Showing papers on "Infestation published in 2004"
TL;DR: The simple models developed should help to guide silvicultural treatments and restoration efforts by establishing stocking levels below which mountain pine beetle-caused mortality is less likely, particularly in the dry sites and poor growing conditions characteristic of the Colorado Front Range.
111 citations
TL;DR: Because rootworm-resistant transgenic maize with high levels of antibiosis has become a part of the agroecosystem, weeds in grassy maize fields as well as adjacent forage grass species may become more important in the western corn rootworm life cycle, particularly because genes conferring resistance to postemergent herbicides such as glyphosate are stacked with transgenic rootworms-resistant maize hybrids.
Abstract: With the recent commercialization of transgenic rootworm-resistant maize with high levels of antibiosis to larval feeding, the biology of western corn rootworm, Diabrotica virgifera virgifera LeConte, on hosts beyond maize, Zea mays L., has become an important topic for which data are limited. Larval survivorship and growth parameters were monitored on the roots of 29 plant species comprised of maize, maize-field weeds, native prairie grasses, forage grasses, and small grain crops. Data on larval recovery and growth (measured as increases in head capsule width and accumulation of dry weight) were recorded at five samplings (6, 10, 14, 20, and 24 d) after initial infestation of the 29 species. Recovery and growth parameters were analyzed for inter- and intraspecific differences within and among sampling dates. Larvae survived at least 6 d after infestation on 27 species and 24 d on 23 plant species. Larval recovery and growth were impacted by both species and time after infestation. Growth and development of larvae were significantly slower on most plant species beyond maize; however, 18 of the species had larvae develop to the second instar, whereas larvae on 14 species developed to the third instar. Adults were recovered from five plant species in addition to maize. Because rootworm-resistant transgenic maize with high levels of antibiosis has become a part of the agroecosystem, weeds in grassy maize fields as well as adjacent forage grass species may become more important in the western corn rootworm life cycle, particularly because genes conferring resistance to postemergent herbicides such as glyphosate are stacked with transgenic rootworm-resistant maize hybrids.
102 citations
TL;DR: Results indicate that dogs and birds are primary hosts for adult and immature stages, respectively, of A. aureolatum in nature, and wild guinea pigs are indicated as another potential primary host for immature ticks.
Abstract: In the first part of this study, monthly infestation by ticks was evaluated on dogs from December 2000 to November 2002 in the rural area of Taiacupeba, Sao Paulo. Adults of Amblyomma aureolatum (Pallas) were found on dogs in all months, with a mean prevalence per month of 46.9 ± 15.7% (range, 25–80%). The mean tick relative abundance per month was 2.4 ± 2.7 ticks (range, 0.5–14 ticks), and the mean tick mean intensity per month was 4.7 ± 4.2 ticks (range, 1.5–23.3 ticks). No A. aureolatum immature ticks were found on dogs. In the second part of this study, we studied the life cycle of A. aureolatum in the laboratory. We tested the suitability of six host species for the immature stages and dogs for the adult stage. Tick developmental periods were observed at different temperatures (23, 25, or 27°C), always with RH >95%, which were satisfactory for all free-living developmental stages of the tick life cycle. Chickens and guinea pigs were the most suitable hosts for larvae and nymphs (recovery rat...
75 citations
TL;DR: The effect of egg density on establishment and dispersal of larvae of the western corn rootworm was evaluated in a 3-yr field study, and initial establishment on a corn plant seemed to not be density-dependent, but subsequent postestablishment larval movement were density- dependent.
