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In this study, we evaluated the potential use of entomopathogenic nematodes as a control for the beetle Aethina tumida Murray (Coleoptera: Nitidulidae). In particular, we conducted 1) four screening bioassays to determine nematode (seven species, 10 total strains tested) and application level effects on A. tumida larvae and pupae, 2) a generational persistence bioassay to determine whether single inoculations with nematodes would control multiple generations of A. tumida larvae in treated soil, and 3) a field bioassay to determine whether the nematodes would remain efficacious in the field. In the screening bioassays, nematode efficacy varied significantly by tested nematode and the infective juvenile (IJ) level at which they were applied. Although nematode virulence was moderate in screening bioassays 1–3 (0–68% A. tumida mortality), A. tumida mortality approached higher levels in screening bioassay 4 (nearly 100% after 39 d) that suggest suitable applicability of some of the test nematodes as field controls for A. tumida. In the generational persistence bioassay, Steinernema riobrave Cabanillas, Poinar & Raulston 7–12 strain and Heterorhabditis indica Poinar, Karunaka & David provided adequate A. tumida control for 19 wk after a single soil inoculation (76–94% mortality in A. tumida pupae). In the field bioassay, the same two nematode species also showed high virulence toward pupating A. tumida (88–100%) mortality. Our data suggest that nematode use may be an integral component of an integrated pest management scheme aimed at reducing A. tumida populations in bee colonies to tolerable levels.
Multiple infections of managed honeybee, Apis mellifera, colonies are inevitable due to the ubiquitous ectoparasitic mite Varroa destructor and might be an underlying cause of winter losses. Here we investigated the role of adult small hive beetles, Aethina tumida, alone and in combination with V. destructor for winter losses and for infections with the microsporidian endoparasite Nosema ceranae. We found no significant influence of A.tumida and V. destructor alone or in combination on the numbers of N. ceranae spores. Likewise, A. tumida alone had no significant effects on winter losses, which is most likely due to the observed high winter mortality of the adult beetles. Therefore, our data suggest that A.tumida is unlikely to contribute to losses of overwintering honeybee colonies. However, high losses occurred in all groups highly infested with V. destructor, supporting the central role of the mite for colony losses.
A low-cost simplified diet has been successfully developed for rearing Spodoptera exigua larvae under laboratory conditions. The cost of ingredients was lower than that of the standard diet based on a modified tobacco hornworm, Manduca sexta (L.), diet. The simplified diet fulfilled larval nutritional requirements without apparent adverse effects on the reproductive capacity of the insect. Survival, pupal sex ratio, and fecundity registered in insects that were reared on the simplified diet did not differ from those observed on the standard diet. The mean larval development period of insects that consumed the simplified diet was also similar to that of insects that consumed the standard diet, whereas weight of pupae and adult longevity were significantly higher in insects reared on simplified diet. Larvae consumed ≈11% more of the standard diet compared with the simplified diet and a corresponding increase was observed in the number of larvae that could be reared through to pupation on each liter of simplified diet. The production of S.. exigua multiple nucleopolyhedrovirus (SeMNPV) occlusion bodies (OBs) in insects grown on each type of diet was also evaluated. Weights of larvae at inoculation and at death, OB yields and biological activity of OBs did not differ significantly for each type of diet. The simplified low-cost diet appears suitable for large-scale in vivo production of SeMNPV OBs.
Mealybugs are under a strict regulation at foreign trades of agricultural products because they are one of the most economically damaging groups of insects on food crops and ornamental plants. However, the absence of morphological characteristics enabling the discrimination of early life stages often cause a significant delay or rejection of a shipment when infested fruit is discovered, causing significant economic loss. A polymerase chain reaction-based method for species identification was developed for six mealybug species known to infest Korean pears including two regulated insects, Planococcus kraunhiae (Kuwana) and Crisicoccus matsumotoi (Siraiwa). Six sets of species-specific primers were designed based on the sequence comparison of the internal transcribed spacer 1 and 2 regions. Efficiency tests against 29 mealybug samples showed that this method could effectively discriminate different mealybug species regardless of their developmental stages. Blind tests against 11 field collected mealybug nymph samples indicated that a single polymerase chain reaction is enough to discriminate unidentified mealybugs collected on Korean pears. This new method will facilitate trade and export requirements, as well as identify the species at any stage of mealybug intercepted.
