Review on exotic Bondar’s nesting whitefly,Paraleyrodes bondari Peracchi infestation on multiple cropping system

Between 2016 and 2020, seven new whitefly species were uncovered in the tropical Southern region of India, wrecking chaos among producers in certain invasive whitefly instances. The repercussions of climate change, improved free trade practices between countries, increased intercontinental migration, enhanced exim operations for planting supplies, etc., may have led to insect invasions. A limited number of invasive insect species only swelled to unmanageable proportions when entered into new geographic locations. Bondar’s Nesting Whitefly (BNW), Paraleyrodes bondari Peracchi (Hemiptera: Aleyrodidae), a native of Brazil to Honduras, was one such species. In May 2017, BNW noticed from the Indian Andaman and Nicobar islands, by December 2018 reached Indian mainland Kerala. Because of its co-existence with other whiteflies and cryptic appearance, BNW identification at immature stages can be challenging and may call for specific instruments and methods. Global analysis of BNW mitochondrial cytochrome oxidase (COI) indicated the presence of highly homogenous population. BNW is polyphagous, co-lives with other whiteflies and feeds by desapping from adaxial leaf surfaces of perennial and seasonal plants, crops, weeds etc., thus promoting sickliness. The land areas invaded and host plants exploited have increased within a short span from its introduction. BNW has no known parasitoids, and only non-specific predators utilize them. The presence of an intensive BNW population warrants frequent adoption of pest control practices. Even though insecticides bring down whiteflies, it is not the sole panacea. The information pertinent to BNW and its sustainable control is limited and scattered. These details mandate reviewing them concerning poly-crop systems practised in tropical ecosystems. This review discusses the possibilities of BNW becoming a significant pest of crops in tropical Indian mainlands and its management prospects.

     

Notes on psyllids (Hemiptera: Psylloidea) intercepted on imported cut flowers and branches in South Korea 2014–2018

A total of 10 species of psyllids from 8 different countries were intercepted by plant health inspectors in South Korea on consignments of fresh cut flowers (and branches for use in flower arrangements) at the ports of entry in South Korea from 2014 to 2018. Of the 10 species that were intercepted, some species are potential pests that could enter and establish in Korea through the import of these flowers and branches. Current information on intercepted psyllids is required to alert plant health inspectors to look carefully at cut flowers to prevent the introduction of non-indigenous species.     

Effects of long-term warming on the aboveground biomass and species diversity in an alpine meadow on the Qinghai-Tibetan Plateau of China

Ecosystems in high-altitude regions are more sensitive and respond more rapidly than other ecosystems to global climate warming.The Qinghai-Tibet Plateau(QTP)of China is an ecologically fragile zone that is sensitive to global climate warming.It is of great importance to study the changes in aboveground biomass and species diversity of alpine meadows on the QTP under predicted future climate warming.In this study,we selected an alpine meadow on the QTP as the study object and used infrared radiators as the warming device for a simulation experiment over eight years(2011-2018).We then analyzed the dynamic changes in aboveground biomass and species diversity of the alpine meadow at different time scales,including an early stage of warming(2011-2013)and a late stage of warming(2016-2018),in order to explore the response of alpine meadows to short-term(three years)and long-term warming(eight years).The results showed that the short-term warming increased air temperature by 0.31℃and decreased relative humidity by 2.54%,resulting in the air being warmer and drier.The long-term warming increased air temperature and relative humidity by 0.19℃and 1.47%,respectively,and the air tended to be warmer and wetter.The short-term warming increased soil temperature by 2.44℃and decreased soil moisture by 12.47%,whereas the long-term warming increased soil temperature by 1.76℃and decreased soil moisture by 9.90%.This caused the shallow soil layer to become warmer and drier under both short-term and long-term warming.Furthermore,the degree of soil drought was alleviated with increased warming duration.Under the long-term warming,the importance value and aboveground biomass of plants in different families changed.The importance values of grasses and sedges decreased by 47.56%and 3.67%,respectively,while the importance value of weeds increased by 1.37%.Aboveground biomass of grasses decreased by 36.55%,while those of sedges and weeds increased by 8.09%and 15.24%,respectively.The increase in temperature had a non-significant effect on species diversity.The species diversity indices increased at the early stage of warming and decreased at the late stage of warming,but none of them reached significant levels(P>0.05).Species diversity had no significant correlation with soil temperature and soil moisture under both short-term and long-term warming.Soil temperature and aboveground biomass were positively correlated in the control plots(P=0.014),but negatively correlated under the long-term warming(P=0.013).Therefore,eight years of warming aggravated drought in the shallow soil layer,which is beneficial for the growth of weeds but not for the growth of grasses.Warming changed the structure of alpine meadow communities and had a certain impact on the community species diversity.Our studies have great significance for the protection and effective utilization of alpine vegetation,as well as for the prevention of grassland degradation or desertification in high-altitude regions.     

