Field distribution patterns of pests are asymmetrically affected by the presence of other herbivores

Because plant phenotypes can change in response to attacks by herbivores in highly variable ways, the distribution of herbivores depends on the occurrence of other herbivore species on the same plant. We carried out a field study to evaluate the co-occurrence of three coconut pests, the mites Aceria guerreronis (Acari: Eriophyidae), Steneotarsonemus concavuscutum (Acari: Tarsonemidae) and the moth Atheloca bondari (Lepidoptera: Pyralidae). The eriophyid mite Ac. guerreronis is the most important coconut pest around the world, whereas S. concavuscutum and At. bondari are economically important only in some areas along the Brazilian coast. A previous study suggested that the necrosis caused by Ac. guerreronis facilitates the infestation of At. bondari larvae. Because all three species infest the area under the perianths on coconuts and S. concavuscutum also causes necrosis that could facilitate At. bondari, we evaluated the co-occurrence of all three species. We found that the occurrence of At. bondari was positively associated with Ac. guerreronis, but negatively associated with S. concavuscutum. In addition, the two mite species showed negative co-occurrence. Atheloca bondari was found on nuts of all ages, but more on nuts that had fallen than on those on the trees, suggesting that nuts infested by At. bondari tend to fall more frequently. We discuss the status of At. bondari as a pest and discuss experiments to test the causes of these co-occurrence patterns.

Effects of Acaricides on the Functional and Numerical Responses of the Phytoseid Predator Neoseiulus idaeus (Acari: Phytoseiidae) to Spider Mite Eggs

Integrated control tactics are often necessary for pest management. This is especially true for organisms such as the two-spotted spider mite, Tetranychus urticae Koch. The management of this mite pest species relies on pesticide use, but its short life cycle associated with high selection pressure results in frequent problems of acaricide resistance and population outbreaks. Therefore, combining acaricides and natural enemies is an appealing strategy for managing this pest species. The predatory mite Neoseiulus idaeus Denmark & Muma (Phytoseiidae) is important in arid environments, where other natural enemies show low efficacy. Thus, we investigated the effects of representative acaricides used for managing spider mites around the world in several crops (i.e., abamectin, fenpyroximate, and azadirachtin), on the functional and numerical responses of the phytoseid predator N. idaeus to increasing egg densities of its prey. Acaricide exposure did not affect the type of N. idaeus functional response or attack rate (a). However, acaricide exposure decreased the amount of consumed prey and increased prey handling time (Th). All acaricides affected the numerical response of the predator, which reduced oviposition rates. Therefore, caution is required in attempts to integrate the control methods.

Bothrops alternatus Snake Venom Induces Cytokine Expression and Oxidative Stress on Renal Function

BACKGROUND

Envenomation caused by Bothrops alternatus is common in Southern Brazil. Acute Kidney Injury occurs after Bothrops snakebite and more information is necessaryrequired to understand its mechanism.

OBJECTIVE

The objective was to evaluate the effect of Bothrops alternatus venom (BaV) on renal cells and rat isolated kidney function.

METHODS

Wistar rats (n = 6, weighing 260-320 g) were perfused with a Krebs-Henseleit solution containing 6 g 100 mL-1 of bovine serum albumin. After 30 minutes, the kidneys were perfused with BaV to a final concentration of 1 and 3 μgmL-1; and subsequently were evaluated for Perfusion Pressure (PP), Renal Vascular Resistance (RVR), Urinary Flow (UF), Glomerular Filtration Rate (GFR), and percentage of electrolyte tubular transport. Renal histological analysis, cytokine release, oxidative stress and cytotoxicity in renal proximal tubular cells were assessed.

RESULTS

BaV reduced PP, RVR, GFR, UF, total and proximal sodium transport (%TNa+), and chloride (%TCl-) in the isolated kidney perfusion model. Histological analysis of perfused kidneys disclosed the presence of proteinaceous material in the glomeruli and renal tubules, vacuolar tubular epithelial cell degeneration, Bowman's capsule degeneration, swelling of glomerular epithelial cells, glomerular atrophy and degeneration, and the presence of intratubular protein. Cytokine release (TNF-α, IL-1β, IL-10) and oxidative stress were increased in the kidneys. The viability of LLC-MK2 cells (IC50: 221.3 μg/mL) was decreased by BaV and necrosis was involved in cell death.