Abstract: The effect of egg density on establishment and dispersal of larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was evaluated in a 3-yr field study. Implications of these data for resistance management plans for Bt crops are discussed. Viable egg levels of 100, 200, 400, 800, and 1,600 eggs per infested plant were evaluated in 2000, 2001, and 2002. A 3,200 viable egg level was also tested in 2001 and 2002. All eggs were infested on one plant per subplot in a field that was planted to soybean, Glycine max (L.), in the previous year. For each subplot, the infested plant, three plants down the row, the closest plant in the adjacent row of the plot, and a control plant at least 1.5 m from any infested plant (six plants total) were sampled. In 2000, there were five sample dates between egg hatch and pupation, and in 2001 and 2002, there were six sample dates. On each sample date, four replications of each egg density were sampled for both larval recovery and plant damage. Initial establishment on a corn plant seemed to not be density-dependent because a similar percentage of larvae was recovered from all infestation rates. Plant damage and, secondarily, subsequent postestablishment larval movement were density-dependent. Very little damage and postestablishment movement occurred at lower infestation levels, but significant damage and movement occurred at higher infestation rates. Movement generally occurred at a similar time as significant plant damage and not at initial establishment, so timing of movement seemed to be motivated by available food resources rather than crowding. At the highest infestation level in 2001, significant movement three plants down the row and across the 0.76 m row was detected, perhaps impacting refuge strategies for transgenic corn.
72 citations
TL;DR: Even though there were records of ectoparasites throughout all the year, a higher intensity was observed during the spring months, most likely as a result of the increase in temperature after the winter months.
69 citations
62 citations
TL;DR: Household environmental characteristics in the town of Chalcatzingo, Morelos were analyzed for association with infestation by Triatoma pallidipennis, the predominant local vector and Junk piles and numbers of dogs, cats, and rabbits were significantly associated with peridomiciliary infestation.
Abstract: Control of Chagas disease requires control of its triatomine vectors, which requires an understanding of the determinants of infestation. Twenty-seven household environmental characteristics in the town of Chalcatzingo, Morelos, were analyzed for association with infestation by Triatoma pallidipennis, the predominant local vector. Data were obtained through timed household searches for triatomines and surveys that characterized intradomicile and peridomicile environments. Of the households surveyed, 28.4% were infested by T. pallidipennis. Cross-sectional multivariate logistic regression analyses were performed that regressed infestation on environmental variables. Of the 530 households in the town, 84% had sufficient data to be included. Adobe walls, agricultural products, junk piles, lack of bednets, and number of rabbits were significantly associated with intradomiciliary infestation. Junk piles and numbers of dogs, cats, and rabbits were significantly associated with peridomiciliary infestation. Junk piles, agricultural products, and numbers of cats, rabbits, and birds were significantly associated with overall infestation. Unexpectedly, presence of stone piles was not associated with infestation. The results of this study provide information for designing Chagas disease control programs in rural Mexican areas infested by T. pallidipennis.
58 citations
Journal Article•
TL;DR: In this article, the authors used Bactrocera oleae Gmel (Gmel) infestation to identify the presence or absence of the olive fruit fly in a given cultivar.
Abstract: Olives (Olea europaea L.) from cultivars Cobrancosa, Madural and Verdeal Transmontana were collected separately and divided into two different groups according to the presence or absence of infestation by the olive fruit fly (Bactrocera oleae Gmel.). These two groups were then mixed in varying percentages to create five groups of olives per cultivar with infestation levels: 0, 12.5, 25, 50 and 100%. Each group was then processed to produce olive oil. The results, regarding mainly acidity, peroxide value, and stability to oxidation, suggest that olive fruit fly infestation reduces the quality of the olive oil. The effects of infestation varied according to cultivar, but in general the total tocopherol content was always lower at the 100% infestation level. The oil from cultivar Verdeal Transmontana had the lowest tocopherol content compared to oil from cultivars Cobrancosa and Madural, which could explain the lower quality of its oil.
52 citations
TL;DR: It is suggested that seasonal changes in chigger abundance are a major factor influencing infestation intensities on S. undulatus and that mean infestation intensity of males declined during the summer in spite of persistently high chiggers.
