enemies, including parasitoids and predators, by means of conservation biological control, which involves providing environments and habitats that sustain natural enemy assemblages. Conservation biological control can be accomplished by providing flowering plants (floral resources) that will attract and retain natural enemies. Natural enemies, in turn, will regulate existing insect pest populations to levels that minimize plant damage. However, evidence is not consistent, based on the scientific literature, that providing natural enemies with flowering plants will result in an abundance of natural enemies sufficient to regulate insect pest populations below economically damaging levels. The reason that conservation biological control has not been found to sufficiently regulate insect pest populations in organic crop production systems across the scientific literature is associated with complex interactions related to intraguild predation, the emission of plant volatiles, weed diversity, and climate and ecosystem resources across locations where studies have been conducted.

Overwintering, Host-Plant Selection, and Insecticide Susceptibility of Systena frontalis (Coleoptera: Chrysomelidae): A Major Insect Pest of Nursery Production Systems.

Systena frontalis (F.) is a major insect pest of nursery production systems in the Midwest and Northeastern regions of the United States with the adults feeding on plant leaves, which reduces salability. However, there is conflicting information on overwintering, and no information on host-plant selection or insecticide susceptibility of S. frontalis adults. Therefore, we conducted a series of experiments under greenhouse, laboratory, and field conditions from 2015 to 2019. The overwintering experiment was isolated in a greenhouse to assess adult emergence from growing medium of containerized plants collected from a wholesale nursery. We found that S. frontalis overwinters in growing medium based on adults captured on yellow sticky cards and the presence of adults on new plant growth. Host-plant selection experiments were conducted at the wholesale nursery and under laboratory conditions to determine feeding selection based on S. frontalis adult feeding damage on whole plants using a foliar damage ranking scale for different cultivars of Itea virginica L., Hydrangea paniculata Siebold, Weigela florida (Bunge), and Cornus sericea L., plants. We found that S. frontalis adults exhibited no preference for the leaves of the plant species or cultivars tested in the field or laboratory. Insecticide efficacy experiments were conducted under field and laboratory conditions. In the field experiments, the insecticides acetamiprid, dinotefuran, and Isaria fumosorosea (Wize) (Hypocreales: Clavicipitaceae) provided better protection of plants from S. frontalis adult feeding than the untreated check. In the laboratory experiments, the acetamiprid and pyrethrins with canola oil treatments provided the highest percent S. frontalis adult mortality.

Effect of Integrating the Entomopathogenic Fungus (Hypocreales: Cordycipitaceae) and the Rove Beetle (Coleoptera: Staphylinidae) in Suppressing Western Flower Thrips (Thysanoptera: Thripidae) Populations Under Greenhouse Conditions.

Western flower thrips, Frankliniella occidentalis (Pergande), is a destructive insect pest in greenhouse production systems. Therefore, integrating the entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin, with the soil-dwelling rove beetle, Dalotia coriaria (Kraatz), targeting different aboveground and belowground life stages may help effectively manage western flower thrips populations. Two greenhouse experiments were conducted evaluating five treatments: 1) insecticides (spinosad, pyridalyl, chlorfenapyr, and abamectin), 2) B. bassiana, 3) D. coriaria, 4) B. bassiana and D. coriaria combination, and 5) water control. The estimated mean number of western flower thrips adults captured on yellow sticky cards was significantly lower for the insecticide treatment (mean range: 0-46 western flower thrips adults per yellow sticky card) than the B. bassiana and D. coriaria combination (0.3-105.1 western flower thrips per yellow card) over 8 wk. There were no significant differences in the final foliar damage ratings of chrysanthemum, Dendranthema × grandiflorum (Ramat.) Kitam., plants among the five treatments in experiment 1, but there were significant differences in experiment 2. In experiment 2, chrysanthemum plants across all treatments were not marketable due to western flower thrips feeding damage. Therefore, using B. bassiana and D. coriaria early in production should suppress population growth by targeting both foliar-feeding and soil-dwelling life stages of western flower thrips simultaneously.

Systemic Insecticide Applications: Effects on Citrus Mealybug (Hemiptera: Pseudococcidae) Populations Under Greenhouse Conditions.

The citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), is a major insect pest of greenhouse-grown horticultural crops. Applications of systemic insecticides as drenches to the growing medium are typically used by greenhouse producers to prevent or suppress citrus mealybug populations. A comprehensive study was conducted that included 11 experimental trials designed to assess the effects of growing medium applications of six systemic insecticides (azadirachtin, dinotefuran, flonicamid, imidacloprid, spirotetramat, and thiamethoxam) in preventing the establishment of and suppressing citrus mealybug populations on different plant species. The experimental trials included four plant species: Solenostemon scutellarioides, Gerbera jamesonii, Begonia × semperflorens-cultorum, and Salvia splendens, with six different cultivars grown in research greenhouses similar to those used in greenhouse production systems. In addition, feeding location (plant stem, leaf top, and leaf bottom) of citrus mealybugs on the various plants was also recorded. Overall, percent citrus mealybug mortality was consistently <50% (n = 255 to 1,598) for any treatment or rate of application; regardless if the systemic insecticides were applied preventatively or curatively. Percent citrus mealybug mortality did reach 78% (n = 36) for thiamethoxam at 8 times the label rate when plants were treated preventatively. Furthermore, none of the treatments prevented development of citrus mealybug F1 individuals to F2 generation egg-laying females on S. scutellarioides or G. jamesonii plants. Citrus mealybugs varied in their spatial distribution on the plant stem, leaf top, and leaf bottom with no noticeable trends. Therefore, based on the results of the study, systemic insecticides are not effective against the citrus mealybug in greenhouse production systems.

Effects of Pesticides on the Survival of Rove Beetle (Coleoptera: Staphylinidae) and Insidious Flower Bug (Hemiptera: Anthocoridae) Adults.

This study determined the direct, indirect, or both effects of pesticides on the rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), and the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae). The pesticides evaluated were Capsicum oleoresin extract, garlic oil, and soybean oil; cyantraniliprole; flupyradifurone; GS-omega/kappa-Hxtx-Hv1; Isaria fumosorosea; tolfenpyrad; pyrethrins; and spinosad. One experiment was conducted in a greenhouse with rove beetle adults exposed to growing medium applications of cyantraniliprole. The number of live and dead rove beetle adults was determined after 10 d. Four additional experiments were conducted under laboratory conditions. Rove beetle or insidious flower bug adults were individually placed into Petri dishes with filter paper treated with the pesticides. After 24, 48, 72, and 96 h, the number of live and dead adults of both natural enemies was recorded. GS-omega/kappa-Hxtx-Hv1 (VST-006340LC); tolfenpyrad; Capsicum oleoresin extract, garlic oil, and soybean oil (Captiva); and Isaria fumosorosea were not directly harmful to O. insidiosus (80-100% adult survival). Likewise, the pesticides such as tolfenpyrad, Captiva, and I. fumosoroea were not directly harmful to D. coriaria (80-100% adult survival). D. coriaria was more sensitive to VST-006340LC (40% survival) than O. insidiosus (100% survival), whereas O. insidiosus was more sensitive to flupyradifurone (0% survival) than D. coriaria (80% and 40% survival for both rates tested, respectively). The pesticides pyrethrins, spinosad, flupyradifurone, and combinations of tolfenpyrad and Captiva were directly harmful (<50% adult survival) to both natural enemies. However, none of the pesticides tested affected the ability of O. insidiosus adults to feed on western flower thrips adults.

Direct and Indirect Effects of Pesticides on the Insidious Flower Bug (Hemiptera: Anthocoridae) Under Laboratory Conditions.