CONCLUSION

These findings indicate that BaV modifies functional parameters in an isolated perfused kidney model and has cytotoxic effects on renal lineage cells.

Fertility Life Table of Tetranychus palmarum Flechtmann & Noronha (Acari: Tetranychidae) in Oil Palm

Some species of spider mites belonging to the Tetranychidae family are known to associate with oil palm (Elaeis guineensis Jacq. - Arecaceae). The occurrence of Tetranychus palmarum Flechtmann & Noronha (Acari, Tetranychidae) was verified on oil palm seedlings under greenhouse conditions in the State of Pará in Northern Brazil. Plants with colonies of T. palmarum presented yellowish spots on leaflets and leaves with chlorosis. The objective of this study was to access the biology and fertility life table of T. palmarum in E. guineensis leaves. The experiment was conducted under four constant temperatures, 22, 25, 28, and 31°C, at 70 ± 10% RH under a 12:12 LD photoperiod. The duration of the egg-to-adult period was 18.4 and 9.8 days, at 22 and 31°C, respectively. The parameters of the fertility life table showed that 28°C is most suitable for the development and reproduction of T. palmarum, with higher values for reproductive parameters (R _o , r _m , and λ) and lower values for duplicating the population (TD). Therefore, it is apparent that the best temperature conditions for the development of T. palmarum are found in the warmer regions of Brazil, such as those observed in northern Brazil.

Predator performance is impaired by the presence of a second prey species

The simultaneous infestation of a plant by several species of herbivores may affect the attractiveness of plants to the natural enemies of one of the herbivores. We studied the effect of coconut fruits infested by the pests Aceria guerreronis and Steneotarsonemus concavuscutum, which are generally found together under the coconut perianth. The predatory mite Neoseiulus baraki produced lower numbers of offspring on fruits infested with S. concavuscutum and on fruits infested with both prey than on fruits with A. guerreronis only. The predators were attracted by odours emanating from coconuts with A. guerreronis, but not by odours from coconuts with S. concavuscutum, even when A. guerreronis were present on the same fruit. Fewer N. baraki were recaptured on fruits with both prey or with S. concavuscutum than on fruits with only A. guerreronis. Furthermore, the quality of A. guerreronis from singly and multiply infested coconuts as food for N. baraki did not differ. Concluding, our results suggest that N. baraki does not perform well when S. concavuscutum is present on the coconuts, and the control of A. guerreronis by N. baraki may be negatively affected by the presence of S. concavuscutum.

Evidence of Amblyseius largoensis and Euseius alatus as biological control agent of Aceria guerreronis

Amblyseius largoensis (Muma) (Acari: Phytoseiidae) and Euseius alatus De Leon (Acari: Phytoseiidae) are predatory mites that are mostly found on leaves and on the exposed fruit surface of coconut plants. Their morphology hampers the access to the microhabitat occupied by Aceria guerreronis Keifer (Acari: Eriophyidae), the most important pest of coconut fruits throughout the world. However, it was suggested that they can prey on A. guerreronis under natural conditions when this pest leaves its refuge to disperse. Since the trophic interactions between A. largoensis or E. alatus and A. guerreronis are unknown, we compare the frequencies of occurrence of A. largoensis and E. alatus under the bracts of coconut fruits and on coconut leaflets. In addition, because phytoseiids feed by liquid ingestion, we used molecular analysis to confirm the potential role of A. largoensis or E. alatus as predators of A. guerreronis and to assess how fast the A. guerreronis DNA fragment is degradated in the A. largoensis digestive tract. Our study demonstrated that E. alatus was only present on coconut leaflets whereas A. largoensis was found mostly on leaflets and, to a much lesser extent, under the bracts of coconuts. Species-specific ITS primers designed for A. guerreronis were shown to have a high degree of specificity for A. guerreronis DNA and did not produce any PCR product from DNA templates of the other insects and mites associated with the coconut agroecosystem. Based on molecular analysis, we confirmed that the predatory mites, A. largoensis and E. alatus, had preyed on the coconut mite in the field. Overall the predatory mites collected in the field exhibited low levels of predation (26.7% of A. largoensis and 8.9% of E. alatus tested positive for A. guerreronis DNA). The fragment of A. guerreronis DNA remained intact for a very short time (no more than 6 h after feeding) in the digestive tract of A. largoensis.