Abstract: Eastern Fence Lizards (Sceloporus undulatus) in middle Tennessee are commonly parasitized by chiggers (Acari: Trombiculidae), but little is known about the ecological significance of this host-parasite system. Thus, I sampled S. undulatus and their habitats monthly to determine the seasonal pattern in chigger abundance and infestation intensity. Chigger abundance was low (mean = 1.8 chiggers) in the spring (April and May), eightfold higher throughout the summer, and declined sixfold in the fall (September and October). In general, infestation intensities on S. undulatus (males, females, and juveniles) followed the same pattern except that mean infestation intensity of males declined during the summer in spite of persistently high chigger abundance. The results of this study suggest that seasonal changes in chigger abundance are a major factor influencing infestation intensities on S. undulatus.
47 citations
TL;DR: The feasibility of using metabolic engineering of glandular trichomes to enhance natural product-based pest resistance is demonstrated and a significant negative correlation was found between high CBTols levels in trichome exudates and aphid infestation.
Abstract: Glandular trichomes of many plants secrete natural products that influence plant/insect interactions. For example, tobacco varieties having relatively high cembratrieneols (CBTols) are known to have enhanced aphid resistance in the field. CBTols and corresponding CBTdiols comprise 1.4 and 62%, respectively, of trichome exudate in the aphid susceptible tobacco variety, T.I. 1068. Using this cultivar we suppressed the CYP71D16 gene that encodes the enzyme that converts CBTols to CBTdiols. In suppressed plants CBTols and CBTdiols accounted for about 27 and 35% of exudate weight, respectively. Total CBTols plus CBTdiols was not changed substantially. Here we studied the relationship between aphid infestation and increased exudate CBTols in the field using self progeny derived from 5 independent primary transgenic T. I. 1068 plants having suppressed CYP71D16 activity. Two hundred individual plants were scored for aphid infestation, and their trichome exudate compositions were determined by gas chromatography. A significant negative correlation was found between high CBTols levels in trichome exudates and aphid infestation. No aphid infestation was observed on the majority of plants with CBTols/CBTdiols ratios of >1.49, which represents a >20-fold increase in CBTols, and a >40% decrease in CBTdiols over control T.I. 1068 exudate. In contrast, aphid infestation occurred on most plants with CBTols/CBTdiols ratios <0.201, which is similar to that of the untransformed control T.I. 1068. These results demonstrate the feasibility of using metabolic engineering of glandular trichomes to enhance natural product-based pest resistance.
45 citations
TL;DR: The sweet oranges were the most susceptible to Tephritoidea infestations in the state of Sao Paulo.
Abstract: From February 1998 to May 2000, fruits of different citrus varieties and hybrids were collected in order to assess the fruit fly infestation levels and tephritoid/parasitoid complex in the state of Sao Paulo. A total of 12,239 fruits (1,416.93 kg) was collected in 25 municipalities. From all the samples 5,252 puparia and 3,039 adults of Tephritoidea were recovered. About 78.1% of all adults collected were Tephritidae [77.1% de Anastrepha sp. and 1.0% de Ceratitis capitata (Wied.)] and 21.9% were Lonchaeidae (Neosilba spp.). All females of Anastrepha were identified as A. fraterculus (Wied.). Adults of Braconidae, Diapriidae and Eucoilinae emerged from the citrus samples. Mean infestation indices were 0.4 puparium/ fruit and 3.70 puparia/kg of fruits. Sweet oranges were the most susceptible to Tephritoidea infestations when the number of puparia/fruit was considered. In isolated samples, 'Cravo mandarin' (Citrus reticulata) and sour orange (Citrus aurantium) showed the highest infestation indices (3.4 and 2.4 puparia/fruit, respectively). Some samples of 'Kunquat'' (Fortunella sp.) and 'Cravo' mandarin reached high levels of infestation (64.0 and 37.9 puparia/kg of fruits, respectively). The sweet oranges were the most susceptible to Tephritoidea infestations in the state of Sao Paulo. The parasitoid Opiinae D. areolatus was the most abundant braconid species.
