Controlled-release Dispensers Research Articles

Field Evaluation of Different Attractants for Detecting and Monitoring Drosophila suzukii

Drosophila suzukii, more commonly known as the spotted-wing drosophila (SWD), is an invasive pest of soft, thin-skinned fruit responsible for significant economic losses for growers worldwide. To detect and monitor this pest, several host attractants have been developed for use in trapping SWD; however, they lack selectivity. Therefore, there is a significant need for more selective monitoring devices to enable growers to make timely pest management decisions to properly protect vulnerable crops. Previous studies identified a quinary blend (QB), based on fermenting apple juice odors, which offers significantly higher selectivity by reducing non-target captures compared with the standard apple cider vinegar bait commonly used by growers in the orchards. In this study, the selectivity and efficacy of a home-made QB dispenser was compared to an industry formulated version of the QB components (ChemTica) and two commercially available (Scentry and Trécé) SWD dispensers across blueberry and raspberry fields in Maryland, West Virginia, and New Jersey in different seasons. Controlled-release dispensers of the QB (home-made and ChemTica) consistently had higher selectivity within the blueberry and raspberry field sites compared with the two commercial dispensers; although efficacy was compromised such that total SWD captures per trap tended to be lower. The selectivity ratio range of SWD to non-targets (all non-SWD) for a QB-based (ChemTica) dispenser averaged from 15 to 57% compared with other commercial dispensers that ranged from 1 to 30% based on location and year. Due to high selectivity of the controlled-release dispenser of the QB, the potential for this dispenser to be utilized by growers as a SWD detection and monitoring tool is high.

Community deployment of a synthetic pheromone of the sand fly Lutzomyia longipalpis co-located with insecticide reduces vector abundance in treated and neighbouring untreated houses: Implications for control of Leishmania infantum.

The rising incidence of visceral leishmaniasis due to Leishmania infantum requires novel methods to control transmission by the sand fly vector. Indoor residual spraying of insecticide (IRS) against these largely exophilic / exophagic vectors may not be the most effective method. A synthetic copy of the male sex-aggregation pheromone of the key vector species Lutzomyia longipalpis in the Americas, was co-located with residual pyrethroid insecticide, and tested for its effects on vector abundance, hence potential transmission, in a Brazilian community study. Houses within eight defined semi-urban blocks in an endemic municipality in Brazil were randomised to synthetic pheromone + insecticide or to placebo treatments. A similar number of houses located >100m from each block were placebo treated and considered as "True Controls" (thus, analysed as three trial arms). Insecticide was sprayed on a 2.6m2 surface area of the property boundary or outbuilding wall, co-located within one metre of 50mg synthetic pheromone in controlled-release dispensers. Vector numbers captured in nearby CDC light traps were recorded at monthly intervals over 3 months post intervention. Recruited sentinel houses under True Control and pheromone + insecticide treatments were similarly monitored at 7-9 day intervals. The intervention effects were estimated by mixed effects negative binomial models compared to the True Control group. Dose-response field assays using 50mg of the synthetic pheromone captured a mean 4.8 (95% C.L.: 3.91, 5.80) to 6.3 (95% C.L.: 3.24, 12.11) times more vectors (female Lu. longipalpis) than using 10mg of synthetic pheromone. The intervention reduced household female vector abundance by 59% (C.L.: 48.7, 66.7%) (IRR = 0.41) estimated by the cross-sectional community study, and by 70% (C.L.: 56.7%, 78.8%) estimated by the longitudinal sentinel study. Similar reductions in male Lu. longipalpis were observed. Beneficial spill-over intervention effects were also observed at nearby untreated households with a mean reduction of 24% (95% C.L.: 0.050%, 39.8%) in female vectors. The spill-over effect in untreated houses was 44% (95% C.L.: 29.7%, 56.1%) as effective as the intervention in pheromone-treated houses. Ownership of chickens increased the intervention effects in both treated and untreated houses, attributed to the suspected synergistic attraction of the synthetic pheromone and chicken kairomones. The variation in IRR between study blocks was not associated with inter-household distances, household densities, or coverage (proportion of total households treated). The study confirms the entomological efficacy of the lure-and-kill method to reduce the abundance of this important sand fly vector in treated and untreated homesteads. The outcomes were achieved by low coverage and using only 1-2% of the quantity of insecticide as normally required for IRS, indicating the potential cost-effectiveness of this method. Implications for programmatic deployment of this vector control method are discussed.