Acaricide-impaired functional predation response of the phytoseiid mite Neoseiulus baraki to the coconut mite Aceria guerreronis

Acaricides may interfere with a myriad of interactions among arthropods, particularly predator-prey interactions. The coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), and its phytoseiid predator, Neoseiulus baraki (Athias-Henriot) (Acari: Phytoseiidae), provide an opportunity to explore such interference because the former is a key coconut pest species that requires both predation and acaricide application for its management. The objective of the present study was to assess the effect of the acaricides abamectin, azadirachtin and fenpyroximate on the functional response of N. baraki to A. guerreronis densities. The following prey densities were tested: 5, 10, 20, 40 and 80 preys. The type of functional response and prey handling time (Th) were not altered by the acaricides. However, the attack rate (a') was modified by abamectin and fenpyroximate, and the consumption peak was reduced by abamectin. All of the acaricides allowed for the maintenance of the predator in the field, but exposure to abamectin and fenpyroximate compromised prey consumption.

Host finding behaviour of the coconut mite Aceria guerreronis

For the coconut mite, Aceria guerreronis Keifer, its host plant, the coconut palm, is not merely a source of food, but more generally a habitat to live in for several generations. For these minute organisms, finding a new plant is difficult and risky, especially because their main mode of dispersal is passive drifting with the wind and because they are highly specialized on their host plant. Consequently, the probability of landing on a suitable host is very low, let alone to land in their specific microhabitat within the host. How coconut mites manage to find their microhabitat within a host plant is still underexplored. We tested the hypothesis that they use volatile chemical information emanating from the plant to find a specific site within their host plants and/or use non-volatile plant chemicals to stay at a profitable site on the plant. This was investigated in a Y-tube olfactometer (i.e. under conditions of a directed wind flow) and on cross-shaped arenas (i.e. under conditions of turbulent air) that either allowed contact with odour sources or not. The mites had to choose between odours from specific parts (leaflet, spikelet or fruit) of a non-infested coconut plant and clean air as the alternative. In the olfactometer experiments, no mites were found to reach the upwind end of the Y-tube: <5 % of the mites were able to pass the bifurcation of the "Y". On the cross-shaped arenas, however, a large number of coconut mites was found only when the arm of the arena contained discs of fruit epidermis and contact with these discs was allowed. The results suggest that coconut mites on palm trees are not attracted to specific sites on the plant by volatile plant chemicals, but that they arrested once they contact the substrate of specific sites. Possibly, they perceive non-volatile chemicals, but these remain to be identified.

Behaviour of coconut mites preceding take-off to passive aerial dispersal

For more than three decades the coconut mite Aceria guerreronis Keifer is one of the most important pests of coconut palms and has recently spread to many coconut production areas worldwide. Colonization of coconut palms is thought to arise from mites dispersing aerially after take-off from other plants within the same plantation or other plantations. The underlying dispersal behaviour of the mite at take-off, in the airborne state and after landing is largely unknown and this is essential to understand how they spread from tree to tree. In this article we studied whether take-off to aerial dispersal of coconut mites is preceded by characteristic behaviour, whether there is a correlation between the body position preceding aerial dispersal and the direction of the wind, and whether the substrate (outer surface of coconut bracts or epidermis) and the wind speed matter to the decision to take-off. We found that take-off can sometimes be preceded by a raised body stance, but more frequently take-off occurs while the mite is walking or resting on its substrate. Coconut mites that become airborne assumed a body stance that had no relation to the wind direction. Take-off was suppressed on a substrate providing food to coconut mites, but occurred significantly more frequently on the outer surface of coconut bracts than on the surface of the fruit. For both substrates, take-off frequency increased with wind speed. We conclude that coconut mites have at least some degree of control over take-off for aerial dispersal and that there is as yet no reason to infer that a raised body stance is necessary to become airborne.

