Biomedical subjects

L J Gut

Publications and source records attributed to L J Gut.

9 recordsLinked to original sources

PubMed2006

Differentiation of competitive vs. non-competitive mechanisms mediating disruption of moth sexual communication by point sources of sex pheromone (part 2): Case studies.

Eleven out of 13 disruption profiles (plots of dispenser density vs. male catch) from moth sex pheromone literature were consistent with a competitive-attraction mechanism, in which dispensers attract males and thereby divert them from females. Mean dispenser activity (D(a)) across all competitive-attraction cases was 0.04 +/- 0.06 (SD); values ranged from 0.0005 for a tiny laminated flake dispenser of racemic disparlure targeting gypsy moth to 0.2 for polyethylene tube dispensers used against lightbrown apple moth. A dispenser application activity (D(Aa)) can be calculated by multiplying D(a) by the number of such dispensers applied per hectare of crop. The highest dispenser application activity (D(Aa)) values approached 200 and corresponded to >99% inhibition of catches of male moths in monitoring traps. Relative to the D(Aa) scale, % inhibition of catches of male moths compressed and obscured large differences in D(Aa) when % disruption exceeded 90%. For cases of competitive attraction, these two efficacy scales can be interconverted by using the formula: D(Aa) approximately = 100/(100 minus % disruption). When disruptive point sources of pheromone were directly observed, male moths were seen approaching pheromone dispensers whose disruption profiles matched competitive attraction. Two cases fit non-competitive disruption mechanisms, which include camouflage, desensitization (adaptation and/or habituation), and sensory imbalance. In these cases, pheromone was released at rates higher than for cases of disruption by competitive attraction. Practical ramifications of the finding that competitive attraction appears to be the prevalent mechanism for moth mating disruption by pheromone point sources are listed. We believe that the congruence of diverse sets of mating disruption field data with explicit a priori predictions validates competitive-attraction theory. The analytical tools and principles governing competitive attraction that were uncovered during this study of mating disruption of moths should be generally applicable to competitive-attraction phenomena.

Animal Communication↗

PubMed2006

Orientational behaviors and EAG responses of male codling moth after exposure to synthetic sex pheromone from various dispensers.

The effect of brief pheromone exposures on responses of codling moth (Cydia pomonella L.) males was tested by flight-tunnel and electroantennogram (EAG) studies. Males were preexposed to pheromone for up to 3 min as they sat in release cages or for shorter times (a few seconds to several min) upon initiating flights or orienting in plumes. Brief exposures to Isomate-C Plus dispensers nearly eliminated moth orientations to 0.1 mg codlemone [(E,E)-8,10-dodecadien-1-ol] and 0.1 mg three-component (codlemone/12OH/14OH, 100:20:5 ratio) lures 15 min later. However, there was no associated change in EAG responses between preexposed and control moths. Behavioral responses of Isomate-C Plus-exposed males were normal 24 hr following exposure. The reduced sexual responsiveness observed following exposure to Isomate dispensers appeared to be associated with an elevation of response threshold. Brief preexposure to 0.1 mg codlemone and three-component lures also reduced orientational behavior of males 15 min later, but to a lesser degree than when preexposed to Isomate-C Plus dispensers. Male behavior following preexposure to a 0.1 mg codlemone/pear ester [(2E,4Z)-2,4-decadienoate] lure (1:1 ratio) was no different from exposure to codlemone only. Orientational disruption in plots treated with 10 dispensers of Isomate-C Plus per tree was 88.3 and 95.9% for 1.0 and 0.1 mg codlemone lures, respectively. Some males did orient to 0.1 mg codlemone lures so we caution that flight-tunnel experiments on preexposure may overestimate the actual pheromone exposure dosage received by feral moths in treated orchards. Importantly, this work documents that a portion of feral males within a population has the capacity to overcome communicational disruption by high densities of Isomate-C Plus dispensers.

