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Western flower thrips, Frankliniella occidentalis, is one of the most destructive insect pests of greenhouse-grown horticultural crops. The primary method of managing western flower thrips populations involves applications of insecticides; however, there is no information associated with the effect of the insect growth regulator, pyriproxyfen, or the entomopathogenic fungus, Isaria fumosorosea, on western flower thrips pupae in growing media. Therefore, four laboratory experiments were conducted to determine the effect of pyriproxyfen and I. fumosorosea applied as a drench to growing media on western flower thrips pupae. Expt. 1 evaluated the efficacy of pyriproxyfen and I. fumosorosea on western flower thrips pupae. Based on the results from Expt. 1, Expt. 2 assessed the effect of pyriproxyfen in two growing media (LC1 and BM1) on western flower thrips pupae. Expts. 3 and 4 determined the residual activity of pyriproxyfen in growing media on western flower thrips pupae 3, 5, 7, and 14 days after treatments were applied. The pyriproxyfen treatment resulted in a significantly lower estimated mean probability of western flower thrips adults captured on yellow sticky cards (17%) compared with the water control (59%), untreated check (88%), and two I. fumosorosea treatments (46% for 1.0 g and 41% for 2.0 g of Ancora) in Expt. 1. However, for the two growing media in Expt. 2, the estimated mean probability of western flower thrips adults captured on yellow sticky cards was not significantly different between the pyriproxyfen treatment (LC1 = 15%; BM1 = 12%) and the water control (LC1 = 41%; BM1 = 24%). For either the pyriproxyfen treatment or the untreated check, there was no evidence of a significant difference between the two growing media on the estimated mean probability of western flower thrips adults captured on yellow sticky cards. Furthermore, there was no evidence of any residual activity 3 days after drench applications of pyriproxyfen. The results of the study have demonstrated that drench applications of pyriproxyfen are not affecting survival of western flower thrips pupae.

Fungus gnats, Bradysia spp. (Diptera: Sciaridae), are major insect pests because the larvae can directly damage plants grown in greenhouse production systems. In general, insecticides are commonly used to suppress fungus gnat larval populations. However, the rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), a commercially available predator of insect pests, including fungus gnat larvae, may be an alternative to using insecticides. Growing medium selection used for growing plants can influence insect pest and predator interactions in greenhouse production systems; however, quantitative information is limited. Therefore, we conducted greenhouse experiments and a laboratory experiment to determine the effects of growing medium type on D. coriaria adult predation and fungus gnat, Bradysia. sp. nr. coprophila (Lintner) (Diptera: Sciaridae), larval survival when feeding on the roots of coleus, Solenostemon scutellarioides (L.) Codd, plants. In addition, experiments were conducted to determine the number of rove beetle adults, based on predator:prey ratios, needed to regulate fungus gnat larval populations. In all three experiments, fewer fungus gnat larvae survived in Pro-Mix BX than the Berger BM1 growing medium, and rove beetles reduced the number of fungus gnat larvae in both growing media in the greenhouse experiments. Although predator:prey ratio was not significant, we found that 10 rove beetle adults per 15.2-cm diameter container (1834.82 cm3 with 2.0 L of growing medium) regulated fungus gnat larval populations at the densities investigated. Therefore, greenhouse producers should consider the effects of production practices, such as growing medium type, when using rove beetles to regulate fungus gnat larval populations.

The fungus gnat, Bradysia sp. nr. coprophila (Lintner) (Diptera: Sciaridae), is an insect pest of greenhouse production systems. The rove beetle, Dalotia coriaria [Kraatz] (Coleoptera: Staphylinidae), is a commercially available predator of certain greenhouse insect pests that reside in growing media, including fungus gnats. There is minimal information discussing how growing medium type and moisture level (watering treatment) impact the interactions between pests and natural enemies. Therefore, we conducted laboratory and greenhouse experiments to investigate the influence of two growing media (Sunshine® LC1 Professional Growing Mix and Fafard® 3B Mix Professional Formula) and two moisture levels (“constantly saturated” and “initially saturated”) on predation by adult D. coriaria on B. sp. nr. coprophila larvae after releasing one or two rove beetle adults. In the laboratory experiment, moisture content or the amount of water retained by the growing medium did not significantly influence the recovery of adult fungus gnats for any of the rove beetle treatments. However, there was a significant difference in the recovery of fungus gnat adults between the two growing media. Fewer fungus gnat adults emerged from the Sunshine® LC1 Professional Growing Mix (0.9 ± 0.2 adults) than the Fafard® 3B Mix Professional Formula (6.0 ± 0.9 adults). Significantly fewer adult fungus gnats were recovered in the treatments where one rove beetle adult was released (2.7 ± 0.7 adults) and two rove beetle adults were released (2.3 ± 0.5 adults) compared with the control without rove beetles (5.4 ± 1.4 adults). However, there was no significant difference between the number of rove beetle adults released. In contrast to the laboratory experiment, moisture content in the greenhouse experiment significantly influenced the recovery of adult fungus gnats. More adult fungus gnats were recovered from the “constantly saturated” treatment (9.9 ± 1.4 adults) than the “initially saturated” treatment (3.8 ± 1.0 adults). Similar to the laboratory experiment, there was a significant difference in the recovery of fungus gnat adults between the two growing media, with fewer adults captured from the Sunshine® LC1 Professional Growing Mix (3.2 ± 0.8 adults) than the Fafard® 3B Mix Professional Formula (10.4 ± 1.4 adults). However, the treatments with rove beetle adults [one rove beetle (6.6 ± 1.8 adults) or two rove beetles (5.3 ± 1.5 adults)] were not significantly different from the control without rove beetles (8.6 ± 1.5 adults), suggesting that the growing media and moisture levels were acting directly on fungus gnat survival. The results of our study demonstrate that survival of fungus gnat larvae that reside in the growing medium and the success of rove beetle adults used to regulate these pests can be influenced by growing media and the moisture content within growing media.