TL;DR: The results of this study demonstrate that the index of host body infestation by fleas can be used reliably as an indicator of the entire population size.
Abstract: . The use of measures of host infestation as a reliable indicator of a flea population size to be used in interspecific comparisons was considered. The abundance of fleas collected from host bodies and collected from host burrows was compared among 55 flea species, controlling for the effect of flea phylogeny. The mean number of fleas on host bodies correlated positively with the mean number of fleas in host burrows/nests both when the entire data pool was analysed and for separate subsets of data on ‘fur’ fleas and ‘nest’ fleas. This was also true for a within-host (Microtus californicus) between-flea comparison. The results of this study demonstrate that, in general, the index of host body infestation by fleas can be used reliably as an indicator of the entire population size.
TL;DR: Genotypic and environmental covariates explained approximately 75% of the GE interaction variation, but other genotypic covariates could be introduced in the model to reduce GE residual variation to a nonsignificant level.
Abstract: Yield under infestation by the pink stem borer [Sesamia nonagrioides (Lefebvre)] has been proposed as the best estimator of maize (Zea mays L.) performance under pink stem borer attack. Yield is a complex trait that greatly interacts with the environment. Several methods could be used to study the genotype x environment (GE) interaction. The objective of this work was to study the GE interaction for yield of 49 maize hybrids in five different environments by the Site Regression (SREG) and factorial regression methods. Locations presented different levels of natural infestation by the pink stem borer. The biplot obtained by applying the SREG method allowed visual cultivar evaluation. The factorial regression method incorporated genotypic and environmental covariates that enhanced biological interpretation of GE interaction. Hybrid A637 × EP42 would be recommended in northwestern Spain under medium and high natural infestation by the pink stem borer because it showed high and stable yielding ability. Genotypic and environmental covariates explained approximately 75% of the GE interaction variation, but other genotypic covariates could be introduced in the model to reduce GE residual variation to a nonsignificant level. In general, GE effects for grain yield were mainly due to earliness, vigor effects, and environmental yield limiting factors such as the mean of minimum temperature and percentage of air humidity.
Journal Article•
TL;DR: Six varieties of okra (Abelmoschus esculentus) namely Pusa Sawani, Sanjam, Varsha Uphar, Arka Anamika, PK-10 and Parbhani Kranti were evaluated for Tetranychus cinnabarinus infestation, finding that Sanjam was least susceptible to mite attack.
Abstract: Six varieties of okra (Abelmoschus esculentus) namely Pusa Sawani, Sanjam, Varsha Uphar, Arka Anamika, PK-10 and Parbhani Kranti were evaluated for Tetranychus cinnabarinus infestation. All the varieties were prone to mite attack. In summer crop, more number of mites were recorded as compared to winter crop. First peak in mite population was observed in the month of June and second in October. Leaf stage and abiotic factors also influenced the mite population on okra varieties. Pusa Sawani and Varsha Uphar harboured maximum number of mites in both the seasons whereas Sanjam was least susceptible to mite attack.
01 Jan 2004
TL;DR: It was observed that differentiation of insect species becomes easier asinfestation levels increase for difference spectra, and prediction performed well for high infestation levels but lower classification accuracies were obtained at low infestation Levels.
