Evaluation of lure dispensers for fruit fly surveillance in New Zealand

BACKGROUND: Fruit flies (Diptera: Tephritidae) represent a major biosecurity threat to the horticulture sector of New Zealand, which is entirely free of these invasive pests. A nationwide surveillance programme is conducted to ensure any incursion is detected as early as possible. A review of the lure dispensers used is reported here. RESULTS: Lure dispenser emission trials found that the currently used lure plugs release lure more slowly under New Zealand subtropical to temperate climates than wafer dispensers. Subsequent trapping experiments at high altitude in Hawaii (as a mimic of New Zealand meteorological and expected fruit fly ecological conditions) compared Lynfield traps baited with the existing lure plug dispensers and newer wafer dispensers. Catches of wild Oriental fruit flies, Bactrocera dorsalis (Hendel), were 9.5-fold higher with methyl eugenol wafers than with the plugs. Recaptures of sterile melon flies, Bactrocera cucurbitae (Coquillet), were 2.6-fold higher with cuelure wafers than with the plugs. Recaptures of sterile Mediterranean fruit flies, Ceratitis capitata Weid., were not significantly higher with trimedlure wafers than with the plugs.CONCLUSIONS: Release rate and trapping experiments found new lure dispensers differed in release rate characteristics from existing dispensers under temperate and subtropical conditions, and indicated some potential for improvement in surveillance efficacy.     

The household economics of rubber intercropping during the immature period in Northeast Thailand

In order to alleviate poverty in Northeast Thailand, the Thai government has promoted rubber farming, which has expanded at the expense of annual crops. Because of a long immature period, planting rubber represents a loss of income for poor farmers in the very first years. This paper analyzed how rubber intercropping during the immature period helps farmers to compensate for this loss of income. Economic performances of the most widespread rubber farming systems were analyzed using information collected from a questionnaire addressed to 35 farmers in Buriram province. A sub-sample of 22 farmers was further interviewed to estimate the contribution of rubber intercropping in the formation of the total annual income during the immature period. The results showed that interest in rubber intercropping has grown, with cassava and rice as the main associated crops. With additional costs of about 14,169 ?/ha/year over monospecific rubber plantations, rubber-cassava intercropping systems generated a gross margin estimated at 11,340 ?/ha/year for a 3-year period. Compared to a monospecific rubber plantation, rubber-cassava intercropping systems reduced management costs by 59% over the 6-year period of rubber immaturity. The cash-income drawn from intercropping ranged from 0 to 26.8% of the household’s total annual income, which can be of considerable importance for low-income farmers.     

An inconvenient truth about xylem resistance to embolism in the model species for refilling <Emphasis Type="Italic">Laurus nobilis</Emphasis> L.

Key message

Direct, non-invasive X-ray microtomography and optical technique observations applied in stems and leaves of intact seedlings revealed that laurel is highly resistant to drought-induced xylem embolism. Contrary to what has been brought forward, daily cycles of embolism formation and refilling are unlikely to occur in this species and to explain how it copes with drought.

Context

There has been considerable controversy regarding xylem embolism resistance for long-vesselled angiosperm species and particularly for the model species for refilling (Laurus nobilis L.).

Aims

The purpose of this study was to resolve the hydraulic properties of this species by documenting vulnerability curves of different organs in intact plants.

Methods

Here, we applied a direct, non-invasive method to visualize xylem embolism in stems and leaves of intact laurel seedlings up to 2-m tall using X-ray microtomography (microCT) observations and the optical vulnerability technique. These approaches were coupled with complementary centrifugation measurements performed on 1-m long branches sampled from adult trees and compared with additional microCT analyses carried out on 80-cm cut branches.

Results

Direct observations of embolism spread during desiccation of intact laurels revealed that 50% loss of xylem conductivity (Ψ₅₀) was reached at ??7.9?±?0.5 and ??8.4?±?0.3 MPa in stems and leaves, respectively, while the minimum xylem water potentials measured in the field were ??4.2 MPa during a moderate drought season. Those findings reveal that embolism formation is not routine in Laurus nobilis contrary to what has been previously reported. These Ψ₅₀ values were close to those based on the flow-centrifuge technique (??9.2?±?0.2 MPa), but at odds with microCT observations of cut branches (??4.0?±?0.5 MPa).