Greenhouse producers are interested in integrating natural enemies along with pesticides to suppress western flower thrips, Frankliniella occidentalis (Pergande), populations. The insidious flower bug, Orius insidiosus (Say), is a commercially available natural enemy of western flower thrips. We conducted a series of laboratory experiments to determine the direct and indirect effects of 28 pesticides (insecticides, miticides, and fungicides), 4 pesticide mixtures, and 4 surfactants (36 total treatments plus a water control) on the adult O. insidiosus survival and predation on western flower thrips adults under laboratory conditions. The number of live and dead O. insidiosus adults was recorded after 24, 48, 72, and 96 h. The results of the study indicate that the fungicides (aluminum tris, azoxystrobin, fenhexamid, and kresoxim-methyl), insect growth regulators (azadirachtin, buprofezin, kinoprene, and pyriproxyfen), botanicals (Capsicum oleoresin extract, garlic oil, soybean oil; and rosemary, rosemary oil, peppermint oil, and cottonseed oil), and entomopathogenic fungi (Beauveria bassiana and Metarhizium anisopliae) were minimally directly harmful to adult O. insidiosus, with 80% to 100% adult survival. However, abamectin, spinosad, pyridalyl, chlorfenapyr, tau-fluvalinate, imidacloprid, dinotefuran, acetamiprid, and thiamethoxam directly affected O. insidiosus survival after 96 h (0-60% adult survival). The pesticide mixtures of abamectin + spinosad and chlorfenapyr + dinotefuran reduced adult survival (20% and 0%, respectively, after 48 h). Furthermore, the surfactants were not directly harmful to O. insidiosus adults. All western flower thrips adults were killed by the surviving adult O. insidiosus after 48 h, indicating no indirect effects of the pesticides on predation.

Ecology of Fungus Gnats (Bradysia spp.) in Greenhouse Production Systems Associated with Disease-Interactions and Alternative Management Strategies.

Fungus gnats (Bradysia spp.) are major insect pests of greenhouse-grown horticultural crops mainly due to the direct feeding damage caused by the larvae, and the ability of larvae to transmit certain soil-borne plant pathogens. Currently, insecticides and biological control agents are being used successively to deal with fungus gnat populations in greenhouse production systems. However, these strategies may only be effective as long as greenhouse producers also implement alternative management strategies such as cultural, physical, and sanitation. This includes elimination of algae, and plant and growing medium debris; placing physical barriers onto the growing medium surface; and using materials that repel fungus gnat adults. This article describes the disease-interactions associated with fungus gnats and foliar and soil-borne diseases, and the alternative management strategies that should be considered by greenhouse producers in order to alleviate problems with fungus gnats in greenhouse production systems.

Insecticide Rotation Programs with Entomopathogenic Organisms for Suppression of Western Flower Thrips (Thysanoptera: Thripidae) Adult Populations under Greenhouse Conditions.

Western flower thrips, Frankliniella occidentalis (Pergande), is one of the most destructive insect pests of greenhouse production systems with the ability to develop resistance to a wide variety of insecticides. A common resistance management strategy is rotating insecticides with different modes of action. By incorporating entomopathogenic organisms (fungi and bacteria), which have discrete modes of action compared to standard insecticides, greenhouse producers may preserve the effectiveness of insecticides used for suppression of western flower thrips populations. The objective of this study was to determine how different rotation programs that include entomopathogenic organisms (Beauveria bassiana, Isaria fumosoroseus, Metarhizium anisopliae, and Chromobacterium subtsugae) and commonly used standard insecticides (spinosad, chlorfenapyr, abamectin, and pyridalyl) may impact the population dynamics of western flower thrips adult populations by means of suppression. Eight-week rotation programs were applied to chrysanthemum, Dendranthema x morifolium plants and weekly counts of western flower thrips adults captured on yellow sticky cards were recorded as a means to evaluate the impact of the rotation programs. A final quality assessment of damage caused by western flower thrips feeding on foliage and flowers was also recorded. Furthermore, a cost comparison of each rotation program was conducted. Overall, insecticide rotation programs that incorporated entomopathogenic organisms were not significantly different than the standard insecticide rotation programs without entomopathogenic organisms in suppressing western flower thrips adult populations. However, there were no significant differences among any of the rotation programs compared to the water control. Moreover, there was no differential effect of the rotation programs on foliage and flower quality. Cost savings of up to 34% (in US dollars) are possible when including entomopathogenic organisms in the rotation program. Therefore, by incorporating entomopathogenic organisms into insecticide rotation programs, greenhouse producers can decrease costs without affecting suppression, as well as diminish selection pressure on western flower thrips adult populations, which may avoid or delay resistance development.

Efficacy of pesticide mixtures against the western flower thrips (Thysanoptera: Thripidae) under laboratory and greenhouse conditions.