Controlled-Release Dispenser and Dry Trap Developments for Drosophila suzukii Detection

The spotted wing drosophila (SWD), Drosophila suzukii, is an exotic vinegar fly originating from South-East Asia and has invaded many American and European countries. This devastating pest has caused severe damage on soft-skinned fruit crops, which has resulted in large economic losses. Although many D. suzukii detection devices have been developed and used by growers/farmers in orchards, most of them did not meet their expectation. More simple, convenient, and efficient detection tools are still urgently needed so that growers/farmers can make timely management decision. In our previous study a quinary blend, containing acetoin, as a long-range, and ethyl octanoate, as a short-range attractant for SWD, had been identified. In this study, a controlled-release polyethylene dispenser containing five identified attractants: acetoin, ethyl octanoate, ethyl acetate, penethyl alcohol, and acetic acid, was tested in laboratory conditions for release rates, as well as in a blueberry field and an adjacent wooded area for trapping activity. Release of the most D. suzukii attractants from the polyethylene dispenser was constant. In the laboratory, release rates of ethyl acetate (0.3 g/day over 14 days), phenethyl alcohol (0.0054 g/day over 36 days), and acetic acid (0.13 g/day over 36 days) followed zero order kinetics. Acetoin and ethyl octanoate were blended together and had a varied release rate. In the field, dry and liquid traps baited with the optimized controlled-release dispenser were evaluated and compared with liquid traps baited with apple cider vinegar (ACV). During blueberry harvest season in 2018, the liquid traps containing drowning solution baited with the optimized controlled-release dispenser caught both male and female D. suzukii two weeks earlier and had significantly higher selectivity than that of ACV traps in the field. Additionally, in 2019 field tests, dry traps baited with the controlled-release dispenser demonstrated earlier detection compared to the ACV traps. Due to the simplicity of the dry trap design and easy processing, it has great potential to be an efficient and convenient D. suzukii detection tool for growers/farmers.

Modulation of current-time traces by two-pore arrangements of polyimide nanofluidic diodes

Liquid state arrangements of two polymeric membranes with single conical nanopores constitute nanofluidic diodes that allow a rich electrical functionality based on the modulation of individual conductances in aqueous electrolyte solutions. In particular, the prescribed sequences of current-time traces can be obtained by preprogramed switching between series and parallel pore connection arrangements. Hybrid nanopore-solid-state circuits are also possible. The basic applied physics of the nanofluidic diode arrangements can be understood from simple circuit theory concepts and should be of widespread interest to sensing and actuating procedures, controlled release dispensers, and energy conversion modules based on electrochemical signals.

Effect of Applications of Isonet L Plus, the Controlled-Release Dispenser in the Protection of Vineyards Against Lobesia Botrana and Eupoecilia Ambiguella in the Southern Slovakia

