Showing papers on "Infestation published in 2020"

Ectoparasites: Pediculosis and tungiasis

Abstract: Pediculosis is an infestation of lice on the body, head, or pubic region that occurs worldwide. Lice are ectoparasites of the order Phthiraptera that feed on the blood of infested hosts. Their morphotype dictates their clinical features. Body lice may transmit bacterial pathogens that cause trench fever, relapsing fever, and epidemic typhus, which are potentially life-threatening diseases that remain relevant in contemporary times. Recent data from some settings suggest that head lice may harbor pathogens. The epidemiology, clinical manifestations, and management of body, head, and pubic louse infestation are reviewed. New therapies for head lice and screening considerations for pubic lice are discussed. Tungiasis is an ectoparasitic disease caused by skin penetration by the female Tunga penetrans or, less commonly, Tunga trimamillata flea. It is endemic in Latin America, the Caribbean and sub-Saharan Africa and seen in travelers returning from these regions. Risk factors for acquiring tungiasis, associated morbidity, and potential strategies for prevention and treatment are discussed.

Measuring the nutritional cost of insect infestation of stored maize and cowpea

Abstract: Our understanding and prevention of postharvest losses are critical if we are to feed a growing global population. Insect infestation-related losses of stored commodities are typically considered only in terms of quantitative, physical weight loss. Insect infestation affects the nutritional value and some nutritional components are impacted more severely than others. We infested maize and cowpea grain with commonly occurring stored product insect pests, and mapped infestation levels against nutritional composition over a 4-to-6 month storage period to analyse how insect infestation relates to different macro- and micro-nutrient contents. Insect infestation decreased the carbohydrate content of the stored grains, causing a relative increase in the proportion of protein and fibre in the remaining grain, and moisture content also increased. Sitophilus zeamais preferentially fed in the floury endosperm of maize, resulting in more carbohydrate loss relative to protein loss. Conversely, Prostephanus truncatus consumed the germ and endosperm, disproportionately reducing the fat, protein, iron and zinc grain contents. Nutrients are distributed more homogenously within cowpea than in maize grains, but Callosobruchus maculatus infestation increased the relative protein, fat, iron and zinc to carbohydrate ratios. This indicates how the nutrient content of insect-infested stored grain depends upon the grain type, the infesting insect, and the infestation level. Insect infestation therefore has consequences for human nutrition beyond those of grain weight loss. Using data collected on the changing nutritional composition of grain over time, with and without insect infestation, we modelled the associations between infestation and nutritional quality to predict estimated nutritional losses that could be associated with consumption of insect-infested stored maize and cowpea.

Maize Infestation of Fall Armyworm (Lepidoptera: Noctuidae) Within Agro-Ecological Zones of Togo and Ghana in West Africa 3 Yr After Its Invasion.

Abstract: The fall armyworm Spodoptera frugiperda (J. E. Smith) invaded several West African countries in 2016 causing severe injury to maize plants and economic damage. This study assesses variations in the occurrence of this species in different Agro-Ecological Zones (AEZs) in Togo and Ghana during the 3 yr following its discovery. The surveys were conducted on 120 farms in Togo and 94 farms in Ghana by collecting larvae from 200 maize plants per hectare. Infestation levels were 68.46% in 2016, 55.82% in 2017, and 17.76% in 2018. The number of larvae recorded per hectare and infestation levels were higher in Togo than in Ghana. The lowest number of collected larvae and infestation levels of S. frugiperda were in 2018, compared to the other 2 yr. Larvae per hectare and the infestation level varied regionally inside the two countries. The southern part of Togo (AEZ five) contained higher numbers of larvae and higher infestation levels during the 2 yr following the invasion of the pest. We concluded that infestation levels of S. frugiperda are much lower in 2018 than the two previous years and it is therefore necessary to determine the factors that affect the population dynamics of S. frugiperda in the field, which is a perquisite for developing management interventions.