Plant-derived essential oils or extracts and their associated volatiles can serve as insect attractants to enhance adult captures when used as whole plants or extracts that are incorporated onto colored sticky traps. In our study, we initially assessed the attractiveness of western flower thrips (WFT) (Frankliniella occidentalis) adults to vanilla extract in the laboratory using choice and no-choice experiments by comparing one (0.05 mL) and two (0.10 mL) drops of vanilla extract (0.029% and 0.059%, respectively). In the choice experiments, a drop of water and drop of vanilla extract were placed on opposite sides of a petri dish. One WFT was placed in the center of the petri dish, and observations were made on whether there was preferential movement to the water or vanilla extract. For the no-choice experiments, one petri dish only contained a drop of water, whereas another petri dish only contained a drop of vanilla extract. One WFT was placed into each petri dish and movement was observed to assess whether the WFT moved toward the water or to the vanilla extract. We then determined if yellow sticky cards containing vanilla extract were more attractive to WFT adults than those with water, by using the number of adults captured on yellow sticky cards as an estimate under greenhouse conditions. Western flower thrips adults were not attracted to vanilla extract based on the results associated with the choice and no-choice tests conducted under laboratory conditions with no differences in selection between vanilla extract and water. In addition, there was no evidence that inoculating yellow sticky cards with vanilla extract enhanced the number of adults captured on yellow sticky cards. Overall, the use of vanilla extract in attracting WFT adults to yellow sticky cards is not justifiable under the parameters of our study.

This study was conducted to assess the direct and indirect effects of Growstones aggregates, which are made from recycled glass, on fungus gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), adult emergence, female egg-laying capacity, and egg survival. A series of experiments were performed under laboratory conditions to evaluate the effect of different sizes (2.0 to 10.0 mm) of Growstones aggregates, layer thicknesses (0.63 to 3.18 cm), and the use of the biological control agent, the rove beetle, Dalotia coriaria, along with different thicknesses (1.27 and 3.18 cm) of small Growstones aggregates on fungus gnat adult emergence. For each experiment, Growstones aggregates were applied to the surface of the growing medium in 473-mL polypropylene deli containers. This study demonstrated that the thickest (3.18 cm) layer of small (2.0 mm) Growstones aggregates significantly reduced or delayed the emergence of fungus gnat adults. In addition, the thickest layer of small Growstones aggregates may have indirectly affected egg survival. However, the use of Growstones along with rove beetle adults did not significantly reduce fungus gnat adult emergence. Fungus gnats are a commonly encountered insect pest of greenhouses (Dennis, 1978; Hamlen and Mead, 1979) and are typically a problem in moist environments such as those that occur in propagation or plug production (Cloyd, 2000). Adults cause minimal direct damage to plants; however, a single female Bradysia sp. nr. coprophila Lintner (Diptera: Sciaridae) can lay 96 eggs on the surface of the growing medium (Meers and Cloyd, 2005). After eggs hatch, larvae feed on plant roots causing plant stunting, wilting, and possibly plant death (Jarvis et al., 1993; Springer, 1995; Wilkinson and Daugherty, 1970). In addition, indirect damage by larvae is associated with transmission of certain soilborne plant pathogens (Gardiner et al., 1990; Gillespie and Menzies, 1993; Jarvis et al., 1993). Currently, insecticides applied as drenches to the growing medium are an effective management strategy against fungus gnat larvae (Hamlen and Mead, 1979; Lindquist, 1994; Lindquist et al., 1985). However, as a result of the limited number of insecticides registered for use in greenhouses, and the costs associated with development and registration of new insecticides (Lewis, 1977), it is important to judiciously use the currently available compounds (Lindquist et al., 1985). Biological control agents such as the rove beetle, Dalotia coriaria Kraatz (Coleoptera: Staphylinidae), have been shown to be an effective predator against fungus gnat larvae (Carney et al., 2002; Echegaray, 2012). However, a number of insecticides are directly and indirectly harmful to rove beetles (Cloyd et al., 2009). Consequently, physical barriers may be a long-term management strategy that could also be used with biological control agents (Banks, 1976). Physical barriers are used to alter the environment so as to make it inaccessible to insect pests (Banks, 1976). There are a number of benefits associated with physical barriers such as compatibility with other insect pest management strategies including biological control and minimal impact on the environment (Boiteau, 2002). Nonetheless, physical barriers do not reduce an insect population immediately, which typically happens with most insecticides (Boiteau, 2002). A physical barrier could be placed on the surface of the growing medium to inhibit adult fungus gnat emergence or possibly reduce adult female egg-laying or egg survival (Cloyd et al., 2007a), whereas rove beetles feed on fungus gnat larvae in the growing medium. Physical barriers have been evaluated as a pest management strategy against insect pests, specifically the fungus gnat, Bradysia sp. nr. coprophila (Cloyd et al., 2007a). Previous research by Cloyd et al. (2007a) evaluated the effect of dry and moist diatomaceous earth and sand as a physical barrier against fungus gnats. Diatomaceous earth affects insects either by removing or absorbing oils and waxes on the outer insect cuticle or by abrading the cuticle causing extensive moisture loss leading to desiccation. However, when diatomaceous earth becomes moist, it loses any abrasive properties (Korunic, 1998). Cloyd et al. (2007a) determined that both dry and moist diatomaceous earth and sand formed cracks or air pockets over time, which decreased their ability to negatively affect fungus gnats. This suggests that diatomaceous earth and sand may not be effective physical barriers. Despite this, there are other materials that may act as physical barriers against fungus gnats such as Growstones (Growstone, Inc., Albuquerque, NM). Growstones aggregates are processed from 100% recycled glass and are primarily used as a hydroponic growing substrate in which plants are inserted into containers containing Growstones aggregates. A nutrient solution is applied to the container. Growstones aggregates are lightweight and can be manufactured into different particle sizes (Evans, 2011). It is possible that Growstones aggregates may serve as a physical barrier against fungus gnats in greenhouses. Therefore, the objectives of this study were 3-fold: 1) to determine the direct effect of Growstones aggregates applied to the growing medium surface on fungus gnat adult emergence; 2) to assess the indirect effect of Growstones aggregates placed on the growing medium surface on female egglaying and/or egg survival and subsequent adult emergence; and 3) to determine if using rove beetle, Dalotia coriaria, adults in conjunction with Growstones is synergistic in affecting fungus gnat adult emergence. Materials and Methods Fungus gnat colony. Laboratory-reared colonies of the fungus gnat, Bradysia sp. nr. coprophila, were located in the Department of Entomology at Kansas State University (Manhattan, KS) and maintained in 8.0-L plastic containers with tight-sealing lids. Openings ( 15 cm square) were cut in the lids and then insect screening [50 · 24 (0.2 · 0.8 mm; Greentek, Edgerton, WI)] was hotglued to the lids to allow for ventilation. The Received for publication 27 Mar. 2014. Accepted for publication 28 Apr. 2014. We thank Growstones, Inc. (Albuquerque, New Mexico) for providing the funds necessary to conduct this research. In addition, we thank Paula Costa of Growstones, Inc. (Albuquerque, NM) and Dr. Mary Beth Kirkham in the Department of Agronomy at Kansas State University (Manhattan, KS) for their valuable feedback associated with previous drafts of the manuscript. To whom reprint requests should be addressed; e-mail rcloyd@ksu.edu. HORTSCIENCE VOL. 49(7) JULY 2014 905 DISEASE AND PEST MANAGEMENT