Abstract The grapevine moth (Lobesia botrana) and the grape berry moth (Eupoecilia ambiguella) are the main pests in southern Slovakia vineyards. While L. botrana represents the most common species in the vineyards, E. ambiguella exists in some sites only. In this study we monitored the occurrence and dynamics of the flights of the grapevine moth and the grape berry moth in the vineyard area Dvory nad Žitavou. The size of the examined area was 60 ha in 2008 and 90 ha in 2009. On these areas, we used pheromone traps type Deltastop LB for grapevine moth and Deltastop EA for grape berry moth. To control the movement of the pests, a set of three pheromone traps for each type was used in observation points which were placed at least 50 m from each other. Monitoring was carried out regularly every second to third day. The control area was located in immediate vicinity of the area. As a threshold, we consider 20 moths for 2 days at an average of three pheromone traps. In 2008, we recorded the first, second and third generation of Lobesia botrana and only the second generation of Eupoecilia ambiguella. In 2009, we saw all three generations for both types of moths. We also examined effectiveness of the protection method of grapevine based on the mating disruption using pheromone dispensers type ISONET L plus. Just before the anticipated start of swarming we distributed 420 dispensers/ha evenly over the entire vineyard; on the edges of the treated area, the basic dose of dispensers i.e. 500 pieces/ha was left. To assess the effectiveness of the product ISONET L plus in 2008 we reached more than 70% efficiency in the border plots, inside 96%. We achieved 69% efficiency in 2009. Based on the results it is be clear that the long-term use of this method of protection has a positive impact in reducing the population of moth. It is suitable for use in an integrated and biological protective system against Lobesia botrana and Eupoecilia ambiguella.

Semiochemical lures reduce emigration and enhance pest control services in open-field predator augmentation

Augmentation biocontrol is a commercially viable pest management tactic in enclosed glasshouse environments, but is far less effective in open-field agriculture where newly released enemies rapidly disperse from release sites. We tested the potential for behavior-modifying semiochemicals to increase the retention of mass released predatory stink bugs, Podisus maculiventris Say (Hemiptera: Pentatomidae), for enhanced consumption of hornworm caterpillars, Manduca sexta L. (Lepidoptera: Sphingidae). To do so, we used controlled-release dispensers to emit the herbivore-induced plant volatile, methyl salicylate (MeSA), or P. maculiventris aggregation pheromone from tomato field plots. Overall, we recaptured ca. 17% of released individuals after 36h. This rate, however, was significantly affected by weather (12% vs. 22% recapture in rainy vs. dry weeks, respectively) and semiochemical deployment, but only under optimal weather conditions (19% vs. 26% recapture in control vs. pheromone plots, respectively, during dry weeks). Further, we detected behavioral responses of wild P. maculiventris to semiochemical treatment with 94% of all captured adults (=84 of 89 total) found in pheromone plots. Only 24 of 567 (4%) captured stink bugs tested positive for immunomarking, suggesting that hornworm predation occurred but at a low frequency. Importantly, we documented that sentinel caterpillar prey were depleted by predators at a higher rate in stink bug augmented plots on tomato plants occurring near (<3m from) the MeSA and pheromone lures. These data empirically demonstrate that both semiochemicals are capable of increasing pest consumption via attraction of P. maculiventris. Future work should focus on mechanisms of lure attraction and the long-term consequences of predator development in fields with elevated semiochemical emissions.

Attracting carnivorous arthropods with plant volatiles: The future of biocontrol or playing with fire?

Herbivore-induced plant volatiles (HIPVs) are potent attractants for entomophagous arthropods and researchers have long speculated that HIPVs can be used to lure natural enemies into crops, reestablishing predator–prey relationships that become decoupled in disturbed agricultural habitats. This speculation has since become reality as the number of field trials investigating HIPV-mediated attraction and its consequences for pest suppression has risen dramatically over the past 10years. Here, I provide an overview of recent field efforts to augment natural enemy populations using HIPVs, with emphasis on those studies manipulating synthetic compounds in controlled-release dispensers, and outline a prospectus for future research needs. Specifically, I review and discuss: (i) choice of compounds and release rates; (ii) functional changes in predator and parasitoid communities; (iii) non-target effects; (iv) mechanisms of attraction and prey suppression; (v) spatial- and landscape-level considerations; (vi) context-dependent responses; and (vii) temporal stability of attraction.