Prediction of the salmon lice infestation pressure in a Norwegian fjord

Abstract: A further growth in the Norwegian aquaculture industry might potentially be hampered by the conclusion that it is not environmentally sustainable. As direct measurements of the lice induced mortality on wild salmonids are impossible, the management is based on a set of high-quality and well-documented sustainability indicators. These indicators combine observations from the national Norwegian salmon lice monitoring programme with salmon lice models. Here, we have documented the quality of one of these models used to identify areas where the impact from farmed to wild salmonids is over the prescribed limit. The Hardangerfjord area has been used as a test area, but the model is general and, therefore, suitable for the rest of the coast. It is shown that the model system is robust and also can be used to test whether new knowledge gained from laboratory experiments improves the model. New findings on salmon lice behaviour at low salinities have been incorporated and the new model, consisting of a high-resolution hydrodynamic model coupled with an individual-based salmon lice model and forced with realistic input of salmon lice larvae from aquaculture farms, represents the best realization of the local potential infestation pressure on wild fish.

Drivers of Spruce Bark Beetle (Ips typographus) Infestations on Downed Trees after Severe Windthrow

Abstract: Research Highlights: Bark beetles are important agents of disturbance regimes in temperate forests, and specifically in a connected wind-bark beetle disturbance system. Large-scale windthrows trigger population growth of the European spruce bark beetle (Ips typographus L.) from endemic to epidemic levels, thereby allowing the killing of Norway spruce trees over several consecutive years. Background and Objectives: There is a lack of evidence to differentiate how outbreaks are promoted by the effects of environmental variables versus beetle preferences of trees from endemic to outbreak. However, little is known about how individual downed-tree characteristics and local conditions such as tree orientation and solar radiation affect beetle colonization of downed trees. Materials and Methods: To answer this question, we investigated the infestation rates and determined tree death categories (uprooted, broken, and stump) in wind-damaged areas in Western Tatra Mts. in Carpathians (Slovakia) from 2014–2016, following a windthrow in May 2014. In total, we investigated 225 trees over eight transects. For every tree, we measured its morphological (tree height, crown characteristics), environmental (solar radiation, terrain conditions, trunk zenith), temporal (time since wind damage), and beetle infestation (presence, location of attack, bark desiccation) parameters. We applied Generalized Additive Mixed Models (GAMM) to unravel the main drivers of I. typographus infestations. Results: Over the first year, beetles preferred to attack broken trees and sun-exposed trunk sides over uprooted trees; the infestation on shaded sides started in the second year along with the infestation of uprooted trees with lower desiccation rates. We found that time since wind damage, stem length, and incident solar radiation increased the probability of beetle infestation, although both solar radiation and trunk zenith exhibited nonlinear variability. Our novel variable trunk zenith appeared to be an important predictor of bark beetle infestation probability. We conclude that trunk zenith as a simple measure defining the position of downed trees over the terrain can anticipate beetle infestation. Conclusions: Our findings contribute to understanding of the bark beetle’s preferences to colonize windthrown trees in the initial years after the primary wind damage. Further, our findings can help to identify trees that are most susceptible to beetle infestation and to prioritize management actions to control beetle population while maintaining biodiversity.

Evaluation of Traits for the Selection of Apis Mellifera for Resistance against Varroa Destructor.

Abstract: Infestation with Varroa destructor is a serious cause of bee colony (Apis mellifera) losses on a global level. However, the presence of untreated survivor populations in many different regions supports the idea that selection for resistance can be successful. As colony survival is difficult or impossible to measure, differences in mite infestation levels and tests for specific behavioral traits are used for selective breeding for Varroa resistance. In this paper we looked into different definitions of mite infestation and linked these with brood hygiene (pin test), brood recapping and suppressed mite reproduction. We based our analyses on datasets of Apis mellifera carnica from three countries: Austria (147 records), Croatia (135) and Germany (207). We concluded that bee infestation in summer, adjusted for the level of natural mite fall in spring, is a suitable trait in the breeding objective, and also suggested including brood infestation rate and the increase rate of bee infestation in summer. Repeatability for bee infestation rate was about 0.55, for cells opened in pin test about 0.33, for recapping 0.35 and for suppressed mite reproduction (SMR) virtually zero. Although in most cases we observed correlations with the expected sign between infestation parameters and behavioral traits, the values were generally low (<0.2) and often not significantly different from zero.

