Occurrence Of Aphids Research Articles

Influences of Salt Stress on Cotton Metabolism and Its Consequential Effects on the Development and Fecundity of Aphis gossypii Glover.

The degree of global soil salinization is gradually deepening, which will inevitably affect agricultural ecology. It has been found that salt stress induces the resistance of host plants to phytophagous pests. However, little is known about the effects of salt-stressed cotton plants on the fitness of cotton aphids (Aphis gossypii Glover). In this study, we investigated the differences between cotton metabolomes under mild (75 mM NaCl) and moderate (150 mM NaCl) salinity conditions and their effects on the fitness of cotton aphids. The results showed that 49 metabolites exhibited significant upregulation, while 86 metabolites were downregulated, with the increasing NaCl concentration. The duration of nymphal aphids under 150 mM NaCl significantly extended to 6.31 days when compared with the control (0 mM NaCl, 4.10 days). Meanwhile, the longevity of adult aphids decreased significantly under 75 and 150 mM NaCl, with an average of 10.38 days (0 mM NaCl) reduced to 8.55 and 4.89 days, respectively. Additionally, the total reproduction number of single females decreased from 31.31 (0 mM NaCl) to 21.13 (75 mM NaCl) and 10.75 (150 mM NaCl), whereas the survival rate of aphids decreased from 81.25% (0 mM NaCl) to 56.25% (75 mM NaCl) and 34.38% (150 mM NaCl) on the 12th day. These results support the hypothesis that plants growing under salt stress are better defended against herbivores. Furthermore, 49 differential metabolites were found to be negatively correlated with the longevity and fecundity of adult aphids, while 86 different metabolites showed the opposite trend. These results provide insights into the occurrence and control of cotton aphids amidst the escalating issue of secondary salinization.

Pesticide thiamethoxam in seed treatment: Uptake, metabolic transformation and associated synergistic effects against wheat aphids

Precise, effective and green control plays an essential role in reducing environmental and ecosystem damage. Seed treatment has proven effective and long-lasting for target organisms, and exploring the reasons for long-term protection is important for sustainable agricultural development. This study examined the uptake and metabolism behaviour of thiamethoxam under seed treatment in wheat samples throughout the whole growth cycle, as well as the associated synergistic effects of thiamethoxam and its metabolites during the most severe period of aphid occurrence. Uptake and metabolism results showed that 41 % of thiamethoxam and its active metabolites (clothianidin and demethyl-clothianidin) accumulated mainly in flag leaves of wheat, severely harming aphids, which was significant in controlling leaf-feeding pests. Combined activity results showed that thiamethoxam, clothianidin and demethyl-clothianidin produced synergistic efficacy in controlling aphids, with cotoxicity coefficients ranging from 179.34 to 452.07. Compared with the control, thiamethoxam seed treatments at a rate of 1.5 a.i. g/kg seeds and 3.0 a.i. g/kg seeds can significantly enhance salicylic acid (55 % and 41 %) and jasmonic acid (168 % and 125 %) concentrations and invoke changes in the concentrations of plant secondary substances, which promoted wheat resistance to aphids. Future studies cannot ignore the synergistic effects of metabolites and plant secondary substances in pest control. These results provided data support for reducing pesticide use, increasing efficiency and making more rational use of neonicotinoid insecticides.

A viral movement protein targets host catalases for 26S proteasome-mediated degradation to facilitate viral infection and aphid transmission in wheat

The infection of host plants by many different viruses causes reactive oxygen species (ROS) accumulation and yellowing symptoms, but the mechanisms through which plant viruses counteract ROS-mediated immunity to facilitate infection and symptom development have not been fully elucidated. Most plant viruses are transmitted by insect vectors in the field, but the molecular mechanisms underlying virus‒host–insect interactions are unclear. In this study, we investigated the interactions among wheat, barley yellow dwarf virus (BYDV), and its aphid vector and found that the BYDV movement protein (MP) interacts with both wheat catalases (CATs) and the 26S proteasome ubiquitin receptor non-ATPase regulatory subunit 2 homolog (PSMD2) to facilitate the 26S proteasome-mediated degradation of CATs, promoting viral infection, disease symptom development, and aphid transmission. Overexpression of the BYDV MP gene in wheat enhanced the degradation of CATs, which leading to increased accumulation of ROS and thereby enhanced viral infection. Interestingly, transgenic wheat lines overexpressing BYDV MP showed significantly reduced proliferation of wingless aphids and an increased number of winged aphids. Consistent with this observation, silencing of CAT genes also enhanced viral accumulation and reduced the proliferation of wingless aphids but increased the occurrence of winged aphids. In contrast, transgenic wheat plants overexpressing TaCAT1 exhibited the opposite changes and showed increases in grain size and weight upon infection with BYDV. Biochemical assays demonstrated that BYDV MP interacts with PSMD2 and promotes 26S proteasome-mediated degradation of TaCAT1 likely in a ubiquitination-independent manner. Collectively, our study reveals a molecular mechanism by which a plant virus manipulates the ROS production system of host plants to facilitate viral infection and transmission, shedding new light on the sophisticated interactions among viruses, host plants, and insect vectors.

