The influence of ice conditions on terrestrial haulouts of the pacific walrus Odobenus rosmarus divergens Illiger, 1815 in the Gulf of Anadyr,Bering Sea

The boundaries of the area of appropriate depths for feeding by the Pacific walrus were determined. Based on the ice maps for the period of 1997–2011, the long-term dynamics of ice breakup and formation in the Gulf of Anadyr (Bering Sea) were analyzed. There was a tendency towards a reduction in the ice-cover period in the Gulf of Anadyr, especially during 2007–2011. In 2008, the number and duration of stay of walruses at terrestrial haulout sites on Meeskyn Spit Island and on Retkyn Spit continued to decrease. Walruses also used other haulouts located in the Gulf of Anadyr at Cape Gek and Cape Retkyn. The age and sex structure of the walrus herd changed: the proportions of adult males and young animals decreased, while the proportion of females with calves increased.     

Demography of the Pacific walrus (Odobenus rosmarus divergens): 1974–2006

Global climate change may fundamentally alter population dynamics of many species for which baseline population parameter estimates are imprecise or lacking. Historically, the Pacific walrus is thought to have been limited by harvest, but it may become limited by global warming‐induced reductions in sea ice. Loss of sea ice, on which walruses rest between foraging bouts, may reduce access to food, thus lowering vital rates. Rigorous walrus survival rate estimates do not exist, and other population parameter estimates are out of date or have well‐documented bias and imprecision. To provide useful population parameter estimates we developed a Bayesian, hidden process demographic model of walrus population dynamics from 1974 through 2006 that combined annual age‐specific harvest estimates with five population size estimates, six standing age structure estimates, and two reproductive rate estimates. Median density independent natural survival was high for juveniles (0.97) and adults (0.99), and annual density dependent vital rates rose from 0.06 to 0.11 for reproduction, 0.31 to 0.59 for survival of neonatal calves, and 0.39 to 0.85 for survival of older calves, concomitant with a population decline. This integrated population model provides a baseline for estimating changing population dynamics resulting from changing harvests or sea ice.     

Combined approaches using sex pheromone and pear ester for behavioural disruption of codling moth (Lepidoptera: Tortricidae)

Attractive properties of pear ester, ethyl (E,Z)‐2,4‐decadienoate, and codlemone, (E,E)‐8,10‐dodecadien‐1‐ol, the sex pheromone of codling moth, Cydia pomonella (L.), were utilized in experiments on behavioural disruption of mating. Standard dispensers loaded with codlemone alone or in combination with pear ester (combo) were applied at 500–1000/ha. Larger (10‐fold) combo dispensers (Meso) were evaluated at a rate of 80/ha. The addition of microencapsulated pear ester, PE‐MEC, sprayed with insecticides at 30 ml/ha was also evaluated. Male moth catches in unmated female‐baited traps were lower in standard combo dispenser than in codlemone dispenser–treated plots. Female moth catch in traps baited with the combination of pear ester, codlemone and acetic acid was lower in standard combo dispenser than in codlemone dispenser–treated plots. In 12 comparative experiments spanning from 2006 to 2012, male moth catch in unmated female‐baited traps was consistently and significantly lower in combo than in codlemone dispenser–treated plots. Male catch in codlemone‐baited traps did not differ between dispenser treatments in eight studies from 2006 to 2009. These results emphasize the benefit of alternatively using traps baited with unmated females over codlemone lures for the analysis of dispenser activity. Fruit injury was significantly reduced with the addition of PE‐MEC to insecticide applications across untreated and dispenser treatments. Proportion of unmated females trapped was higher in standard combo dispenser than in codlemone dispenser–treated and untreated plots. Similarly, the proportion of unmated females caught was higher in the Meso combo dispenser than in nearby or distant codlemone dispenser–treated plots. These field studies conducted in apple over 3 years demonstrate that adding pear ester both to pheromone dispensers, either standard or Meso, and to supplementary insecticide sprays can provide a significant increase in the disruption of sexual communication, reductions in female mating and reductions in fruit injury.     