Western flower thrips, Frankliniella occidentalis Pergande is a commonly encountered and economically important insect pest of greenhouses. Greenhouse producers typically apply pesticides as mixtures to mitigate western flower thrips populations; however, there is limited information available on the compatibility and efficacy of commonly used pesticide mixtures. This study assessed nine binary and three tertiary pesticide mixtures used in greenhouses which included pesticides containing abamectin, acephate, azadirachtin, bifenazate, bifenthrin, fenpropathrin, imidacloprid, novaluron, pymetrozine, and spinosad. Compatibility was determined for the binary pesticide mixtures using jar tests. In addition, the binary mixtures were applied to nine horticultural plant species to determine phytotoxicity based on visual appearance assessed 7 d after treatment. Bean-dip bioassays were performed in a laboratory using green bean (Phaseolus vulgaris L.) to determine LC50 values for each individual pesticide and the mixtures to establish whether the mixtures were synergistic, antagonistic, or there was no effect. The mortality of western flower thrips was assessed after 24 h, and LC50 values were calculated. Furthermore, semifield bioassays were performed in greenhouses for binary and tertiary mixtures to evaluate the efficacy (based on percent mortality) of the pesticide mixtures against western flower thrips. Results indicated that all binary mixtures were visibly compatible, and not phytotoxic to any of the plant species evaluated. Combination index calculations based on laboratory results indicated most of the binary mixtures were synergistic; however, the mixture containing spinosad + bifenazate appeared to be antagonistic against western flower thrips. The semifield bioassays demonstrated significantly reduced efficacy associated with mixtures containing azadirachtin, however, all binary mixtures provided approximately 80% western flower thrips mortality.

Interactions of light intensity, insecticide concentration, and time on the efficacy of systemic insecticides in suppressing populations of the sweetpotato whitefly (Hemiptera: Aleyrodidae) and the citrus mealybug (Hemiptera: Pseudococcidae).

The impact of light intensity on the uptake and persistence of the systemic neonicotinoid insecticides, imidacloprid and dinotefuran, were evaluated in poinsettia (Euphorbia pulcherrima Willd.) and yellow sage (Lantana camara L.). Insecticide residues were measured in leaves sampled from the treated plants at four time intervals after treatment to determine the relationship between insecticide concentration and efficacy against two insect pests: sweetpotato whitefly, Bemisia tabaci Gennadius, and the citrus mealybug, Planococcus citri Risso. The insecticides were evaluated at their respective label rate and at the comparable label rate of the other insecticide under two different light environments: ambient and shade. The uptake of dinotefuran into yellow sage was more rapid at both treatment rates than both rates of imidacloprid, resulting in higher percent mortality of whitefly nymphs (89.8-100) compared with imidacloprid (14.1-89.2) across all 4 wk. Additionally, plants that received both rates of dinotefuran had fewer whitefly pupae (< 1.0) at week 4 compared with imidacloprid-treated plants (23.7-25.3). The uptake of dinotefuran into poinsettia plants was also more rapid and resulted in quicker and higher percent mortality of whitefly nymphs (89.5-99.6) compared with imidacloprid (14.1-89.2) across all 4 wk. However, despite efficient uptake, the efficacy of both systemic insecticides was less for citrus mealybug where percent mortality values were <50% among all the treatments across the 4 wk. The use of the two systemic insecticides evaluated in regards to pest management in horticultural cropping systems is discussed.

Plant architecture and prey distribution influence foraging behavior of the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae).

The arrangement, number, and size of plant parts may influence predator foraging behavior, either directly, by altering the rate or pattern of predator movement, or, indirectly, by affecting the distribution and abundance of prey. We report on the effects of both plant architecture and prey distribution on foraging by the predatory mite, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae), on cucumber (Cucumis sativus L.). Plants differed in leaf number (2- or 6-leafed), and there were associated differences in leaf size, plant height, and relative proportions of plant parts; but all had the same total surface area. The prey, the twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae), were distributed either on the basal leaf or on all leaves. The effect of plant architecture on predator foraging behavior varied depending on prey distribution. The dimensions of individual plant parts affected time allocated to moving and feeding, but they did not appear to influence the frequency with which predators moved among different plant parts. Overall, P. persimilis moved less, and fed upon prey longer, on 6-leafed plants with prey on all leaves than on plants representing other treatment combinations. Our findings suggest that both plant architecture and pattern of prey distribution should be considered, along with other factors such as herbivore-induced plant volatiles, in augmentative biological control programs.