FraxForFuture—research on European ash dieback in Germany

Journal of Plant Diseases and Protection - European ash dieback caused by the alien, invasive ascomycete species Hymenoscyphus fraxineus currently represents, along with its side effects, the...     

What makes Haloxylon persicum grow on sand dunes while H. ammodendron grow on interdune lowlands： a proof from reciprocal transplant experiments

Determining the mechanisms underlying the spatial distribution of plant species is one of the central themes in biogeography and ecology. However, we are still far from gaining a full understanding of the autecological processes needed to unravel species distribution patterns. In the current study, by comparing seedling recruitment, seedling morphological performance and biomass allocation of two Haloxylon species, we try to identify the causes of the dune/interdune distribution pattern of these two species. Our results show the soil on the dune had less nutrients but was less saline than that of the interdune; with prolonged summer drought, soil water availability was lower on the dune than on the interdune. Both species had higher densities of seedlings at every stage of recruitment in their native habitat than the adjacent habitat. The contrasting different adaptation to nutrients, salinity and soil water conditions in the seedling recruitment stage strongly determined the distribution patterns of the two species on the dune/interdune. Haloxylon persicum on the dunes had lower total dry biomass, shoot and root dry biomass, but allocated a higher percentage of its biomass to roots and possessed a higher specific root length and specific root area by phenotypic traits specialization than that of Haloxylon ammodendron on the interdune. All of these allowed H. persicum to be more adapted to water stress and nutrient shortage. The differences in morphology and allocation facilitated the ability of these two species to persist in their own environments.     

Three years of banning neonicotinoid insecticides based on sub‐lethal effects: can we expect to see effects on bees?

The 2013 EU ban of three neonicotinoids used in seed coating of pollinator attractive crops was put in place because of concern about declining wild pollinator populations and numbers of honeybee colonies. It was also concluded that there is an urgent need for good field data to fill knowledge gaps. In the meantime such data have been generated. Based on recent literature we question the existence of recent pollinator declines and their possible link with the use of neonicotinoids. Because of temporal non‐coincidence we conclude that declines of wild pollinators and of honeybees are not likely caused by neonicotinoids. Even if bee decline does occur and if there is a causal relationship with the use of neonicotinoids, we argue that it is not possible on such short term to evaluate the effects of the 2013 ban. In order to supply future debate with realistic (field) data and to discourage extrapolating the effects of studies using overdoses that are not of environmental relevance, we propose – in addition to field studies performed by the chemical industry – to use the ‘semi‐field worst case’ treated artificial diet studies approach to free flying colonies in the field. This kind of study may provide realistic estimates for risk and be useful to study realistic interactions with non‐pesticide stressors. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Effects of variability in landscape types on the microclimate across a desert–oasis region on the southern margins of the Tarim Basin,China

Microclimates play important roles in controlling water budgets and water vapor transportation, as well as vegetation growth characteristics. In order to understand the differences in meteorological parameters under different vegetation cover (VC) and terrain conditions, wind velocity, air temperature, relative humidity (RH), photosynthetically active radiation (PAR), and solar radiation were simultaneously monitored on shifting, semi-fixed and fixed sandy lands, and an oasis. The air temperature and RH differences among the four landscape types were obvious in the period from May to October. It was found that the higher elevations of semi-fixed sandy land can influence PAR and solar radiation during sand-blowing weather. The differences of air temperature and RH among the four sites during the dust-storm and rainy days were not obvious, but their differences during sand-blowing weather were greater than during rainy weather and less than during floating-dust and sunny weather. The differences of PAR and solar radiation among the four landscape types were most obvious during the dust-storm event. During most of the weather types studied, significant positive correlations were found between wind velocity and temperature, PAR, and solar radiation, as well as between temperature and PAR, and solar radiation. Meanwhile, significant negative correlations were found between RH and wind velocity, temperature, PAR, and solar radiation. VC and topography were found to be the main factors influencing the changes in meteorological parameters between desert–oasis ecotone and oasis.     