Both laboratory and greenhouse experiments were conducted to determine if the fungicide, MilStop (BioWorks, Victor, NY), which contains the active ingredient, potassium bicarbonate, has direct activity on the citrus mealybug, Planococcus citri Risso. Spray applications of four different rates (4.5, 5.9, 7.4, and 14.9 g·L) were applied to green coleus, Solenostemon scutellarioides (L.) Codd., plants infested with citrus mealybugs. In addition, experiments were conducted to assess both the direct and indirect effects of MilStop on two natural enemies of the citrus mealybug: the parasitoid, Leptomastix dactylopii (Howard), and the coccinellid beetle, Cryptolaemus montrouzieri (Mulsant). MilStop provided between 56% and 86% mortality of citrus mealybug; however, the highest rate (14.9 g·L) was phytotoxic to coleus plants. Percent mortality associated with the second highest rate (7.4 g·L) was 82%, which was comparable to acetamiprid (84%) applied at 0.05 g·L. For the natural enemies, MilStop treatment rates of 1.5 and 3.5 g·L resulted in 16% mortality, whereas the 5.5and 9.0-g·L rates resulted in 33% mortality of L. dactylopii adults. MilStop treatment rates of 3.5, 5.5, 9.0, and 12.0 g·L resulted in 30%, 60%, 40%, and 90% mortality, respectively, of C. montrouzieri adults. Therefore, depending on the application rate, this fungicide may inadvertently kill citrus mealybugs when used to control fungal plant pathogens. It should not disrupt biological control programs targeting citrus mealybug in greenhouses that involve releases of L. dactylopii when used at low application rates, whereas MilStop applications should be properly timed when using C. montrouzieri. Pesticides are used to manage arthropod (insect and mite) pest populations and diseases in greenhouses (Bethke and Cloyd, 2009; Tauber and Helgesen, 1978). Fungicides are applied to control plant pathogenic fungi, although certain fungicides have been shown to directly affect populations of arthropod pests including spider mites (Biggs and Hagley, 1988; Bower et al., 1995). However, no efficacy data are available for other arthropod pests including the citrus mealybug, Planococcus citri Risso, a major insect pest of greenhouses and other interior plantscapes throughout the United States (Kole and Hennekam, 1990; Kosztarab, 1996; McKenzie, 1967). If fungicides are efficacious against both plant pathogens and insect pests such as citrus mealybugs, the number of pesticide applications required during a cropping cycle could be reduced. Furthermore, because greenhouse producers may use biological control to regulate arthropod pest populations including the citrus mealybug (Bartlett, 1978; Doutt, 1952; Pilkington et al., 2010), it is important to determine if fungicides could potentially disrupt biological control programs. In general, specific fungicides are considered to be less harmful to natural enemies than insecticides and miticides (Wright and Verkerk, 1995). However, fungicides used in greenhouse production systems may negatively affect pest-natural enemy interactions, thus compromising the success of biological control programs (Cloyd, 2012; Echegaray and Cloyd, 2012). Potassium bicarbonate (MilStop ; BioWorks, Victor, NY) is a fungicide registered for use in agricultural and greenhouse cropping systems for the control of various foliar plant pathogens (Abd-El-Kareem, 2007; Cushman et al., 2007; Ziv and and Hagiladi, 1993; Ziv and Zitter, 1992). The effects of potassium bicarbonate have not been extensively evaluated against arthropod pests and there is minimal information on any direct or indirect effects on natural enemies. Gradish et al. (2011) showed that potassium bicarbonate and other pesticides evaluated were not directly harmful to the natural enemies, Orius insidiosus (Say), Amblyseius swirskii (Athias-Henriot), and Eretmocerus eremicus Rose & Zolnerowich, under laboratory and greenhouse conditions. Therefore, the objectives of this study were to 1) determine the efficacy of MilStop and other pesticides against the citrus mealybug; and 2) assess any direct and/or indirect effects on the natural enemies of the citrus mealybug, Leptomastix dactylopii (Howard) and Crytolaemus montrouzieri (Mulsant), also known as the ‘‘mealybug destroyer,’’ under both greenhouse and laboratory conditions. Materials and Methods Experiments were conducted to determine the direct effects of MilStop (active ingredient = potassium bicarbonate) on the citrus mealybug, Planococcus citri (Expt. 1) and the direct and indirect effects on two natural enemies of the citrus mealybug, Leptomastix dactylopii and Cryptolaemus montrouzieri (Expts. 2 through 4). Expt. 1: Effects of potassium bicarbonate (MilStop ) on the citrus mealybug. Sixty plants of green coleus, Solenostemon scutellarioides (L.) Codd., were started from cuttings taken from stock plants and transplanted into 15.2-cm containers (Kord Products, Toronto, Canada) in a growing medium (Universal SB 300 Mix; Strong-Lite Horticulture Products, Pine Bluff, AR) consisting of 50% composted pine bark, 20% Canadian sphagnum peatmoss, 20% medium coarse vermiculite, 10% perlite, a starter nutrient charge, and a wetting agent. Plants were fertilized with 20N–8.3P–8.8K at 250 ppm nitrogen in a constant liquid feed program and grown in a glass greenhouse on 12 · 3-m wire-mesh raised benches and arranged in a completely randomized design. There were a total of 10 treatments, which included four rates of potassium bicarbonate and six other compounds including sesame oil, pyrethrins, polyetherpolymethylsiloxane, acetamiprid, alkyl aryl polyoxyethylene, and azadirachtin (Table 1). There were five replications per treatment. In addition, a water control and an untreated control (no water applied) were included. Effects of treatments on the citrus mealybug were evaluated 7 d post-application. Received for publication 2 Aug. 2013. Accepted for publication 10 Oct. 2013. We acknowledge Drs. Mary Beth Kirkham (Department of Agronomy) and Kun Yan Zhu (Department of Entomology) of Kansas State University, Manhattan, KS, and Dr. Randy Martin of BioWorks, Inc., Victor, NY, for reviewing previous versions of the manuscript. We also wish to thank three anonymous reviewers. The feedback we received from everyone was very much appreciated. To whom reprint requests should be addressed; e-mail rcloyd@ksu.edu. HORTSCIENCE VOL. 48(12) DECEMBER 2013 1513 DISEASE AND PEST MANAGEMENT