Traslucent pheromone traps increase trapping efficiency of ambrosia beetle Megaplatypus mutatus

Megaplatypus mutatus (= Platypus mutatus) is an ambrosia beetle native to South America. Unlike most ambrosia beetles, it attacks only living trees, penetrating the xylem of its host by boring long tunnels. These galleries cause severe stem-breakage and mortality in commercial poplar plantations. In previous studies we showed that volatile emissions from pioneer male M. mutatus are composed of (+)-6-methyl-5-hepten-2-ol, 6-methyl-5-hepten-2-one and 3-pentanol. Recently, we developed reservoir type controlled release dispensers and tested the efficacy of various trap designs in the field. Results showed that black cross-vane traps (CIPEIN-CV) captured significantly more insects than other traps designs baited with the same dispensers. In the present study we modified the colour, the construction material and the size of traps with the aim of increasing trapping efficacy and reducing the final trap cost. The results showed that significantly more female and male M. mutatus were captured in small and large traslucent traps (CIPEIN-CVt) than in black CIPEIN-CV trap. Furthermore, traslucent CIPEIN-CVt trap costs were significantly lower than costs for CIPEIN-CV traps. Significantly improved trapping efficacy with an important decrease in final costs will allow detection of considerably lower populations of M. mutatus in monitoring programs.

Identification of limonene as a potential kairomone of the harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae)

Chemical cues involved in both host location and oviposition by Harmonia axyridis Pallas (Coleoptera: Coccinellidae) were investigated in laboratory and field experiments. Among the five volatiles tested in a four-arm olfactometer ((E)-&beta;-farnesene, &beta;-pinene, &beta;-caryophyllene, cis-3-hexen-1-ol, and limonene), gravid H. axyridis females were significantly attracted to limonene and &beta;-caryophyllene. These two chemicals also increased H. axyridis oviposition on plants. Attraction of H. axyridis towards limonene was further tested under field conditions using controlled-release dispensers. (E)-&beta;-farnesene, a major aphid alarm pheromone and a potential predator kaironome, was also tested in this study. Field data confirmed those from laboratory studies concerning the attraction of H. axyridis towards limonene and a lack of response to (E)-&beta;-farnesene. In contrast, the aphid predator Episyrphus balteatus DeGeer (Diptera: Syrphidae) was attracted to (E)-&beta;-farnesene but not to limonene. These findings indicate that H. axyridis uses chemicals, such as limonene, for prey location and oviposition, and support the potential use of volatiles in the management of H. axyridis.

Synthetic Herbivore-induced Plant Volatiles Increase Field Captures of Parasitic Wasps

Field evidence for attraction of parasitic wasps from the families Encyrtidae and Mymaridae to grapevines baited with synthetic versions of three herbivore-induced plant volatiles (HIPV) is presented. In a replicated experiment conducted in a juice grape vineyard, sticky cards in blocks baited with controlled-release dispensers of methyl salicylate (MeSA), methyl jasmonate (MeJA) or (Z)-3-hexenyl acetate (HA), trapped significantly greater numbers of Metaphycus sp. (Encyrtidae) than cards in unbaited blocks during May–September. Significantly greater numbers of Anagrus spp. (Mymaridae) were trapped in MeSA and MeJA-baited blocks than in unbaited blocks, during August–September. Greater numbers were recorded in HA-baited blocks in September only. Previous studies showed Encyrtidae and Anagrus spp. were not attracted to sticky cards baited with vials of MeSA, MeJA or HA. Possible reasons for attraction in this study are discussed including the possibility that synthetic, gaseous HIPV from controlled-release dispensers may stimulate plants to produce natural blends of parasitoid-attracting volatiles.