Effects of reduced-risk pesticides and plant growth regulators on rove beetle (Coleoptera: Staphylinidae) adults.

In many regions, pest management of greenhouse crops relies on the use of biological control agents; however, pesticides are also widely used, especially when dealing with multiple arthropod pests and attempting to maintain high esthetic standards. As such, there is interest in using biological control agents in conjunction with chemical control. However, the prospects of combining natural enemies and pesticides are not well known in many systems. The rove beetle, Atheta coriaria (Kraatz), is a biological control agent mainly used against fungus gnats (Bradysia spp.). This study evaluated the effects of reduced-risk pesticides and plant growth regulators on A. coriaria adult survival, development, and prey consumption under laboratory conditions. Rove beetle survival was consistently higher when adults were released 24 h after rather than before applying pesticides. The pesticides acetamiprid, lambda-cyhalothrin, and cyfluthrin were harmful to rove beetle adults, whereas Beauveria bassiana (Balsamo) Vuillemin, azadirachtin, and organic oils (cinnamon oils, rosemary oil, thyme oil, and clove oil) were nontoxic to A. coriaria adults. Similarly, the plant growth regulators acymidol, paclobutrazol, and uniconazole were not harmful to rove beetle adults. In addition, B. bassiana, azadirachtin, kinoprene, organic oils, and the plant growth regulators did not negatively affect A. coriaria development. However, B. bassiana did negatively affect adult prey consumption. This study demonstrated that A. coriaria may not be used when applying the pesticides, acetamiprid, lambda-cyhalothrin, and cyfluthrin, whereas organic oils, B. bassiana, azadirachtin, and the plant growth regulators evaluated may be used in conjunction with A. coriaria adults. As such, these compounds may be used in combination with A. coriaria in greenhouse production systems.

Repellency of naturally occurring volatile alcohols to fungus gnat Bradysia sp. nr. coprophila (Diptera: Sciaridae) adults under laboratory conditions.

This study, conducted under laboratory conditions, was designed to determine the repellent activity of 10 naturally occurring volatile alcohol constituents against adults of the fungus gnat, Bradysia sp. nr. coprophila (Lintner) (Diptera: Sciaridae). The essential oil constituents were octanoic acid, furfural, acetophenone, benzaldehyde, dimethoxybenzene, borneol, menthol, 1-octen-3-ol, and 7-hydroxycitronellol, and alpha-terpineol. alpha-Terpineol, octanoic acid and furfural were tested at several concentrations, whereas the remaining seven were tested at only one concentration. The essential oil constituents' menthol, 1-octen-3-ol, and borneol displayed the most repellent activity. The mean percentage of fungus gnat adults recovered from the test compound petri dishes associated with the three essential oil constituents was between 6 and 15% compared with between 36 and 50% for the petri dishes with distilled water. The mean +/- SEM number of fungus gnat adults present in the sample compartments associated with menthol (10.4 +/- 2.6), 1-octen-3-ol (18.8 +/- 2.4), and borneol (23.4 +/- 5.6) was statistically lower than those in the petri dishes containing distilled water (60.9 +/- 7.4, 49.8 +/- 4.0, and 79.7 +/- 13.5), respectively. Only the highest concentration of alpha-terpineol (8.0 micromol) displayed significant repellent activity against fungus gnat adults. The other essential constituents tested, including octanoic acid (all three concentrations), furfural (both concentrations), acetophenone, dimethoxybenzene, and 7-hydroxycitronellol, were not statistically different from the distilled water control. The results of this study indicate that certain essential oil constituents repel fungus gnat adults, which may be useful, from a practical standpoint, in deterring adults from laying eggs into growing media.

Impact of neonicotinoid insecticides on natural enemies in greenhouse and interiorscape environments.