Abstract: Paliwal, J., Wang, W., Symons, S.J. and Karunakaran, C. 2004. Insect species and infestation level determination in stored wheat using near-infrared spectroscopy. Canadian Biosystems Engineering/Le genie des biosystemes au Canada 46: 7.17 7.24. Near-infrared spectroscopy (NIRS) technique was evaluated for detection of four different life stages (i.e. eggs, larvae, pupae, and adults) of Sitophilus oryzae (rice weevil) in artificially infested bulk samples of Canada Western Red Spring (CWRS) wheat at infestation levels from 0 through 50% at 5% infestation intervals. Sound wheat kernels were also infested with Rhyzopertha dominica (lesser grain borer) to create infestation levels of 0, 5, 10, 20, 25, 50, 75, and 100% and the spectral data from their pupae were compared to the pupal stage of rice weevil at corresponding levels of infestation. To distinguish wheat kernels infested with pupae of lesser grain borer from those infested with rice weevil, Principal Component Analysis (PCA) was employed and insect differentiation was done by examining score plots of spectral data. Original and difference spectra of infested wheat kernels and sound wheat kernels were tested. It was observed that differentiation of insect species becomes easier as infestation levels increase for difference spectra. Calibration models for quantitative determination of infestation levels were developed using Partial Least Square Regression (PLSR). Multiplicative Scatter Correction (MSC) and Standard Normal Variant (SNV) followed by detrending were found equally effective in removing irrelevant spectral information. Prediction performed well for high infestation levels but lower classification accuracies were obtained at low infestation levels.
TL;DR: Tolerance to silverleaf disorder does not prevent stunting in zucchini seedlings nor does it protect against the systemic loss of photosynthetic and protoprotectant pigments induced by feeding of B. argentifolii whiteflies.
Abstract: We investigated the effect of different levels of infestation by whiteflies, Bemisia argentifolii Bellows & Perring, on the growth and pigment concentrations of seedlings of zucchini, Cucurbita pepo L., that differed in their tolerance to squash silverleaf disorder. Genetically similar sister lines that were either tolerant (ZUC76-SLR) or susceptible (ZUC61) to silverleaf disorder exhibited reduced plant height, internode length, plant dry weight, and petiole length in response to whitefly feeding. Similar plant growth responses to whitefly feeding were observed despite that the foliage of ZUC61 silvered severely, whereas the foliage of ZUC76-SLR showed no silvering in a greenhouse experiment conducted in the spring and showed only minimal silvering in a similar greenhouse experiment conducted in the fall. In plants of both sister lines infested with 50 pairs of whiteflies and their progeny, petioles, but not the leaf blades, of uninfested leaves had reduced chlorophyll content. In another experiment, two different genetic sources of tolerance to silverleaf disorder (ZUC33-SLR/PMR and ZUC76-SLR) and a commercial silverleaf-susceptible zucchini hybrid ('Zucchini Elite') responded similarly to whitefly feeding, except the tolerant genotypes did not exhibit leaf silvering. All genotypes, silverleaf tolerant or not, had reduced dry weight, plant height, and internode length that became more pronounced as whitefly infestation increased. All genotypes had reduced levels of chlorophylls and carotenoids in uninfested young leaf blades and petioles from infested plants. Petioles, however, were more affected by feeding than leaf blades, showing a 66% reduction in chlorophylls a+b and carotenoids at the lowest infestation level (30 pairs of whitefly and their progeny), whereas pigments in leaf blades declined more slowly in response to whitefly feeding density, averaging 14-15% less at the highest infestation level (90 pairs of whitefly and their progeny). We conclude that tolerance to silverleaf disorder does not prevent stunting in zucchini seedlings nor does it protect against the systemic loss of photosynthetic and protoprotectant pigments induced by feeding of B. argentifolii whiteflies.
TL;DR: Tungiasis (jigger) is endemic in many impoverished communities in many parts of Brazil and the attack rate of Tunga penetrans infestation had already approached 100% by the end of the third week.
Abstract: Tungiasis (jigger) is endemic in many impoverished communities in many parts of Brazil. Forty-seven individuals entering an endemic area were followed up for a period of six weeks and regularly examined for the presence of newly embedded sand fleas. At the end of the third week, the attack rate of Tunga penetrans infestation had already approached 100%.
TL;DR: An oviposition preference gradient among the species, with different degrees of attractiveness; Acanthospermum hispidum was the most infested species whereas Amaranthus deflexus was the least infested one, which indicates a dilution effect on tomato infestation in the presence of weeds.