Conclusion

In summary, independent methods converge toward the same conclusion that laurel is highly resistant to xylem embolism regardless its development stage. Under typical growth conditions without extreme drought events, this species maintains positive hydraulic safety margin, while daily cycles of embolism formation and refilling are unlikely to occur in this species.

     

Crop loss and control of Pseudocercospora fruit and leaf spot of citrus in Ghana

Pseudocercospora fruit and leaf spot (PFLS) of citrus, caused by Pseudocercospora angolensis, was recently described in Ghana and has spread in most citrus-growing areas of the country. A survey of PFLS incidence was conducted in the Eastern Region. Orchards were georeferenced and data on altitude, annual mean temperature, and annual precipitation were obtained from the WorldClim database. Fruit drop due to PFLS and other pests and diseases was evaluated in three orchards. Field efficacies of 4-week, 6-week and 8-week schedules with carbendazim + mancozeb were evaluated in the major and minor fruit production seasons. Ordinal logistic regression and generalized linear models were fitted in each case according to the nature of the data and possible overdispersion. Disease incidence in the sweet orange orchards surveyed was 25–100 %, with higher values in higher altitude areas exposed to lower temperatures and higher rainfall. PFLS was the main problem causing yield losses, associated with 84–87 % of fruit dropped on the orchard floor. PFLS severity on shoots and incidence on fruit 12 weeks after full bloom was significantly reduced by all fungicide schedules evaluated. The effects of fungicides on PFLS severity in fruit at harvest were not substantial because of intense fruit drop. The 8-week schedule showed the lowest effectiveness in reducing fruit drop and thus the 6-week schedule is preferred. Further research is needed for an integrated management of PFLS in Ghana.     

Multi-scale Modeling of Animal Movement and General Behavior Data Using Hidden Markov Models with Hierarchical Structures

Hidden Markov models (HMMs) are commonly used to model animal movement data and infer aspects of animal behavior. An HMM assumes that each data point from a time series of observations stems from one of N possible states. The states are loosely connected to behavioral modes that manifest themselves at the temporal resolution at which observations are made. Due to advances in tag technology and tracking with digital video recordings, data can be collected at increasingly fine temporal resolutions. Yet, inferences at time scales cruder than those at which data are collected and, which correspond to larger-scale behavioral processes, are not yet answered via HMMs. We include additional hierarchical structures to the basic HMM framework, incorporating multiple Markov chains at various time scales. The hierarchically structured HMMs allow for behavioral inferences at multiple time scales and can also serve as a means to avoid coarsening data. Our proposed framework is one of the first that models animal behavior simultaneously at multiple time scales, opening new possibilities in the area of animal movement and behavior modeling. We illustrate the application of hierarchically structured HMMs in two real-data examples: (i) vertical movements of harbor porpoises observed in the field, and (ii) garter snake movement data collected as part of an experimental design. Supplementary materials accompanying this paper appear online.     

The effect of quality bucking and automatic bucking on harvesting productivity and product recovery in a pine-dominated stand

On-board computers (OBC) of harvesting machines can now provide optimized bucking (task of cutting stems into different log lengths) by relying on value and demand matrices. Despite existing benefits of these systems in certain countries, they remain largely underutilized and generally poorly understood in German mechanized forest operations. The study aimed to compare and quantify the differences in harvesting productivity and value recovery between two treatments: quality bucking (OFF) and automatic bucking (ON). A mature forest stand with a high proportion of Scots pine (Pinus sylvestris L.) was divided into plots (30 m × 100 m) where initial tests of both treatments were randomly distributed and replicated 10 times for a total of 11 plots per treatment. Pre-harvest inventory was performed on each tree targeted for removal via a commercial thinning silvicultural treatment. Mechanized harvesting was performed with an excavator-based Atlas Kern T23 Königstiger single-grip harvester. The same assortment specifications and prices were used for both treatments but on-board optimized bucking solutions were applied in the ON plots, whereas the operator had full control of the products to be recovered in the OFF plots. During harvesting operations, continuous time and motion was performed in all plots. Average harvesting productivity was higher—but not statistically significant—in OFF plots compared to ON plots by 2.0 and 0.46 m³/PMH₀ for pine and spruce trees, respectively. Even if there was no difference detected in volume recovery for both treatments and tree species, value recovery was more than 1.60 € per cubic meter higher for pine in larger diameter classes when using quality bucking. This may be due to the fact that the algorithm of the OBC is designed for pine trees with a simpler crown architecture than trees harvested in this study. Results supporting quality bucking over automatic bucking in a Scots pine-dominated stands provide important forest operational information to managers.