Two greenhouse studies were conducted to examine effects of nitrogen source on primary and secondary metabolism of pac choi (Brassica rapa L. subsp. chinensis cv. Mei Qing Choi) and diamondback moth (Plutella xylostella L.) consumption, development, survival, and body weight. Applications of a liquid organic source of nitrogen (fish hydrolysate fertilizer) were compared with a conventional fertilizer to determine whether nitrogen source directly impacts pac choi chemistry (elemental composition and phenolics) and biomass and indirectly affects diamondback moth fitness parameters. There was no significant effect of fertility treatment on pac choi chemistry or biomass with the exception of percent leaf phosphorus, which was significantly higher in the conventional fertility treatment, and p-coumarin, which was significantly higher in the organic fertility treatment. Diamondback moth also affected plant chemistry. Both calcium (Ca) and magnesium (Mg) were significantly higher in plants infested with larvae compared with uninfested plants. Fertilizer affected diamondback moth fitness with percent survival and cohort development significantly reduced on pac choi associated with the organic fertilizer. However, pac choi receiving the organic treatment was similar in regard to primary nutrients and secondary compounds compared with plants that received a conventional fertilizer.

This study was conducted to assess the repellency of Bounce® original brand fabric softener dryer sheets against fungus gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), adults. For all five experiments conducted under laboratory conditions, fungus gnat adults collected in the sample compartments that included Bounce® original brand fabric softener dryer sheets ranged between 12% and 18% compared with the mean proportion of fungus gnat adults recovered from sample compartments that excluded dryer sheets, ranging in mean proportion from 33% to 48%. Chemical analysis using a steam distillation procedure to isolate volatile constituents found linalool as one of the major volatiles detected in the Bounce® original brand fabric softener dryer sheets. Additional constituents isolated were benzyl acetate, beta-citronellol, and hedione. Based on the results from our study, under laboratory conditions, Bounce® fabric softener dryer sheets do in fact repel B. sp. nr. coprophila adults.

Mealybugs are major insect pests of greenhouses, interiorscapes, and conservatories feeding on a wide range of horticultural crops. However, mealybugs are difficult to regulate with insecticides as a result of the presence of a nearly impervious protective waxy covering, which means that alternative management strategies are required. As such, this study was designed to determine the value of applying silicon-based fertilizers such as potassium silicate to fiddleleaf fig, Ficus lyrata, plants as a means of alleviating outbreaks of the citrus mealybug, Planococcus citri. The study evaluated the effects of applying a commercially available silicon-based fertilizer product, ProTek® 0-0-3 The Silicon Solution, as a drench to the growing medium at different rates (0, 100, 400, 800, and 1600 ppm silicon). We determined the effect of the silicon-based fertilizer rate treatments on citrus mealybug life history parameters, including number of eggs laid by the female, body size (mm), and development time (days) from first instar to ovipositing adult female. In addition, we used a plant alkaline fusion technique to assess the concentration (mg·kg−1 or ppm) of silicon in the aboveground tissues (leaves and stems) of fiddleleaf fig plants at variable time intervals (days). This technique involves dry-ashing plant tissue in a muffle furnace followed by alkaline fusion and then colorimetric analysis. We found that the silicon-based fertilizer rate treatments did not negatively affect any of the citrus mealybug life history parameters measured. Citrus mealybug female egg load ranged from 132.3 to 159.2 and the development time (days) ranged from 66.9 to 68.7 d. The silicon concentrations present in the fiddleleaf fig plants on the final harvest date were between 4419.2 and 7241.7 mg·kg−1 silicon with fiddleleaf fig plants that received the 1600 ppm silicon-based fertilizer rate treatment having the highest silicon concentration. Moisture content was not significantly different among plants receiving the different silicon concentrations. Our results seem to suggest that fiddleleaf fig may actually be a silicon “rejector” and, as such, applications of silicon-based fertilizers are not beneficial to fiddleleaf fig plants because they do not accumulate sufficient quantities of silicon to impact citrus mealybugs.

This study was conducted to assess the attractiveness of growing media containing parboiled rice hulls (PBH) to fungus gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), adults. In comparing commercially prepared PBH with peatmoss (LC1) and pine bark (SB200)-based growing media, it was established that the fungus gnat adults were not specifically attracted to any of the growing media, even those containing PBH, with the mean proportion of fungus gnat adults recovered in the sample compartments ranging from 0.16 to 0.23. Moisture content was more important in terms of fungus gnat adult attractiveness to the growing media. In addition, the volatile constituents of the various growing media were determined using a steam distillation procedure. The component that was present in the highest concentration (39.2%) in the dried PBH as determined by gas chromatography analysis was palmitic acid, a straight-chain C16 fatty acid. S8 (cyclo-octasulfur), a well-known odoriferous component of degraded waste materials, was present at a higher concentration (6.2%) in the RH1 growing medium (80% peatmoss) compared with the other growing media evaluated. The data indicate that PBH, when incorporated in certain growing media, do not attract fungus gnat adults, and as such, greenhouse producers can use PBH as an amendment to growing medium without having to be concerned with the prospect of luring fungus gnat adults and sustaining plant damage.

Twospotted spider mite, Tetranychus urticae, is a major arthropod pest in greenhouses. Greenhouse producers typically use miticides to control twospotted spider mite (TSM) populations. This study, which involved two replicated experiments, was designed to assess the persistence or longevity and efficacy of translaminar miticides with the active ingredient (a.i.) etoxazole, chlorfenapyr, abamectin, and spiromesifen by applying these miticides to either butterfly bush (Buddleia davidii) or marigold (Tagetes erecta) plants, depending on the experiment, and then artificially infesting the plants with TSM. Based on percent mortality and number of live and dead TSM, several miticides provided adequate control of TSM even after having been applied to the test plants 14 days before being artificially infested with TSM. This suggests that these miticides have extended residual activity. The etoxazole 10 to 12 μm and etoxazole water-dispersible formulations provided control (greater than 85% mortality) of TSM over the course of Expt. 1 with four or less live TSM recovered from treated plants across the three evaluation times (21, 28, and 42 days). Spiromesifen, in Expt. 2, was significantly more effective against both the nymph (89% to 99.2%) and adult (37.3% to 87.9%) stages of the TSM than the other miticides and killed more nymphs (165 to 227) than the other treatments. In general, none of the miticides provided consistent or adequate control of TSM adults across all three evaluation times (49, 56, and 70 days).

