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From 1907 when the fever tick eradication campaign began until 1933, the tick eradication methods of dipping cattle in an acaricide or “pasture vacation” were enormously successful in eradicating southern cattle ticks [Rhipicephalus (Boophilus) microplus (Canestrini) ], until failures began to occur in some areas of Florida. Regarding the failures in Florida, the consensus was that populations of white-tailed deer [Odocoileus virginianus (Zimmermann)] infested with southern cattle ticks were responsible. After numerous deer in several counties were killed, eradication was achieved in Florida. As in Florida, in Texas increasing numbers of failures of the pasture vacation approach to tick eradication from the 1970s to the present are known to be related to the abundance of white-tailed deer and perhaps other wild ungulate species. A sizable body of evidence confirms the hypothesis that white-tailed deer support the dispersal and maintenance of both cattle ticks [Rhipicephalus (Boophilus) annulatus (Say)] and southern cattle ticks (cattle fever ticks) within the permanent quarantine or buffer zone in South Texas along the Rio Grande, as well as in the so-called free (“cattle fever tick-free”) area north and east of the buffer zone and extending to the east coast of the United States. As of August 2009, in addition to the permanent quarantine zone of ≈2,233 km2, three temporary preventative or blanket quarantines were established. Currently, only two methodologies exist to control ticks feeding on white-tailed deer: 1) a systemic treatment method involving dispersal of ivermectin-medicated corn, Zea mays L.; and 2) two topical treatment methods, ‘4-poster’ deer treatment bait stations and ‘2-poster’ deer treatment feeder adapters, both of which passively apply topically active acaricide to deer for the eradication of populations of cattle fever tick associated with white-tailed deer. This study presents and summarizes confirmational support for the role of white-tailed deer derived from historical accounts, circumstantial evidence from review of recent infestations, and cattle fever tick infestations on white-tailed deer that were live-captured and examined specifically for cattle fever ticks.
Uniform and controlled applications of insecticides constitute a fundamental aspect of applied research on performance of insecticides, We describe and evaluate a spraying device made from an artist airbrush and a soda bottle, the “bottle sprayer,” which can be used to apply insecticide formulations both under laboratory and field conditions. Using the bottle sprayer in conjunction with quantitative behavioral analysis, it was shown that 1) miticides can significantly affect movement patterns and 2) it is possible to quantify mite repellency to miticides. The combination of controlled sprays to portions of trial arenas and quantification of behavioral responses by individual spider mites may be used to address a wide range of applied questions related to spider mite ecology. We used the bottle sprayer to apply water on water-sensitive cards and used simple image analysis techniques to correlate average reflectance per pixels (quadratic reflectance in blue color band) with water dose applied. Consequently, we were able to propose a method to quantify dose applied based on average color on water-sensitive cards. The spray card analysis based on data generated with the bottle sprayer was used to interpret spray card data obtained from spray applications in a commercial potato, Solanum tuberosum L., field and to discuss the possibility of developing quality control procedures for insecticide applications in field crops.
Intensive activity of honey bees, Apis mellifera L., is essential for high fruit set in avocado, Persea americana Mill, orchards, but even when hives are located inside the orchard, many bees still search for alternative blooms. We tested for a possible genetic component for a preference of avocado bloom relative to competing bloom. The honey from each hive was extracted at the end of the avocado bloom and the concentration of perseitol, a carbohydrate that is unique to avocado, was analyzed as a measure for avocado foraging. During the first year, five bee strains were compared in three different sites in Israel. Significant differences were found between strains in honey perseitol concentrations, suggesting differences in their efficiency as avocado pollinators, although these differences were site dependent. At two sites, colonies with the highest and lowest perseitol concentrations were selected as parental “high” and “low” lines, Queens were raised from the selected colonies and were instrumentally inseminated by drones from other colonies of this line, During the second and third years, colonies with inseminated queens were introduced to the avocado orchards, together with the selected colonies still surviving from the previous year. Colonies of the high line had greater perseitol concentrations than those of the low line, Selected colonies that survived from the previous year performed consistently vis-à-vis perseitol concentration, in the second year of testing. Heritability value of 0.22 was estimated based on regression of offspring on midparent. The results reveal a heritable component for willingness of honey bees to collect avocado nectar.
A useful technique for synchronizing pollinators with the alfalfa, Medicago savita L. (Fabaceae), bloom is to interrupt the late spring incubation of developing bee pupae and pharate adults of Megachile rotundata (F.) (Hymenoptera: Megachilidae) with short-term low-temperature storage. However, low-temperature exposure can be stressful depending on the temperature, duration of exposure, and the developmental stage exposed. To evaluate the effect of low-temperature storage after development had already been initiated by exposure to 29°C, three developmental stages (eye pigment pupae, body pigment pupae, and pharate adults ready to emerge) were exposed to 6, 12, or 18°C for durations up to 28 d. The effect of delaying the termination of overwintering storage (6°C) from April to July (“April bees” and “July bees,” respectively) also was examined. The following observations were made: 1) All developmental stages of the April bees and July bees examined can be stored without harmful effects, as measured by percentage of survival, for 14 d at 12°C and above. 2) Postponing the termination of overwintering storage at 6°C from April until July significantly decreased the mean number of days to 95% adult emergence in the July ready-to-emerge bees across the three temperatures tested. 3) The increase of overwintering duration also caused a decrease in the postemergence longevity of the ready-to-emerge adults stored at 6°C for 14 d. 4) Of the three storage temperatures examined, 18°C seems to be the optimal storage temperature for short-term storage of developing bees because of their slow but continuing development without increased mortality either during storage or after emergence.
Inundative releases of beneficial insects are frequently used to suppress pest insects but not commonly attempted as a method of weed biological control because of the difficulty in obtaining the required large numbers of insects. The successful establishment of a flea beetle complex, mixed Aphthona lacertosa (Rosenhauer) and Aphthona nigriscutus Foundras (87 and 13%, respectively), for the control of leafy spurge, Euphorbia esula L., provided an easily collectable source of these natural enemies that enabled us to attempt inundative release as a possible leafy spurge control method in a sensitive riparian ecological zone where chemical control is restricted. Our target weed populations were small isolated patches of leafy spurge along three streams in southwestern, central, and northeastern Idaho. This study assessed leafy spurge and associated vegetation responses to inundative releases of 10 and 50 beetles per spurge flowering stem over two consecutive years. Releasing 10 beetles per flowering stem had inconclusive effects on spurge biomass, crown, stem, and seedling density. Alternatively, releasing 50 beetles per flowering stem resulted in a reduction of biomass, crown and stem density in the range of 60–80% at all three study sites, and about an ≈60% reduction of seedling density at one site, compared with untreated plots, In contrast to leafy spurge, associated vegetation did not conclusively respond to beetle release, indicating that it may take more than two years for desired riparian vegetation to respond to reductions in leafy spurge competition.