Mating disruption of codling moth Cydia pomonella with high densities of Ecodian sex pheromone dispensers

A mating disruption approach using high densities of pheromone dispensers, has recently been proposed for controlling codling moth, Cydia pomonella (L.) (Lep., Tortricidae). Ecodian® CP dispensers, made of low‐cost biodegradable material and easy to apply, were formulated with 10 mg of codlemone and placed at a rate of 1400–2000 dispensers/ha. Seasonal dispenser performance was evaluated using different methods. The release rate of new Ecodian dispensers, measured directly by solid‐phase micro‐extraction (SPME), was significantly higher than that of the standard monitoring lure. The release rate of field‐aged dispensers decreased over time; it was comparable with that of the standard monitoring lure after 55–90 days of field exposure and significantly lower beyond. Electroantennographic (EAG) recordings showed that field‐aged dispensers strongly stimulated virgin male moths’ antennae. Dispensers elicited close‐range approaches in wind tunnel irrespective of their age. Traps baited with aged Ecodian CP dispensers captured males throughout the season. Our results demonstrate that Ecodian dispensers achieved a good level of activity and longevity over the season. Field trials carried out from 2002 to 2004 confirmed the efficacy of Ecodian CP dispensers for codling moth control, regardless of the size of the treated area. The potential of this strategy for the control of C. pomonella is discussed.     

Comparative Statistical Study of the Cornwall, LKB, and Micromedic Dispensers

The working precisions of the 5.0-ml-capacity Cornwall, the LKB 2075, and the Micromedic model 25000 dispensers were compared, and the bias of the LKB dispenser was contrasted with that of the Micromedic dispenser. Three technologists used six Cornwall dispensers, three LKB units with four different pumps, and three Micromedic units with six different pumps to dispense (in 1.0-ml amounts) sucrose solution adjusted to match the normal viscosity of serum. Under these conditions, the LKB dispenser was approximately 30% more precise than the Micromedic dispenser, which was approximately four times as precise as the Cornwall dispenser. Although the left pump site of the Micromedic was slightly more precise than the LKB, overall the Micromedic was less precise than the LKB. Moreover, the LKB was easier to use than the Micromedic.     

Honey bee dispersal of biocontrol agents: An evaluation of dispensing devices

Many reports have been published lately on the use of honey bees to disseminate biocontrol agents to flowers, using various kinds of inoculum dispensers. This technique is mainly used to deliver agents for controlling fire blight and gray mold. The present study evaluated the relative efficiency of a newly developed 'Triwaks' dispenser with three other dispenser types, 'Peng', 'Tub', and 'Harwood', with respect to effects of the dispensers on bee activity, and effectiveness for contaminating bees with high levels of inoculum for a long period of time after its application. We found differences in these parameters of performance between dispenser types, with the Triwaks dispenser having the overall best performance. This dispenser could prove to be an effective tool for biocontrol. The evaluation methods that we present could be used for evaluating other dispenser types.     

A comparison of various mating disruption technologies for control of two internally feeding Lepidoptera in apples

Sex pheromone mating disruption (MD) is an approach used to control several moth pest species of pome fruit by disrupting the ability of the males to find females and consequently prevent mating. The following experiments were performed to determine the effectiveness of several new and experimental sex pheromone MD technologies, and dispenser densities for simultaneous control of the codling moth (CM), Cydia pomonella (L.), and the oriental fruit moth (OFM), Grapholita molesta (Busck) (both Lepidoptera: Tortricidae), in Pennsylvania apple orchards. In one study, three MD approaches to control CM and oriental fruit moth – CM and OFM Disrupt Micro‐Flakes, Isomate CM/OFM TT, and both a CideTrak OFM and a CideTrak CM dispenser containing both codlemone and pear ester – and an insecticides‐only treatment were compared over the course of 2 years. In the other studies, the efficacy of several CheckMate Duel dispenser densities (i.e., 250, 375, 425, and 500 dispensers ha^?1) were compared against Isomate CM/OFM TT, and an insecticides‐only treatment. The CideTrak CM/pear ester combination and Isomate CM/OFM TT treatments both substantially reduced CM captures in traps in 2007 and 2008. Meanwhile, OFM trap shutdown was highest in the CheckMate Duel densities of 375 (99.9 ± 0.08%) and 500 dispensers ha^?1 (98.9 ± 0.07%) and the Isomate CM/OFM TT treatment (98.0 ± 1.13%), and lowest in the 250 dispensers ha^?1 density treatment (94.3 ± 3.23%). In orchards where OFM is the dominant pest species, a CheckMate Duel dispenser density of 375 ha^?1 is necessary for effective control, whereas higher densities are needed to control CM.     

