Ronald D. Oetting

In Vitro Fungicidal Activity of Acidic Electrolyzed Oxidizing Water

Acidic electrolyzed oxidizing (EO) water, generated by electrolysis of a dilute salt solution, recently gained attention in the food industry as a nonthermal method for microbial inactivation. Our objective was to determine if EO water has potential to control foliar diseases in greenhouses. Test fungi suspended in distilled water were combined with EO water (1:9 water:EO water) for various time periods, the EO water was neutralized, and germination was assessed after 24 h. Germination of all 22 fungal species tested was significantly reduced or prevented by EO water. All relatively thin-walled species (e.g., Botrytis, Monilinia) were killed by incubation times of 30 s or less. Thicker-walled, pigmented fungi (e.g., Curvularia, Helminthosporium) required 2 min or longer for germination to be reduced significantly. Dilution of EO water with tap water at ratios of 1:4 and 1:9 (EO:tap water) decreased efficacy against Botrytis cinerea. The presence of Triton X-100 (all concentrations) and Tween 20 (1 and 10%) eliminated the activity of EO water against B. cinerea. EO water did not damage geranium leaf tissue and inhibited lesion development by B. cinerea when applied up to 24 h postinoculation. EO water has a wide fungicidal activity which could facilitate its use as a contact fungicide on aerial plant surfaces and for general sanitation in the greenhouse.

Distribution of Bemisia tabaci (Hemiptera: Aleyrodidae) Biotypes in North America After the Q Invasion

ABSTRACT After the 2004 discovery of the Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Q biotype in the United States, there was a vital need to determine the geographical and host distribution as well as its interaction with the resident B biotype because of its innate ability to rapidly develop high-level insecticide resistance that persists in the absence of exposure. As part of a coordinated country-wide effort, an extensive survey of B. tabaci biotypes was conducted in North America, with the cooperation of growers, industry, local, state, and federal agencies, to monitor the introduction and distribution of the Q biotype. The biotype status of submitted B. tabaci samples was determined either by polymerase chain reaction amplification and sequencing of a mitochondrial cytochrome oxidase I small subunit gene fragment and characterization of two biotype discriminating nuclear microsatellite markers or esterase zymogram analysis. Two hundred and eighty collections were sampled from the United States, Bermuda, Canada, and Mexico during January 2005 through December 2011. Host plants were split between ornamental plant and culinary herb (67%) and vegetable and field crop (33%) commodities. The New World biotype was detected on field-grown tomatoes (Solanum lycopersicum L) in Mexico (two) and in commercial greenhouses in Texas (three) and represented 100% of these five collections. To our knowledge, the latter identification represents the first report of the New World biotype in the United States since its rapid displacement in the late 1980s after the introduction of biotype B. Seventy-one percent of all collections contained at least one biotype B individual, and 53% of all collections contained only biotype B whiteflies. Biotype Q was detected in 23 states in the United States, Canada (British Columbia and Ontario territories), Bermuda, and Mexico. Forty-five percent of all collections were found to contain biotype Q in samples from ornamentals, herbs and a single collection from tomato transplants located in protected commercial horticultural greenhouses, but there were no Q detections in outdoor agriculture (vegetable or field crops). Ten of the 15 collections (67%) from Canada and a single collection from Bermuda contained biotype Q, representing the first reports of biotype Q for both countries. Three distinct mitochondrial haplotypes of B. tabaci biotype Q whiteflies were detected in North America. Our data are consistent with the inference of independent invasions from at least three different locations. Of the 4,641 individuals analyzed from 517 collections that include data from our previous work, only 16 individuals contained genetic or zymogram evidence of possible hybridization of the Q and B biotypes, and there was no evidence that rare hybrid B-Q marker co-occurrences persisted in any populations.

A Review of the Scientific Literature on Fungus Gnats (Diptera: Sciaridae) in the Genus Bradysia2

The majority of the literature concerning fungus gnats in the genus Bradysia (Family Sciaridae) can be divided into two groups, addressing their cytogenetics or their role as economically important pests. Cytological anomalies in sciarids are recognized in (1) chromosome complement, (2) differential chromosome contributions of the sperm and egg, (3) alteration of chromosome complement during embryogenesis, (4) and alteration during gametogenesis. The literature concerning these cytological events is reviewed within the context of the development of the science of cytogenetics and as they relate to the taxonomy and systematics of this group. Although species of Bradysia were recognized as pests of various seedling plants over a century ago, their economic importance in plant and mushroom production was largely overlooked until recently. A review of the scientific literature on the biology and management of the sciarids indicates that members of the genus Bradysia may be especially pestiferous in greenhouse...