Synchronization between a parasitoid and its preferred host is an essential strategy for successful biological control. Two ecotypes of Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) in North America are distinguished by their voltinism. In this study, the differential impact of a specialist parasitoid, Macrocentrus cingulum Brischke (Hymenoptera: Braconidae), on the univoltine and multivoltine populations of O. nubilalis is investigated. Four years of field and laboratory study suggested that M. cingulum emergence was synchronized with the spring emergence of the multivoltine ecotypes of O. nubilalis in Pennsylvania. Univoltine populations experienced minimal parasitism from M. cingulum. Field-collected data suggested that the postdiapause multivoltine O. nubilalis field population was male biased, whereas the univoltine population was female biased. M. cingulum-parasitized postdiapause O. nubilalis larvae were significantly heavier than the male and nonparasitized female larvae. Sex ratio differences observed in overwintered O. nubilalis populations in the presence or absence of M. cingulum parasitism suggested preferential parasitism between male and female O. nubilalis larvae. Correlation between the larger parasitized O. nubilalis larval host and the number of adult parasitoids emerging per host suggested a potential evolutionary advantage to parasitizing female or larger hosts.
The insecticidal effect of Mamestra brassicae nucleopolyhedrovirus (MabrNPV) T5 against Mamestra brassicae (L.) and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), important pests of various vegetables and ornamental crops in Japan as well as many other countries, and the enhancing activity of proteins derived from occlusion bodies of Xestia c-nigrum granulovirus (XecnGV) α-4, which was named GVPs, on the infectivity of MabrNPV were evaluated in a bioassay with second-instar larvae fed on virus-applied cabbage, Brassica oleracea L. var. capitata, plants. The lethal concentrations of MabrNPV achieving 95% mortality (LC95) were estimated to be 7.7 × 105 and 1.8 × 105 OBs per ml for M. brassicae and H. armigera, respectively, with MabrNPV-alone treatment. Because the mean areas of cabbage leaf consumed by one larva in 60 h were not significantly different between M. brassicae and H. armigera, we conclude that MabrNPV is more infectious to H. armigera than to M. brassicae. When larvae were fed on cabbage plants treated with 104 OBs per ml MabrNPV and various concentrations of the GVPs, the mortality of the two noctuid larvae increased in relation to GVP concentration. The requisite concentrations of the GVPs achieving 95% mortality with the MabrNPV for M. brassicae and H. armigera were estimated to be 5.93–8.30 and 1.94–3,48 µg/ml, respectively, In a comparison of the MabrNPV-alone treatment with equivalent 95% mortality, addition of GVPs increased the rate of larval death at younger instars, especially in M. brassicae. Our results indicate that GVPs are a potentially useful additive for improving the insecticidal efficacy of MabrNPV.
Controlled atmosphere/temperature treatment system (CATTS) is an environmentally friendly postharvest mitigation treatment that uses high temperature forced-air combined with a low oxygen and high carbon dioxide atmosphere to control quarantine pests. The development of CATTS treatments is expensive and time-consuming. For a more rapid assessment of different species and life stages' tolerances to heated controlled atmospheres, the controlled atmosphere water bath (CAWB) system can be used to help advance the development of CATTS treatments for pests. The CAWB system was used to test the response of eggs and larval stages of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). Eggs and larvae at different developmental stages were treated under regular air and a modified controlled atmosphere of 1% O2 and 15% CO2, at two ramping heat rates: 12 and 24°C/h. Typically the faster heat rate and modified atmosphere reduced treatment times required to control the different life stages. T. leucotreta larvae were more tolerant of the treatments than eggs. The most tolerant life stage was the fourth instar. Effective treatments against the most tolerant life stage determined by the CAWB system can now be used to develop CATTS technology against T. leucotreta. Further research will focus on developing CATTS treatments using infested fruit to determine effective treatments that maintain fruit quality.
Controlled atmosphere treatments with ultralow oxygen (ULO treatments) were developed successfully for control of vine mealybug, Planococcus ficus Signoret (Hemiptera: Pseudococcidae), on dormant grape (Vitis spp.) benchgrafts. At 30 ppm oxygen, 3-d ULO treatment at 25°C and 4-d ULO treatment at 15°C achieved complete control of all life stages of P. ficus. At a much lower oxygen level (<1 ppm), the two ULO treatments with the same exposure periods of 3 d at 25°C and 4 d at 15°C were tested on six table and wine grape cultivars grafted on rootstocks along with P. ficus. The benchgrafts were then potted in a greenhouse, together with untreated controls, to determine treatment effects on rootstock viability, Both ULO treatments achieved complete control of P. ficus and did not have any negative effects on vine growth, compared with the control. Results indicate that ULO treatments can be used to control P. ficus on dormant grape benchgrafts. The advantages of the ULO treatments are also discussed with respect to hot water treatments.
Bamboo (genera Bambusa and Phyllstachys) is one of the fastest growing and economically important plants in the world, and it is cultivated widely throughout southern China. China annually exports to the United States significant quantities of bamboo garden stakes (Bambusa spp,). In recent years, Plant Protection and Quarantine officers of the U.S. Department of Agriculture-Animal and Plant Health Inspection Service have made numerous interceptions of the bamboo borer, Chlorophorus annularis Fairmaire (Coleoptera: Cerambycidae), in bamboo products from China. This species is considered to have high pest risk potential in the trade of bamboo products, As a fumigant, sulfuryl fluoride (SF) would be a practical alternative to methyl bromide (MeBr) fumigation. Here, we report the results of SF fumigation tests for C. annularis in bamboo poles at three doses—96 g/m3 at 15.9°C, 80 g/m3 at 21.5°C, and 64 g/m3 at 26.0°C—in glass test chambers. Commercial standard fumigations were also conducted in a standard 6.1-m-long, 33.2-m3 (standard height, 20-feet) marine general cargo container loaded to 80% (vol:vol) with similar bamboo poles, and sufficient levels of SF were obtained during the 24-h fumigations. During the course of these tests, 2,424 larvae, 90 pupae, and 23 adults in total were killed, with no survivors. A treatment schedule using SF is proposed for bamboo as an alternative to MeBr at several temperatures tested.
The leafminer Caloptilia porphyretica Braun (Lepidoptera: Gracillariidae), has become a frequent pest in commercial highbush blueberries, Vaccinium corymbosum L., in New Jersey, but little is known about its seasonal abundance, life history, and parasitism rates. Monitoring programs were conducted from 2003 to 2006 on seven blueberry farms to determine the relative abundance of this leafminer by using pheromone-baited traps and by sampling vegetative and flower/fruit clusters and new shoot growth. We found at least three distinct generations per year, with populations reaching their highest peak in the second generation. Laboratory studies characterized the life history of C. porphyretica and its parasitoid Pholetesor sp. prob. salalicus (Mason). The developmental period of C. porphyretica, from egg to adult, took 927, 838, and 912 degree-days (DD) at 20, 25, and 30°C, respectively, by using a developmental threshold of 4.8°C. This was equivalent to an average of 892 DD to complete development to adult, which compared with 870 and 880 DD between the first and second, and second and third generations, respectively, by using pheromone trap data averaged from 2004 to 2006. Although C. porphyretica populations varied greatly, the number of larvae in cluster and new shoot samples was highly correlated with the number of adults in traps. Field parasitism rate was ≈29%, with the braconid Pholetesor sp. the most abundant parasitoid. Ten of the 13 parasitoid species collected belonged to the family Eulophidae. When different ages of leafminers were exposed to Pholetesor sp., we found that the parasitoid attacks 9-15-d-old instars that reside in the mines of leaves.
Alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), is among the most destructive pests of alfalfa, Medicago sativa L., in the world. Survivorship and fecundity schedules of H. postica were investigated to characterize the population growth potential of the weevil at six constant temperatures: 11.5, 14.0, 19.0, 24.0, 29.0, and 31.5°C. Preoviposition period, oviposition period and female longevity significantly decreased with rising temperature within the temperature range tested, At the respective temperatures adult female lived an average of 294.2, 230.2, 163.6, 141.0, 84.10, and 32.9 d, with average lifetime progeny production of 470, 814, 2,209, 3,619, 2,656, and 338 eggs per female, The net reproductive rates (R0) were 86.9, 288.0, 869.7, 1,479.7, 989.8, and 107.8 females per female, respectively. Mean daily fecundity (Mx) was modeled as a function of time by using both Enkegaard and Analytis models. Survivorship data (Ix) of adult females were summarized and compared using the shape and scale parameters of the Weibull frequency distribution model across the temperature range tested. Life table entropy values within the range 14.0–31.5°C (H <0.5) indicates Slobodkin's type I survivorship curve; however, the value of 0.806 at 11.5°C (H >0.5) corresponds to type III. As temperature increased, the rm exhibited an asymmetrical dome-shaped pattern, with a maximum value of 0.114 females per female per d at 29.0°C. The rm-temperature relation of weevils was modeled and critical temperatures (TMin, TOpt, and TMax) for intrinsic rate of increase of the weevil were computed as 8.83, 30.61, and 32.14°C and 5.72, 29.94, and 32.12°C by using Analytis/Allahyari and Analytis/Briere-2 models, respectively.
The sunflower stem weevil, Cylindrocopturus adspersus (LeConte) (Coleoptera: Curculionidae), has caused yield losses across much of the western Great Plains, Little is known about the field biology of this pest. Simple prediction models, such as degree-day models, are an integral tool for development of C. adspersus management strategies. Using data collected in Colorado, Kansas, and Nebraska, we sought for predictable variation between C. adspersus pupation, adult eclosion, and emergence and accumulated degree-days Celsius (DD) by using a temperature threshold of 5°C. Accurate phenological models can be used to time scouting efforts and pesticide applications. The relationship between phenological data and accumulated DD fit nonlinear, Gaussian distributions better than uniform distributions. Phenological models were developed to describe these distributions for pupation, adult presence within the stalk and adult emergence, The pupation model predicts 50% pupation at 197 DD and 90% at 307 DD. Model results predict that 50% of adult eclosion within the stalks will have transpired at 396 DD and 90% at 529 DD. A model-averaged result from two data sets predicts 5% adult emergence from stalks at 262 DD, 50% emergence at 540 DD, 75% emergence at 657 DD, and 90% at 777 DD. Scouting for adults thus can be initiated at 262 DD. Current chemical controls target adults to prevent oviposition. Thus, applications therefore should not be made before this point.
Trichogramma are used for the biological control of numerous pests, For Trichogramma, as for other insects, the specificity of matings is ensured by several barriers that prevent copulation attempts between insects from different species, We have recently shown that insecticides may totally suppress species recognition that occurs from pheromonal communications between two Trichogramma species, a sublethal effect that will increase mating attempts between two different species, In this work, we have assessed the fitness cost of such interspecific matings and demonstrate that they are very costly for females, After an interspecific mating, females can generate only males because fertilized eggs degenerate (Trichogramma are haplo-diploid species; males are issued from unfertilized eggs and females from fertilized eggs), The resulting offspring are reduced in number by more than half, corresponding to the missing progeny from fertilized eggs. After an interspecific mating, the fecundity of females cannot be restored even if females subsequently mate intraspecifically. These results highlight the strong fitness cost of any event that would decrease the specificity of matings in Trichogramma. Because Trichogramma are key species regulating insect populations, these effects must be considered in the context of sustainable development.
We identified a four-component sex pheromone blend that is as attractive or more attractive to male navel orangeworm moths, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), than either unmated females or hexane extracts of pheromone glands of females. The blend consisted of (11Z,13Z)-hexadecadienal; (11Z,13Z)-hexadecadien-1-ol; (11Z,13E)-hexadecadien-l-ol; and a hydrocarbon, (3Z,6Z,9Z,12Z,15Z)-tricosapentaene (C23 pentaene), in ratios of ≈100:100:5:5. Other minor components of pheromone gland extracts included (11Z,13E)-hexadecadienal; (11E,13Z)hexadecadienal; (11Z,13Z)-hexadecadien-l-yl acetate; (Z)-11-hexadecenal; hexadecanal; hexadecanl-ol; and a second pentaene, (3Z,6Z,9Z,12Z,15Z)-pentacosapentaene (C25 pentaene). These minor components did not increase attraction of male navel orangeworm to the basic four-component blend. The use of another, cross-attracted pyralid moth, Pyralis farinalis L., as a model species was crucial in implicating the C23 pentaene as an important component of the navel orangeworm pheromone blend. The four-component navel orangeworm pheromone blend was optimized using a combination of wind tunnel and field bioassays. Attractiveness of field deployed synthetic pheromone lures decreased rapidly despite incorporation of stabilizers and use of different release devices, suggesting that degradation products antagonize male navel orangeworm responses. Overall, the combination of type I lepidopteran pheromone components consisting of C16 aldehydes and alcohols with type II components consisting of long-chain polyunsaturated hydrocarbons has now been documented in several lepidopteran species and may indicate a paradigm shift in the range of compounds that constitute sex pheromone blends for individual lepidopteran species. This suggests that careful reexamination of pheromone gland contents for both type I and type II compounds may prove fruitful in species that have been studied but for which full attractant blends have eluded identification.
Neonate movement and dispersal behavior of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), were investigated under controlled conditions on Bacillus thuringiensis (Bt) and non-Bt corn, Zea mays L., to assess plant abandonment, dispersal from their natal plant, and silking behavior after Bt and non-Bt preexposure. With continuous airflow, neonates on a Bt corn plant for 24 h abandoned that plant 1.78 times more frequently than neonates on a non-Bt corn plant. Indirect evidence indicated that at least one third of the neonates were capable of ballooning within 24 h. In the greenhouse, some neonates were recovered after 24 h from plants 76 and 152 cm away that likely ballooned from their natal plant. After 1 h of preexposure on a Bt corn leaf, neonates placed on a new corn leaf and observed for 10 min began silking off of a new Bt leaf significantly sooner than a new non-Bt leaf. Results suggest that neonates are unable to detect Bt in the corn within 10 min but that they can detect it within the first hour.
The obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), is one of the most destructive pests of tree fruit in Washington. The development of insecticide resistance in C. rosaceana has led us to explore new management tactics. The use of very low doses of insecticides that have strong sublethal effects represents an environmentally friendly option to improve existing integrated pest management (IPM) strategies. We tested the insect growth regulator pyriproxyfen to determine its lethal and sublethal effects on growth and development of C. rosaceana. A leaf-disk bioassay was used to test seven concentrations of pyriproxyfen ranging from 0 to 30 ppm on fifth-instar C. rosaceana. Male and female larvae were assessed separately for mortality as well as other parameters of growth and development, The LC50 values for males and females were 2.4 and 4.8 ppm, respectively. The response to pyriproxyfen was concentration-dependent: only 5–6% of the larvae treated with the highest concentration emerged as morphologically normal adults compared with 86% emergence in the controls, The pupation and adult emergence was significantly delayed at concentrations higher than 1 ppm, The weights of C. rosaceana pupae and adults were significantly increased, whereas fecundity and fertility were significantly reduced at a sublethal concentration of 0.3 ppm. We conclude that both lethal and sublethal effects might exhibit significant impacts on the population dynamics of C. rosaceana in tree fruit orchards treated with low concentrations of pyriproxyfen.
We studied the effects of downy brome, Bromus tectorum L., winter cover crop on several corn, Zea mays L., pests in the summer crop after the cover crop. An experiment was conducted that consisted of two trials with two levels of irrigation, two levels of weed control, and two levels of downy brome. Corn was grown three consecutive years after the downy brome grown during the winter. Banks grass mites, Oligonychus pratensis (Banks), twospotted spider mites, Tetranychus urticae Koch, and predatory mites from the genus Neoseiulus were present in downy brome at the beginning of the growing season. They moved into corn, but their numbers did not differ significantly across the treatments, Larval western corn rootworm, Diabrotica virgifera virgifera LeConte, feeding on corn roots was evaluated the second and third years of corn, production. Irrigation and herbicide treatments had no significant effects on rootworm injury levels. In one trial, rootworm injury ratings were significantly greater in treatments with a history of high versus low brome, but this effect was not significant in the other trial. Rootworm injury seemed to be similar across plots with different surface soil moistures. This suggests that the use of a winter cover crop such as downy brome will not have a major negative impact the arthropods studied.
Boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), trapping and pheromone quantitative analysis of extended-life pheromone lures manufactured with 0, 10, 20, and 30 mg of eugenol was conducted in the Rio Grande Valley of Texas under spring and summer conditions. Boll weevils responded positively to eugenol on one of 12 trapping weeks when densities were high, but when densities were low (<2 weevils trap-1 wk-1), there were no significant differences in captures for any dosage of eugenol offered in a standard boll weevil trap. Weekly grandlure volatilization did not differ by eugenol dose but was significantly different when evaluated over three different trapping periods and by week within trapping period due to differences in ambient temperature. The amount of grandlure that remained after 4 wk in moderate temperatures of spring was 13.1 = 0.19 mg (55.7% of original 25 mg of content) compared with 5.5 ± 0.15mg remaining (22.8% of original 25 mg content) after for 4 wk in summer heat. Weekly volatilization of grandlure for the summer trapping period was 9.8 ± 0.32 mg for the first week, declining steadily to 1.0 ± 0.09 mg by the fourth week of age. The data indicate that at high summer temperatures >30°C, accumulative grandlure loss per week may be too high, leaving too little residual grandlure to effectively attract boll weevils at the end of 3 wk of trapping. Eugenol plays no role in reserving or encouraging the release of grandlure, or in increasing boll weevil captures when boll weevil densities are low.
Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an important agricultural pest that is endemic to Puerto Rico and the rest of the Caribbean islands. Relatively little is known about the population movements of fall armyworm in the Caribbean and the magnitude of genetic interactions, if any, with populations from North, South, and Central America. To address this issue, a novel method involving mitochondrial haplotype ratios currently being used to study the migration of fall armyworm in North America was applied to populations in Puerto Rico. The results indicate limited interactions between Puerto Rico fall armyworm and those from Brazil or Texas but the potential for significant exchanges with populations in Florida.
The hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), is an exotic insect species dramatically reducing populations of eastern hemlock, Tsuga canadensis (L.) Carrieré, throughout the eastern United States, Systemic imidacloprid is one of the primary chemicals used to successfully control infestations of the hemlock woolly adelgid, The concentration levels for this systemic insecticide present in the sap of eastern hemlocks were evaluated from three strata within the canopy over a two year time span, Enzyme-linked immunosorbent assays were conducted every three months posttreatment to assess imidacloprid concentration within the sap. The effect of application timing (fall versus spring) and application method (soil drench, soil injection, and tree injection) on the translocation of imidacloprid throughout the canopy, and the quantity of imidacloprid translocated in the sap of eastern hemlock branches and the terminal twig and needle tissue was determined. Concentration levels progressively declined from the bottom strata to the top strata of the canopy. This trend was consistent in all chemically treated trees. Tree injections provided the lowest concentration and the most nonuniform distribution of imidacloprid throughout the canopy. The highest insecticide concentrations within the tree across all strata over the two year period were consistently associated with the soil drench method followed by the soil injection method. Imidacloprid concentrations peaked between month 9 and 12 posttreatment, and then declined; however, at two years posttreatment, soil drench and soil injected trees contained concentrations reported as being effective for control of the hemlock woolly adelgid.
Green apple aphid, Aphis pomi De Geer, and Aphis spiraecola Patch (both Hemiptera: Aphididae), are sympatric aphid species that are pests of apples (Malus spp.) and other crops, A. spiraecola has been shown to be significantly more tolerant to several insecticides compared with A. pomi. To establish the mechanisms contributing to this difference in insecticide response, clones of both species were collected from British Columbia, Canada, and Washington state. Dose—response bioassays were conducted to determine relative tolerances to the insecticides pirimicarb, dimethoate, and imidacloprid; these results have been reported previously, Samples of adult aphids from each clone were assayed for the activity of esterase enzymes often involved in the detoxification of insecticides. A. spiraecola had higher esterase activity compared with A. pomi; this was apparent for two model substrates, α-naphthyl acetate (α-NA) and α-naphthyl butyrate (α-NB), Aphid clones of both species collected from Washington had higher esterase activity than clones collected from British Columbia. Clones from both species and locations hydrolyzed α-NA to a greater extent than α-NB. Esterase activity measured with both substrates was significantly positively correlated with the relative response to pirimicarb and dimethoate; a significant positive correlation also was found for hydrolysis of α-NB and imidacloprid. The apparent involvement of esterases in the differential response of A. pomi and A. spiraecola to insecticides indicated that the choice of control chemicals for A. spiraecola should not involve chemistries that are metabolized predominantly by esterases.
Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), is a major pest of sweet cherry, Prunus avium (L.) L., in the Pacific Northwest of the United States, Spinosad bait is applied weekly to kill flies before they develop eggs, but its effects on oviposition by reproductively mature flies are unknown. In this study, the main objective was to identify insecticide bait treatments that can prevent oviposition after being ingested by reproductively mature R. indifferens. First, flies were fed liquid bait. Of flies fed spinosad bait, 20% oviposited and all died within 1 d. Of flies fed acetamiprid sucrose, 72% oviposited after 1 wk, and all recovered from paralysis within 1 d. Of flies fed spinosad bait acetamiprid, 7% oviposited and most died within 1 d. None of the flies fed spinosad bait thiamethoxam oviposited and all died within 1 d. Of flies fed thiamethoxam sucrose, 2% oviposited and most died within 1 d. None of the flies fed spinosad thiamethoxam sucrose oviposited and all died within 1 d. Of flies fed spinosad sucrose, 11% oviposited and almost all died within 1 d. Next, flies were fed 2-d-old dried baits. No flies fed dried spinosad thiamethoxam sucrose and thiamethoxam sucrose oviposited. On the basis of absolute numbers of eggs laid by flies fed liquid and dried treatments, spinosad thiamethoxam sucrose may be the most effective of the seven insecticide baits tested for preventing oviposition by reproductively mature R. indifferens.
Petroleum-derived spray oils (PDSOs) offer an interesting alternative to acaricides to control the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), a key pest of clementine mandarins, Citrus reticulata Blanco. However, there is a lack of knowledge on how these products should be used. In this study, we evaluated the efficacy of four PDSOs (Sunspray Ultrafine, Volck Miscible, Texaco D-C-Tron Plus, and Agroaceite) at five concentrations (0.5, 1.0, 1.5, 2.0, and 3.0%) against eggs, protonymphs, and adults of T. urticae. We also characterized the PDSOs deposition pattern to find out the possible relationship between this factor and efficacy. In general, for all PDSO assayed, the higher the concentration, the higher the coverage, the mean area of impacts and efficacy on T. urticae. The biggest mean area of the impacts corresponded to Texaco D-C-Tron Plus. This PDSO was the most effective one and its efficacy was independent of concentration for concentrations higher than 1.0%. The same applied for concentrations higher than 1.5–2.0% for Agroaceite, Volck Miscible, and Sunspray Ultrafine, with high efficacies against eggs, protonymphs, and adults. PDSOs are highly effective against T. urticae, the use of these products should be encouraged in integrated citrus pest management programs in Spain. The next step will be to ascertain the efficacy under real field conditions.
Apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is a key pest in apple (Malus spp.) production areas located in the northeastern and midwestern United States and the eastern provinces of Canada. The development of Surround WP has offered a new approach for controlling apple maggot and other tephritid species, because this material is considered to be compatible with advanced integrated pest management and organic production systems. We conducted studies aimed at identifying the behavioral and biological effects of this material on apple maggots. Specifically, we examined the effect of Surround WP on the visual ecology of adult flies under field conditions, on tactile responses of flies in semifield trials, and on fly mortality in laboratory-based-bioassays. We demonstrated that an even coating of white particles over a fruit-mimicking sphere surface reduced visual attractiveness. We also found that spotty-coated fruit-mimicking spheres (meant to mimic ripe fruit bearing an uneven coating of Surround WP) were perceived by flies as not having the ideal round silhouette shape stimulus. Surround WP served as a tactile deterrent; the residence time of females introduced on to treated fruit was much shorter compared with untreated fruit. Surround WP also had a toxic effect on both adult apple maggot and Rhagoletis suavis (Loew); flies exposed to and forced to stand on Surround-treated surfaces died in <2 d in all trials. The combined effectiveness of Surround WP is based on a reduction in the attractiveness of fruit-based visual cues, an increase in the likelihood of flies leaving treated surfaces due to tactile deterrence, and a potential for increased mortality due to exposure to Surround WP particles.
The weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is an important pest of palms. It has recently colonized the Mediterranean Basin where it is a serious problem on ornamental Phoenix canariensis (hort. ex Chabaud) palms. The efficacy of an insecticidal paint based on chlorpyrifos and pyriproxyfen in a microencapsulated formulation (Inesfly IGR FITO, Industrias Químicas Inesba S.L., Paiporta, Spain) against this weevil has been studied, Laboratory results proved that pyriproxyfen has no effect against R. ferrugineus when applied in this microen-capsulated formulation, Semifield trials dismissed Inesfly IGR FITO as a curative insecticide but showed the potential of this product in the preventative control of R. ferrugineus in palms. One single application could prevent infestation for up to 6 mo with a mean efficacy of 83.3%.
Methyl eugenol (ME) and cue-lure (C-L) traps with solid lure dispensers were deployed in areas with low and high populations of oriental fruit fly, Bactrocera dorsalis (Hendel), and melon fly, Bactrocera cucurbitae (Coquillett), respectively. In low-density areas, standard Jackson traps or Hawaii Fruit Fly Areawide Pest Management (AWPM) traps with FT Mallet ME wafers impregnated with dimethyl dichloro-vinyl phosphate (DDVP) or AWPM traps with Scentry ME cones and vapor tape performed equally as well as standard Jackson traps with liquid ME/C-L and naled. Standard Jackson traps or AWPM traps with FT Mallet C-L wafers impregnated with DDVP or AWPM traps with Scentry C-L plugs with vapor tape performed equally as well as standard Jackson traps with a lure-naled solution. In high density areas, captures with traps containing FT Mallet wafers (ME and C-L) outperformed AWPM traps with Scentry cones and plugs (ME and C-L) with DDVP insecticidal strips over a 6-mo period, Captures of B. dorsalis and B. Cucurbitae with wafers containing both ME and raspberry ketone (FT Mallet MC) were equivalent to those containing separate lures. From a worker safety and convenience standpoint, FT Mallet ME and C-L wafers with DDVP or Scentry plugs, with or without DDVP vapor tape, are more convenient and safer to handle than standard liquid insecticide formulations used for monitoring and male annihilation programs in Hawaii, and for detections traps used on the U.S. mainland. Furthermore, the FT Mallet MC wafer might be used in a single trap in place of two separate traps for detection of both ME and C-L responding fruit flies.