Animals↗

PubMed2006

Differentiation of competitive vs. non-competitive mechanisms mediating disruption of moth sexual communication by point sources of sex pheromone (part I): Theory.

This study establishes a theoretical framework for differentiating among possible behavioral mechanisms whereby sexual communication of moths is disrupted in crops treated with point sources of pheromone. The major mechanisms recognized in the mating disruption literature fall into two main categories: competitive (competitive attraction = false-plume-following) and non-competitive (camouflage, desensitization, and sensory imbalance). Each disruption mechanism has been precisely defined verbally, and then the distinguishing characteristics of the two categories were defined mathematically. The sets of predictions associated with each category were visualized by graphical plots of mathematical simulations. Profiles of simulated male visitation rates to pheromone-baited traps deployed in pheromone-treated crops were graphed against density of pheromone dispensers by using various types of axes. Key traits of non-competitive attraction are as follows: concave profiles on untransformed axes, with an asymptotic approach to zero catch of male moths in traps; a straight line with positive slope when 1/catch is plotted against dispenser density (Miller-Gut plot); and a straight line with negative slope when catch is plotted against dispenser density * catch (Miller-de Lame plot). Key traits of non-competitive disruption profiles include: an initial linear disruption profile on untransformed axes; a concave Miller-Gut plot; and a recurving Miller-de Lame plot. These differences in profiles provide a basis for distinguishing competitive from non-competitive mechanisms when analyzing disruption profiles from field experiments. Slopes and intercepts of these secondary plots can also reveal both male and female moth densities, if the relative attractiveness of traps, females, and dispensers is known. The absolute value of the slope of the Miller-de Lame plot is a measure of each dispenser's activity (D(a)) for suppressing catch of male moths in traps. An application activity (D(Aa)) for a given dispenser can be calculated by multiplying D(a) by the number of such dispensers applied per hectare of crop.

Animal Communication↗

PubMed2006

Behavioral responses of Rhagoletis cingulata (Diptera: Tephritidae) to GF-120 insecticidal bait enhanced with ammonium acetate.

GF-120 is a baited formulation of the insecticide spinosad containing 1% ammonium acetate, developed for control of economically important fruit flies. The response of feral cherry fruit flies, Rhagoletis cingulata Loew, to GF-120 augmented with 0, 5, or 10% ammonium acetate was evaluated under orchard conditions. Significantly more flies were observed within 30 cm of bait droplets with 10% ammonium acetate added compared with standard bait or to a water control. These fly visits to GF-120 enhanced with 10 or 5% ammonium acetate lasted an average of 263.2 +/- 85.2 and 337.6 +/- 72.6 s, respectively, compared with 50.3 +/- 36.4 s for standard GF-120. Droplets containing additional ammonium acetate also were contacted by more flies, and more flies fed upon these droplets than on GF-120 or the water control. Furthermore, the duration of feeding on GF-120 bait enhanced with either level of additional ammonium acetate was significantly greater compared with standard GF-120 or water. Feeding events lasted between 61.5 +/- 30.7 and 73.4 +/- 21.0 s on enhanced GF-120 compared with 6.8 +/- 5.7 s on standard GF-120. Collectively, these results indicate that the interaction of feral R. cingulata with GF-120 droplets and the toxicant spinosad can be increased by addition of ammonium acetate.

Acetates↗

PubMed2006

Higher densities of distributed pheromone sources provide disruption of codling moth (Lepidoptera: Tortricidae) superior to that of lower densities of clumped sources.