Influence of light on the Monilinia laxa–stone fruit interaction

Light represents a signal for the regulation of virulence in many microbial pathogens. Two stone fruits, nectarines and cherries, were used to investigate the influence of light on brown rot caused by Monilinia laxa. Three single-spore isolates were inoculated on nectarines and incubated under different white lights, red light, blue light, green light, and black light with two photoperiods. In addition, to understand the effect of daylight irradiance on brown rot, M. laxa was inoculated on different cherry cultivars and incubated under two simulated solar irradiations. Significantly higher disease severity and sporulation were reported on inoculated nectarines incubated under 58 W white light for 12 hr light/12 hr darkness than on nectarines incubated in continuous darkness. Only red light caused a significant increase in the incidence and severity of the disease in nectarines inoculated with the three M. laxa isolates, compared to fruit incubated under white light. High light intensity (185.45 W/m²), caused greater brown rot severity in all cherry cultivars, both early and late varieties, than low irradiance (145.85 W/m²). Significant up-regulation of the pathogenicity-related MlPNL2 gene was observed as an early response after cherry inoculation under high-intensity light, especially in late cherry cultivars, while MlPG1 expression did not show any changes under different light irradiances. M. laxa was shown to be a light-responsive fungal pathogen, and light seemed to play an active role in brown rot development.     

Impacts of climate change on plant diseases—opinions and trends

There has been a remarkable scientific output on the topic of how climate change is likely to affect plant diseases. This overview addresses the need for review of this burgeoning literature by summarizing opinions of previous reviews and trends in recent studies on the impacts of climate change on plant health. Sudden Oak Death is used as an introductory case study: Californian forests could become even more susceptible to this emerging plant disease, if spring precipitations will be accompanied by warmer temperatures, although climate shifts may also affect the current synchronicity between host cambium activity and pathogen colonization rate. A summary of observed and predicted climate changes, as well as of direct effects of climate change on pathosystems, is provided. Prediction and management of climate change effects on plant health are complicated by indirect effects and the interactions with global change drivers. Uncertainty in models of plant disease development under climate change calls for a diversity of management strategies, from more participatory approaches to interdisciplinary science. Involvement of stakeholders and scientists from outside plant pathology shows the importance of trade-offs, for example in the land-sharing vs. sparing debate. Further research is needed on climate change and plant health in mountain, boreal, Mediterranean and tropical regions, with multiple climate change factors and scenarios (including our responses to it, e.g. the assisted migration of plants), in relation to endophytes, viruses and mycorrhiza, using long-term and large-scale datasets and considering various plant disease control methods.     

Rhabdocline needle cast—investigations on various Douglas fir tissue types

Douglas fir (Pseudotsuga menziesii) is one of the most important non-indigenous tree species in Germany. The species is characterized by a wide amplitude of growing conditions, and is of increasing interest, in particular from the perspective of climate change. Douglas fir is nevertheless particularly susceptible to fungal pathogens, such as Rhabdocline pseudotsugae . The aim of the present study was therefore to develop an early detection method for R. pseudotsugae based on the polymerase chain reaction (PCR). Existing molecular techniques were adapted and optimized to detect the pathogen in small sample volumes. Both healthy and infected Douglas firs were examined, with various tissue types (buds, cambial tissue, needles) and seeds tested for the presence of R. pseudotsugae. Non-infected Douglas firs did not give positive responses in the molecular analyses, but the pathogen was clearly detected in buds, cambial tissues, needles and seeds of infected trees. To date, the fungus has been considered an obligate biotrophic needle parasite. The present results provide clear evidence, however, for the existence of an endophytic stage in the life cycle of R. pseudotsugae. In contrast with previous studies, this paper investigates the dispersal of the fungus via seeds.     

Focus on ecological weed management: what is hindering adoption?