Occurrence of European Mistletoe (Viscum album L.) on Forest Trees in Poland and Its Dynamics of Spread in the Period 2008–2018

Abstract: As recently reported, European mistletoe has become an important agent of damage to forest trees in Central Europe. To document the extent of its impact, host and environmental preferences, as well as spatial and temporal dynamics, we have analyzed the results of 10 years of annual assessments of tree damage in level 1 plots of country-wide national forest monitoring. Mistletoe was found on 12 forest tree species, most frequently on silver fir and Scots pine, much less often on birches and deciduous admixture species. Common beech, pedunculate, and sessile oaks, as well as coniferous admixture species, were found to be free from the parasite. Mistletoe was more common on larger trees, mainly those in the 1st and 2nd Kraft classes, characterized by a higher DBH value than trees without V. album. Infestation was also age-dependent with low numbers of infested trees in young age classes and a much higher proportion of infested trees being over 80–100 years in age. Defoliation of trees colonized by mistletoe was found to be significantly higher than in trees free from the parasite, confirming the adverse effect of infestation on tree health. The increase of relative incidence of tree infestation by mistletoe in forests in Poland was high throughout the entire period 2008–2018 and significant for the most threatened host species: silver fir, Scots pine, and birches. It was also found that spread direction was from west to east and that the occurrence of V. album shows clear regionalization. The most endangered forests were located within a 200 km wide zone ranging through lowland Central Poland from the border with Germany down to the border with Ukraine and Belarus. The highest concentration occurred in the Western part of the country. Outside this zone (to the north and south) the mistletoe was much less abundant as expressed by the amount of injuries caused by the parasite or infested trees per plot.

Spatial modelling of the infestation indices of Aedes aegypti : an innovative strategy for vector control actions in developing countries

Abstract: Larval indices such as the house index (HI), Breteau index (BI) and container index (CI) are widely used to interpret arbovirus vector density in surveillance programmes. However, the use of such data as an alarm signal is rarely considered consciously when planning programmes. The present study aims to investigate the spatial distribution pattern of the infestation of Aedes aegypti, considering the data available in the Ae. aegypti Infestation Index Rapid Survey (LIRAa) for the city of Campina Grande, Paraiba State in Brazil. The global and local Moranʼs indices were used in spatial analysis to measure the effects of spatial dependencies between neighbourhoods, using secondary data related to HI and BI gathered from surveillance service. Our analysis shows that there is a predominance of high rates of mosquito infestation, placing Campina Grande at a near-constant risk of arbovirus outbreaks and epidemics. A highly significant Moranʼs index value (P < 0.001) was observed, indicating a positive spatial dependency between the neighbourhoods in Campina Grande. Using the Moran mapping and LISA mapping, the autocorrelation patterns of Ae. aegypti infestation rates among neighbourhoods have revealed hotpots that should be considered a priority to preventive actions of the entomological surveillance services. Predominance of high infestation rates and clearer relationships of these between neighbourhoods were observed between the months of May and July, the period with the highest rainfall in the city. This analysis is an innovative strategy capable of providing detailed information on infestation locations to the relevant public health authorities, which will enable a more efficient allocation of resources, particularly for arbovirus prevention.

Correction to: Transcriptional and metabolite analysis reveal a shift in direct and indirect defences in response to spider‑mite infestation in cucumber (Cucumis sativus).

Abstract: In the above mentioned publication, part of Fig. 1b was distorted (48 h after TSSM Infestation). The original article has been corrected and the proper version of Fig. 1 is also published here.