The hidden indirect environmental effect undercuts the contribution of crop nitrogen fertilizer application to the net ecosystem economic benefit

The current environmental and economic challenges of the application of nitrogen (N) fertilizer on crops are not only to provide an adequate food supply but also to reduce the resulting environmental pollution. A comprehensive understanding of the multiple effects of N fertilizer application on crops will help to more accurately guide the application of N fertilizer to meet current challenges, and to promote sustainable crop production. It is widely known that excessive N fertilizer applied to crops can lead to N-related direct environmental effects, including reactive N (Nr) losses, greenhouse gas emissions, and high environmental costs. However, few studies have revealed the hidden indirect environmental effect of crop N fertilizer application and its impact on the net ecosystem economic benefit (NEEB), which may be triggered by a N-crop-pest cascade pathway. In this study, we conducted three-year wheat field experiments at five N fertilizer application rates (0, 70, 140, 210, and 280 kg ha−1) in a city on the North China Plain. Excluding wheat yield and direct N-related environmental effects, the indirect effects of N fertilizer application, including the occurrence of cereal aphids (the most important wheat insect pests), the use of chemical pesticides for pest control, the impacts on the environmental and human health damage costs and NEEB were studied. Our results showed that the abundances of cereal aphids positively correlated with the N fertilizer application rates. At each N fertilizer application rate (70, 140, 210, 280 kg ha−1), 0.447 kg of active ingredients of chemical pesticides (0.222 kg insecticides and 0.225 g fungicides) per hectare per season were used to control insect pests and pathogens, while no pesticides were used at 0 kg ha−1(i.e., no N fertilizer was applied). The environmental and human health damage costs of pesticides for pest control increased $8 per hectare for wheat at four N fertilizer application rates and then reduced NEEB by the same amount. Our work extends previous studies and reveals the indirect negative environmental effect of N fertilizer application on crops triggered by a N-crop-pest cascade pathway. This effect undercuts the contribution of crop N fertilizer application on NEEB.

Detection of cassava brown streak ipomoviruses in aphids collected from cassava plants

Cassava is an important staple food in Africa and a major source of carbohydrates for 800 million people globally. However, cassava suffers severe yield losses caused by many factors including pests and diseases. A devastating disease of cassava is cassava brown streak disease (CBSD) caused by the cassava brown streak ipomoviruses (CBSIs) (family Potyviridae), Cassava brown streak virus (CBSV), and Ugandan cassava brown streak virus (UCBSV). Spread of CBSD is mainly through planting infected stem cuttings used for propagation. Transmission of CBSIs by the insect vector (Bemisia tabaci) has been reported. However, experimental transmission efficiencies of CBSIs are usually low. Recent research has showed the occurrence of a DAG motif associated with aphid transmission in other potyviruses, within the coat protein gene of CBSV. Consequently this study aimed to explore the possibility that besides whiteflies, aphids may transmit CBSIs. Cassava plants were assessed during a survey for occurrence of CBSD and aphids as potential alternative CBSIs vectors. We collected aphids from CBSD-symptomatic and symptomless cassava plants within farmers' fields in Uganda during April–July 2020. The aphids were analyzed for the presence of CBSIs by reverse transcriptase-polymerase chain reaction (RT-PCR) and to determine aphid species using mitochondrial cytochrome oxidase (mtCOI) barcoding. Unusual aphid infestation of cassava plants was observed at 35 locations in nine districts across Uganda and on 11 other plant species within or adjacent to cassava fields. This is the first report of aphids infesting cassava in Uganda. Molecular analysis of the aphid confirmed presence of three different aphid species in the surveyed cassava fields, namely, Aphis solanella, Aphis fabae mordvilkoi, and Rhopalosiphum sp. mtCOI nucleotide sequences for the aphids in which CBSIs were detected are deposited with Genbank under accession numbers OP223337-40. Both UCBSV and CBSV were detected by RT-PCR in aphids collected from cassava fields with CBSD-affected plants. The CBSIs were detected in 14 aphid samples collected from 19 CBSD-symptomatic cassava plants. These results suggest the ability of aphids to acquire CBSIs, but transmission experiments are required on their vector potential.