The neonicotinoid insecticides imidacloprid, acetamiprid, dinotefuran, thiamethoxam and clothianidin are commonly used in greenhouses and/or interiorscapes (plant interiorscapes and conservatories) to manage a wide range of plant-feeding insects such as aphids, mealybugs and whiteflies. However, these systemic insecticides may also be harmful to natural enemies, including predators and parasitoids. Predatory insects and mites may be adversely affected by neonicotinoid systemic insecticides when they: (1) feed on pollen, nectar or plant tissue contaminated with the active ingredient; (2) consume the active ingredient of neonicotinoid insecticides while ingesting plant fluids; (3) feed on hosts (prey) that have consumed leaves contaminated with the active ingredient. Parasitoids may be affected negatively by neonicotinoid insecticides because foliar, drench or granular applications may decrease host population levels so that there are not enough hosts to attack and thus sustain parasitoid populations. Furthermore, host quality may be unacceptable for egg laying by parasitoid females. In addition, female parasitoids that host feed may inadvertently ingest a lethal concentration of the active ingredient or a sublethal dose that inhibits foraging or egg laying. There are, however, issues that require further consideration, such as: the types of plant and flower that accumulate active ingredients, and the concentrations in which they are accumulated; the influence of flower age on the level of exposure of natural enemies to the active ingredient; the effect of neonicotinoid metabolites produced within the plant. As such, the application of neonicotinoid insecticides in conjunction with natural enemies in protected culture and interiorscape environments needs further investigation.

Effect of pesticides on adult rove beetle Atheta coriaria (Coleoptera: Staphylinidae) survival in growing medium.

The rove beetle Atheta coriaria (Kraatz) (Coleoptera: Staphylinidae) is a natural enemy (biological control agent) commercially available for control of certain greenhouse insect pests, including fungus gnats, shore flies, and thrips. This study assessed the compatibility of pesticides (insecticides and fungicides) used in greenhouses with A. coriaria adults. Treatments were applied to 473-ml deli squat containers half-filled with a growing medium. We evaluated the effects of the pesticides when releases of A. coriaria adults were performed both before and after application of the designated pesticide solutions. All three of the neonicotinoid-based insecticides (clothianidin, dinotefuran, and thiamethoxam) were directly harmful to A. coriaria adults with < or = 3.2 adults recovered (out of 20) among all three treatments across all experiments. In addition, the organophosphate insecticide chlorpyrifos at the low (0.25 fl oz/100 gal) and high (0.50 fl oz/100 gal) label rates; the plant-derived essential oil product (Indoor Pharm) containing soybean and rosemary oil; and the insecticide/miticide chlorfenpyr were directly harmful to A. coriaria adults with recovery rates -8.6 (out of 20) among all the treatments. The fungicides (azoxystrobin, fosetyl-aluminum, and mefenoxam) were not directly toxic to A. coriaria adults, with < or = 17.7 adults recovered (out of 20) across all experiments. The insecticides (Bacillus thuringiensis subsp. israelensis, flonicamid, Metarhizium anisopliae strain52, and spinosad) and insect growth regulator azadirachtin were also not directly toxic to A. coriaria adults. Furthermore, many of these same treatments did not inhibit the ability of adult A. coriaria to consume fungus gnat (Bradysia sp. nr. coprophila) larvae in a feeding behavior experiment. Although the neonicotinoid-based insecticides were directly harmful to adult A. coriaria, when adults were released 48, 72, or 96 h after application, survival increased dramatically over time. This study has quantitatively demonstrated that certain pesticides (both insecticides and fungicides) are compatible with and can be used along with A. coriaria in systems that use this natural enemy to manage fungus gnat larvae.

Effect of commercially available plant-derived essential oil products on arthropod pests.