Ectoparasites of small mammals in a fragmented area of the southern Amazonia: interaction networks and correlations with seasonality and host sex

Abstract: The present work aimed to analyze the ectoparasite-host interaction network and possible differences of this interaction related to two seasonal periods and host sex. During November 2016 and July 2017, non-flying small mammals were captured in 17 forest fragments located in the southern portion of the Amazon biome. We captured 96 individuals belonging to 10 host species that were parasitized with a total of 3668 ectoparasites. Overall, we identified 24 ectoparasite taxa belonging to the mite and insect groups Ixodida (ticks), Mesostigmata, Sarcoptiformes, Trombidiformes (mites), Phthiraptera (lice), and Siphonaptera (fleas). The interaction network between all ectoparasites and hosts showed significant deviation from random, with moderately high specialization index (H2′ = 0.80). There was seasonal difference in prevalence for Amblyomma cajennense (Fabricius) sensu stricto (s.s), Amblyomma coelebs Neumann and larvae of Amblyomma. This difference was also found in the mean intensity of infestation of Amblyomma larvae and the mite Tur aragaoi (Fonseca). Only mean intensity of infestation differed in relation to host sex for the species Marmosa constantiae Thomas. Our results demonstrate that specificity between ectoparasites and small mammals in this region is moderately high and that the pattern of aggregation of some ectoparasite taxa differed between two seasons, as well as between sexes in M. constantiae.

The Effectiveness of Varroa destructor Infestation Classification Using an E-Nose Depending on the Time of Day.

Abstract: Honey bees are subject to a number of stressors. In recent years, there has been a worldwide decline in the population of these insects. Losses raise a serious concern, because bees have an indispensable role in the food supply of humankind. This work is focused on the method of assessment of honey bee colony infestation by Varroa destructor. The approach allows to detect several categories of infestation: "Low", "Medium" and "High". The method of detection consists of two components: (1) the measurements of beehive air using a gas sensor array and (2) classification, which is based on the measurement data. In this work, we indicate the sensitivity of the bee colony infestation assessment to the timing of measurement data collection. It was observed that the semiconductor gas sensor responses to the atmosphere of a defined beehive, collected during 24 h, displayed temporal variation. We demonstrated that the success rate of the bee colony infestation assessment also altered depending on the time of day when the gas sensor array measurement was done. Moreover, it was found that different times of day were the most favorable to detect the particular infestation category. This result could indicate that the representation of the disease in the beehive air may be confounded during the day, due to some interferences. More studies are needed to explain this fact and determine the best measurement periods. The problem addressed in this work is very important for scheduling the beekeeping practices aimed at Varroa destructor infestation assessment, using the proposed method.

Structural and Functional Dynamics of Soil Microbes following Spruce Beetle Infestation.

Abstract: As the range of bark beetles expands into new forests and woodlands, the need to understand their effects on multiple trophic levels becomes increasingly important. To date, much attention has been paid to the aboveground processes affected by bark beetle infestation, with a focus on photoautotrophs and ecosystem level processes. However, indirect effects of bark beetle on belowground processes, especially the structure and function of soil microbiota remains largely a black box. Our study examined the impacts of bark beetle-induced tree mortality on soil microbial community structure and function using high-throughput sequencing of the soil bacterial and fungal communities and measurements of extracellular enzyme activities. The results suggest bark beetle infestation affected edaphic conditions through increased soil water content, pH, electrical conductivity, and carbon/nitrogen ratio and altered bulk and rhizosphere soil microbial community structure and function. Finally, increased enzymatic activity suggests heightened microbial decomposition following bark beetle infestation. With this increase in enzymatic activity, nutrients trapped in organic substrates may become accessible to seedlings and potentially alter the trajectory of forest regeneration. Our results indicate the need for incorporation of microbial processes into ecosystem level models. IMPORTANCE Belowground impacts of bark beetle infestation have not been explored as thoroughly as their aboveground counterparts. In order to accurately model impacts of bark beetle-induced tree mortality on carbon and nutrient cycling and forest regeneration, the intricacies of soil microbial communities must be examined. In this study, we investigated the structure and function of soil bacterial and fungal communities following bark beetle infestation. Our results show bark beetle infestation to impact soil conditions, as well as soil microbial community structure and function.