Multiple-choice experimental arenas, with sample compartments, were used to assess the response of fungus gnat, Bradysia sp. nr. coprophila (Lintner) (Diptera: Sciaridae), adults to varying light intensities in environmentally controlled walk-in chambers. Each sample compartment contained a yellow sticky card (2.5 × 2.5 cm) to capture fungus gnat adults. Under conditions of darkness, fungus gnat adults migrated randomly with no significant differences among the six sample compartments. Fungus gnat adults were observed to positively respond to light intensities less than 0.08374 μmol·m−2·s−1. In addition, adults responded to light intensities that were below the detection threshold of a photosynthetically active radiation light sensor. A higher percentage of fungus gnat adults (22% to 39%) were captured on yellow sticky cards in the sample compartments that were closest to a directional light source compared with sample compartments that were located further away from the light source (2% to 9%). Fungus gnat adults exhibited a significant response when exposed to two distinct ranges of light intensities (0.12 to 0.26 versus 0.87 to 1.02 μmol·m−2·s−1) with adults significantly more attracted to the highest light intensities (0.87 to 1.02 μmol·m−2·s−1). The results obtained in this study indicate that fungus gnat adults are positively phototactic, and as light intensity increases, they display a preference for those higher light intensities. It is possible that modifications in light intensity may be a feasible management strategy for alleviating problems with fungus gnats in greenhouses.

In this study, we report on the compatibility of two commercially available predatory mites, Neoseiulus californicus and Phytoseiulus persimilis, with three miticides used in greenhouse production systems to control the twospotted spider mite, Tetranychus urticae. We determined the lethal effects of the miticides chlorfenapyr, spiromesifen, and bifenazate to both predatory mite species 24 hours after exposure to spray applications in petri dishes. Two rates of chlorfenapyr (0.40 and 0.81 mL/2-L) and spiromesifen (0.15 and 0.31 mL·L -1 ), and one rate of bifenazate (0.62 mL·L -1 ) were used. All rates were based on the manufacturer label recommendations for twospotted spider mite. Both rates of chlorfenapyr and spiromesifen, and the single rate of bifenazate were not harmful to N. californicus with percent live mite values i 85% for chlorfenapyr and i 95% for spirome- sifen, and 93% for bifenazate. However, these same miticides were substantially toxic to P. persimilis with percent live mite values of i 63% for all the miticides tested. Based on the results of this study, the miticides chlorfenapyr, spiromesifen, and bifenazate are compatible with N. californicus whereas these miticides are toxic to P. persimilis indicating a difference in susceptibility based on predatory mite species. Twospotted spider mite, Tetranychus ur- ticae Koch (Acari: Tetranychidae) is a major arthropod pest in greenhouses, particularly during the warm season when populations can reach excessive levels within a short pe- riod of time (Helle and Sabelis, 1985; Zhang, 2003). Commercially available miticides are typically used to control twospotted spider mite outbreaks. However, continued reliance on miticides increases the probability of T. urticae populations developing resistance (Dittrich, 1975; Carbonaro et al., 1986). As a result, greenhouse producers are evaluating the use of alternative management strategies for twospotted spider mite that may avoid relying strictly on miticides (Sabelis, 1981). An alternative management strategy, as opposed to relying solely on miticides, is to incorporate the use of predatory mites into greenhouse production systems. Two preda- tory mites that are available to greenhouse producers are Phytoseiulus persimilis Athias- Henriot (Acari: Phytoseiidae) and Neoseiulus

Fungus gnats (Bradysia spp.) are major insect pests in greenhouses. The adult stage is primarily a nuisance whereas the larval stage is directly responsible for plant injury by feeding on plant roots or tunneling into stems. Insecticides are used to deal with fungus gnat larvae in growing medium, although sometimes with limited success. This study evaluated the potential of using a soil amendment—diatomaceous earth (DE) incorporated into growing media—for controlling the fungus gnat Bradysia sp. nr. coprophila. Two experiments were conducted by testing a series of growing media containing various concentrations of diatomaceous earth, and several without diatomaceous earth. The effects of the growing media containing diatomaceous earth on both the 2nd and 3rd instars of fungus gnat larvae were determined by recording the number of adults captured on yellow sticky cards (2.5 × 2.5 cm). Based on the results obtained from both experiments, the addition of DE to growing medium, at the concentrations tested, did not negatively affect or increase efficacy against both the 2nd and 3rd instars. This suggests that incorporating DE into commercially available growing medium may not be beneficial to greenhouse producers. However, further research is needed to assess whether differential larval susceptibility and moisture content influence the ability of DE to control soil-dwelling arthropods.

Western flower thrips (Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)] collected from greenhouse, laboratory, and native populations were evaluated for resistance to the insecticide spinosad. Individual cut stems of transvaal daisy (Gerbera jamesonii H. Bolus ex Hook. f.) were inoculated with 25 adults from 1 of 9 thrips populations and maintained in isolation chambers. Treatments of no spray, water spray, spinosad at one-half label rate (0.41 mL·L-1) and spinosad at the recommended label rate (0.81 mL·L-1) were applied to the flowers. Three days after treatment, the number of live and dead thrips was recorded. Significantly more thrips were recovered from the control treatments than the spinosad treatments. Thrips survival varied by treatment and insect population. Based on an odds ratio analysis, the likelihood of recovering live thrips was greater in the IL-GH1 (Illinois greenhouse) population than in the NV-N1 (Nevada native) reference population for both spinosad treatments, suggesting resistance to spinosad in the IL-GH1 population. The IL-GH1 population was collected from a greenhouse regularly sprayed with spinosad whereas the NV-N1 population was collected in Incline Village, Nev., on wildflowers with no history of exposure to spinosad. This is the first documented indication of spinosad resistance in a thrips population. In comparison to the NV-N1 reference population, none of the populations collected from laboratory or native nonagricultural environments exhibited evidence of resistance to spinosad. Resistance to an insecticide with a novel mode of action, such as spinosad, indicates the necessity of rotating insecticides and implementing alternative methods of managing western flower thrips. Chemical names used: spinosad including spinosyn A and spinosyn D (Conserve SC).