The combination of heat and low levels of oxygen increases mortality to insects infesting fruit compared with either heat or low oxygen alone. This combination treatment shows promise to disinfest commodities of quarantine pests. Heated air/modified atmosphere treatments employ the modified atmosphere (e.g., low oxygen) during the entire treatment interval. There is a positive relationship between temperature and efficacy of heat/modified atmosphere treatments. Efficacy of delaying atmospheric modification in a heat/modified atmosphere treatment was studied with the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), a quarantine pest of citrus and other fruit in Mexico, Central America, and southern Texas. Larvae were subjected to heat/low oxygen treatments in vitro as well as in grapefruit, Citrus paradisi Macfayden. The relationship between time delay of the modified atmosphere and estimated time required to kill 99% of Mexican fruit fly third instars was not linear, which would indicate an additive relationship, but followed a sigmoid relationship. When infested grapefruit were heated with 47°C air in three atmospheric regimes: 1) air; 2) N2 at 99 kPa plus O2 at 1 kPa; or 3) air for 55 min then N2 at 99 kPa plus O2 at 1 kPa for the remainder of the treatment, estimated 99% prevention of pupariation was 157, 127, and 141 min, respectively.
Juvenile hormone levels and adult diet have important effects on the attractiveness and competitiveness of male Anastrepha suspensa (Loew) (Caribbean fruit fly). Because the success of the sterile insect technique requires the release of males that can compete in the wild, these effects are of crucial importance. Laboratory and field cage experiments were conducted to compare male sexual performance on a lifetime basis and daily basis when submitted to four different treatments: (MP-) application of the juvenile hormone analog, methoprene (M) and sugar and hydrolyzed yeast as adult food; (MP-) application of M and sugar as adult food; (M-P) no application of M and sugar and hydrolyzed yeast as adult food; and (M-P-) no application of M and sugar as adult food. On a daily basis, MP males always performed better sexually, and 10% of these individuals were able to mate three consecutive times in the same day. However, the copula duration decreased with the increased number of matings on same day. In addition, M caused earlier maturation. On a lifetime basis, MP males had significantly greater sexual success than other flies. The substantial improvement in male sexual performance because of the hormone application, protein supply, and interaction of hormone and protein has the potential of producing more efficacious sterile males.
The most common thrips species found in Cyprus citrus orchards between 2003 and 2008 were Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and Thrips tabaci (Lindeman) (Thysanoptera: Thripidae). Only Pezothrips kellyanus, Kelly's citrus thrips (KCT) causes feeding damage on citrus fruits in Cyprus. KCT adults prefer to concentrate mostly in the northern and eastern sides of both lemon and grapefruit canopies. The attractiveness of white, sky blue, marine blue, and yellow color to KCT was evaluated. White was found to be the most attractive color to adults of KCT, F. occidentalis, and T. tabaci. A range of incidental and breeding host plants grown within and outside citrus orchards in Cyprus were identified. KCT adults were found on flowers of all citrus varieties, and various other flowering plants including Malva nicaeensis, Malva silvestris, Sinapis alba, Oxalis pes-caprae, Calendula arvensis, Urospermum picroides, Jasminum officinale, Gardenia jasminoides, Jasminum sambac, Prunus dulcis, Mangifera indica, Persea americana, and Eriobotrya japonica. KCT larvae were found only on lemon, grapefruit, Jasmine spp., and Gardenia flowers.
The effect of genetically modified corn (event MON810, YieldGard Corn Borer) expressing the Bacillus thuringiensis sp. kurstaki (Berliner) (Bt) endotoxin, Cry1Ab, on the survival of western bean cutworm, Striacosta albicosta (Smith), larvae was examined during intraguild competition studies with either European corn borer, Ostrinia nubilalis (Hübner), or corn earworm, Helicoverpa zea (Boddie), larvae. Competition scenarios were constructed by using either a laboratory or field competition arena containing one of five different diets and one of 13 different larval size-by-species scenarios. The survival of western bean cutworms competing with corn earworms in the laboratory arenas on either a meridic diet or isoline corn silk diet was significantly lower (P ≤ 0.01) than the controls in 13 out of 14 competition scenarios and larval survival was frequently zero. In contrast, the survival of western bean cutworm competing with corn earworm on a Cry1Ab-MON810 corn silk diet was significant higher (P ≤ 0.01) than the controls in four out of six competition scenarios. The results observed in the three way competitions involving the addition of European corn borers generally did not alter the outcomes observed in the western bean cutworm and corn earworm only two-way competitions. These data suggest that Cry1Ab-MON810 corn may confer a competitive advantage to western bean cutworm larvae during intraguild competition, particularly from corn earworms, and that western bean cutworms become equal competitors only when they are of equal or larger size and the diet is Cry1Ab-MON810 corn.