Investigating Plant Phenotype, Salinity, and Infestation by the Roseau Cane Scale as Factors in the Die-Back of Phragmites australis in the Mississippi River Delta, USA

Abstract: Die-back of Phragmites australis in the Mississippi River Delta (MRD), Louisiana, USA, is associated with large populations of nonnative Roseau Cane Scale (RCS), Nipponaclerda biwakoensis. Initial observations suggested different P. australis phenotypes displayed different susceptibilities to scale infestation and die-back, but the role of scale infestation on die-back was unknown. To understand the effect of RCS on P. australis, paired stands of Delta and European phenotypes in the MRD were monitored for stem heights, densities, and scale infestation over two years. A mesocosm experiment was conducted to assess whether RCS abundance and P. australis growth were dependent on water salinity and phenotype. Three Phragmites australis phenotypes were grown in small pools under fresh or mesohaline conditions, and RCS infestated or non-infested treatments. Scale densities were up to 7 times greater on the Delta compared to the European phenotype. Scale infestation resulted in 22%–39% reductions in the proportion of stems with green leaf tissue for all phenotypes, and 12% reduction in stem heights for Delta-type. Salinity was detrimental to all phenotypes, reducing stem heights by 20% compared to freshwater. Our results provide evidence that the RCS can result in die-back symptoms similar to what is observed in the MRD.

Urbanisation, risk stratification and house infestation with a major vector of Chagas disease in an endemic municipality of the Argentine Chaco.

Abstract: The occurrence of the major vectors of Chagas disease has historically been linked to poor rural housing, but urban or peri-urban infestations are increasingly being reported We evaluated a simple risk index to detect houses infested with Triatoma infestans and tested whether house infestation and vector abundance increased across the urban-to-rural gradient in Avia Terai, an endemic municipality of the Argentine Chaco; whether the association between infestation and selected ecological determinants varied across the gradient; and whether urban and peri-urban infestations were associated with population settlement history We conducted a screening survey of house infestation in 2296 urban, peri-urban and rural dwellings to identify high-risk houses based on a simple index, and then searched for triatomines in all high-risk houses and in a systematic sample of low-risk houses The risk index had maximum sensitivity and negative predictive value, and low specificity The combined number of infested houses in peri-urban and urban areas equalled that in rural areas House infestation prevalence was 45%, 227% and 424% across the gradient, and paralleled the increasing trend in the frequency of domestic animals and peridomestic structures Multiple logistic regression analysis showed that house infestation was positively and significantly associated with the availability of poultry and bug refuges in walls, and was negatively associated with domestic insecticide use Several pieces of evidence, including absence of spatial aggregation of house infestation, support that T infestans has been a long-established occupant of urban, peri-urban and rural settings in Avia Terai An integrated vector management strategy targeting chicken coops and good husbandry practices may provide more cost-effective returns to insecticide-based vector elimination efforts

Texture features explain the susceptibility of grapevine cultivars to Drosophila suzukii (Diptera: Drosophilidae) infestation in ripening and drying grapes

Abstract: Grapevine is a well-known host plant of the invasive pest Drosophila suzukii, but its susceptibility to pest oviposition and development greatly depends on the cultivar To address environmental sustainability during viticultural zoning planning, new vineyard plantation and Integrated Pest Management programmes, it is essential to take pest pressure and cultivar susceptibility into account To determine the different grapevine cultivars susceptibility to D suzukii, we tested twelve widely spread cultivars during the ripening period We also tested three cultivars during the drying period for raisin wine production The infestation and emergence rates were consequently related to chemical and texture features of the berries to explain the role of skin and pulp characteristics in determining the nature of the susceptibility Our results showed that susceptibility to D suzukii infestation varies across cultivars On ripening grapes, infestation is primarily influenced by skin and pulp firmness, elasticity and consistency Suitability for egg development resulted mainly related to skin and pulp deformation In a drying loft, infestation may also occur in relation to skin and pulp consistency Lastly, we discuss the practical implication of the underestimated role of berry texture in D suzukii oviposition and emergence success, in both ripening and drying grapes

Trirachys holosericeus (apple stem borer)

Abstract: Datasheet report for Trirachys holosericeus (apple stem borer). Trirachys holosericeus, a highly polyphagous longhorned beetle, is native to southern Asia from Pakistan to the Philippines. It is a stem-boring pest in natural and planted forests and fruit trees. It attacks primarily hardwoods, and at least one conifer. Both healthy and stressed trees are attacked, often leading to crown dieback and possibly tree death after one or more years of infestation.