     

Integrating functional diversity into tropical forest plantation designs to study ecosystem processes

? The elucidation of relationships between biodiversity and ecosystem processes has been limited by the definition of metrics of biodiversity and their integration into experimental design. Functional trait screening can strengthen the performance of these designs.

? We suggest the use of Rao’s quadratic entropy to measure both functional diversity and phylogenetic diversity of species mixtures proposed for an experimental design, and demonstrate how they can provide complementary information.

? We also present an index assessing the statistical performance of these independent variables in different experimental designs. Measurement of independent variables as continuous vs. discrete variables reduces statistical performance, but improves the model by quantifying species differences masked by group assignments.

? To illustrate these advances, we present an example from a tropical forest tree community in which we screened 38 species for nine functional traits. The proposed TropiDEP design is based on the relative orthogonality of two multivariate trait axes defined using principal component analysis.

? We propose that independent variables describing functional diversity might be grouped to calculate independent variables describing suites of different traits with potentially different effects on particular ecosystem processes. In other systems these axes may differ from those reported here, yet the methods of analysis integrating functional and phylogenetic diversity into experimental design could be universal.

     

Hyperglycaemia but not hyperlipidaemia decreases serum amylase and increases neutrophils in the exocrine pancreas of cats

The goal of the study was to determine whether hyperglycaemia or hyperlipidaemia causes pancreatitis in cats and to assess the effect of excess serum glucose and lipids on amylase and lipase activity. Ten-day hyperglycaemic and hyperlipidaemic clamps were carried out in five and six healthy cats, respectively. Ten healthy cats received saline and served as controls. The activity of amylase was below the normal range in 4 of 5 hyperglycaemic cats by day 10. The activity of lipase did not vary in any of the cats. Samples of exocrine pancreas were normal on histological examination, but the number of tissue neutrophils was increased in hyperglycaemic cats (P < 0.05). In a retrospective study 14 of 40 (35%) cats with naturally occurring diabetes mellitus had amylase activities below the reference range at the time of admission. Amylase activities normalised within 1 week of insulin therapy and subsequent glycaemic control. Lipase activity was increased in 26 of 40 (65%) diabetic cats and remained elevated despite glycaemic control. In conclusion, hyperglycaemia, but not hyperlipidaemia, increases pancreatic neutrophils in cats. However, because the histological morphology of the exocrine pancreas was normal, hyperglycaemia may play only a minor role in the pathogenesis of pancreatitis. Low amylase activities in diabetic cats may reflect an imbalance in glucose metabolism rather than pancreatitis.     

Signatures of adaptation to obligate biotrophy in the Hyaloperonospora arabidopsidis genome

Many oomycete and fungal plant pathogens are obligate biotrophs, which extract nutrients only from living plant tissue and cannot grow apart from their hosts. Although these pathogens cause substantial crop losses, little is known about the molecular basis or evolution of obligate biotrophy. Here, we report the genome sequence of the oomycete Hyaloperonospora arabidopsidis (Hpa), an obligate biotroph and natural pathogen of Arabidopsis thaliana. In comparison with genomes of related, hemibiotrophic Phytophthora species, the Hpa genome exhibits dramatic reductions in genes encoding (i) RXLR effectors and other secreted pathogenicity proteins, (ii) enzymes for assimilation of inorganic nitrogen and sulfur, and (iii) proteins associated with zoospore formation and motility. These attributes comprise a genomic signature of evolution toward obligate biotrophy.