Filbertworm, Cydia latiferreana (Walsingham) (Lepidoptera: Tortricidae), is a key insect pest associated with hazelnuts, Corylus avellana L. (Fagales: Betulaceae), in North America. This study investigated the feasibility of entomopathogenic nematodes as an alternative strategy for filbertworm control. Laboratory and field experiments were conducted between October 2007 and May 2008 in Benton County, OR, to evaluate the ability of the nematode Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae) to infect filbertworm larvae and pupae. The susceptibility of larvae with and without hibernacula as well as pupae to S. carpocapsae was tested in laboratory bioassays using nematode concentrations between 40 and 200 infective juveniles (IJs) per cm2. Percentage of nematode infection was not significantly affected by the presence of hibernacula (infection range, 90–92%) compared with larvae without hibernacula (80–95%), or by pupal stage (50–75%) compared with larvae (65–75%). In additional field trials, the effect of nematode rate, water application rate, and orchard floor cover on nematode efficacy was determined in October 2007 and May/June 2008. Sentinel filbertworm larvae in plots with either bare soil or debris (leaves, twigs, husks, and blank nuts) were treated with S. carpocapsae at rates ranging from 40 to 150 IJs per cm2 applied in 75 or 190 ml/m2 water. Average filbertworm mortality ranged from 2 to 11% and from 50 to 78% in October and May, respectively. Larval mortality increased with increasing nematode concentration, but was not significantly affected by water application rate or orchard floor cover. Our experiments suggest that S. carpocapsae can play a role in the control of filbertworm larvae overwintering on the orchard floor.
The efficacy of bistrifluron, a chitin synthesis inhibitor, in cellulose bait pellets was evaluated on the mound-building subterranean termite, Coptotermes acinaciformis (Froggatt). Three concentrations of the bistrifluron were used: 0 (untreated control), 0.5, and 1.0% over an 8 wk period. Both doses of bistrifluron bait eliminated (viz. termites absent from nest or mound) termite colonies: 83% of colonies (10 of 12) were either eliminated or moribund (viz. colony had no reproductive capacity and decreased workforce) after 8 wk, compared with none of the control colonies. The remaining two treated colonies were deemed to be in decline. Early signs that bistrifluron was affecting the colonies included: 3 wk after baiting mound temperatures showed a loss of metabolic heat, 4 wk after baiting foraging activity in feeding stations was reduced or absent, and dissection of two mounds at 4 wk showed they were moribund. Colony elimination was achieved in around half or less the time, and with less bait toxicant, than other bait products tested under similar conditions in the field, because of either the active ingredient, the high surface area of the pellets, or a combination of both. This suggests the sometimes long times reported for control using baits may be reduced significantly. The use of a mound building species demonstrated clearly colony level effects before and after termites stopped foraging in bait stations.
The initial soil penetration of Premise 75 and Termidor SC, containing imidacloprid and fipronil, respectively, were tested in laboratory columns of five different soils, Three combinations of application concentration and volume were used: double the recommended active ingredient concentration at one half the recommended volume (DR), the full concentration and volume (FR), and one half the concentration and twice the volume (HR), In all three cases, the same total amount of active ingredient (0.01 g of imidacloprid for Premise and 0.012 g of fipronil for Termidor) was applied to the same soil surface area (45.36 cm2), Regardless of soil or application method, the concentration of active ingredient was highest in the top 1 cm of soil. Within each soil, the concentration in the top 1 cm was highest in the DR treatment and lowest in the HR treatment. At each depth below 1 cm, active ingredient concentration was highest in the HR treatment and lowest in the DR treatment. The DR treatment therefore results in a thinner barrier of higher initial concentration in the top 1 cm, whereas the HR treatment results in a thicker barrier but of lower initial concentration in the top 1 cm.
Moisture is an important physical factor for the survival of termites. The effects of different moisture levels (0, 5, 10, 15, 20, and 25%) of a sand substrate on the behavior of laboratory groups of Microcerotermes crassus Snyder and Coptotermes gestroi (Wasmann) (Blattodea: Termitidae: Rhinotermitidae) were evaluated. Moisture content of sand affected wood consumption and influenced termite distribution across a moisture gradient for M. crassus. Changing the moisture parameters affected the location preference of C. gestroi, but the effect on wood consumption was not significant. Nonetheless, M. crassus and C. gestroi showed a similar distribution pattern of association with particular moisture levels.
Here, we describe the biology of a relatively new pest cockroach species in Southeast Asia, Symploce pallens (Stephens) (Dictyoptera: Blattellidae). S. pallens collected from Penang Island, Malaysia, were used for the biological parameter studies and were observed for molting and reproduction events. Nymphal development took 118.2 ± 1.7 d, with a mean of 9.5 ± 0.1 molts. The oothecal incubation period was 36.1 ± 0.2 d. Females produced a mean of 16.0 ± 10.2 oothecae, with mean 17.6 ± 0.1 nymphs per ootheca. Nymphal survivorship per ootheca was 90.4%, and 90.7% of nymphs achieved adulthood, The sex ratio did not deviate from 1:1. The mean longevity of adult males and females was 309.3 ± 7.6 and 322.6 ± 14.8 d, respectively. In general, S. pallens exhibited higher oothecal production and longer nymphal development and longevity compared with the German cockroach, Blattella germanica (L.).
The toxicity of 12 essential oil components [carvacrol, 1,8-cineole, trans-cinnamaldehyde, citronellic acid, eugenol, geraniol, S-(-)-limonene, (-)-linalool, (-)-menthone, ( )-αpinene, (-)-β-pinene, and thymol] to adult male; adult female; gravid female; and large, medium, and small nymphs of the German cockroach, Bhttella germanica (L.) (Dictyoptera: Blattellidae), was determined. Thymol was the most toxic essential oil component to adult males, gravid females, and medium nymphs, with LD50 values of 0.07, 0.12, and 0.06 mg per cockroach, respectively. trans-Cinnamaldehyde was the most toxic essential oil component to adult females, large nymphs, and small nymphs, with LD50 values of 0.19, 0.12, and 0.04 mg per cockroach, respectively, ( )-α-Pinene was the least toxic essential oil component to all stages of the German cockroach. The most frequently occurring susceptibility ranking for the stages was small nymphs > medium nymphs > adult males > large nymphs > gravid females > adult females. Adult females were the least susceptible to the essential oils, so they will be the determining factor when considering a rate for field application. Toxicity was positively correlated with essential oil component density and boiling point; however, there was no significant correlation between toxicity and lipophilicity. The effect of essential oil components on ootheca hatch was also investigated, S-(-)-limonene had the least effect on ootheca hatch, with 35.21 (mean) nymphs hatching per ootheca, (-)-menthone had the greatest effect on ootheca hatch with 20.89 nymphs hatching per ootheca. The numbers of nymphs hatching from each ootheca generally declined as dose increased. No essential oil component completely prevented ootheca hatch suggesting that multiple treatments might be required in the field to prevent reinfestation.