Plant-derived essential oil products, in general, are considered minimum-risk pesticides and are exempt from Environmental Protection Agency registration under section 25(b) of the Federal Insecticide Fungicide and Rodenticide Act. However, many of the plant-derived essential products available to consumers (homeowners) have not been judiciously evaluated for both efficacy and plant safety. In fact, numerous plant-derived essential oil products labeled for control of arthropod pests have not been subject to rigorous evaluation, and there is minimal scientific information or supporting data associated with efficacy against arthropod pests. We conducted a series of greenhouse experiments to determine the efficacy and phytotoxicity of an array of plant-derived essential oil products available to consumers on arthropod pests including the citrus mealybug, Planococcus citri (Risso); western flower thrips, Frankliniella occidentalis (Pergande); twospotted spider mite, Tetranychus urticae Koch; sweetpotato whitefly B-biotype, Bemisia tabaci (Gennadius); and green peach aphid, Myzus persicae (Sulzer). Although the products Flower Pharm (cottonseed, cinnamon, and rosemary oil) and Indoor Pharm (soybean, rosemary, and lavender oil) provided > 90% mortality of citrus mealybug, they were also the most phytotoxic to the coleus, Solenostemon scutellarioides (L.) Codd, plants. Both GC-Mite (cottonseed, clove, and garlic oil) and Bugzyme (citric acid) were most effective against the twospotted spider mite (> or = 90% mortality). However, SMC (canola, coriander oil, and triethanolamine), neem (clarified hydrophobic extract of neem oil), and Bug Assassin (eugenol, sodium lauryl sulfate, peppermint, and citronella oil) provided > 80% mortality. Monterey Garden Insect Spray, which contained 0.5% spinosad, was most effective against western flower thrips with 100% mortality. All the other products evaluated failed to provide sufficient control of western flower thrips with < 30% mortality. In addition, the products Pest Out (cottonseed, clove, and garlic oil), Bang (Pipereaceae), and Fruit & Vegetable Insect Spray (rosemary, cinnamon, clove oil, and garlic extract) had the highest flower (transvaal daisy, Gerberajamesonii [H. Bolus ex Hook.f]) phytotoxicity ratings (> or = 4.5 of 5) among all the products. None of the plant-derived essential oil products provided sufficient control of sweetpotato whitefly B-biotype or green peach aphid 7, 14, and 21 d after application. Furthermore, the products Bug Assassin (eugenol, sodium lauryl sulfate, peppermint, and citronella oil) and Sharpshooter (sodium lauryl sulfate and clove oil) were phytotoxic to the poinsettia, Euphorbia pulcherrima Willd. ex Klotzsch, plants. This study is one of the first to quantitatively demonstrate that commercially available plant-derived essential oil products vary in their effectiveness against certain arthropod pests stated on the label and are phytotoxic.

Pesticide use in ornamental production: what are the benefits?

Pest control in ornamental production is challenging owing to the diversity of crops grown, the desired aesthetic perfection, the potential economic loss due to failure and the multitude of arthropod pests encountered. Agricultural crops of less value per acre, such as row crops, can tolerate a certain level of damage from arthropod pests without compromising yields. Damage thresholds for ornamentals, however, are essentially zero. Pesticides are a viable method of protection for such a crop in lieu of alternatives. Therefore, the purpose of this paper is to emphasize the importance of pesticides to the ornamental industry. Pesticides provide many benefits to ornamental producers, including: (1) consistent availability; (2) rapid kill; (3) reliable and consistent control; (4) increased crop production and quality; (5) they may be used to prevent movement of invasive pests; (6) they are less expensive (in general) than alternatives; (7) they may reduce plant pathogenic transmission; (8) they may be used in conjunction with natural enemies. Pesticide use will continue to be a significant strategy for dealing with arthropod pests so that ornamental producers can stay competitive in both national and international markets.

Effect of silicon-based fertilizer applications on the reproduction and development of the citrus mealybug (Hemiptera: Pseudococcidae) feeding on green coleus.

Mealybugs are major insect pests of greenhouses, interiorscapes, and conservatories because they feed on a wide-range of horticultural crops. Furthermore, mealybugs are difficult to regulate with insecticides due to the presence of a nearly impervious protective waxy covering, which means that alternative management strategies are required. As such, this study, involving two replicated experiments, was designed to determine the value of applying silicon-based fertilizers, as potassium silicate, to coleus, Solenstemon scutellarioides (L.) Codd, plants as a way to prevent outbreaks of the citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae). The first experiment evaluated the effects of different application methods (foliar and drench), at 50 ppm silicon, using the commercially-available product, ProTek 0-0-3 The Silicon Solution. The second experiment entailed applying the silicon-based fertilizer as a drench to the growing medium at different rates (0, 100, 400, 800, and 1,600 ppm silicon). We determined the effects of the silicon-based fertilizer treatments on citrus mealybug life history parameters including number of eggs laid by the adult female, body size, and developmental time from first instar to ovipositing adult female. Furthermore, we used a plant alkaline fusion technique to assess the concentration (milligrams per kilogram or ppm) of silicon in the coleus plant tissues at variable time intervals (days). In general, this technique involved dry-ashing plant tissue in a muffle furnace, followed by alkaline fusion and then colormetric analysis. The silicon-based fertilizer application treatments, in both experiments, did not negatively affect any of the citrus mealybug life history parameters measured. In the first experiment, citrus mealybug female egg load ranged from 199.5 (drench application) to 219.4 (combination spray and drench application), and developmental time (days) from first instar crawler to ovipositing female ranged from 34.2 (combination spray and drench application) to 35.7 (drench application). For the second experiment, citrus mealybug female egg load ranged from 223.1 (1,600 ppm silicon) to 249.2 (800 ppm silicon). Developmental time from first-instar crawler to ovipositing female ranged from 35.0 (400 ppm silicon) to 36.6 (800 ppm silicon). Our results indicate that coleus is a silicon "rejector," and as such, applications of silicon-based fertilizers may not benefit dicot plants such as coleus as much as monocot plants in regards to avoiding insect pest outbreaks because dicots tend not to accumulate sufficient quantities of silicon.