Application of synthetic herbivore‐induced plant volatiles causes increased parasitism of herbivores in the field

We previously reported that Cotesia vestalis (Hymenoptera, Braconidae), a parasitoid of diamondback moth (DBM) (Plutella xylostella; Lepidoptera, Plutellidae) larvae, was attracted to volatiles from crucifer plants infested by moth larvae kept in a desktop acrylic box, and that a blend of four DBM‐induced plant volatiles was responsible for this attraction. In this study, using a specially designed dispenser to release the four compounds, we demonstrated that the wasp was attracted to intact komatsuna plants (Brassica rapa var. perviridis). The experiments were performed in a climate‐controlled room, which was approximately 1000 times larger than the acrylic box used previously. Similarly, using the dispenser in the field, C. vestalis females were attracted to intact komatsuna plants with the dispenser from a distance of three metres. We also examined the effect of the volatile blend on the incidence of parasitism of DBM larvae in the field. Three small containers containing DBM‐infested komatsuna plants with dispensers, and three control containers containing only infested plants (control) were arranged in two lines running perpendicular to a komatsuna field in which both DBM larvae and C. vestalis populations were maintained, at distances of 12, 30 and 70 m. The results showed that the incidence of DBM parasitism was significantly higher in containers containing dispensers than in the control containers, suggesting that the blend could potentially be applied to DBM control in agroecosystems.     

A simple automatic dispensing apparatus

A simple dispenser using a 2-ml disposable syringe is described. The range of operation is 0.02–1.5 ml and an unusual accuracy is obtained by employing a new principle for dispensers: the dispensed volume is only a fraction of total tidal flow of fluid in the dispenser.     

Attraction of forest cockchafer Melolontha hippocastani to (Z)-3-hexen-1-ol and 1,4-benzoquinone: application aspects

Abstract The application aspects of chemicals which attract the forest cockchafer, Melolontha hippocastani F., were investigated in field and laboratory experiments. Previous studies have shown that males of M. hippocastani are attracted by a synthetic mixture of green leaf volatiles (GLV) and the sex pheromone 1,4‐benzoquinone (BQ), that synergistically enhances the male response to GLV. In the present study, we demonstrated that BQ also synergised the male response to one single component of the GLV mixture, the leaf alcohol (Z)‐3‐hexen‐1‐ol (Z‐3‐ol). BQ enhanced the attractiveness of Z‐3‐ol at doses between 0.05 and 5 mg per trap, reaching a maximum at 5 × 10^?1 mg day^?1. The addition of an insecticide (cyhalothrin) to traps baited with BQ and Z‐3‐ol did not affect the lures’ attractiveness. However, when a conidiospore formulation of the entomopathogenic fungus Beauveria brongniartii (Saccardo) Petch was added, the attractiveness of baited traps was significantly reduced. Furthermore, two types of dispensers baited with a solution of BQ in Z‐3‐ol at 20 mg ml^?1 were tested over the entire 4‐week flight season. Both a membrane dispenser and a dispenser based on a porous polyethylene (PPE) absorbent disk attracted more males than controls over the entire 4 weeks. The membrane dispenser attracted as many males each week as a reference formulation that was renewed daily. Furthermore, the membrane dispenser attracted more males than the PPE dispenser in weeks 2–4, although laboratory experiments showed that the latter released even higher or at least equal amounts of the joined lure over the entire 4 weeks. However, estimation of the BQ/Z‐3‐ol ratios of the released material by solid phase microextraction (SPME) and coupled gas chromatography–mass spectrometry (GC‐MS) revealed that the membrane dispenser released a higher proportion of BQ than the PPE dispenser in weeks 2–4. Therefore, a higher BQ/Z‐3‐ol ratio might be responsible for the advantage of the membrane dispenser in the field.     