Despite increased concerns regarding the heavy reliance of many cropping systems on chemical weed control, adoption of ecological weed management practices is only steadily progressing. For this reason, this paper reflects on both the possibilities and limitations of cultural weed control practices. Cultural weed control utilises a number of principles, predominantly: (i) a reduced recruitment of weed seedlings from the soil seedbank, (ii) an alteration of crop–weed competitive relations to the benefit of the crop and (iii) a gradual reduction of the size of the weed seedbank. Compared with chemical control, the general applicability, reliability and efficacy of most measures is only moderate, and consequently, cultural control strategies need to consist of a combination of measures, resulting in increased systems complexity. Combined with the trade‐offs connected to some of the measures, this hampers large‐scale implementation. It is argued that tailoring cultural weed management strategies to the needs and skills of individual farmers would be an important step forward. Research can aid in improving the utilisation of cultural weed control strategies by focussing on a broadening of the range of available measures and by providing clear quantitative insight in efficacy, variability in outcome and trade‐offs of these measures.     

Transdisciplinary weed research: new leverage on challenging weed problems?

Transdisciplinary weed research (TWR) is a promising path to more effective management of challenging weed problems. We define TWR as an integrated process of inquiry and action that addresses complex weed problems in the context of broader efforts to improve economic, environmental and social aspects of ecosystem sustainability. TWR seeks to integrate scholarly and practical knowledge across many stakeholder groups (e.g. scientists, private sector, farmers and extension officers) and levels (e.g. local, regional and landscape). Furthermore, TWR features democratic and iterative processes of decision‐making and collective action that aims to align the interests, viewpoints and agendas of a wide range of stakeholders. The fundamental rationale for TWR is that many challenging weed problems (e.g. herbicide resistance or extensive plant invasions in natural areas) are better addressed systemically, as a part of broad‐based efforts to advance ecosystem sustainability, rather than as isolated problems. Addressing challenging weed problems systemically can offer important new leverage on such problems, by creating new opportunities to manage their root causes and by improving complementarity between weed management and other activities. While promising, this approach is complicated by the multidimensional, multilevel, diversely defined and unpredictable nature of ecosystem sustainability. In practice, TWR can be undertaken as a cyclic process of (i) initial problem formulation, (ii) ‘broadening’ of the problem formulation and recruitment of stakeholder participants, (iii) deliberation, negotiation and design of an action agenda for systemic change, (iv) implementation action, (v) monitoring and assessment of outcomes and (vi) reformulation of the problem situation and renegotiation of further actions. Notably, ‘purposive’ disciplines (design, humanities and arts) have central, critical and recurrent roles in this process, as do integrative analyses of relevant multidimensional and multilevel factors, via multiple natural and social science disciplines. We exemplify this process in prospect and retrospect. Importantly TWR is not a replacement for current weed research; rather, the intent is to powerfully leverage current efforts.     

Can weed hosts increase aggressiveness of Phytophthora infestans on potato?

Potato late blight, caused by Phytophthora infestans, is a major disease in potato production throughout the world. In southern Sweden, hairy nightshade (Solanum physalifolium), an alternative non-crop host to the pathogen, is an increasing weed problem. Single-lesion leaves infected by P. infestans were collected from potato and hairy nightshade to determine phenotypic and genotypic population differentiation of P. infestans between the two hosts. Genotypic variation was estimated using microsatellites as markers. The results showed no genotypic differentiation in the samples between the two hosts. Aggressiveness tests were performed using the sampled isolates to cross-inoculate potato and hairy nightshade. The proportion of infected leaves, latency period, lesion growth rate, and sporulation capacity were measured. For isolates from hairy nightshade, the odds of infection were higher on both hosts combined. When tested on potato leaves, isolates from hairy nightshade showed a significantly shorter latency period and higher sporulation capacity compared with isolates from potato. This indicates that an alternative host can filter populations of P. infestans toward a higher aggressiveness, which could lead to increasing problems in controlling potato late blight.     