Susceptibility of eucalypt taxa to a natural infestation by Leptocybe invasa

Abstract: Recently, pest occurrence in forest plantations has been increasing influenced by genotypes and environmental conditions such as climate change, thus impacting production negatively. In 2008, the exotic pest Leptocybe invasa (Hym: Eulophidae), known as the blue gum chalcid, was introduced in Brazil causing damage to eucalypt plantations in many regions of the country. To this end, this study evaluated the susceptibility of Eucalyptus camaldulensis (one seedlot), E. grandis (four seedlots), E. urophylla (four seedlots), and the “E. urograndis” hybrid (E. urophylla × E. grandis) (three seedlots) exposed to a natural infestation by L. invasa in two seasons (winter and summer). The attack on seedlings was classified in terms of severity as healthy (no pest attack), oviposition (only oviposition signs) and gall formation. The results show a significant higher pest incidence in summer compared to winter. Further, Eucalyptus urophylla was the least attacked and 90% of the seedlings were healthy whereas E. grandis showed the highest number of seedlings with galls. The E. urograndis hybrid showed intermediate results between the two species. Differences in susceptibility were observed between seedlots within species. Eucalyptus camaldulensis, which was expected to have the highest incidence of galls, had a high oviposition incidence (60%) and low gall incidence (< 10%), probably due to its provenance. The susceptibility of the different eucalypt families varied significantly with respect to L. invasa infestation, and family heritability ranged from 0.27 to 0.68. The genetic control of L. invasa is possible through the selection of tolerant and resistant material, considering the species, provenance, and family.

Causes and consequences of liana infestation in southern Amazonia

Abstract: 1. Lianas, a key component of tropical forests, can limit growth of trees, impacting both the structure and functioning of forests, and are expected to benefit from fragmentation and potentially from global climatic changes. While it is critical to understand the impacts of liana infestation on contemporary tropical forests across large geographical areas, to date most liana studies have been focussed on single or few sites. 2. We measured and quantified liana infestation of 16,066 trees with diameter ≥10 cm in 27 plots distributed across southern Amazonia, a region characterized by substantial ecological and environmental variation and environmental change. We examined the influence of potential drivers of liana infestation at the plot, species and individual tree level. Additionally, we evaluated the effect of liana infestation on tree growth. 3. More than half of all trees had lianas in their crown. At the plot level, infestation by lianas was driven by forest structure but not by the studied climate or soil fertility variables, though low levels of liana infestation were found in seasonally flooded forests. 4. At the tree level, larger and stouter trees had a greater proportion of their crown infested with lianas. At the species level, trees belonging to intrinsically slow‐growing, dense‐wooded species were more susceptible to liana infestation. 5. Liana infestation had a negative impact on tree growth, with growth of heavily infested trees reduced by 33% compared to non‐infested. The impact of liana infestation on tree growth was strongest for the best‐lit tree crowns, indicating that lianas act to reduce the large competitive advantage that well‐lit trees otherwise hold over their neighbours. 6. Synthesis. Lianas are a pervasive and influential feature of the extensive forests at the southern edge of Amazonia. The degree of liana infestation in forests was closely linked to species‐level variables such as potential growth and wood density as well as the size of the individual tree. The growth of heavily infested trees was particularly restricted by lianas, and especially so for trees growing in otherwise favourable conditions, indicating the potential for lianas not only to reduce forest growth rates overall, but also to modify competitive hierarchies among trees within tropical forests.

Rice phenolamindes reduce the survival of female adults of the white-backed planthopper Sogatella furcifera.