A new long-life trimedlure dispenser for Mediterranean fruit fly

New agricultural techniques are attempting to reduce the application of synthesized pesticides and replace them with new environmentally friendly methods such as mass trapping, mating disruption, or chemosterilization techniques. All these methods are based on the release of a lure for insect attraction or confusion. The success of the chosen method depends on the quality of the attractant emission from the dispenser. Currently, used dispensers with a polymeric matrix and new dispensers with mesoporous inorganic materials were evaluated to obtain more efficient emission kinetics. In this study, the selected pest was the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) and the lure used was trimedlure (TML). The dispensers were validated by means of a field study comparing insect catches with attractant release values. As a result, we have demonstrated that mesoporous dispensers have a clearly longer lifetime than the polymeric plug. Furthermore, the attractant release rate is less dependent on temperature in mesoporous than in polymeric dispensers.     

Dual pheromone dispenser for combined control of codling moth Cydia pomonella L. and oriental fruit moth Grapholita molesta (Busck) (Lep., Tortricidae) in pears

Codling moth (CM) and oriental fruit moth (OFM) are very important orchard pests worldwide, and particularly in Victoria, Australia, where both species damage pome fruit. Individually CM and OFM have been controlled successfully by pheromone‐mediated mating disruption, but treatment of pome fruit with full registered rates of two individual hand‐applied dispensers for CM and OFM could be uneconomical for growers. Field trials conducted over three seasons in plots sprayed with insecticides consistently demonstrated that dual Isomate C/OFM TT dispensers, designed to disrupt both CM and OFM, were as effective as Isomate CTT and Isomate OFM Rosso dispensers applied individually in pears for control of CM and OFM respectively. The dual‐ and individual‐species dispensers reduced moth catches and fruit damage to a similar degree. The results suggest that combined control of CM and OFM in pears by applying dual Isomate C/OFM TT dispensers at the full‐recommended rate of 500 dispensers per hectare will be more economical than use of individual species dispensers, because the price and application cost of dual dispenser is about half that for individual dispensers.     

Results and evaluation of a survey to estimate Pacific walrus population size, 20061

In spring 2006, we conducted a collaborative U.S.–Russia survey to estimate abundance of the Pacific walrus (Odobenus rosmarus divergens). The Bering Sea was partitioned into survey blocks, and a systematic random sample of transects within a subset of the blocks was surveyed with airborne thermal scanners using standard strip‐transect methodology. Counts of walruses in photographed groups were used to model the relation between thermal signatures and the number of walruses in groups, which was used to estimate the number of walruses in groups that were detected by the scanner but not photographed. We also modeled the probability of thermally detecting various‐sized walrus groups to estimate the number of walruses in groups undetected by the scanner. We used data from radio‐tagged walruses to adjust on‐ice estimates to account for walruses in the water during the survey. The estimated area of available habitat averaged 668,000 km² and the area of surveyed blocks was 318,204 km². The number of Pacific walruses within the surveyed area was estimated at 129,000 with 95% confidence limits of 55,000–507,000 individuals. Poor weather conditions precluded surveying in other areas; therefore, this value represents the number of Pacific walruses within about half of potential walrus habitat.     

Evaluation of traps and lures for mass trapping of Mediterranean fruit fly in citrus groves

Mass trapping has proven to be a powerful weapon in the control of Ceratitis capitata (Wiedemann), and its application in Mediterranean countries has currently increased notably as a control method. In this study, the efficacy of newly developed traps and dispensers of attractants were assessed with the aim of finding the best trap and set the lifetime of the dispensers, thus improving the total efficacy of mass trapping. Efficacy trials with six different types of traps and six different types of female dispensers were carried out. Moreover, the lifetime of three female dispensers, including a new attractant composition dispenser with n-methyl pyrrolidine, were studied. Results show significant differences among the trap types using female attractants, with an advantage of nearly 3 times more catches in best trap. Tested female dispensers showed no significant differences in efficacy between trimethylamine and putrescine attractants regard n-methyl pyrrolidine, however we observed differences in lifetime between dispensers. Thus, there are significant differences among different types of traps and dispensers in efficacy, and the appropriate selection of the trap and dispenser will improve the mass trapping results.     