Limits to ambulatory displacement of coconut mites in absence and presence of food-related cues

Ambulatory movement of plant-feeding mites sets limits to the distances they can cover to reach a new food source. In absence of food-related cues these limits are determined by survival, walking activity, walking path tortuosity and walking speed, whereas in presence of food the limits are also determined by the ability to orient and direct the path towards the food source location. For eriophyoid mites such limits are even more severe because they are among the smallest mites on earth, because they have only two pairs of legs and because they are very sensitive to desiccation. In this article we test how coconut mites (Aceria guerreronis Keifer) are constrained in their effective displacement by their ability to survive in absence of food (meristematic tissue under the coconut perianth) and by their ability to walk and orient in absence or presence of food-related cues. We found that the mean survival time decreased with increasing temperature and decreasing humidity. Under climatic conditions representative for the Tropics (27 °C and 75 % relative humidity) coconut mites survived on average for 11 h and covered 0.4 m, representing the effective linear displacement away from the origin. Within a period of 5 h, coconut mites collected from old fruits outside the perianth moved further away from the origin than mites collected under the perianth of young fruits. However, in the presence of food-related cues coconut mites traveled over 30 % larger distances than in absence of these cues. These results show that ambulatory movement of eriophyoid mites may well bring them to other coconuts within the same bunch and perhaps also to other bunches on the same coconut palm, but it is unlikely to help them move from palm to palm, given that palms usually do not touch each other.

Pinpointing differentially expressed domains in complex protein mixtures with the cloud service of PatternLab for Proteomics

Mass-spectrometry-based shotgun proteomics has become a widespread technology for analyzing complex protein mixtures. Here we describe a new module integrated into PatternLab for Proteomics that allows the pinpointing of differentially expressed domains. This is accomplished by inferring functional domains through our cloud service, using HMMER3 and Pfam remotely, and then mapping the quantitation values into domains for downstream analysis. In all, spotting which functional domains are changing when comparing biological states serves as a complementary approach to facilitate the understanding of a system's biology. We exemplify the new module's use by reanalyzing a previously published MudPIT dataset of Cryptococcus gattii cultivated under iron-depleted and replete conditions. We show how the differential analysis of functional domains can facilitate the interpretation of proteomic data by providing further valuable insight.

Enteric parasites and HIV infection: occurrence in AIDS patients in Rio de Janeiro, Brazil

The occurrence of intestinal parasites, its relation with the transmission mechanism of HIV, and the clinical state of the AIDS patients, were analyzed in 99 Group IV patients (CDC, 1986), treated at "Hospital Universitário Pedro Ernesto" (HUPE), between 1986 and 1988. The group consisted of 79 (79.8%) patients whose HIV transmission mechanism took place through sexual contact and of 16 (20.2%) who were infected through blood. Feces samples from each patient were examined by four distincts methods (Faust et al., Kato-Katz, Baermann-Moraes and Baxby et al.). The most occurring parasites were: Cryptosporidium sp., Entamoeba coli and Endolimax nana (18.2%), Strongyloides stercoralis and Giardia lamblia (15.2%), E. histolytica and/or E. hartmanni (13.1%), Ascaris lumbricoides (11.1%) and Isospora belli (10.1%). Furthermore, 74.7% of the patients carried at least one species. Intestinal parasites were found in 78.5% of the patients who acquired the HIV through sexual intercourse and in 56.3% of those infected by blood contamination. The difference, was not statistically significant (p greater than 0.05). In the group under study, the increase of the occurrence of parasitic infections does not seem to depend on the acquisition of HIV through sexual contact. It appears that in developing countries, the dependency is more related to the classic mechanisms of parasites transmission and its endemicity.