Abstract: In response to infestation by herbivores, rice plants rapidly biosynthesize defense compounds by activating a series of defense-related pathways. However, which defensive compounds in rice are effective against herbivores remains largely unknown. We found that the infestation of white-backed planthopper (WBPH) Sogatella furcifera gravid females significantly increased levels of jasmonic acid (JA), jasmonoyl-isoleucine (JA-Ile) and H2O2, and reduced the level of ethylene in rice; levels of 11 of the tested 12 phenolamides (PAs) were subsequently enhanced. In contrast, WBPH nymph infestation had no effect on levels of JA, JA-Ile, ethylene and H2O2 in rice, and enhanced levels of only 2 of 12 PAs. Moreover, infestation by brown planthopper Nilaparvata lugens gravid females also affected the production of these PAs differently. Bioassays revealed that 4 PAs - N-feruloylputrescine, N-feruloyltyramine, feruloylagmatine and N1,N10-diferuloylspermidine - were toxic to newly emerged WBPH female adults. Our results suggest that WBPH- or BPH-induced biosynthesis of PAs in rice seems to be shaped primarily by the specific profile of defense-related signals elicited by the herbivore and that PAs play a role in conferring the resistance to WBPH on rice.

Potential of the Blattisocius mali Mite (Acari: Blattisociidae) as a Biological Control Agent of Potato Tubermoth (Lepidoptera: Gelechiidae) in Stored Potatoes

Abstract: Potato tubermoth (PTM) Phthorimaea operculella (Lep.: Gelechiidae) is one of the pest species affecting Solanaceae worldwide. It can cause up to 80% of losses in potato open air crops as well as damage up to 100% of tubers during storage. Blattisocius (= Typhlodromus) mali (Acari: Blattisociidae), a predatory mite, was studied as a potential biological control agent of PTM. A prey acceptance bioassay of PTM eggs was carried out. Additionally, two bioassays have been conducted under microcosm conditions, which assessed the densities of mite releases at two levels of PTM infestation. The results showed that B. mali female adults accept PTM eggs as prey, and they cause a mortality rate 89.63 ± 2.47%, 48 h later. In addition to this, under microcosm conditions with potato tubers, we found at low infestation level that the effectiveness of the predatory mite varied from 72.50 ± 28.50 to 100%, 28 days later, according to the release rate of mites. Under high infestation level, the effectiveness of biological control of the pest varied from 53.36 ± 25.55 to 92.51 ± 7.88%, also according to the release rate of the mites. The possible use of biological control with B. mali of PTM, in different types of potato storage, is analysed and discussed.

Impact of variable physical conditions and future increased aquaculture production on lice infestation pressure and its sustainability in Norway

Abstract: Salmon lice infestation is a challenge for wild post-smolt salmon during migration from their natal river to the sea in several regions of Norway. The traffic-light management system regulates growth in the aquaculture industry, where growth in production (6%) is only allowed if the impact of salmon lice on wild fish can be kept at a minimum and up to 10% mortality of wild salmonids are considered within the sustainability goal. We used a numerical ocean model, combined with an individual-based model for salmon lice, to evaluate the interannual variability in salmon lice concentrations in Production Zone 7, which was granted permission for production growth in 2017. Salmon lice releases were kept constant for 3 yr, while the physical conditions, e.g. wind and ocean circulation, varied. The total area of elevated lice infestations varied between 3.2 and 8.4% of the area within 5 km from the coast, due only to interannual physical variability mainly caused by variable wind patterns. Modeled post-smolts migrating out from the Namsen River (64.5°N, central Norway) towards the open ocean experienced mortality between 5 and 9%. Since Production Zone 7 was granted growth, we have simulated increased production and corresponding increases in lice releases. After 5 to 8 increments of 6% increase in production, the increase in salmon post-smolt mortality was of the same order of magnitude as the interannual variability. Information regarding migration route and time is crucial input to the model calculating post-smolt mortality, and inadequate information can affect the results significantly. These 2 methods (determining area of elevated lice infestations and estimating post-smolt mortality) provide complementary information and should be used in combination when the overall assessment of a production zone is made.

