Higher Fertilizer Inputs Increase Fitness Traits of Brown Planthopper in Rice.

Rice (Oryza sativa L.) is the primary staple food source for more than half of the world's population. In many developing countries, increased use of fertilizers is a response to increase demand for rice. In this study, we investigated the effects of three principal fertilizer components (nitrogen, phosphorus and potassium) on the development of potted rice plants and their effects on fitness traits of the brown planthopper (BPH) [Nilaparvata lugens (Stål) (Homoptera: Delphacidae)], which is a major pest of rice in Bangladesh and elsewhere. Compared to low fertilizer inputs, high fertilizer treatments induced plant growth but also favored BPH development. The BPH had higher survival, developed faster, and the intrinsic rate of natural increase (r m ) was higher on well-fertilized than under-fertilized plants. Among the fertilizer inputs, nitrogen had the strongest effect on the fitness traits of BPH. Furthermore, both the "Plant vigor hypothesis" and the "Plant stress hypothesis" were supported by the results, the former hypothesis more so than the latter. These hypotheses suggest that the most suitable/attractive hosts for insect herbivores are the most vigorous plants. Our findings emphasized that an exclusive focus on yield increases through only enhanced crop fertilization may have unforeseen, indirect, effects on crop susceptibility to pests, such as BPH

Aging blow fly pupae using hyperspectral imaging

See attache

Sensitivity of Prostephanus truncatus (Horn) (Coleoptera:Bostrichidae) flight activity to environmental variables in Benin, West Africa

Published online: 01 Dec 2001Based on pheromone trap catches, a model of weekly Prostephanus truncatus (Horn) flight activity was generated for southern Benin. Using response surface regression, the following environmental variables were examined: number of rainy days per week, precipitation, minimum and maximum temperatures, minimum relative air humidity, and daylength. A time-variable, year, was included to account for the variance between years. From step-wise exclusion of variables with the lowest contribution to the model fit, a model was generated which included three environmental variables (daylength, minimum relative air humidity, and minimum temperature) that explained 55% of the total variance, and the yearly variable explaining 8%. The response surface regression analysis of P. truncatus flight activity revealed the following: (1) it was positively correlated with daylength when daily minimum temperature and relative air humidity were low, (2) it was positively associated with minimum relative air humidity when lower than 75%, (3) it was negatively associated with minimum temperature, (4) unexplained yearly variation was important for the predictive strength of the model, (5) interactions of environmental variables contributed substantially to the model fit, and (6) precipitation, both as mm rain and as number of rainy days, had little influence on P. truncatus flight activity. Independent data showed that the model predicted P. truncatus flight activity well elsewhere in southern Benin, whereas in central Benin new coefficients for the same environmental variables were needed to produce an adequate prediction. The model did not fit pheromone baited trap catches from northern Benin

The effect of exposure to synthetic pheromone lures on male Zygaena filipendulae mating behaviour: implications for monitoring species of conservation interest

Pheromone based monitoring of insects of conservation value has the potential to revolutionise the way in which surveys are carried out. However, due to their effective use in pest management, concerns have been raised about potential negative effects of pheromone exposure on populations of rare insects. The effect of exposure to synthetic pheromone lures on male mating behaviour was examined in laboratory and field conditions using the six spot burnet moth Zygaena filipendulae (Linnaeus, 1758). For the laboratory experiment larvae were collected and cultured separately under controlled conditions. Virgin males were exposed to a synthetic pheromone lure for 24 h; then tested for responsiveness immediately after this exposure, 1 and 24 h later. Control males were tested three times: initially, 1 h later and 24 h later. The time taken for males to detect females, shown by exposure of their anal claspers, and the time taken for males to locate females were recorded. No significant difference was found between the time taken for control and exposed males to detect or locate females, and no significant difference between the proportions of males that successfully located females in exposed and control groups was found. In the field experiment the time males spent in the presence of contained females, both with and without a pheromone lure present, was recorded. Males spent more time in the presence of the females when the pheromone lure was present. Both experiments indicate male Z. filipendulae mating behaviour is not adversely affected by exposure to synthetic pheromone lures