The impact of electronic dipole tags on the walking activity of three insects was determined using video tracking software. Results varied within and between the three species studied. The heaviest tag mounted on the pronotum of the Colorado potato beetle, Leptinotarsa decemlineata (Say), reduced its mean horizontal speed slightly but significantly. The mean horizontal speed of plum curculio, Conotrachelus nenuphar (Herbst), was significantly reduced by a light tag but not by heavier tags. The mean horizontal speed of the western corn rootworm, Diabrotica virgifera virgifera (LeConte), increased slightly when a tag was attached. A tag mounted to the dorsum of the Colorado potato beetle and the plum curculio slightly changed their climbing speed. Changes in the walking speed were variable but remained well within the range of values recorded in the literature. The impact of the additional tag weight was within the range of constraints to movement (e.g., slopes, barriers, etc.) normally experienced by insects in their environment. The results confirm that tags presently available will have minimal impact on the walking behavior of Colorado potato beetle, provide an estimate of the optimal tag weight for the plum curculio and show that a lighter tag and a better attachment method are required for the western corn rootworm. Because of the ability of insects to adapt to a wide range of landscapes and to their own body weight changes, the additional tag weight had a limited impact compared with the value of the ecological information gathered using this technology.
Bactrocera latifrons (Hendel) is a pest of Asian origin, first detected in Africa in 2006. We assessed the host utilization of this quarantine pest in Morogoro region, eastern central Tanzania, by collecting a wide range of cultivated and wild host plants of species belonging to Solanaceae and Cucurbitaceae from April 2007 to April 2008. Fruit were collected from 29 plant species and varieties (16 Solanaceae and 13 Cucurbitaceae) in all agroecological zones of Morogoro region. Twelve solanaceous fruit species yielded B. latifrons of which four are new host records: Capsicum annuum L. cov. longum A. DC., Capsicum chinense Jacq., Solanum sodomeum L., and Solanum scabrum Mill. Similarly, three cucurbitaceous fruit species provided positive rearings and are new host records: Citrullus lanatus (Thunb.) Matsum & Nakai, Cucumis dipsaceus L., and Momordica cf trifoliata L. The infestation rate and incidence of the pest was mainly high in the solanaceous hosts of nightshades (Solanum nigrum L. and Solanum scabrum) and African eggplants (Solanum aethiopicum Lam. and Solanum anguivi). In a host preference study involving limited number of cultivated solanaceous crops, S. scabrum was recorded as the most preferred host. The pest has been found to outnumber Bactrocera invadens (Drew et al), Bactrocera Cucurbitae (Coquillett), and Ceratitis capitata (Wiedemann) inmost of the common solanaceous hosts.
The percentage of viable eggs of the western corn rootworm, Diabrotica virgifera virgifera LeConte, which survived to the adult stage was evaluated for the effect of egg density in 2005 and 2007 in central Missouri. In 2005, each plot was 2.44 by 3.05 m and contained 64 maize (corn), Zea mays L., plants. In 2007, plots were 3.05 by 3.05 m and again contained 64 corn plants. Seven egg densities (2,400, 1,200, 600, 300, 100, 50, and 25 viable eggs per 30.5 cm) were evaluated with four to six replications in each year in a completely randomized design. In 2007 only, an additional row was infested near each plot to evaluate plant damage. In both years, there was no correlation of infestation level and percentage of emergence between infestation levels of 25–600 viable eggs per 30.5 cm, indicating that density-dependent mortality did not occur at these egg densities. In 2005, 8.04% of the viable eggs established on a corn plant and produced an adult at these lower infestation rates. In 2007, this value was 2.9%. Regardless of egg density, ≈92–97% failed to establish and produce adults (density-independent mortality). In 2005 and in the combined analysis, as viable egg densities increased from 600 to 2400 per 30.5 cm there was a significant decrease in percentage of emergence. In a broken line analysis of the 2005 data, the point where density-dependent mortality began in the combined analysis was 851 eggs per 30.5 cm with a 95% confidence interval from 678 to 1024. That year density-dependent mortality was important at high infestations and killed 54.4% of those larvae that successfully established on a plant at the highest egg density. However, little or no density-dependent mortality occurred at infestation levels <850 viable eggs per 30.5 cm in either year of the study. Combining data from both years with all previously published data in a broken line analysis indicated that density-dependent mortality began at ≈800 viable eggs per 30.5 cm. These data are discussed in terms of dose calculations for products targeting the western corn rootworm.