Reproduction of ectoparasitic mites in a coevolved system: Varroa spp.—Eastern honey bees, Apis cerana

Abstract: Parasite host shifts can impose a high selective pressure on novel hosts. Even though the coevolved systems can reveal fundamental aspects of host-parasite interactions, research often focuses on the new host-parasite relationships. This holds true for two ectoparasitic mite species, Varroa destructor and Varroa jacobsonii, which have shifted hosts from Eastern honey bees, Apis cerana, to Western honey bees, Apis mellifera, generating colony losses of these pollinators globally. Here, we study infestation rates and reproduction of V. destructor and V. jacobsonii haplotypes in 185 A. cerana colonies of six populations in China and Thailand to investigate how coevolution shaped these features. Reproductive success was mostly similar and low, indicating constraints imposed by hosts and/or mite physiology. Infestation rates varied between mite haplotypes, suggesting distinct local co-evolutionary scenarios. The differences in infestation rates and reproductive output between haplotypes did not correlate with the virulence of the respective host-shifted lineages suggesting distinct selection scenarios in novel and original host. The occasional worker brood infestation was significantly lower than that of drone brood, except for the V. destructor haplotype (Korea) from which the invasive lineage derived. Whether mites infesting and reproducing in atypical intraspecific hosts (i.e., workers and queens) actually predisposes for and may govern the impact of host shifts on novel hosts should be determined by identifying the underlying mechanisms. In general, the apparent gaps in our knowledge of this coevolved system need to be further addressed to foster the adequate protection of wild and managed honey bees from these mites globally.

Crop losses and economic impact associated with papaya mealybug (Paracoccus marginatus) infestation in Kenya

Abstract: This study quantified crop losses and economic impacts associated with papaya mealybug (Paracoccus marginatus) infestation in Kenya and identified the most important predictors of papaya tree (Cari...

Determinants of intentions to prevent triatomine infestation based on the health belief model: An application in rural southern Ecuador.

Abstract: Introduction Control of triatomine infestation is a key strategy for the prevention of Chagas disease (CD). To promote this strategy, it is important to know which antecedents to behavioral change are the best to emphasize when promoting prevention. Objective The aim of this study was to determine predictors for intention to prevent home infestation based on the Health Belief Model (HBM), a commonly used health intervention planning theory. Materials & methods A cross-sectional study was conducted with 112 heads of household in six communities with endemic and high rates of triatomine infestation in Loja province, Ecuador. The data was collected by a questionnaire including perceived severity, susceptibility, benefits to action, barriers to action, and self-efficacy. These data were also used to predict actual infestation of homes. Results Community members reported strong intentions to prevent home infestation. HBM constructs predicted about 14% of the observed variance in intentions. Perceived susceptibility and severity did not predict behavioral intention well; perceived barriers to small-scale action that reduce likelihood of infestation and self-efficacy in participating in surveillance systems did. Self-efficacy and perception of barriers were equally powerful predictors. The HBM constructs, however, did not predict well actual infestation. Conclusion The findings supported the HBM as a way to predict intentions to prevent infestation of the home by triatomine bugs. The findings highlight that messages emphasizing self-efficacy in participating in surveillance systems and overcoming barriers to small-scale action that reduce likelihood of infestation, rather than a focus on risk, should be central messages when designing and implementing educational interventions for CD. The gap between behavioral intention and actual infestation reveals the need to assess home practices and their actual efficacy to fully enact and apply the HBM.

Physical and Physiological Monitoring on Red Palm Weevil-Infested Oil Palms.

Abstract: The red palm weevil (RPW) is a stem boring Coleoptera that decimates host palm trees from within The challenge of managing this pest is due to a lack of physical symptoms during the early stages of infestation Investigating the physiological changes that occur within RPW-infested palm trees may be useful in establishing a new approach in RPW detection In this study, the effects of RPW infestation were investigated in Elaeis guineensis by observing changes in physical and physiological parameters during the progress of infestation by visual inspection and the comparison of growth, gas exchange, stomatal conductance, and chlorophyll content between the non-infested control, physically wounded, and RPW-infested E guineensis groups During the study period, four distinct levels of physical infestation were observed and recorded The RPW-infested group displayed significantly lower maximum photosynthesis activity (Amax) starting from the third week post-infestation However, growth in terms of change in plant height and stem circumference, leaves’ stomatal conductance, and chlorophyll content were not significantly different between the three groups during the duration of the study The significant drop in photosynthesis was observed one week before physical changes appeared This suggests the promising utilisation of photosynthesis activity as a signal for detecting RPW infestation at the early stage of attacks, which could be useful for integration in integrated pest management (IPM)