The resistance profiles of 22 field-collected populations of the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae), from various localities in Singapore were determined by topical bioassay against novel and conventional insecticides from six classes: 1) pyrethroid (beta-cyfluthrin, deltamethrin), 2) carbamate (propoxur), 3) organophosphate (chlorpyrifos), 4) phenyl pyrazole (fipronil), 5) neonicotinoid (imidacloprid), and 6) oxadiazine (indoxacarb). Compared with a laboratory susceptible strain, resistance levels ranged from 3.0 to 468.0× for the pyrethroids, from 3.9 to 21.5× for the carbamate, from 1.5 to 22.8× for the organophosphate, from 1.0 to 10.0× for phenyl pyrazole, and were absent or low for the neonicotinoid (0.8–3.8×) and the oxadiazine (1.4–5.3×). One strain demonstrated broad-spectrum resistance to most of the insecticides. Synergism studies using piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) in combination with a discriminating dose (LD99) of selected insecticides were conducted to test for possible resistance mechanisms. Resistance to pyrethroid was reduced with PBO and DEF, suggesting the involvement of P450 monooxygenase and esterases in conferring resistance. Propoxur resistance also was suppressed with PBO and DEF, and coadministration of both synergists resulted in complete negation of the resistance, indicating the involvement of both P450 monooxygenase and esterase. In six B. geimanica field strains evaluated, esterases were found to play a role in chlorpyrifos resistance, whereas the P450 monoxygenase involvement was registered in three strains, Additional resistance mechanisms such as kdr-type and Rdl mutation contributing toward pyrethroid and fipronil resistance, respectively, also may be involved in some strains in which the resistance levels were not affected by the synergists. We conclude that insecticide resistance is prevalent in field German cockroach populations in Singapore.
F2 and F1 tests to detect resistance to Cry2Ab in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) were performed during the 2007–2008 summer. F2 tests indicated a resistance frequency of 0.006, which is similar to the published resistance frequencies for this species during the summers spanning 2002–2006, In contrast F1 tests indicated a resistance frequency of 0.033, Thus, F1 tests isolated Cry2Ab resistance alleles almost six-fold more frequently than the F2 method. A discrepancy might be expected if the F2 tests detected resistance conferred by more than one locus because F1 tests identify only the form of resistance present in the tester resistant colony. However, if so, F2 tests would detect more, not fewer, cases of resistance, In addition, complementation tests on 10 separate isolates indicate that there is only one common form of resistance. We hypothesized that some “resistance alleles” are homozygous lethal if autozygous (as generated in F2 tests) but not as allozygous homozygotes (as generated in F1 tests). The hypothesis was extended to accommodate the possibility that alleles at linked loci may be homozygous lethal. Neither of two tests of the hypothesis provided evidence that any alleles that confer resistance are associated with severe fitness costs. Thus we are presently unable to explain the basis of the difference in frequencies between the methods. Because of the simplicity of the F1 tests, it is difficult to imagine that it overestimates the frequency of resistance and we therefore accept that this test should provide a more robust method to estimate the frequency of Cry2Ab resistance in H. armigera.
The mechanisms associated with resistance of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), to organophosphate insecticides in pome fruit orchards have been shown to depend on the area. Our objectives were to evaluate the susceptibility of Spanish codling moth populations to chlorpyrifos-ethyl, azinphos-methyl, and phosalone, and the activity of three enzymatic systems reported to be involved in resistance. Eleven field populations and a susceptible strain used as a reference were tested using a bioassay consisting in the topical application of a diagnostic concentration on postdiapausing larvae. The enzymatic activity of mixed function oxidases (MFO), glutathione transferases (GST), and esterases (EST) was measured in postdiapausing larvae and adults. A significant decrease in the efficacy of the organophosphates was observed for all field populations, although the decrease was smaller in the case of chlorpyrifos-ethyl. No differences between sexes were detected. In postdiapausing larvae, the activity of the three enzymatic systems was higher in all the field populations than in the susceptible population. The possible implication of EST in codling moth insecticide resistance is reported for the first time in European field populations. In adults, only MFO and GST were implicated. Codling moth resistance to organophosphates in Spanish populations must be taken into account in the implementation of antiresistance strategies.
Greenhouse tests showed that 0.2% camptothecin emulsifiable concentrate (EC) has strong contact toxicity to three agricultural pests, with LC50 and LC90 values of 0.1–0.6 and 0.4–5.0 mg liter-1, respectively. The descending order of susceptibility was Nilaparvata lugens (Ståhl) > Brevicoryne brassicae (L.) > Chilo suppressalis (Walker). Field tests showed that the corrected mortality of B. brassicae and N. lugens was 94.6 and 69.1%, respectively, which was not significantly different from that with 10% imidacloprid WP at 98.4 and 63.4%, respectively. The corrected mortality of C. suppressalis was 85.8%, which was not significantly different from that with 5% Regent SC at 93.0%. Camptothecin EC showed no acute oral toxicity to the mouse (LD50 > 5,000 mg/kg) nor acute dermal toxicity (LD50 > 2,000 mg/kg).
Biotin-binding proteins (BBPs), expressed in transgenic plants, are insecticidal to a very wide range of insects. The expression levels required are generally low (≈100 ppm), and although higher than required for Bacillus thuringiensis (Bt) δ-endotoxins, BBPs are effective across a broader range of insect orders and other invertebrates than the Bt Cry proteins. Avidin and streptavidin, in particular, have been reported as causing death or severe growth reduction in at least 40 species of insects across five insect orders (Lepidoptera, Coleoptera, Orthoptera, Diptera, and leaf-eating Hymenoptera) and mites. In addition, due largely to its rapid dilution in ecosystems, no adverse impacts on nontarget microorganisms or invertebrates have been recorded, Because the target, biotin, cannot itself be modified to prevent it binding to BBPs and remain effective as a vitamin, the major avenue open to insects to develop resistance is unavailable. Two properties of the biotin-avidin complex make it highly suitable for use in transgenic plant crop protection strategies against a large range of insects; its extreme stability and its resistance to proteolysis, However, because the nutritional value of the plant could potentially be compromised in the absence of biotin supplementation, its use in nonfood crops such as fiber, forestry, and biofuel crops is seen as the most suitable initial focus for this technology.
Shortly after its arrival, the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), became established as the most important insect pest of soybean, Glycine max L. (Merr.), in the northern part of the North American soybean production region. Soybean resistance is an environmentally sustainable method to manage the pest and new soybean aphid resistant cultivars are beginning to be deployed into production. However, an earlier study identifying a soybean aphid biotype that could colonize plants with the Ragl resistance gene has raised concerns about the durability of soybean aphid resistance genes. Choice and nonchoice tests conducted in this study characterized the colonization of a soybean aphid isolate, collected from the overwintering host Frangula alnus P. Mill in Springfield Fen, IN, on different aphid resistant soybean genotypes, This isolate readily colonized plants with the Rag2 resistance gene, distinguishing it from the two biotypes previously characterized and indicating that it represented a new biotype named biotype 3. The identification of soybean aphid biotypes that can overcome Rag1 and Rag2 resistance, even before soybean cultivars with the resistance genes have been deployed in production, suggests that there is high variability in virulence within soybean aphid populations present in North America. Such variability in virulence gives the pest a high potential to adapt to and reduce the effective life of resistance genes deployed in production. The search for new soybean aphid resistance genes must, therefore, continue, along with the development of alternative sustainable strategies to manage the pest.