Field-Testing of Methyl Salicylate for Recruitment and Retention of Beneficial Insects in Grapes and Hops

Evidence for recruitment and retention of beneficial insects in grapes and hops using controlled-release dispensers of methyl salicylate (MeSA), a component of herbivore-induced volatile blends, is presented. In a replicated experiment conducted in a juice grape vineyard, sticky cards in blocks baited with MeSA captured significantly greater numbers of five species of predatory insects (Chrysopa nigricornis, Hemerobius sp., Deraeocoris brevis, Stethorus punctum picipes, Orius tristicolor) than unbaited blocks. Four insect families (Syrphidae, Braconidae, Empididae, Sarcophagidae) were also significantly more abundant in the MeSA-baited blocks, as indicated by sticky card captures. Canopy shake samples and sticky card monitoring conducted in a MeSA-baited, unsprayed hop yard indicated development and maintenance of a beneficial arthropod population that was nearly four times greater than that present in an unbaited reference yard. Four times as many S. punctum picipes and six times as many O. tristicolor were sampled in the MeSA yard. Similar contrasts in abundance of these predators and others were apparent when compared with levels recorded in the yard in previous years. The large population of predatory insects in the MeSA-baited hop yard was associated with a dramatic reduction in spider mite numbers, the major arthropod pest of hops, in late June, and subeconomic populations were maintained for the rest of the season. The evidence presented here is highly suggestive that the use of controlled-release MeSA in a crop could increase recruitment and residency of populations of certain beneficial insects. This strategy may have the potential to enhance the efficacy and reliability of conservation biological control in crop pest management.

Composition of chemical attractants affects trap catches of the Australian sheep blowfly, Lucilia cuprina, and other blowflies.

Numbers of Lucilia cuprina (Australian sheep blowfly), Chrysomya spp., and Calliphora spp. blowflies caught on sticky traps baited with various synthetic attractants or a standard liver/sodium sulfide attractant in western Queensland were recorded. Numbers of each genus collected were influenced by the composition of the chemical attractants. Attractant mixtures based on 2-mercaptoethanol, indole, butanoic/pentanoic acid, and a sodium sulfide solution gave 5- to 20-fold higher L. cuprina catches than the liver standard. These blends attracted similar numbers of Chrysomya spp. (0.85-2.7x) and fewer Calliphora spp. (0.02-0.2x) compared to the liver standard. These synthetic attractants were more effective and selective for L. cuprina than the standard liver/sodium sulfide attractant, and they can be packaged in controlled-release dispensers to generate constant, prolonged release of the attractant.

TRAPPING YELLOWJACKETS (HYMENOPTERA: VESPIDAE) WITH HEPTYL BUTYRATE EMITTED FROM CONTROLLED-RELEASE DISPENSERS

Numbers of workers of Vespula pensylvanica (Saussure) (western yellowjacket) and V. atropilosa (Sladen) trapped with heptyl butyrate in Washington increased with greater release of the attractant from vial dispensers, up to an estimated 2.3 milligrams heptyl butyrate per hour. Vespula germanica (F.) (German yellowjacket) workers were also captured in significant numbers, and numbers of workers captured increased with increased release of heptyl butyrate, up to an estimated 1.4 milligrams per hour. Numbers of workers of Vespula squamosa (Drury) trapped with heptyl butyrate in Oklahoma increased with increased release of heptyl butyrate from dispensers, up to an estimated 3.3 milligrams per hour. Vial dispensers, with holes of 6, 12, 22, and 33 mm diameter in the vial lid, lost 0.42, 1.4, 2.3, and 3.3 milligrams of heptyl butyrate per hour in the laboratory and these rates changed little over a period of 4 weeks, indicating close to a zero order rate of release pattern. Rates of loss of 2 ml heptyl butyrate applied to a cotton ball decreased with exposure time, from an initial rate of 6.0 milligrams per hour to near zero at 16 days post-treatment. Captures of wasps in traps sold commercially might be improved with the use of a controlled-release dispenser.