Field experiments quantified the effect of synthetic pheromone release-site density and distribution on 1) orientational disruption of male codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), to pheromone-baited traps; and 2) fruit injury. A clustering test varied pheromone release-site density from 0 to 1,000 Isomate-C Plus dispensers per ha while maintaining the total number of dispensers at 1,000. Percentage of orientational disruption of pheromone-baited traps increased significantly as a function of increasing density of release sites. Fruit injury decreased as the density of release sites increased and was lowest in plots treated with Isomate-C Plus dispensers distributed as 1,000 point sources per ha. We also manipulated point source density of 0.1-ml paraffin-wax drops containing 5% codlemone [(E,E)-8,10-dodecadien-1-ol], and thus the total amount of pheromone deployed per hectare. The percentage of disruption of traps baited with either 1.0- or 0.1-mg codlemone lures increased with increasing density of wax drops deployed. Both trapping and field observations confirmed that wax drops were attractive to male codling moths, suggesting that disruption was mediated by competitive attraction. Development of dispensers that can be mechanically applied at high densities has potential to improve the efficacy and economics of codling moth disruption at high population densities.

Animals↗

PubMed2006

Mechanized applicator for large-scale field deployment of paraffin-wax dispensers of pheromone for mating disruption in tree fruit.

A tractor-mounted mechanized applicator was developed for large-scale deployment of paraffin-wax dispensers of pheromone for mating disruption of oriental fruit moth, Grapholita molesta (Busck). The wax formulation was mostly water and emulsified paraffin wax containing 5% (by weight) pheromone [93:6:1 blend of (Z)-8-dodecen-1-yl-acetate:(E)-8-dodecen-1-yl-acetate: (Z)-8-dodecen-1-ol]. Ten milliliters of wax was applied per tree as approximately 160 deposits (0.04 ml of wax per drop). An average of 23 min was required to treat 1 ha of crop. Disruption efficacy of mechanically applied wax was measured relative to an untreated control in replicated 0.4-ha blocks within a recently abandoned apple orchard. From 6 May to 27 June, 100% disruption of tethered virgin females and 97% inhibition of pheromone traps was achieved for 52 d with two applications of wax. However, during mid- to late summer (July-August), this level of efficacy was maintained for only approximately 1 wk after each of two applications. Higher temperatures later in the season may have accounted for abbreviated efficacy of the applied small drops. Mechanically applied paraffin-wax technology may increase adoption of mating disruption given that a higher level of efficacy was achieved despite deploying less active ingredient per hectare relative to that used with reservoir dispensers. The savings in labor by not requiring hand application of reservoir dispensers could be directed toward cost of machinery. However, the short duration of efficacy obtained with the current wax formulation and mechanical applicator is judged uneconomical given the eight or more applications that would have been required for high-performance disruption over the full season. Larger drops with lower surface area-to-volume ratios are expected to prolong pheromone release for extended efficacy and desirable overall economics.

Animals↗

PubMed2006

Sprayable microencapsulated sex pheromone formulation for mating disruption of oriental fruit moth (Lepidoptera: Tortricidae) in Australian peach and pear orchards.

Areawide mating disruption treatments have been effective in controlling infestation of oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), in Australian pome and stone fruit orchards. Although successful, the areawide mating disruption program has been an expensive approach by using hand-applied Isomate dispensers. Sprayable microencapsulated (MEC) pheromone formulations that can be applied with standard spray equipment could substantially reduce the cost of application. Field trials conducted during two consecutive seasons (2002-2004) demonstrated that monthly applications of MEC-OFM phase V (3M Canada, London, Ontario, Canada) at a rate of 125 ml/ha (37.1 g [AI]/ha) in replicated 2-ha blocks of both peaches and pears reduced oriental fruit moth shoot tip and fruit damage as effectively as a single application of Isomate OFM Rosso hand-applied dispensers (500 dispensers per ha) and as or more effectively than standard broad-spectrum insecticide sprays. Fruit protection was achieved despite high oriental fruit moth population densities in both crops as measured by moth catches in terpinyl acetate food and pheromone traps. Similar numbers of oriental fruit moths were captured among all treatments in food traps but captures of males in pheromone traps were disrupted (96-99%) in pheromone-treated blocks relative to controls. The results of this study suggest that microencapsulated formulations of pheromone could be effectively used in areawide mating disruption programs for oriental fruit moth in Australia as a cost-saving alternative to reservoir-style dispensers requiring labor-intensive hand application.