Recent fears of terrorism have provoked an increase in delays and denials of transboundary shipments of radioisotopes. This represents a serious constraint to sterile insect technique (SIT) programs around the world as they rely on the use of ionizing radiation from radioisotopes for insect sterilization. To validate a novel X ray irradiator, a series of studies on Ceratitis capitata (Wiedemann) and Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) were carried out, comparing the relative biological effectiveness (RBE) between X rays and traditional γ radiation from 60Co. Male C. capitata pupae and pupae of both sexes of A. fraterculus, both 24–48 h before adult emergence, were irradiated with doses ranging from 15 to 120 Gy and 10–70 Gy, respectively. Estimated mean doses of 91.2 Gy of X and 124.9 Gy of γ radiation induced 99% sterility in C. capitata males. Irradiated A. fraterculus were 99% sterile at ≈40 – 60 Gy for both radiation treatments. Standard quality control parameters and mating indices were not significantly affected by the two types of radiation. The RBE did not differ significantly between the tested X and γ radiation, and X rays are as biologically effective for SIT purposes as γ rays are. This work confirms the suitability of this new generation of X ray irradiators for pest control programs that integrate the SIT.
Tomicus yunnanensis Kirkendall and Faccoli (Coleoptera: Curculionidae: Scolytinae) is a newly described pine shoot beetle found in southwestern China. This beetle has affected >200,000 ha of Pinus yunnanensis (Franchet) forests over the past 30 yr. After maturation feeding in the shoots, adults attack the boles in December to produce a new generation. A hanging bolt study was initiated in November 2006 to detect the beetle flight patterns and to test if dispersing beetles respond to infested and uninfested material. Treatments tested were females only, males only, male and female pairs, and uninfested bolts. Beetles were collected on the bolts between 9:30 and 18:30, with peak catch in the afternoon between 14:00 and 18:30. No beetles were collected during the dark. Though trunk attacks in the field were observed in November, beetles were first collected on the bolts in January. No beetles were captured after March. Differences in numbers of beetles collected between treatments with infested bolts varied by month, but uninfested bolts always attracted fewer adults.
Bamboo (Bambusa spp.) users in Laguna and Rizal, Philippines, were surveyed regarding their willingness to accept varying degrees of bamboo powderpost beetle, Dinoderus minutus (F.) (Coleoptera: Bostrichidae), damage. The efficacy of deltamethrin, permethrin, or disodium octaborate tetrahydrate in water or in kerosene was then assessed against beetles on freshly cut bamboo (Bambusa vulgaris Schrader ex Wendland). Adult D. minutus in groups of 100 were capable of inflicting 50% cross-sectional damage on 30-cm-long bamboo samples within a 4-wk test period. Deltamethrin (0.01% [AI]). in water or kerosene provided significantly better protection against D. minutus attack on bamboo for 5 wk than did all other treatments. The results from a survey were then used to assess the cost/benefit ratio for each prophylactic treatment. Successful prophylactic treatment provided up to a 12:1 return, illustrating the benefits of such treatments.