Pacific Walrus (Odobenus rosmarus divergens) Resource Selection in the Northern Bering Sea

The Pacific walrus is a large benthivore with an annual range extending across the continental shelves of the Bering and Chukchi Seas. We used a discrete choice model to estimate site selection by adult radio-tagged walruses relative to the availability of the caloric biomass of benthic infauna and sea ice concentration in a prominent walrus wintering area in the northern Bering Sea (St. Lawrence Island polynya) in 2006, 2008, and 2009. At least 60% of the total caloric biomass of dominant macroinfauna in the study area was composed of members of the bivalve families Nuculidae, Tellinidae, and Nuculanidae. Model estimates indicated walrus site selection was related most strongly to tellinid bivalve caloric biomass distribution and that walruses selected lower ice concentrations from the mostly high ice concentrations that were available to them (quartiles: 76%, 93%, and 99%). Areas with high average predicted walrus site selection generally coincided with areas of high organic carbon input identified in other studies. Projected decreases in sea ice in the St. Lawrence Island polynya and the potential for a concomitant decline of bivalves in the region could result in a northward shift in the wintering grounds of walruses in the northern Bering Sea.     

Regional walrus abundance estimate in the United States Chukchi Sea in autumn

Human activities (e.g., shipping, tourism, oil, gas development) have increased in the Chukchi Sea because of declining sea ice. The declining sea ice itself and these activities may affect Pacific walrus (Odobenus rosmarus divergens) abundance; however, previous walrus abundance estimates have been notably imprecise. When sea ice is absent from the eastern Chukchi Sea, walruses in waters of the United States usually rest together onshore at a single Alaska coastal haulout, where they can be surveyed more easily than when they rest on dispersed offshore ice floes. We estimated the number of walruses on land (herd size) at this haulout from 13 unoccupied aircraft system (UAS) surveys flown within a 10-day period in each of 2018 and 2019. We estimated population size of walruses using the haulout over the course of the surveys by combining herd size data with data from satellite-linked transmitters that indicated whether tagged walruses were in or out of water during each survey. Our estimates of the population size of walruses using the haulout during each year's survey period were similar to each other and more precise than historical walrus abundance estimates: posterior means (95% credibility intervals) were 166,000 (133,000–201,000) for 2018 and 189,000 (135,000–251,000) for 2019. Auxiliary observations support using these estimates to represent the size of the population using the eastern Chukchi Sea in autumn during the surveyed years. Our study site was the only substantial Chukchi Sea coastal haulout in the United States during the survey periods and study-specific tracking data (consistent with known distribution and movement patterns) indicated tagged walruses remained in eastern Chukchi waters during the survey periods. In addition, the imagery, telemetry, and analytical methods developed for this study advance the prospect for precise range-wide walrus population size estimates.     

Projected status of the Pacific walrus (Odobenus rosmarus divergens) in the twenty-first century

Extensive and rapid losses of sea ice in the Arctic have raised conservation concerns for the Pacific walrus (Odobenus rosmarus divergens), a large pinniped inhabiting arctic and subarctic continental shelf waters of the Chukchi and Bering seas. We developed a Bayesian network model to integrate potential effects of changing environmental conditions and anthropogenic stressors on the future status of the Pacific walrus population at four periods through the twenty-first century. The model framework allowed for inclusion of various sources and levels of knowledge, and representation of structural and parameter uncertainties. Walrus outcome probabilities through the century reflected a clear trend of worsening conditions for the subspecies. From the current observation period to the end of century, the greatest change in walrus outcome probabilities was a progressive decrease in the outcome state of robust and a concomitant increase in the outcome state of vulnerable. The probabilities of rare and extirpated states each progressively increased but remained <10% through the end of the century. The summed probabilities of vulnerable, rare, and extirpated (P(v,r,e)) increased from a current level of 10% in 2004 to 22% by 2050 and 40% by 2095. The degree of uncertainty in walrus outcomes increased monotonically over future periods. In the model, sea ice habitat (particularly for summer/fall) and harvest levels had the greatest influence on future population outcomes. Other potential stressors had much smaller influences on walrus outcomes, mostly because of uncertainty in their future states and our current poor understanding of their mechanistic influence on walrus abundance.     