Weather and landscape drivers of the regional level of pest occurrence in arable agriculture: A multi-pest analysis at the French national scale

Limiting crop pests while favouring environmentally friendly practices is challenging. It is required to identify the main drivers of infestation for multiple pests at different scales. In particular, large scale approaches are missing, while they could contribute to increase the predictability of pest infestation. In this study, the French national Epiphyt dataset (part of the national epidemiological monitoring service) was used to assess the relative importance of weather and landscape drivers on the between-region variability in the level of occurrence of some agricultural pests. Using a regional resolution, we analysed the proportion of occurrence of slugs, cereal aphids and oilseed rape pests over 181 small agricultural areas (‘regions’) across France in 2018. The mean proportion of occurrence per region was 0.17 for slugs, 0.25 for cereal aphids and 0.61 for oilseed rape pests. Weather variables were more explanatory than landscape ones for the proportion of occurrence of slugs and oilseed rape pests while the two types of variables had a similar level of explanation for the regional proportion of aphid occurrence. Slugs were favoured by high winter temperatures, high soil wetness index and important proportions of hedgerows in the region but negatively influenced by high winter rainfalls. Cereal aphids and oilseed rape pests were negatively influenced by the regional proportion of grassland. Additionally, the winter air humidity and the proportion of perennial crops in the region decreased the proportion of occurrence of oilseed rape pests. We detected no effect of the proportion of host crop or the proportion of organic farming in the region. This study emphasises that, in line with findings derived from more local studies, weather characteristics are an important driver of the regional level of pest occurrence in arable fields; it also highlights that the proportion of grassland at the regional scale could be a key tool to design insect-pest suppressive landscapes.

Studies on insect-pests complex in mustard (Brassica juncea L.)

The present investigation was carried out at Students’ Instructional Farm of Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya during Rabi, 2016. Among various Brassica oilseed crop mustard is an important Rabi oilseed crop, attacked by mustard aphid (Lipaphis erysimi), mustard sawfly (Athalia lugens proxima), painted bug (Bagrada hilaris) and cabbage butterfly (Pieris brassicae) insectpests at different part of plant at different growth stages. The result of present studies revealed that the populations of mustard sawfly appeared at an early stage of crop growth 45th SW of 2016 which continued up to 1st SW of 2017 with varying population ranging from 0.33 grubs/plant to 3.33 grubs/plant. The maximum population of mustard sawfly was recorded as 3.33 grubs/plant in 48th SW of 2016. The 1st occurrence of mustard aphid was recorded during 49th SW of 2016 which continued up to 10th SW of 2017 with varying population ranging from 0.41 to 212.67 aphids/10 cm central twig/plant. The peak period of occurrence of mustard aphid was observed in 7th SW of 2017, the maximum population of this insect was recorded as 212.67 aphids/10 cm central twig/plant. The population of painted bug initiated during 2nd SW of 2017 and remained up to 9th SW of 2017. The bug population ranged from 0.33 to 2.67 bugs/plant. The maximum population of bug was recorded as 2.67 bugs/plant in 5th SW of 2017. The other insect-pests (grass hopper, green bug cabbage butterfly, etc.) made its first appearance during 46th SW of 2016 and continued up to 11th SW of 2017 with population varying from 0.33 to 4.00 insects/plant.

Studies on insect-pests complex in mustard (Brassica juncea L.)

The present investigation was carried out at Students’ Instructional Farm of Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya during Rabi, 2016. Among various Brassica oilseed crop mustard is an important Rabi oilseed crop, attacked by mustard aphid (Lipaphis erysimi), mustard sawfly (Athalia lugens proxima), painted bug (Bagrada hilaris) and cabbage butterfly (Pieris brassicae) insect-pests at different part of plant at different growth stages. The result of present studies revealed that the populations of mustard sawfly appeared at an early stage of crop growth 45th SW of 2016 which continued up to 1st SW of 2017 with varying population ranging from 0.33 grubs/plant to 3.33 grubs/plant. The maximum population of mustard sawfly was recorded as 3.33 grubs/plant in 48th SW of 2016. The 1st occurrence of mustard aphid was recorded during 49th SW of 2016 which continued up to 10th SW of 2017 with varying population ranging from 0.41 to 212.67 aphids/10cm central twig/plant. The peak period of occurrence of mustard aphid was observed in 7th SW of 2017, the maximum population of this insect was recorded as 212.67 aphids/10 cm central twig/plant. The population of painted bug initiated during 2nd SW of 2017 and remained up to 9th SW of 2017.The bug population ranged from 0.33 to 2.67 bugs/plant. The maximum population of bug was recorded as 2.67 bugs/plant in 5th SW of 2017. The other insect-pests (grass hopper, green bug cabbage butterfly, etc.) made its first appearance during 46th SW of 2016 and continued up to 11th SW of 2017 with population varying from 0.33 to 4.00 insects/plant.