As international trade increases so does the prominence of urban areas as gateways for exotic forest insects (EFI). Delimiting hot spots for invasions (i.e., areas where establishment is likely) within urban areas would facilitate monitoring efforts. We used a propagule-pressure framework to delimit establishment hot spots of a hypothetical generalist EFI in six U.S. urban areas: Chicago, Detroit, Houston, Los Angeles-Long Beach-Santa Ana, New York-Newark, and Seattle. We assessed how urban tree cover and propagule pressure interact to delimit establishment hot spots and compared the location of these hot spots with actual recent U.S. detections of two EFI: the Asian strain of the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), and Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae). Using a lattice of 5-km-diameter cells for each urban area, we used the input data (urban tree cover and propagule pressure) to model establishment and Moran's I to delimit hot spots. We used urban population size and the area of commercial-industrial land use as indicators of propagule pressure in the model. Relative establishment of EFI was influenced more by the two propagule pressure indicators than by tree cover. The delimited land use-based hot spots for Los Angeles-Long Beach-Santa Ana and New York-Newark encompassed more of the actual detections of L. dispar and A. glabripennis, respectively, than the population-based hot spots. No significant difference occurred between hot spot types for A. glabripennis detections in the Chicago urban area. Implications of these findings for management and design of monitoring programs in urban areas are discussed.
We conducted field trials at five different locations over a period of 6 yr to investigate the efficacy of imidacloprid applied each spring as a basal soil drench for protection against emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). Canopy thinning and emerald ash borer larval density were used to evaluate efficacy for 3–4 yr at each location while treatments continued. Test sites included small urban trees (5–15 cm diameter at breast height [dbh]), medium to large (15–65 cm dbh) trees at golf courses, and medium to large street trees. Annual basal drenches with imidacloprid gave complete protection of small ash trees for three years. At three sites where the size of trees ranged from 23 to 37 cm dbh, we successfully protected all ash trees beginning the test with <60% canopy thinning. Regression analysis of data from two sites reveals that tree size explains 46% of the variation in efficacy of imidacloprid drenches. The smallest trees (<30 cm dbh) remained in excellent condition for 3 yr, whereas most of the largest trees (>38 cm dbh) declined to a weakened state and undesirable appearance. The five-fold increase in trunk and branch surface area of ash trees as the tree dbh doubles may account for reduced efficacy on larger trees, and suggests a need to increase treatment rates for larger trees.
The application of insecticides to control Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is a principal component of the current management for citrus greening disease or Huanglongbing. It is recommended that growers apply systemic insecticides such as imidacloprid and thiamethoxam every 2 mo after seedling planting, but this practice renders the seedlings insecticide-free and vulnerable to psyllid infestation in the first 2 mo. We evaluated the risk of vector invasion during this period from field studies of the psyllid in five new king mandarin, Citrus nobilis Loureiro, orchards in the Mekong Delta region of Vietnam. The first psyllids were found after the first 2 wk, and 2 to 60% of the trees were finally infested by psyllids during the 2 mo. The risk of psyllid invasion could be significantly reduced if the insecticide were applied to seedlings before planting. Three systemics, imidacloprid, thiamethoxam, and clothianidin, were examined in both a net house and in the field to assess how quickly they could be effective after application and how long their efficacy could continue. High psyllid mortality >80% was attained in 10 d after application, and this level was maintained for 90 d in the net house and for 60 d in the field. Based on these results, we propose the effective use of neonicotinoids for protection of citrus seedlings against invasive psyllids during the first 2 mo after planting.
The common bed bug, Cimex lectularius (L.) (Hemiptera: Cimicidae) is known to become associated, from time to time, with clothing or linen. In such locations, it may escape insecticide treatment, and may be carried to new locations. We test the suggestion that laundering is sufficient to kill all life stages and thus help prevent reinfestation and dispersion. We establish minimum temperatures for washing and minimum temperatures and times for tumble-drying, as well as testing cold soaking, dry cleaning, and freezing as alternative strategies for delicate items. Data loggers were used to confirm temperature settings and monitor temperature changes during the treatments. Adult bed bugs, nymphs, and eggs were sealed into small, permeable cotton pouches, which were then placed into garments of clothing. Washing at 60°C was found to be effective against all life stages, as was tumble drying on a hot cycle (>40°C) for at least 30 min, dry cleaning with perchloroethylene, and freezing at -17°C for at least 2 h. Using data loggers it was also shown that 2.5 kg of loosely packed, dry laundry takes ≈8 h to reach -17°C. Soaking for 24 h in detergent-free water was found to be effective against active stages but had no effect on eggs.