Report on the palm aphid, <Emphasis Type="Italic">Cerataphis brasiliensis</Emphasis> on ‘Kalparaksha’ coconut cultivar

Aggregations of palm aphid Cerataphis brasiliensis (Hempel) (Aphididae: Hemiptera) on the unfurled spindle leaf of ‘Kalparaksha’ variety of coconut, a selection from Malayan Green Dwarf, is reported for the first time. C. brasiliensis has not yet been observed from other coconut varieties, viz., West Coast Tall, Chowghat Orange Dwarf, Chowghat Green Dwarf, and Dwarf x Tall hybrids planted in the research farm of Central Plantation Crops Research Institute, Kayangulam, Kerala, India. Only the apterous form of the palm aphid was noticed in the semi-tall variety and a variety-induced emergence of C. brasiliensis is indicated under natural conditions. Due to the presence of two phoretic ant species, no natural predator was observed in the aphid colonies. Two sprays of dimethoate (0.05%) at an interval of 15–20 days were effective in suppression of the pest on Kalparaksha.     

Studies on insects and mites causing galls on the leaves of European aspenPopulus tremula L. in the Ojców National Park in Poland

Analytical studies were conducted on the species composition of galls occurring on the leaves of European aspen Populus tremula L. in the Ojców National Park in 1997–1998. The species composition of galls was similar in two consecutive years, i.e 6 and 7 species, respectively (a total of 5492 galls). The most numerous species wasPhyllocoptes populi Nalepa in both years. Index of occurrence frequency and Agrell’s index of species co-existence have been calculated. This index reached the highest values in both years in case ofHarmandia cavernosa (Rübsaamen) andH. tremulae Winnertz.     

Studies on insects and mites causing galls on the leaves of European aspenPopulus tremula L. in the Ojców National Park in Poland

Analytical studies were conducted on the species composition of galls occurring on the leaves of European aspen Populus tremula L. in the Ojców National Park in 1997–1998. The species composition of galls was similar in two consecutive years, i.e 6 and 7 species, respectively (a total of 5492 galls). The most numerous species wasPhyllocoptes populi Nalepa in both years. Index of occurrence frequency and Agrell’s index of species co-existence have been calculated. This index reached the highest values in both years in case ofHarmandia cavernosa (Rübsaamen) andH. tremulae Winnertz.     

Natural diterpene β-lactone derivative as photosystem II inhibitor on spinach chloroplasts

α,7β-Dihydroxyvouacapan-17β-oic acid (1) was isolated from Pterodon polygalaeflorus Benth. Then, (1) was modified to obtain 6α-hydroxyvouacapan-7β,17β-lactone (2). Inhibition properties of both (1) and (2) were evaluated in spinach chloroplasts. Only compound (2) inhibited non-cyclic electron transport and ATP synthesis, i.e., (2) behaved as a Hill reaction inhibitor. Compound (2) did not affect photosystem I (PSI) activity but it did inhibit electron flow through PSII. Analysis of the partial PSII reactions from water to DCPIP_ox, water to silicomolybdate, and diphenylcarbazide to DCPIP_ox allowed locating inhibition sites at (i) the oxygen-evolving complex (OEC) and (ii) the redox enzymes of the electron transport chain, in the span of P₆₈₀ to Q_A. Chlorophyll a fluorescence measurements confirmed the action site for (2).     

Studies on insects and mites causing galls on the leaves of purple willow Salix purpurea L. in the Ojców National Park in Poland

Analytical studies were conducted on the species composition of galls occurring on the leaves of Salix purpurea L. in the Ojców National Park in 1999–2000. The species composition of galls was identical in two consecutive years. Galls were caused by 5species (a total of 480galls). The most numerous species in both years was Pontania viminalis (L.). Index of occurrence frequency and Agrell's index of species co-existence have been calculated. This index reached the highest values in case of Pontania dolichura (Thoms.) and P. viminalis (L.) in 1999 as well as Phyllocolpa leucaspis (Tischb.) and P. viminalis (L.) in 2000.     

Studies on insects and mites causing galls on the leaves of purple willow Salix purpurea L. in the Ojców National Park in Poland

Analytical studies were conducted on the species composition of galls occurring on the leaves of Salix purpurea L. in the Ojców National Park in 1999–2000. The species composition of galls was identical in two consecutive years. Galls were caused by 5species (a total of 480galls). The most numerous species in both years was Pontania viminalis (L.). Index of occurrence frequency and Agrell's index of species co-existence have been calculated. This index reached the highest values in case of Pontania dolichura (Thoms.) and P. viminalis (L.) in 1999 as well as Phyllocolpa leucaspis (Tischb.) and P. viminalis (L.) in 2000.