Comparison of Two Types of Traps and Lure Dispensers for Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)

ABSTRACTTwo types of traps were compared for a period of 8 weeks in a citrus orchard to decide on the most suitable to use in a surveillance program for the Mediterranean fruit fly (Ceratitis capitata). the results showed that the Lynfield “pot” trap was significantly more efficient than the Jackson “sticky” trap, cheaper to construct, easier to maintain, and better suited to the monitoring program. Magnet® TML 70‐0 solid controlled release dispensers were compared over a period of 15 weeks in citrus orchards with standard Capilure cotton wicks. While both attracted equal numbers of C. capitata, Magnet® TML 70‐0 dispensers at 10 times the cost øf capilure wicks were not economical in large‐scale trapping programs.

Controlled-release pheromone dispenser for use in traps to monitor flight activity of false codling moth

Field trials were conducted in the western Cape Province, South Africa, to develop a sex pheromone dispenser suitable for monitoring the flight activity of false codling moth. A controlled-release dispenser capable of releasing sex pheromone at a predetermined and constant release rate without replacement for more than seven months was produced.

Controlled-release panel traps for the Mediterranean fruit fly (Diptera: Tephritidae).

Solid, controlled-release dispensers containing 2 g of the synthetic attractant trimedlure now are used in Jackson traps to detect the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Panel traps consisting of trimedlure mixed in a sticky substance and spread on the surfaces of a plastic panel are used to delineate the limits of discovered insect infestations in California. We describe the development of controlled-release, polymeric panels that prolong release of trimedlure and a highly attractive analog, ceralure. Attractants were incorporated in a polyethylene matrix to form panels and in a polymer coating on cardboard panels that then were evaluated by biological and chemical assay. In addition, commercial polymer matrix panels were evaluated. Field bioassay tests conducted in Hilo, HI, using released flies and in Guatemala in a natural population showed that the polyethylene matrix panel became brittle and cracked during field exposure and that release rates of the attractants were relatively low. The coated cardboard panels were stable under field conditions and yielded high fly captures for up to 6 wk. Farma Tech commercial panels containing 12.3 and 23.4 g of trimedlure remained highly attractive throughout a 134-d test in Hawaii and appear to be a long-lasting alternative to panels coated with trimedlure in Stikem. The cost of the relatively high dose of trimedlure is offset by the prolonged active life of the panel. Commercial panels from AgriSense (10 g trimedlure and 10 g ceralure) released the attractants at a slower rate and were less attractive.

Performance characteristics of a commercial controlled-release dispenser of sex pheromone for control of codling moth (Cydia pomonella) by mating disruption

Performance characteristics of polyethylene tube dispensers containing a mixture of (E,E)-8,10-dodecadien-1-ol (1), dodecan-1-ol (2), and tetradecan-1-ol (3) were evaluated for suitability as a mating disruptant for codling moth control. The rate of loss of pheromone component from a dispenser at any time was found to be described by the equation: -dP/dt=(k 1 k 2 +k d)P whereP is the amount of pheromone component in the dispenser well;t is time;k 1 is the ratio of the amount dissolved in the dispenser wall to the amount in the dispenser well;k 1 is the ratio of the evaporation rate to the amount dissolved in the dispenser wall;k d is the rate constant for chemical decomposition. The evaporation rate,E, of a pheromone component at any time was given by:E=k 1 k 2 P For all three components during the first three weeks,k 1 decreased from ca. 0.25 to ca. 0.10 and was approximately constant thereafter. The decrease ofk 1 with time may have been caused by weather-induced cross-linking of the polyethylene. Over timek 2 was constant and was 1.27 ± 0.26 × 10(-3)/hr for1, 1.96 ± 0.33 × 10su-3/hr for 2, and 0.31± 0.05 × 10(-3)/hr for 3. Thek 2 was zero for2 and3 and 6.96 × 10(-4) for1. After 150 days in an orchard in 1991, 95% of1 was lost from the dispensers (61% of the loss was by chemical decomposition and 39% by evaporation). The heat summation units in a Yakima valley orchard during 1991 were 4.7% above the average for the 1980-1991 period, while during 1990 they were the highest for this period (26% above average). After the first three weeks of dispenser aging, the regression line half-lives for1 for 1990 and 1991 were 31.0 and 35.1 days, respectively. The difference in temperature between 1990 and 1991 did not affect the half-life of1 very much because so much of the loss was from photochemically induced decomposition. Based on an estimate of the required minimum evaporation rate for mating disruption of 2 mg/ha-hr and a half-life of 35 days for1, 2345 dispensers/ha would be required for one application per season; 944 dispensers/ha for two applications per season; and 734 dispensers/ha for three applications per season. If a different emission rate of1 is required for reliable mating disruption, then the number of dispensers required would be changed proportionately.