Effect of diatomaceous earth and Trichoderma harzianum T-22 (Rifai strain KRL-AG2) on the fungus gnat Bradysia sp. nr. coprophila (Diptera: Sciaridae).

This study, consisting of three experiments, was designed to assess whether diatomaceous earth, when applied to the surface of growing media, reduces adult fungus gnat Bradysia sp. nr. coprophila (Diptera: Sciaridae) emergence or inhibits the females from laying eggs; and whether fungus gnat adults are attracted to the fungus Trichoderma harzianum T-22 (Rifai strain KRL-AG2) under laboratory conditions. In the first two experiments, diatomaceous earth was applied at two different thicknesses (3.1 and 6.3 mm) and conditions (dry and moist) to the surface of a growing medium (Universal SB 300 Mix) after the growing medium had been artificially inoculated with second or third instars of fungus gnats, or before female fungus gnat adults were released into each deli squat container. In the third experiment, preparations of the fungus T. harzianum at the highest recommended label rate (0.889 kg/m3) were amended into the growing medium and processed 24, 48, or 72 h before use in a series of three two-choice trials with a two-armed experimental arena. In the first two experiments, the dry or moist layers of diatomaceous earth, in general, did not affect fungus gnats in terms of preventing adult emergence or egg laying by the females. During the course of these experiments, we observed that the diatomaceous earth dry treatments expanded as a result of absorbing moisture from the growing medium, creating fissures that allowed the fungus gnat larvae to pupate and females to lay eggs. In the third experiment, fungus gnat adults were not attracted to the T. harzianum treatments in any of the trials.

Activity of an essential oil derived from Chenopodium ambrosioides on greenhouse insect pests.

This study involved both greenhouse and laboratory experiments evaluating the effect of an essential oil product (QRD 400) derived from Chenopodium ambrosioides variety nr. Ambrosioides L. (Chenopodiaceae) on greenhouse insect pests that feed on different plant parts: citrus mealybug, Planococcus citri (Risso); longtailed mealybug, Pseudococcus longispinus (Targioni Tozzetti); western flower thrips, Frankliniella occidentalis (Pergande), and fungus gnats (Bradysia spp.). Treatments were applied to coleus, Solenostemon scutellarioides plants; transvaal daisy, Gerbera jamesonii flowers; or growing medium, depending on the insect pest. The essential oil was most effective, based on adult emergence, on both the second and third instars of the fungus gnat Bradysia sp. nr. coprophila when applied as a drench to growing medium. In addition, there was a significant rate response for QRD 400 on fungus gnats. The QRD 400 treatment had the highest percentage of mortality on longtailed mealybug (55%) compared with the other treatments. However, the essential oil was less effective against citrus mealybug (3% mortality) and western flower thrips adults (18-34% mortality) compared with standard insecticides, such as acetamiprid (TriStar) and spinosad (Conserve), which are typically used by greenhouse producers. This lack of efficacy may be associated with volatility and short residual properties of the essential oil or with the essential oil taking longer to kill insect pests. Other insecticides and miticides evaluated, including sesame oil, garlic, paraffinic oil, and Bacillus thuringiensis subsp. israelensis, provided minimal control of the designated insect pests. In addition, adult rove beetle Atheta coriaria Kraatz adults were not effective in controlling the larval instars of fungus gnats when applied at a rate of five adults per container.