Although silicon is not an essential element, it is taken up by plants but is rarely quantified. Therefore, this study quantified the silicon concentration in 10 commonly grown horticultural plants including meadow sage (Salvia ×sylvestris), tickseed (Coreopsis verticillata), garden phlox (Phlox paniculata), New England aster (Symphyotrichum novae-angliae), Chinese astilbe (Astilbe chinensis), coral flower (Heuchera hybrid), garden zinnia (Zinnia elegans), French marigold (Tagetes patula), sweet basil (Basil spp.), and rosemary (Rosmarinus officinalis) using a plant alkaline fusion technique, which involved dry-ashing plant tissue samples and measuring color development with a spectrophotometer. Both zinnia and aster accumulated substantially more silicon from the municipal water source and growing medium (5365 and 4797 mg·kg−1 silicon, respectively) than the other plants evaluated, which had concentrations less than 2500 mg·kg−1 silicon. This study is just one of a few in which the silicon concentration in various horticultural plants has been quantified. Consequently, this may lead to better understanding those plants that will or will not benefit from applications of silicon-based fertilizers to promote cold-hardiness and/or plant resistance to fungal pathogens and insect pests.

Zoysiagrass, in general, has few insect pest problems but may suffer significant damage from infestations of the bluegrass billbug (Sphenophorus parvulus Gyllenhal). This study evaluated ‘Meyer’ and DALZ 0102 zoysiagrass (both Zoysia japonica Steud.) and 31 experimental zoysiagrass progeny, including reciprocal crosses between Z. japonica × Z. matrella (L.) Merr. or crosses between ‘Emerald’ (Z. japonica × Z. pacifica Goudsw.) × Z. japonica. These grasses were evaluated in adjacent experiments with 18 progeny in one and 13 in another. Plots were maintained under golf course fairway conditions and experienced natural infestations of the bluegrass billbug in 2009 and 2010 with larval damage primarily evident in June and continuing throughout the remainder of the growing season. ‘Meyer’ suffered the highest level of damage on each of six rating dates, ranging from 17% to 38% of the experimental plot area affected. Among the zoysiagrass progeny, damage ranged from 0% to 35% with most showing less than 15% damage. Overall, zoysiagrass progeny associated with reciprocal crosses of Z. japonica × Z. matrella or ‘Emerald’ × Z. japonica were less susceptible to bluegrass billbug than ‘Meyer’.

The twospotted spider mite, Tetranychus urticae, is a major arthropod pest of many greenhouse-grown horticultural crops. Greenhouse producers use a variety of miticides to suppress twospotted spider mite populations. A group of miticides known as mitochondria electron transport inhibitors or METIs include acequinocyl, fenpyroximate, and pyridaben. In addition, there are strobilurin-based fungicides such as azoxystrobin, kresoxim-methyl, and trifloxystrobin that are also known as METIs. We conducted a study to determine if these METI fungicides had any miticidal properties against the nymph and adult stages of the twospotted spider mite. The designated treatments were applied to marigold (Tagetes erecta) plants naturally infested with twospotted spider mites. Assessments of live and dead twospotted spider mite nymphs and adults were conducted 3, 7, and 14 days after applying the treatments. None of the METI fungicides had any activity against the nymph and adult life stages of the twospotted spider mite, with percentage mortality values

Fungus gnats, Bradysia spp., are major insect pests in greenhouses and interiorscapes. Management typically involves the use of either insecticides or biological control agents such as entomopathogenic nematodes. Efficacy trials provide information to greenhouse producers on the effectiveness of these management options. However, a simple procedure that rapidly evaluates the performance of control products against fungus gnat larvae is needed. Because fungus gnat larvae inhabit the growing medium, excess or deficient growing medium moisture may reduce adult fungus gnat emergence, thus confounding effects from efficacy trial treatments. Therefore, it is important to determine the amount of moisture and moisture content that results in the highest recovery of fungus gnat adults. We conducted two replicated experiments in a completely randomized design using a range of initial water volumes (treatments) and two larval stages (second and third) of the fungus gnat, Bradysia sp. nr. coprophila. The success of the procedure was based on the number of fungus gnat adults that emerged per treatment. In the first experiment, initial water volumes of 0, 25, 50, 75, 100, 150, and 200 mL were applied to 300 mL of a soilless growing medium consisting of 50% composted pine bark, 20% Canadian sphagnum peatmoss, 10% perlite, and 20% medium coarse vermiculite (SB300 Universal Mix). In general, the highest mean numbers (range, 11.2 to 14.6) of fungus gnat adults were recovered from growing medium treated with 50, 75, and 100 mL of water. In the second experiment, initial water volumes (treatments) of 50, 55, 60, 65, 70, and 75 mL were applied to 300 mL of the soilless growing medium (SB300 Universal Mix). There were no significant differences in the mean number of fungus gnat adults recovered regardless of the larval instar (second instar: 15.8 to 17.7; third instar: 14.4 to 17.4). The final percent moisture content ranged from 65% to 68% for the second instars and 56% to 66% for third instars. This study demonstrates that the highest number of fungus gnat adults may be recovered from soilless growing medium (SB300 Universal Mix) treated with between 50 and 75 mL of water, thus enhancing the confidence in any data set generated when evaluating insecticides or biological control agents for control of fungus gnats.