Analysis of the level of colonization of winter wheat by grain aphid (Sitobion avenae F.) in various regions of Poland in 2009–2018

The grain aphid (Sitobion avenae F.) is one of the most economically important cereal pests in Europe, causing both direct feeding damage (especially on the ears) and indirect virus transmission. For this reason, systematic monitoring of its intensity on crops and the damage it causes is crucial in the protection of winter wheat and other cereal plants in order to determine the current level of risk. The summary of observations illustrated the changing intensity of the occurrence of grain aphids over selected years in individual regions of the country and provinces.

Establish real-time monitoring models of cotton aphid quantity based on different leaf positions in cotton seedlings

Cotton aphids, Aphis gossypii glover, are major pest threats to cotton plants, leading to quality and yield loss of cotton. Rapid and accurate evaluation on the occurrence and quantity of cotton aphids can help precision management and treatment of cotton aphids. The occurrence rules of cotton aphids on different leaf positions in cotton seedling stage for two cultivars of cotton were studied. The quantity of cotton aphids in the whole cotton seedlings were predicted based on the single leaf cotton aphid quantity. The correlation analysis results showed that cotton aphids of single leaf were significantly and positively correlated with the infected time, the all leaves of the whole plant, the whole plant contained all leaves and branches. The variance analysis results showed that cotton aphids of single leaf were significant difference with the extension of infected time. Based on different leaf positions, monitoring models were constructed respectively. The modelling set’s determination coefficient of ‘Xinluzao-45’ was greater than 0.8, while ‘Lumainyan-24’ was greater than 0.6. The best monitoring leaf position was the third for ‘Xinluzao-45’, the sixth for ‘Lumianyan-24’. From the data analysis, we can realize that it is feasible to construct a monitoring model based on the occurrence of cotton aphid in one leaf in cotton seedling, and different cotton varieties have different leaf positions. This will greatly reduce the investment of manpower and time.

DIVERSITY AND ABUNDANCE OF LANDING APHIDS IN TWO AREAS OF SEED POTATO PRODUCTION IN TUNISIA; RELATIVE TO THE INCIDENCE OF POTATO VIRUSES

Aphid flight activities were monitored in 2015 in two areas of seed potato production in Tunisia. Yellow water traps were used to investigate the diversity of aphidofauna and the incidence of aphids involved in potato virus transmission. A total of 9966 specimens belonged to 73 taxa were captured. The cumulative abundance recorded in Douala (first site) was much higher than in El Ogla (second site) (8768 vs 1189 specimens). The most preponderant species in Douala were Aphis spiraecola Patch (66.1%) and Aphis spp. group (13.5%). In El Ogla Rhopalosiphum padi (L.) comprised 58.9% of total catches, followed by Acyrthosiphon pisum (Harris) (12%) and Aploneura lentisci (Passerini) (10.4%). The highest values of diversity indices were recorded on April 23 th [Shannon-Wiener index (H’)=2.58; Simpson index (1-D)=0.88] in Douala and on May 12th (H’=1.70; 1-D=0.75) in El Ogla. The detection of viral infections by DAS-ELISA determined the predominance of Potato virus Y amongst five main potato viruses tested. Overall Chi-square analysis determined significant differences crossing all areas of seed and ware potatoes and season crops. The highest incidence of viruses was recorded in Douala (18.5%) while El Ogla was under the threshold value (4%). This might be attributed to the occurrence of aphids in early season known previously to be efficient vectors of PVY and to the characteristics of area including climatic conditions, altitude and landscape structure. These results provide new evidence for El Ogla as ideal site to produce healthy tubers while conversely Douala is favourable for the propagation of vectors and viruses.