Evaluation of acidic electrolyzed water for phytotoxic symptoms on foliage and flowers of bedding plants

Abstract Acidic electrolyzed oxidizing (EO) water quickly kills a variety of fungi and shows promise as a broad-spectrum contact fungicide for control of foliar diseases of greenhouse-grown ornamentals. One requirement for use in the greenhouse is that EO water will not cause excessive phytotoxic symptoms on a wide variety of species. In one experiment, two applications of EO water did not damage 15 species of bedding plants. In a second experiment, EO water applied as a foliar spray three times per week for 4–7 weeks did not produce any visible phytoxicity on seven of the 12 species tested. Small, white spots were observed on flowers of geranium ( Pelargonium x hortorum ), impatiens ( Impatiens walleriana ), and vinca ( Catharanthus roseus ). Slight necrosis was observed on some leaf edges of petunia ( Petunia x hybrida ), and snapdragon ( Antirrhinum majus ). EO water generated from magnesium chloride produced more phytotoxicity than EO water generated by potassium chloride or sodium chloride. Phytotoxicity ratings of greater than 3 (0–10 scale) were not observed on any of the species tested. EO water caused slight damage to some plant species but, in general, appears to be safe to use as a foliar spray on a wide variety of bedding plants grown under greenhouse conditions.

Temperature Effects on the Development, Survival, and Reproduction of the Madeira Mealybug, Phenacoccus madeirensis Green (Hemiptera: Pseudococcidae), on Chrysanthemum

Abstract The Madeira mealybug, Phenacoccus madeirensis Green (Hemiptera: Pseudococcidae), has become an increasingly damaging pest in greenhouse ornamental production. Current management tactics of P. madeirensis require a regular chemical application schedule targeting the immature stages. Knowledge of the life cycle of P. madeirensis is important to the success of its management program. We investigated the effects of constant temperature (15, 20, 25, 30, 35, and 40°C) on the development, survival, and reproduction of P. madeirensis on chrysanthemum (Dendrathema x grandiflora Kitam.). We failed to establish colonies at 30–40°C. Between 15 and 25°C, the duration of development of all developmental stages were shortened at higher temperatures. The total duration of development of female mealybugs was ≈30 d at 25°C, 46 d at 20°C, and 66 d at 15°C. Developmental time of males was 3–9 d longer than females. Survival rates of individual instars ranged between 88 and 100% and were not influenced by temperature. Overall, >75% of eggs completed development to adulthood. Female mealybugs made up 50% of the adult populations in all temperature treatments. Adult longevity at 25°C was ≈3 and 20 d for males and ovipositing females, respectively. Females at 20°C produced the highest number of eggs (491 ± 38 eggs/female).

Management strategy, shade, and landscape composition effects on urban landscape plant quality and arthropod abundance.

Abstract Intensity and type of management, the cultural variable shade, and the combination of woody and herbaceous annual and perennial plants were evaluated for their effect on key landscape arthropod pests. Azalea lace bugs, Stephanitis pyrioides (Scott), and twolined spittlebugs, Prosapia bicincta (Say), were most effectively suppressed in landscape designed with resistant plant species of woody ornamentals and turf. Landscapes containing susceptible plant counterparts were heavily infested by these two insect species in untreated control plots. A traditional management program of prescribed herbicide, insecticide, and fungicide applications effectively suppressed azalea lace bug and produced a high-quality landscape. Targeted integrated pest management with solely horticultural oils resulted in intermediate levels of azalea lace bug. Neither program completely controlled twolined spittlebug on hollies or turf. Carabidae, Staphylinidae, Formicidae, and Araneae were not reduced by any management strategy. Lace bugs (Stephanitis) were more common in plots with 50% shade than those in full sun. Spittlebugs (Prosapia) were more common in the shade during 1996 and in the sun during 1997. Spiders and ants were more often collected in full sun plots. Carabids, staphylinids, and spiders were more commonly collected from pitfall traps in turf than in wood-chip mulched plant beds, whereas ants were equally common in both locations. The addition of herbaceous plants to the landscape beds had little effect on pest insect abundance.