Evaluation of Pheromone Dispensers for Use in Gypsy Moth Detection (Lepidoptera: Lymantriidae)2

Seven controlled-release dispenser formulations containing 500 μg of gypsy moth pheromone (+)-disparlure, were compared in laboratory and field tests. Pheromone release rates, residual pheromone contents, and male moth captures in traps baited with the dispensers were compared following pre-aging of the dispensers in a greenhouse at 35 °C for 0, 4, 12, and 16 wk. The laminate dispenser, now used in USDA detection traps, became less attractive over time as its pheromone release rate and content dropped below the threshold values previously reported as necessary for effective attraction. A polyvinyl chloride coated twine dispenser produced high male moth captures and gave release rates and residual contents above these thresholds (30 ng/h release rate and 100 μg content) at all aging periods. The tube-A dispenser was the most effective of the new commercially prepared formulations, followed by the membrane and tube-B whose male moth captures and release rates tended to increase with aging time. The capsule and film dispensers were the least effective of the formulations tested.

Antimicrobial effect of chlorhexidine in a controlled release delivery system

Chlorhexidine is widely used as a mouth rinse in the prevention and treatment of periodontal diseases and dental caries. The purpose of the present study was to evaluate the in vitro antimicrobial effect of chlorhexidine in a controlled release delivery system. The controlled release dispenser comprised a polymeric inner core matrix containing the medicament with an outer vinyl membrane controlling the drug release. The effect on the following bacteria was studied: Actinobacillus actinomycetemcomitans, Actinomyces viscosus, Streptococcus mutans, Wolinella recta, Bacteroides gingivalis, Bacteroides intermedius, Eikenella corrodens, Pseudomonas aeruginosa, Enterobacter aerogenes, and Enterobacter cloacae. Chlorhexidine-containing vinyl patches with a diameter of 5.5 mm were placed on blood agar plates containing the various bacteria. The plates were incubated aerobically or anaerobically at 37 degrees C for 24 h or longer, when appropriate, and examined for inhibition of bacterial growth. Distinct zones of inhibition were seen surrounding all vinyl patches on all plates with all bacteria. Thus, the vinyl dispenser appeared to be an effective vehicle for releasing chlorhexidine to a localized area such as the surface of a tooth, a periodontal pocket, or a root canal.

Design, Effectiveness, and Performance Criteria of Dispenser Formulations of Trimedlure, an Attractant of the Mediterranean Fruit Fly (Diptera: Tephritidae)

Controlled-release dispensers of trimedlure (TML), a synthetic attractant of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were evaluated in seven aging tests in natural and released populations. Insect captures and laboratory-measured release rates and residual contents showed that the cotton wick dispensers, which were formerly used for 2 g liquid TML (density = 1.0 g/ml), were generally ineffective after 2-4 wk of field exposure; a 4-g dose of TML increased the longevity, but not the initial biological activity of the cotton wick. Two controlled-release formulations, a polymeric plug (70% by weight TML) and a plastic laminate, extended the effective lifetime of 2 g TML to about 8 wk. A polymeric plug with 4 g TML further extended the duration of effectiveness to 12 wk or longer. Laboratory and field data suggested definitive values for relative insect capture, release rate, and residual trimedlure content, which have been used as performance criteria in the purchase of trimedlure dispensers.