Greenhouse trials were conducted in 2000-2001 to evaluate the indirect effects of insect growth regulators, whether stimulatory or inhibitory, on the egg production of female citrus mealybug [Planococcus citri (Risso)]. Green coleus [Solenostemon scutellarioides (L.) Codd] were infested with 10 late third instar female citrus mealybugs. The insect growth regulators kinoprene, pyriproxyfen, azadirachtin, buprofezin, and novaluron were applied to infested plants at both the high and low manufacturer recommended rates. Beginning two days after treatments were applied, plants were monitored daily to determine when female mealybugs began to oviposit. Individual mealybugs were removed from plants, placed into glass vials containing 70% isopropyl alcohol when female mealybugs started to oviposit, and dissected to determine the number of eggs. Overall, there were no consistent patterns to suggest that the insect growth regulators and different rates tested had any effect on the egg production of citrus mealybug females. Although, in one instance, the insect growth regulators kinoprene and pyriproxyfen actually lowered citrus mealybug egg production. In addition, the insect growth regulator buprofezin numerically increased female citrus mealybug egg production.

Greenhouse managers tank mix pesticides to broaden the spectrum of pest control, and reduce pesticide and labor costs. However, the effect of tank mixing an assortment of pesticides on efficacy to control pests has not been documented. This study assessed how tank mixing commercially available insecticides and miticides in two-, three-, and four-way combinations impacts the control of western flower thrips (WFT), Frankliniella occidentalis in greenhouse experiments and a laboratory bioassay. The pesticides screened were spinosad, abamectin, bifenazate, azadirachtin, and imidacloprid. Each pesticide was applied at the label-recommended rate. In the greenhouse experiments, transvaal daisy (Gerbera jamesonii) and lisianthus (Eustoma grandiflorum) flowers were inoculated with 25 adult WFT, and then flowers were sprayed with the designated treatments. After 72 hours, flowers were emasculated to assess the numbers of live and dead WFT. In the laboratory bioassay, chrysanthemum (Dendranthema grandiflora) leaf disks, treated with each pesticide and all tank mixes, were exposed to 15 adult WFT. The numbers of live and dead WFT were assessed after 48 hours. For all three experiments, no antagonistic tank mixes were identified. All treatments with spinosad, including the individual application and tank mixes, resulted in high mortality of WFT based on the numbers of live and dead WFT recovered. Our data suggest that tank mixes of spinosad with the other pesticides tested do not affect the efficacy of spinosad in controlling WFT. This information is important to greenhouse managers who want to tank mix pesticides and still control WFT in addition to the other plant-feeding arthropods found in greenhouses.

A greenhouse study was conducted from Oct. 1999 through Feb. 2000, and Mar. 2001 through Apr. 2001, to determine the potential phytotoxic effects of selected insecticides on Spanish lavender (Lavandula stoechas L.), oregano (Origanum vulgare L. `Santa Cruz'), rosemary (Rosmarinus officinalis L.), St. Johnswort (Hypericum perforatum L. `Topaz'), wolly thyme (Thymus vulgaris L. `Wolly'), and nutmeg thyme (Thymus vulgaris L. `Nutmeg'). Insecticides used for the study were Beauveria bassiana Strain GHA, pyrethrin [+ piperonyl butoxide (PBO)], azadirachtin, potassium salts of fatty acids, two rates of cinnamaldehyde, paraffinic oil, and capsaicin. Visual observations of phytotoxicity were made 7 days after the final application. Pyrethrin, potassium salts of fatty acids, and both rates of cinnamaldehyde were consistently more phytotoxic than the other insecticides. Despite the phytotoxic effects from some of the insecticides, new growth that emerged following treatments compensated for the initial damage, and the herbs were still saleable.

An affordable device comprised of off-the-shelf parts, initially called the “Small Insect Aspirator” was developed to gently collect western flower thrips, Frankliniella occidentalis (Pergande), from a rearing colony for use in insecticide efficacy trials. This device allows for a designated number of thrips to be placed onto any experimental test plant. The device is a battery-motorized driven aspirator comprised of two pieces of copper tubing (6.0 mm in diameter) attached to a copper housing, which contains a threaded plastic lid and glass vial (20-mL). The aspirator is fully portable when attached to a battery-driven vacuum device, which allows researchers to efficiently collect thrips in outdoor field situations. When turned on, the vacuum gently pulls western flower thrips (adult and larval stages) through the copper tubing and deposits them into the collection vial. The vial is then detached and sealed with a threaded lid until the collected thrips are deposited onto experimental test plants.