Susceptibility of the Two-Spotted Spider Mite, Tetranychus Urticae Koch, to the Fungal Pathogen Hirsutella Thompsonii Fisher

Laboratory bioassays determined the susceptibility of the two-spotted spider mite, Tetranychus urticae Koch, to Hirsutella thompsonii thompsonii Fisher. Direct placement of conidia onto mites which were placed on bean leaf discs floating on distilled water in covered petri dishes yielded a mean mortality of 96.5%. Mortality of mites placed on leaf discs cut from bean plants previously sprayed with a commercial formulation of the bioacaricide (Mycar, Abbott Laboratories, North Chicago, IL) and placed in the covered dishes ranged from ca. 24 to 99%. No significant response to dose of Mycar occurred at the rates tested (1.2-9.6 g/liter). Under greenhouse conditions (22-30@*C; 50-90% RH), the formulated material failed to either sporulate on sprayed foliage or cause mite mortality. Raising humidity levels with intermittent misting of foliage increased sporulation of the fungal inoculum on plant surfaces, but no infections occurred in mites on those plants.

EFFICACY OF BEAUVERIA BASSIANA PLUS INSECT ATTRACTANTS FOR ENHANCED CONTROL OF FRANKLINIELLA OCCIDENTALIS (THYSANOPTERA: THRIPIDAE)

Beauveria bassiana (Balsamo) Vuillemin strain GHA effectively controls western flower thrips, Frankliniella occidentalis (Pergande), on greenhouse ornamentals (Murphy et al. 1998). Although greenhouse growers commonly add additives, such as attractants, to tank mixes for enhanced insect control, little research has been conducted to test this practice. Thrips must come into contact with the Beauveria spores while they are still viable. The use of attractants theoretically would attract the insects to the spores soon after application. The objective of this study was to determine if the addition of insect attractants improve the effectiveness of Beauveria bassiana against western flower thrips on greenhouse grown chrysanthemums. Growers use attractants to enhance activity of some insecticides, our results will indicate if this practice aids in thrips management when attractants are used together with B. bassiana . One rooted chrysanthemum ‘Charm’, Dendranthema × grandiflora (Ramat.) Kitamura, cutting was planted per 15 cm plastic pot containing Pro-Gro Professional Growing Medium®300 (ProGro Products Inc., McCormick, SC). Each pot received an initial application of 4.5 g of 14-14-14 Osmocote® (Scotts, Marysville, OH). Plant terminals were removed to promote branching 2 and 4 wks after potting. A foliar application of 5,000 ppm daminozide (Uniroyal, Middlebury, CT), a plant growth regulator, was applied 6 wks after potting. Before the experiment began, plants were watered daily and fertilized two times a week with 200 ppm N [20-10-20 Peter’s Peat-lite Special® (Scotts)]. The experiment was conducted as a randomized complete block design with eight treatments in two trials. Each study had six replicate pots of each treatment. Two greenhouses were used, each containing three replicates. The greenhouse temperature and humidity were similar so greenhouse effects were ignored and the data pooled. At the initiation of the experiment each pot was placed in fiber plant sleeve 20 × 61 × 51 cm (B × H × T) (Kleen Test Products, Milwaukee, WI). The plant sleeves confined thrips to plants and prevented movement between treatments. Plants were placed onto and watered using ebb and flood tables. This eliminated the need for opening the sleeves to maintain the plants. As a result, the foliage remained dry and humidity within the sleeves was consistent with the surrounding greenhouse. To water the plants, benches were flooded daily with a solution containing 100 ppm N (20-10-20 Peter’s Peat-lite Special®). The eight treatments investigated were 2.5 ml/l of Beauveria bassiana strain GHA (BotaniGard® ES, Mycotech, Butte, MO), 2.5 ml/l of Lure® Insect Attractant (Setre Chemical Co., Memphis, TN), 0.5ml/l of Stirrup® (Troy Bioscience, Phoenix, AZ), 1.2 g/l of sugar, a water control, and B. bassiana + Stirrup®, B. bassiana + sugar, B. bassiana + Lure® at the previously described rates. Treatments were applied using a hand sprayer at 241 kPa and applied to runoff. Stirrup® is a biochemical designed to modify the behavior of mites for use in combination with miticides. Lure® Insect Attractant is a commercially available 40.5% blend of monoand polysaccharides. Consumer grade white granulated sugar was used in the sugar treatments. Treatments in the first trial were initiated at bud break and continued weekly for a total of three applications. Treatments in the second trial were initiated when the bud were large. Thrips populations were determined weekly by randomly collecting four flowers (first trial) or buds (second trial) per pot and placing them in 200 ml of ethyl alcohol. Flowers or buds were removed from the alcohol and the number of adult and immature thrips remaining were counted. Temperature and humidity were recorded in the plant sleeves using StowAway® XTI temperature loggers and StowAway® RH relative humidity loggers (Onset Computer Corp., Pocasset, MA). Data were transformed [log10 (x+1)] to make the variance independent of the means (Sokal & Rohlf 1995). Treatment efficacy, as measured by the number of thrips per sample period, was subjected to Analysis of Variance (GLM procedure). Means separation was accomplished using the least significant difference test (LSD) at the P < 0.05 level (SAS Institute 1985). Data are presented as untransformed means. A sample was taken from each B. bassiana treatment to determine the spore viability of the treatment solution. Serial dilutions of 10 -5 and 10 -6