Aerosols↗

PubMed2005

Small plot trials documenting effective mating disruption of oriental fruit moth by using high densities of wax-drop pheromone dispensers.

In 2004 field experiments, we compared the effectiveness of various deployment densities of 0.1-ml paraffin wax drops containing 5% pheromone versus Isomate M-Rosso "rope" dispensers for disruption of Grapholita molesta (Busck). Treatments were evaluated in 0.05-ha (12-tree) plots of 'Delicious' apples receiving regular maintenance according to growers' standards, but not sprayed with insecticides. The application densities of 0.1-ml wax drops were 3 per tree (820/ha), 10 per tree (2,700/ha), 30 per tree (8,200/ha), and 100 per tree (27,300/ha). Wax drops were compared with 3-ml dispensers of pheromone-containing paraffin wax or Isomate M-Rosso ropes at 1.8 per tree (500/ha) and untreated control plots. Treatments were applied before the start of each of three moth generations. Orientational disruption, as measured by inhibition of moth captures in pheromone-baited delta traps, was greatest in plots that received 100 drops per tree (99.2%) and 30 drops per tree (99.4%). More than 55% of tethered, virgin females were mated in control plots after one night of deployment. However, no mating was recorded at the two highest application densities of wax drops where orientational disruption of traps exceeded 99%. Mating ranged from 7 to 20% among the other treatments, including Isomate rope dispensers. G. molesta males were observed closely approaching pheromone dispensers in plots containing ropes and wax drops, documenting competitive attraction between synthetic pheromone sources and feral females. The majority of observed G. molesta males approached within 60 cm of wax drops or pheromone ropes and departed within 20 s by flying upwind. Thirty wax drops per tree yielded higher mating disruption of G. molesta than did Isomate M-Rosso dispensers deployed at the recommended rate of 500/ha (1.8 per tree). Measurement of release rates confirmed behavioral data indicating that paraffin wax dispensers would need to be applied once per G. molesta generation in Michigan. Paraffin wax drops are a promising technology for moth mating disruption. They are cheaper and easier to produce, require less total pheromone per annual application, and produce better mating disruption at appropriate deployment densities compared with Isomate M-Rosso dispensers under high G. molesta population densities. The cost-effectiveness of this approach will require an appropriate mechanized applicator for wax drops.

Animals↗

PubMed2003

Comparison of microcapsule density with various apple tissues and formulations of oriental fruit moth (Lepidoptera: Tortricidae) sprayable pheromone.

The density of microcapsules was compared on 'Golden Delicious' mature and immature foliage, fruit, and 1-yr-old limbs after dip treatments with Phase III oriental fruit moth, Grapholita molesta (Busck), microencapsulated pheromone. Microcapsules were counted with a dissecting microscope at 50x magnification after apple tissues were treated with a two-step dye staining process to increase the visibility of the microcapsules. The number of Phase III microcapsules on 1-yr limbs treated with a field concentration was two- to threefold greater than the number of microcapsules on similarly treated fruit or foliage. Phase I, III, and V OFM MEC and Checkmate OFM-F formulations of microencapsulated pheromone also were compared to determine their abundance on mature apple foliage. The Phase V OFM MEC formulation had the highest density of microcapsules when mature foliage was treated at the field rate. The Phase I treatment had the greatest difference between upper and lower leaf surfaces with 18-fold greater microcapsule density on the upper surface. On mature apple leaves treated with Phase III MEC, the number of microcapsules/cm2 was two- to threefold greater on fields of view without the mid-vein than those that included the mid-vein. The cuticle structure and abundance of trichomes are two factors that may have contributed to differences in microcapsule density among plant tissue types, top and bottom leaf surfaces, and fields of view with and without the mid-vein.

Alkanes↗