The response of field-collected populations of the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), to chlorantraniliprole, spinetoram, spinosad, and azinphosmethyl was assessed using a diet incorporation bioassay. Populations of obliquebanded leafroller were collected from nine orchards in Chelan, Douglas, Grant, and Okanogan counties of Washington. The neonates of the F1 or F2 generation were used in all assays. The parameters of probit regression lines were estimated and lethal concentration ratios were calculated for all populations compared with a susceptible laboratory population. Significant variation was detected in response to all four insecticides including chlorantraniliprole and spinetoram, which had never been used in the field, lethal concentration ratios were 3.9–39.7 for azinphosmethyl, 0.5–3.6 for spinosad, 1.2–5.3 for chlorantraniliprole, and 0.5–4.1 for spinetoram. Correlation analysis indicated possibility of cross-resistance between spinosad and spinetoram, which are both members of spinosyn class. The occurrence of low but significant levels of resistance against chlorantraniliprole and spinetoram in field-collected populations of C. rosaceana before their first field application indicates that the risk of resistance evolution against these two new reduced-risk insecticides exists. However, it is likely that these low levels of resistance can be managed if the insecticides are used judiciously in conjunction with sound resistance management programs. Implications of these results for developing and implementing resistance management strategies are discussed.
Resistance management is essential for maintaining the efficacy and long-term durability of transgenic corn engineered to control western corn rootworm (Diabrotica virgifera virgifera Le Conte). Theoretically, a refuge can be provided by growing susceptible (refuge) plants in either a separate section of the field adjacent to resistant (transgenic) plants, or as a seed mixture. We examined the effects of varying the structure of a 10 and 20% refuge between currently approved structured refuges (block or strip plantings), as well as deploying the refuge within a seed mix, on adult emergence timing and magnitude, root damage and yield. Our 2-yr field study used naturally occurring western corn rootworm populations and included seven treatments: 10 and 20% block refuge, 10 and 20% strip refuge, 10 and 20% seed mix refuge, and 100% refuge. Beetles emerging from refuge corn emerged more synchronously with those emerging from transgenic (Bacillus thuringiensis [Berliner] Bt-RW) corn in seed mix refuges when compared with block refuges. The proportion of beetles emerging from refuge plants was significantly greater in a block and strip refuge structure than in a seed mix refuge. More beetles emerged from Bt-RW corn plants when they were grown as part of a seed mix. We discuss the potential benefits and drawbacks of a seed mix refuge structure in light of these findings.
Juvenile hormone (JH) analog insecticides are relatively nontoxic to vertebrates and provide efficient control of key arthropod pests. One JH analog, pyriproxyfen, has provided over a decade of exceptional management of whiteflies in cotton of the southwestern United States. Thwarting resistance to pyriproxyfen in Bemisia tabaci (Gannadius) (a.k.a. Bemisia argentifolii Bellows and Perring) has been the focus of an integrated resistance management program because this insecticide was first registered for use in Arizona cotton in 1996. Resistance levels have increased slowly in field populations in recent years but have not demonstrably affected field performance of pyriproxyfen. Resistant strains have been isolated and studied in the laboratory to determine the mechanism of resistance and identify optimal strategies for controlling resistant whiteflies. Synergism bioassays showed that resistance in a laboratory-selected strain QC02-R, was partially suppressible with piperonyl butoxid (PBO) and diethyl maleate (DEM) but not with S, S, S-tributyl phosphorotrithioate (DEF). Consistent with the synergism bioassay results, enzymatic assays revealed that the enzyme activities of cytochrome P450 monooxygenases (P450) and glutathione S-transferases (GST) but not esterases were significantly higher in the pyriproxyfen-resistant QC02-R strain than in the susceptible strain. These results indicate that both P450 and GST are involved in whitefly resistance to pyriproxyfen.