Imidacloprid Applications by Subirrigation for Control of Silverleaf Whitefly (Homoptera: Aleyrodidae) on Poinsettia

Abstract The objective of this study was to determine whether silverleaf whiteflies, Bemisia argentifolii Bellows & Perring, on poinsettia, Euphorbia pulcherrima Willdenow ex Klotsch, can be controlled with imidacloprid applied by subirrigation. Different amounts of imidacloprid uptake by the growing medium were obtained by not watering the subirrigated plants for 0, 1, 2, or 4 d before the imidacloprid application. These treatments resulted in absorption of 12–175 ml of imidacloprid solution by the growing medium. These treatments were compared with untreated control plants and plants that were treated with a standard drench application (100 ml) to the top of the growing medium. All imidacloprid treatments resulted in a significant decrease in both the survival of adult whiteflies and number of immature whiteflies on the plants. Subirrigation treatments resulted in better control of adult and immature whiteflies than drench application. Withholding water for 2 or 4 d before the imidacloprid application by subirrigation improved control of immature whiteflies. This indicates that the application of imidacloprid to poinsettia by subirrigation is a practical and efficient method to control silverleaf whiteflies.

Host stage selection of the mealybug parasitoid Anagyrus spec. nov near sinope

The mealybug parasitoid Anagyrus spec. nov near sinope (Hymenoptera: Encyrtidae) is an undescribed parasitoid of the Madeira mealybug, Phenacoccus madeirensis Green (Homoptera: Pseudococcidae). We investigated the preference of Anagyrus spec. nov near sinope for six developmental stadia (first‐ and second‐instar nymphs, third‐instar immature females, third‐ or fourth‐instar immature males, pre‐reproductive adult females, and ovipositing adult females) of P. madeirensis and the fitness consequences of the host stage selection behavior. In the no‐choice test, Anagyrus spec. nov near sinope parasitized and completed development in all host stadia except third‐instar immature males. When all host stadia were offered simultaneously, the parasitoids preferred third‐instar immature and pre‐reproductive adult females. Dissection of the stung mealybugs revealed that the clutch size (number of eggs per host) was approximately four and three in the third‐instar and pre‐reproductive females, respectively, and one egg per first‐instar nymph. Parasitoids emerged from P. madeirensis parasitized at third‐instar or pre‐reproductive adult female completed development in the shortest duration, achieved a higher progeny survival rate, larger brood and body size, and the lowest proportion of males. We showed that the continued development of mealybugs had significant influence on the fitness of the parasitoids. Although deposited as eggs in first‐ or second‐instar nymphs, parasitoids emerged from mummies that had attained third‐instar or adult development achieved similar progeny survival rate, brood size, body size, and sex ratio as those parasitoids deposited and developed in third‐instar or adult mealybugs. By delaying larval development in young mealybugs, Anagyrus spec. nov near sinope achieved higher fitness by allowing the parasitized mealybugs to grow and accumulate body size and resources. We suggest that the fitness consequence of host stage selection of a koinobiont parasitoid should be evaluated on both the time of parasitism and the time of mummification.