Abstract: Integrated Bemisia tabaci (Gennadius) management requires quantitative knowledge on the mechanisms of persistence of pest populations in non-commercial host plants. We investigated B. tabaci oviposition preference among tomato and four weed species, and the insect population fluctuation under field conditions in the semi-arid region. At weekly intervals, we determined the level (number of eggs and nymphs per leaf) and the density of infestation (number of eggs and nymphs per leaf area) in all species. We observed an oviposition preference gradient among the species, with different degrees of attractiveness; Acanthospermum hispidum was the most infested species whereas Amaranthus deflexus was the least infested one. We also detected a significantly higher infestation on tomato when planted solely, which indicates a dilution effect on tomato infestation in the presence of weeds. Weeds can act as important reservoirs for whiteflies and/or their natural enemies or even as viral sources for cultivated plants. Their incorporation in integrated B. tabaci management programs depends on how those variables can be manoeuvred for the reduction of insect damage.
TL;DR: Subsequent tree defoliation was significantly positively correlated with infestation at a phenotypic, genetic and environmental level and the cage experiment proved to be a good predictor of field oviposition.
Abstract: The southern eucalypt leaf beetle, Chrysophtharta agricola (Chapuis), is an outbreak insect pest of commercial Eucalyptus globulus Labill. plantations in south-eastern Australia. We surveyed a young E. globulus family trial in southern Tasmania to determine whether genetic variation existed in the susceptibility of trees to C. agricola field oviposition. The family trial consisted of 225 families, derived from open-pollinated seed collected from native stands at 24 different localities, representing nine geographic subraces. The survey showed that E. globulus subraces from Victoria were significantly more susceptible to C. agricola oviposition than Tasmanian subraces. Significant additive genetic variation within subraces was evident for the number of egg batches, larval clutches and their combination (infestation level), although these heritability scores were all low (egg batches h2op = 0.09; larval clutches h2op = 0.14 and infestation level h2op = 0.11). Subsequent tree defoliation was significantly positively correlated with infestation at a phenotypic, genetic and environmental level. No significant differences in C. agricola oviposition on foliage sprigs was detected among subraces in an ex situ caged oviposition experiment. However, the cage experiment proved to be a good predictor of field oviposition, accounting for 70 and 88% of variation in field oviposition among localities and subraces, respectively.
TL;DR: The ovipositional response, laraval orientation, larval settling, feeding, food assimilation, growth and development of maize stemborer ChUo partellus (Swinhoe) on a susceptible maize genotype was compared to five wild plant species of the family Poaceae (Gramineae) in the laboratory and greenhouse.
Abstract: The ovipositional response, larval orientation, larval settling, feeding, food assimilation, growth and development of maize stemborer ChUo partellus (Swinhoe) (Lepidoptera: Pyralidae) on a susceptible maize (Zea mays L.) genotype (Inbred A) was compared to five wild plant species of the family Poaceae (Gramineae) in the laboratory and greenhouse. The intensity of oviposition differed among the test plants. Pennisetum purpureum Schumach was the most preferred test plant for oviposition when offered in a two-choice situation with maize. Likewise, P. purpureum and Sorghum versicolor Anderss were the most preferred test plant for oviposition when offered in multiple-choice tests. In no-choice tests C. partellus responses to the test plants were not significantly different. The number of first instar larvae that settled on leaf cuts of test plants in Petri dishes was significantly higher on maize and S. versicolor than on the other test plants at 24 h after infestation in a multiple-choice test. No significant differences were observed in larval settling among wild grasses at 4 h and 24 h after infestation in a no-choice test. In a two- choice test there was no significant difference in the number of neonate larvae that settled on maize and S. versicolor at 1 h and 24 h after infestation. Feeding by fourth-instar larvae was significantly higher on maize than on Echinochloa pyramidalis (Lam.) and Hyparrhenia rufa (Nees) Stapf. Larvae fed on maize assimilated significantly more food than those fed on E. pyramidalis, Panicum maximum Jacq. or H. rufa. Larval growth and development was significantly faster on maize and S. versicolor in comparison to other test plants.