The impact of herbivory on plants is variable and influenced by several factors, The current study examined causes of variation in the impact of larval stem mining by the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), on spring wheat, Triticum aestivum L. We performed greenhouse experiments over 2 yr to 1) study whether biotic (hollow versus solid stemmed host wheat) and abiotic (water, phosphorus stress) factors interact with C. cinctus stem mining to influence degree of mined stem physiological (photosynthesis) and yield (grain weight) reductions; and 2) determine whether whole plant yield compensatory responses occur to offset stem-mining reductions, Flag leaf photosynthetic reduction was not detected 16–20 d after infestation, but were detected at 40–42 d and doubled from water or phosphorus stresses. Main stem grain weight decreased from 10 to 25% from stem mining, largely due to reductions in grain size, with greater reductions under low phosphorus and/or water levels. Phosphorus-deficient plants without water stress were most susceptible to C. cinctus, more than doubling the grain weight reduction due to larval feeding relative to other water and phosphorus treatments. Two solid stemmed varieties with stem mining had less grain weight loss than a hollow stemmed variety, so greater internal mechanical resistance may reduce larval stem mining and plant yield reductions, Our results emphasize the importance of sufficient water and macronutrients for plants grown in regions impacted by C. cinctus. Also, solid stemmed varieties not only reduce wheat lodging from C. cinctus, they may reduce harvested grain losses from infested stems.
Cotton, Gossypium hirsutum L., bolls were sampled in commercial fields for stink bug (Hemiptera: Pentatomidae) injury during 2007 and 2008 in South Carolina and Georgia. Across both years of this study, boll-injury percentages averaged 14.8 ± 0.3 (SEM). At average boll injury treatment levels of 10, 20, 30, and 50%, the percentage of samples with at least one injured boll was 82, 97, 100, and 100%, respectively. Percentage of field-sampling date combinations with average injury <10, 20, 30, and 50% was 35, 80, 95, and 99%, respectively. At the average of 14.8% boll injury or 2.9 injured bolls per 20-boll sample, 112 samples Dx = 0.1 (within 10% of the mean) were required for population estimation, compared with only 15 samples at Dx = 0.3. Using a sample size of 20 bolls, our study indicated that, at the 10% threshold and α = β = 0.2 (with 80% confidence), control was not needed when <1.03 bolls were injured. The sampling plan required continued sampling for a range of 1.03–3.8 injured bolls per 20-boll sample. Only when injury was >3.8 injured bolls per 20-boll sample was a control measure needed. Sequential sampling plans were also determined for thresholds of 20, 30, and 50% injured bolls. Sample sizes for sequential sampling plans were significantly reduced when compared with a fixed sampling plan (n = 10) for all thresholds and error rates.
Release—recapture studies were conducted with both feral and sterile females of the Caribbean fruit fly, Anastrepha suspensa (Loew) (Diptera: Tephritidae), to determine sampling range for a liquid protein bait (torula yeast/borax) and for a two-component synthetic lure (ammonium acetate and putrescine). Tests were done in a guava, Psidium guajava L., grove and involved releasing flies at a central point and recording the numbers captured after 7 h and 1, 2, 3, and 6 d in an array of 25 Multilure traps located 9–46 m from the release point, In all tests, highest rate of recapture occurred within the first day of release, so estimations of sampling range were based on a 24-h period. Trap distances were grouped into four categories (<10, 10–20, 20–30, and >30 m from release point) and relative trapping efficiency (percentage of capture) was determined for each distance group. Effective sampling range was defined as the maximum distance at which relative trapping efficiency was ≥25%. This corresponded to the area in which 90% of the recaptures occured. Contour analysis was also performed to document spatial distribution of fly dispersal. In tests with sterile flies, immature females dispersed farther and were recovered in higher numbers than mature females, regardless of attractant, and recapture of both cohorts was higher with torula yeast. For mature feral flies, range of the synthetic lure was determined to be 30 m. With sterile females, effective range of both attractants was 20 m. Contour maps indicated that wind direction had a strong influence on the active space of attractants, as reflected by distribution of captured flies.
Sampling statistics were obtained to develop a sampling protocol for estimating numbers of adult Diaphorina citri Kuwayama (Hemiptera: Psyllidae) in citrus by using two different sampling methods: yellow sticky traps and stem—tap samples, A 4.0-ha block of mature orange trees was stratified into 10 0.4-ha strata and sampled using each method seven times over a 7-mo period. One sticky trap was deployed per tree on each of 16 trees randomly selected in each stratum, and numbers of adults on the traps were counted 1 wk later. One stem—tap sample in which the number of adults falling into a pan after three rapid taps to a branch was taken per tree on each of 16 trees randomly selected in each stratum. A sampling protocol of one yellow sticky trap on each of 20 trees, or of one stem—tap sample on each of 30 trees, distributed uniformly across an area up to 4.0 ha (excluding block edges) was projected to provide an average sampling precision rate of ≤25% (SEM/mean × 100) at means of one or more adults per trap or stem—tap sample. Validation sampling indicated 20 sticky trap samples consistently provided the desired precision level at means of approximately two or more adults per trap but not at means of 1.0–1.5 per trap. A sample size of 30 stem—tap samples consistently provided the desired average precision level, but the precision of some individual estimates was >25% at means of around one adult per tap sample.
House fly responses to metaflumizone bait were studied in southern California. Fieldstrain, laboratory-reared flies in outdoor cages had access for 5 d to water and two containers of untreated sugar/dry milk (control), one container of untreated food and one container of metaflumizone bait, or one container of untreated food and one container of spinosad bait (positive control). Most fly mortality occurred between 0 and 48 h for spinosad and between 48 and 96 h for metaflumizone. On a commercial dairy, fly visitation and bait consumption were higher for metaflumizone bait than for sugar or imidacloprid bait. Flies seldom visited or consumed the imidacloprid bait. Approximately 32% of field flies collected directly from metaflumizone bait (single exposure) died when held in the laboratory with untreated food for 72 h versus <5% mortality for flies from sugar or imidacloprid bait. Individual laboratory-reared females from a field strain and a susceptible laboratory strain were videotaped in the laboratory after exposure to untreated dry milk/sugar, metaflumizone bait, spinosad bait, and imidacloprid bait. Imidacloprid-induced mortality in field strain flies was low; when on the bait they spent proportionally less time feeding (38%) than did the laboratory strain flies (63%). Feeding by the field strain was more variable, and they fed less on all bait/food sources except metaflumizone. Metaflumizone has promise as a relatively slow-acting fly bait.
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