Optimizing pesticide spray coverage using a novel web and smartphone tool, SnapCard

International audienceThe overuse of pesticides leads to contamination of water and food. Therefore, there is a need for tools and strategies to optimize pesticide application. Here we present SnapCard, a user-friendly and freely available decision support tool for farmers and agricultural consultants, available at snapcard.agric.wa.gov.au. SnapCard allows to predict, measure, and archive pesticide spray coverage quantified from water-sensitive spray cards. Variables include spray settings such as nozzle orifice size, sprayer speed, water carrier rate and adjuvant, and weather variables such as barometric pressure, relative humidity, temperature, and wind speed at ground level. We use separate regression models for four nozzles types. Our results showed that there are strong and positive correlations between water carrier rate and spray coverage for all four nozzle types. Moreover, sprayer speed is highly negatively correlated with obtained spray coverage. In addition, there is no consistent effect of either nozzle type or use of a particular adjuvant, across water carrier intervals. We conclude that varying combinations of spray settings and weather conditions caused marked ranges of spray coverages among the four nozzle types, thus highlighting the importance of selecting the right nozzle orifice size and type. We demonstrate that realistic scenarios of environmental conditions and spray settings can lead to predictions of very low spray coverage with at least one of the four nozzle types. We discuss how the novel and freely available smartphone app, SnapCard, can be used to optimize spray coverage, reduce spray drift, and minimize the risk of resistance development in target pest populations

High susceptibility to lipopolysaccharide-induced lethal shock in encephalomyocarditis virus-infected mice

Secondary bacterial infection in humans is one of the pathological conditions requiring clinical attention. In this study, we examined the effect of lipopolysaccharide (LPS) on encephalomyocarditis virus (EMCV) infected mice. All mice inoculated with EMCV at 5 days before LPS challenge died within 24 h. LPS-induced TNF-α mRNA expression was significantly increased in the brain and heart at 5 days after EMCV infection. CD11b+/TLR4+ cell population in the heart was remarkably elevated at 5 days after EMCV infection, and sorted CD11b+ cells at 5 days after EMCV infection produced a large amount of TNF-α on LPS stimulation in vivo and in vitro. In conclusion, we found that the infiltration of CD11b+ cells into infected organs is involved in the subsequent LPS-induced lethal shock in viral encephalomyocarditis. This new experimental model can help define the mechanism by which secondary bacterial infection causes a lethal shock in viral encephalomyocarditis

The Search Behavior of Omnivorous Thrips Larvae is Influenced by Spider Mite Cues

The western flower thrips is an omnivorous insect that consumes both leaf tissue and spider mite eggs. For this reason, these thrips are often described as ‘opportunistic predators’ of spider mites. Several studies have shown that western flower thrips are often found in association with spider mites, and the development time of thrips decreases and their survivorship increases when they consume spider mite eggs. We tested the hypothesis that thrips larvae may respond to chemical cues from spider mites, and that they may modify their prey-searching behavior when these spider mite-induced cues are present. We prepared hexane extracts from: 1) webbing of spider mites isolated from maize leaves, 2) webbing produced by spider mites inside an empty glass tube to exclude any plant-derived cues from the extract, and 3) spider mite cuticle extracts. These three extracts were subsequently applied in droplets to one-half of filter papers, and hexane alone was applied in droplets to the other half. We showed that residence time of thrips larvae was higher on filter paper with spider mite webbing extract, especially when the extract originated from spider mites isolated in glass tubes. In the presence of webbing extracts, we also observed: 1) a decrease in velocity, 2) an increase of angular velocity and 3) an increase in time immobile. Extracts from spider mite cuticle only increased velocity and proportion of time immobile of the thrips larvae. Our results suggest that chemical cues from spider mite webbing induce an arrestment response and play an important role in the non-random search behavior of thrips larvae searching for eggs on spider mite infested plant leaves