TL;DR: The results suggest that birds are important in the maintenance of the life cycle of A. tigrinum ticks in the area, and the number of ticks observed on Zenaida auriculata, C. californica and N. perdicaria living in non-irrigated areas as compared with irrigated areas is suggested.
Abstract: For the first time, larvae and nymphs of Amblyomma tigrinum ticks were found on three species of wild birds (Zenaida auriculata, Callipepla californica and Nothoprocta perdicaria) in Chile. A significant higher number of A. tigrinum was found on fledglings of Z. auriculata and N. perdicaria than on adults of these species of birds. A significant higher number was also observed on N. perdicaria living in non-irrigated areas as compared with irrigated areas. Infestation levels were 6.5, 6.3 and 10.2 ticks for Z. auriculata, C. californica and N. perdicaria, respectively. Our results suggest that birds are important in the maintenance of the life cycle of A. tigrinum ticks in the area.
TL;DR: Yield loss was found positively correlated with ‘dead heart’ and/or ‘white head’ infestations of vegetative, reproductive and mature phases of the crop.
Abstract: The extent of damage and yield loss due to six species of stemborers were studied on 9 (nine) rice varieties, in vegetative, reproductive and mature phases of the plant. The hybrid variety was found the most susceptible against all the borers, and local varieties were resistant. The percentage yield loss due to stemborer's infestation was found highest (27.09, 24.54, 25.32, 36.26, 17.74 and 22.19% by C. polychrysa (Meyrick), C. suppressalis (Walker), C. partellus (Swinhoe), S. incertulas (Walker), S. innotata (Walker) and S. inferens (Walker) respectively) on the variety, BR31 and lowest (11.17, 10.18, 10.54, 8.77, 8.10, and 7.07% by C. polychrysa, C. suppressalis, C. partellus, S. incertulas, S. innotata and S. inferens respectively) on the variety, Bansphul. Yield loss was found positively correlated with ‘dead heart’ and/or ‘white head’ infestations of vegetative, reproductive and mature phases of the crop.
TL;DR: Results from both field trials and greenhouse tests suggest the possible expression of tolerance as a mechanism of resistance to T. palmi in the resistant genotype EMP 486, and confirm the existence of antixenosis in FEB 115, whereas tolerance might be combined with other resistance mechanisms in Brunca.
Abstract: Tolerance as a mechanism of resistance to the melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae), in common beans, Phaseolus vulgaris L., was evaluated under field and greenhouse conditions. Seven resistant (Brunca, BH-5, BH-60, BH-130, BH-144, EMP 486, and FEB 115) and five susceptible (PVA 773, EMP 514, BAT 477, APN 18, and RAZ 136) bean genotypes were assessed according to adult and larval populations, visual damage and reproductive adaptation scores, and yield components in field trials. From these genotypes, four resistant (Brunca, BH-130, EMP 486, and FEB 115) and two susceptible (APN 18 and RAZ 136) genotypes were selected for quantification of proportional plant weight and height increase changes due to thrips infestation in greenhouse tests. Under medium to high thrips infestation in the field, most resistant genotypes tended to have higher reproductive adaptation and lower yield losses, though they did not always suffer less damage, as compared to susceptible genotypes. In the greenhouse, resistant genotypes showed less reduction in plant dry weight and height increase than did some susceptible ones under the same infestation pressure. Results from both field trials and greenhouse tests suggest the possible expression of tolerance as a mechanism of resistance to T. palmi in the resistant genotype EMP 486, and confirm the existence of antixenosis in FEB 115, whereas tolerance might be combined with other resistance mechanisms in Brunca.