M. A. Navarro-Silva, J.E.L. Duque, E. N. Ramires, C.F.S. Andrade, E. Marques-Da-Silva, F. A. Marques, C. E. Delay, J. D. Fontana, A.C.S. Silva, G. M. Fraguas
Bites from the recluse or brown spiders (genus Loxosceles) can cause necrotic lesions and systemic effects in humans throughout the world. In the state of Paraná, Brazil, loxoscelism is considered a serious public health problem, and Loxosceles intermedia Mello-Leitão (Araneae: Sicariidae) is associated with the majority of reported accidents. In the present research we evaluated the susceptibility of L. intermedia to pyrethroid insecticides currently used for the control of spiders in both field and laboratory conditions. In laboratory tests, the most active pesticides in descending order were microencapsulated lambda-cyhalothrin (LC50 = 0.023 mg/kg), nonmicroencapsulated lambda-cyhalothrin (LC50 = 0.047 mg/kg), deltamethrin (LC50 = 0.26 mg/kg), and Cypermethrin (LC50 = 1.38 mg/kg). Cockroaches, Phoetalia circumvagans (Burmeister) (n = 30), killed with microencapsulated lambdacyalothrin, were offered to the spiders. L. intermedia fed on 63.3% of the dead cockroaches during the first 6 h of experiment; none of the spiders died during the subsequent 15 d. Microencapsulated lambdacyalothrin was chosen for application in two contiguous houses. The mean volume applied was 22.8 mg (AI) /m2. Dead spiders were found during all the inspections up to 60 d after the initial application. In total, 297 dead spiders were collected; 65.7% in the attic shared by the two homes, 10.8% inside the house that had most cracks and crevices sealed and 23.6% in the control house. The use of lambda-cyhalothrin-based products for L. intermedia control is discussed.
Bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae), are a fast-growing urban pest of significant public health importance in the United States and many other countries. Yet, there is very little field research on the ecology of this pest due to its near absence in the United States and most developed nations for several decades. We investigated characteristics of the bed bug infestation and dispersal in a 223-unit high-rise apartment building through visual inspections, intercepting devices, and resident and staff interviews between December 2008 and April 2009. The following results were obtained: 1) 101 apartments (45% of the high-rise building complex) experienced bed bug infestations (within 41 mo of the first confirmed introduction), 2) 78% of the bed bugs trapped were nymphs, 3) an average of six bed bugs were detected dispersing through apartment entry doors every 4 wk, 4) adult bed bugs were 9 times more likely to disperse than nymphs, 5) 53% of apartments adjacent to infested apartments also were infested, and 6) 50% of the interviewed residents who had infestations were unaware of the bed bugs in their apartments. In addition to active dispersal, several passive bed bug dispersal mechanisms were observed: bringing bed bug-infested furniture into the building, travel, resident turnover, resident visits, and use of a bed bug-infested wheelchair in building common areas. These findings validate an urgent need for public education, early detection, and adoption of more effective bed bug monitoring and intervention programs to curb the exploding problem of bed bug infestations.
We analyzed the accumulation of six phytohormones and phytohormone-related compounds in a wheat, Triticum aestivium L., genotype, ‘Molly’, after attacks by avirulent and virulent Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), larvae, respectively, and we examined the expression of genes in the jasmonic acid (JA) pathway by Northern blot analysis. Compared with uninfested plants, attacks by avirulent larvae resulted in increased accumulation of salicylic acid (SA) by 11.3- and 8.2-fold, 12-oxo-phytodienoic acid (OPDA) by 36.4-and 18.7-fold, 18:3 fatty acid by 4.5- and 2.2-fold, and 18:1 fatty acid by 1.8- and 1.9-fold at 24 and 72 h post-initial attack (hpia), respectively, but an 20% decrease in JA accumulation at 24 hpia at the attack site. Attacks by the virulent larvae did not affect the accumulation of SA, OPDA, and 18:3 and 18:1 fatty acids but dramatically increased the concentration of auxin (AUX) from undetectable in uninfested plants to 381.7 ng/g fresh weight at 24 hpia and 71.0 ng/g fresh weight at 72 hpia in infested plants. Transcript levels of genes encoding lipoxygenase 2, allene oxide synthase, and Arabidopsis storage protein 2 were increased after avirulent larval attacks but decreased after virulent larval attacks. Our results suggest that OPDA and SA may act together in wheat resistance to the Hessian fly, whereas AUX may play a role in the susceptibility of wheat plants. The increased OPDA accumulation after avirulent larval attacks was at least partially regulated through gene transcription.