Sex pheromone traps for monitoring the codling moth: effect of dispenser type, field aging of dispenser, pheromone dose and type of trap on male captures

The effects of dispenser type, dispenser aging in the field, pheromone dose in the dispenser and trap type on trapping efficiency of codling moth,Cydia pomonella (L.), males were investigated in Israel. An Israeli-manufactured rubber septum was significantly better than the CM Pherocon cap in attracting males to a Pherocon 1C cap trap or an IPS trap. The effect of aging of the dispenser in the field on trapping efficiency was significant in CM Pherocon caps and the Israeli septa. Captures in traps were negatively correlated with aging of septa. The effect of aging of dispensers was more marked during summer than during spring. The fairly rapid loss of attractancy indicates that the lures should be replaced after 2 weeks at the most. The release rate of the pheromone from the dispensers was measured in a flow system. The emission from the Israeli septa and Pherocon caps decreased sharply after 2 weeks and then was almost constant, which explains the lower attractancy of aged septa. However, there was a marked difference in the release profiles of the pheromone from the two types of dispensers, which may explain the different performance of the two dispensers. Within the range of 0.1 to 100 μg pheromone per dispenser, male response increased positively with the pheromone dose. Pheromone loadings of 100 or 1000 μg per dispenser did not differ significantly in their attractiveness for males. A load of 5000 μg per dispenser was significantly less attractive to males than was 100 or 1000 μg per dispenser. The non-sticky IPS trap was significantly better in capturing codling moth males than was the sticky, commonly used Pherocon 1C trap, provided it was baited with the Israeli dispenser. The two traps were equally effective when baited with the CM Pherocon caps. The possibility of using the non-sticky, nonsaturating and easy-to-handle IPS traps for monitoring codling moth is of great importance. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan 50-250, Israel. No 3702-E, 1992 series.     

Evaluating dispensers loaded with codlemone and pear ester for disruption of codling moth (Lepidoptera: Tortricidae)

Polyvinyl chloride polymer (PVC) dispensers loaded with ethyl (E,Z)-2,4-decadienoate (pear ester) plus the sex pheromone, (E,E)-8,10-dodecadien-1-ol (codlemone) of codling moth, Cydia pomonella (L.), were compared with PVC dispensers and a commercial dispenser (Isomate-C Plus) loaded with codlemone. Evaluations were conducted in replicated plots (0.1-0.2 ha) in apple, Malus domestica (Borkhausen) during both generations of codling moth from 2007 to 2009. Dispensers were applied at 1,000 ha(-1). Male captures in traps baited with virgin female moths and codlemone lures were recorded. Residual analysis of field-aged dispensers over both moth generations was conducted. Dispensers exhibited linear declines in release rates of both attractants, and pear ester was released at a significantly higher rate than codlemone during both time periods. The proportion of virgin female-baited traps catching males was significantly lower with combo dispenser TRE24 (45/110, mg codlemone/mg pear ester) during the second generation in 2007 and the combo dispensers TRE144 (45/75) and TRE145 (75/45) during the first generation in 2008 compared with Isomate-C Plus. Similarly, male catches in female-baited traps in plots treated with the combo dispensers TRE144 during the first generation in 2008 and TRE23 (75/110) during the second generation, in 2007 were significantly lower than in plots treated with Isomate-C Plus. No significant differences were found for male catches in codlemone-baited traps in plots treated with Isomate-C Plus and any of the combo dispensers. However, male catches were significantly lower in plots treated with Cidetrak CM (codlemone-only dispenser) than the combo TRE144 dispenser during both generations in 2009.     

Antibodies to marine caliciviruses in the Pacific walrus (Odobenus rosmarus divergens Illiger)

Sera from 155 Pacific walruses (Odobenus rosmarus divergens Illiger), sampled in the Chukchi Sea during the summer of 1983, were tested for serum neutralizing (SN) antibodies to six marine calicivirus serotypes. Serotypes tested included San Miguel sea lion virus (SMSV) types 1, 5, 8, and 10, previously isolated from northern fur seals (Callorhinus ursinus Linné) in the Bering Sea; walrus calicivirus (WCV), previously isolated from walrus feces collected off sea ice in the Chukchi Sea; and Tillamook calicivirus (TCV), a bovine isolate from Oregon of suspected marine origin. No antibodies were found to SMSV-1, SMSV-10, or TCV. Antibodies to SMSV-5 were found in two animals (titers 1:20 and 1:160); antibodies to SMSV-8 were found in four animals (all 1:20); and antibodies to WCV were found in one animal (titer 1:40). Antibodies to WCV have been found in the Pacific walrus previously; however, this represents the first report of antibodies to any of the SMSV serotypes in this marine mammal.