TL;DR: A survey was carried out in Catalonia, Spain to determine the prevalence of parasitic helminths infesting the digestive tract of nocturnal raptors (Strigiformes), showing the highest levels of infestation were little owls (Athene noctua), 86.7% of which were infested.
Abstract: A survey was carried out in Catalonia, Spain to determine the prevalence of parasitic helminths infesting the digestive tract of nocturnal raptors (Strigiformes). One hundred birds belonging to six owl species were examined. The number of birds examined ranged between three and 30. The overall level of infestation was 65% and the most frequent helminths present were nematodes, followed by trematodes, cestodes and acanthocephalans. Strigiformes showing the highest levels of infestation were little owls (Athene noctua), 86.7% of which were infested. Helminths with the highest prevalence were Synhimantus spp., intestinal capillarids, Brachylaima spp., cestodes and Centrorhynchus aluconis.
TL;DR: There was a significant positive correlation between infestation level and the amounts of djenkolic acid in the seeds, indicating that the beetles may have found a means of utilizing djenKolic acid for their own benefit.
Abstract: Acacia trees in the Negev desert and the Arava valley of Israel are suffering high levels of mortality due to water stress. Additionally, recruitment is negatively affected by bruchid beetles. We hypothesized that water-stressed trees would be less able to produce secondary defense compounds, such as the nonprotein amino acids, pipecolic acid and djenkolic acid, in their seeds to decrease seed herbivory. We further hypothesized that the high seed infestation reported is due to increased fitness of beetles infesting trees that are in a poor physiological state. Contrary to our prediction, pipecolic acid concentration was higher in water-stressed Acacia raddiana trees. We found that infestation rates and beetle fitness were higher in trees in a poor physiological state, despite the higher levels of pipecolic acid in these trees. There was a significant positive correlation between infestation level and the amounts of djenkolic acid in the seeds, indicating that the beetles may have found a means of utilizing djenkolic acid for their own benefit.
TL;DR: Differences in susceptibility of Brassicaceae species to the cabbage seedpod weevil were relatively consistent in both field and laboratory studies and may have important implications for total yield loss, particularly in areas where opportunistic pests utilize weevil exit holes to gain access to seeds.
Abstract: Various genotypes of seven species of Brassicaceae (Brassica rapa L., B. napus L., B. juncea (L.) Czern., B. nigra (L.) Koch, B. tournefortii Gouan, Sinapis alba L., Crambe abyssinica Hochst. ex R.E. Fries, and B. napus × S. alba) were evaluated for susceptibility to infestation by the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham). In the field, weevils were counted by excising and dissecting pod samples weekly for the presence of eggs, larvae, and larval exit holes. In the laboratory, excised pods from potted plants were exposed to gravid female weevils for 24 or 48 h and then the numbers of eggs and (or) feeding punctures were assessed. Differences in susceptibility of Brassicaceae species to the cabbage seedpod weevil were relatively consistent in both field and laboratory studies. Brassica rapa was the most susceptible. Intermediate susceptibility was observed for B. napus, B. napus × S. alba, B. tournefortii, and B. juncea, although the last species displayed some antixenotic resistance. Sinapis alba, B. nigra, and C. abyssinica were least susceptible. Pods of some species more frequently contained single, rather than multiple, larvae and this may have important implications for total yield loss, particularly in areas where opportunistic pests utilize weevil exit holes to gain access to seeds. New-generation adults fed on all Brassicaceae, and therefore all species may be susceptible to some yield loss. Canola growers in regions infested with C. obstrictus at high population densities can reduce losses by seeding S. alba, B. juncea, or a less susceptible genotype of B. napus.
TL;DR: In this article, after infestation of naive sheep with Psoroptes ovis mites, significant influxes of eosinophils and neutrophils were detected within 24 hours of infestation and a significant increase in mast cell numbers was observed by 96 h post-infestation.
TL;DR: The greatest increase in total intensity levels coincided with the onset of spring, and a possible seasonal component to the reproduction of this sabellid is discussed.