The current study evaluated the potential of using counts of winged adults captured in suction traps to forecast the local abundance of soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in soybean, Glycine max (L.) Merr., fields. The abundance of aphids was evaluated weekly by sampling plants in four to 11 soybean fields and recording the number of aphids in suction traps between 2006 and 2008 in four counties in Indiana and Illinois. Fields in each county were located within 10 km of their respective suction trap, which allowed us to evaluate the relation between aphid abundance on soybean plants and in suction traps at the county level. Migrant soybean aphids caught in suction traps exhibited distinct seasonal trends each year: in 2006, trapped migrants consisted predominantly of individuals dispersing from soybean to buckthorn (Rhamnus sp.); in 2007, in contrast, the majority of trapped migrants were apparently individuals dispersing among soybean fields. The cumulative number of aphids captured in suction traps was positively related to aphid densities on soybean plants. However, the utility of suction traps as a monitoring tool may be limited by the variation in temporal patterns observed in suction traps and on soybean plants each year, and the spatial variation in aphid abundance among soybean fields within a county.
Laboratory bioassays were conducted to evaluate the effect of different diatomaceous earth (DE) formulations against adults and immature stages of the stored-product mite species Tyrophagus putrescentiae (Schrank). Five DE formulations were used in the tests: SilicoSec, PyriSec, Insecto, Protect-It, and DEA-P. The tests were conducted at 25°C and 75% RH, on wheat, Triticum aestivum L., treated with DEs at two dose rates, 0.2 and 0.5 g/kg. The mortality of mite individuals was measured after 5 d of exposure, and after 30 d the treated wheat was checked for T. putrescentiae offspring. Significant differences were noted among the DEs tested. Application of the lowest dose rate (0.2 g/kg) provided mortality of both adults and immatures that exceeded 78%, whereas the respective data for 0.5 g/kg were almost in all cases 100%. The adults of T. putrescentiae were more tolerant to DEs than the immature stages. Generally, PyriSec was the most effective against adults. Progeny production was dramatically reduced with the increase of dose. The results of the present work indicate that T. putrescentiae can be effectively controlled by DEs on wheat, at dose rates as low as 0.2 g/kg.
The effect of short exposures to spinosad-treated wheat, Triticum aestivum L., or maize, Zea mays L., was evaluated against adults of four stored-product insect species: lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae); rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae); red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae); and the psocid Lepinotus reticulatus (Enderlein) (Psocoptera: Trogiidae). Adult mortality of these species was recorded after 0, 2, 4, 8, 16, and 40 h on commodities treated with 1 ppm of spinosad (immediate mortality). Then, the surviving individuals were removed and placed on untreated wheat or maize, and mortality was recorded again 7 d later (delayed mortality). Progeny production then was determined 65 and 35 d later for the beetles and psocids, respectively. Among the four species tested, R. dominica was the most susceptible, and immediate mortality after 40 h reached 78 and 72% on wheat and maize, respectively. Moreover, 7 d later, all adults that had been exposed for >2 h were dead on both commodities. Progeny production was significantly reduced in comparison with the controls, and no progeny were found when parental adults had been exposed for >8 or >4 h on wheat and maize, respectively. For S. oryzae, 40-h exposures significantly increased delayed mortality on both wheat and maize, but progeny production still was high. Generally, no effect of short exposures was noted for T. castaneum. For L. reticulatus, despite the fact that the increase of exposure interval increased mortality on maize, progeny production was not avoided. With the exception of T. castaneum, more progeny were found on wheat than on maize. The results of the current study indicate that R. dominica is very susceptible after short exposures to spinosad-treated substrate, but the other species are able to survive and reproduce at the exposure range examined.
The biopesticide Spinosad controls many insect pests of stored-food products. Laboratory and field trials were carried out to determine the efficacy of this pesticide against the cowpea weevil, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), the main storage pest of cowpea, Vigna unguiculata, Walp, in West Africa. In the laboratory, Spinosad caused high mortality of adult C. maculatus and decreased the number of eggs laid by females. Spinosad, however, was less toxic in the 24 h treatment to C. maculatus than deltamethrin, an insecticide commonly used in Burkina Faso to control this insect. In “on-farm” experiments, Spinosad was effective in controlling C. maculatus. After 6 mo of storage, the number of insects emerging from cowpeas seeds was reduced by >80% by coating seeds with Spinosad but only by 43% by coating with deltamethrin. Less than 20% of the seeds were perforated in the Spinosad treatment compared with 29% for deltamethrin. Spinosad controlled C. maculatus throughout the 6 mo of cowpea storage whereas deltamethrin failed to control C. maculatus after 3 mo of storage. Spinosad has the potential to be more effective in controlling C. maculatus than deltamethrin.
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