Suitability of NDVI index to pea condition evaluation at diverse phosphorus fertilization

In this 3-year study the suitability of the normalized differenced vegetation index (NDVI) to the evaluation of pea plant infestation by aphids and expected seeds yield was investigated. The effect was assessed in the conditions of the increasing doses of phosphorus fertilization (0, 70, and 140 kg P2O5 ha–1) and in the different pea aphid (Acyrthosiphon pisum Harris) occurrence on six various cultivars of pea. Independent of the dose, the phosphorus fertilization supported the occurrence of aphids on pea plants of Batuta, Model, and Protecta cultivars where in Tarchalska and Mecenas cultivars only the standard dose (70 kg ha–1) showed such effect. NDVI index was not clearly, unambiguously correlated to the intensity of A. pisum occurrence. Such factors as the deficiency or excessive amount of phosphorus, as well as meteorological conditions and the cultivar of host plant had the greater effect on its value than the presence of aphids. All this testifies that the NDVI index is not reliable indicator of aphid occurrence on pea, however it can offer a promising method to select the cultivars under sub-opitmal conditions. The seed yield was strongly related to agronomical factors (fertilization, cultivars) and plant (NDVI) variable, while marginally to environmental variable (aphids).

DIVERSITY AND ABUNDANCE OF APHIDS AND THEIR NATURAL ENNEMIES IN A CEREAL ECOSYSTEM IN BISKRA REGION (SOUTHEAST OF ALGERIA)

Ponte Academic JournalApr 2020, Volume 76, Issue 4 DIVERSITY AND SEASONAL OCCURRENCE OF APHIDS AND THEIR NATURAL ENEMIES IN A CEREAL ECOSYSTEM IN BISKRA REGION (SOUTHEAST OF ALGERIA)Author(s): Nour-Elhouda Bakroune ,Mehdi Sellami, Hafsa Bakroune, Mostapha AbabsaJ. Ponte - Apr 2020 - Volume 76 - Issue 4 doi: 10.21506/j.ponte.2020.4.14 Abstract:Field surveys were carried to determine the seasonal occurrence of aphids and their natural enemies on durum wheat in Biskra (southeastern of Algeria), between december and june 2015. The sample was composed of 18 aphid species and 28 of their natural enemies. The species Rhopalosiphum maidis, captured is the most abundant species. The ladybug Coccinella septempunctata L., is the most abundant auxiliary. Predators from the following families were determined: Coccinellidae (Coleoptera), Chrysopidae (Neuroptera), Syrphidae. Braconidae (Hymenoptera). Aphid numbers fluctuated from early janury to the beginning of june and were highest from late febrery to early april. This richness of natural enemies of aphids negated the need for pesticides application. Therefore, conservation of natural enemies to fight against pests of agronomic interest such as aphids is a way of promoting biological control in the cereal agro-ecosystem in Biskra region. Download full text:Check if you have access through your login credentials or your institution Username Password

Evaluation of forewarning models for mustard aphids in different agro-climatic zones of India.

Mustard aphid, Lipaphis erysimi (Kaltenbach), is the most serious pest of Rapeseed-Mustard which is known to be responsible for a tremendous loss in yield and oil content, under various agro-climatic conditions of India. Information support on aphid occurrence and intensity is necessary for effective management by the farmers in the mustard-growing belt. In this study, an effort is made to develop forewarning model using the field data on aphid for 12 consecutive rabi seasons from 2003-2004 to 2014-2015 under different agro-climatic locations in India. Three main components of aphid-related stages were identified for which necessary forewarnings were needed to be issued: (1) severity, (2) the time of reaching the economic threshold level (ETL) for decision-making on pesticide application, and (3) time of occurrence of peak population. To address these, three different models were developed/used and validated using incident field dataset. Those field observations when the infestation level were below severe category (< 60) during rising phase of the aphid population were found to indicate highest R sqr. (0.82) for the model-I during validation. When model-II was used, 11 out of 14 locations (78.57%) stood validated. The assumptions made in model-III also got validated when humidity thermal ratio (HTR) of the week of peak population ranged between 1.5 and 4 (lowest among the weeks considered), and population reached severe category. The models showed better results during real-time validation in seasons 2016-2017 and 2017-2018, thus suggesting that these three models can be used to ascertain the severity, week of ETL, and week of peak aphid population for Brassica juncea varieties all over the mustard belt in India and can be operationalized spatially to forewarn against the aphid pest population in future under Gramin Krishi Mausam Sewa (GKMS) scheme.

Effects of elevated CO2 on foliar soluble nutrients and functional components of tea, and population dynamics of tea aphid, Toxoptera aurantii

The rising atmospheric CO2 concentration has shown to affect plant physiology and chemistry by altering plant primary and secondary metabolisms. Nevertheless, the impacts of elevated CO2 on plant nutrients and functional components of tea remain largely unknown, which will likely affect tea quality and taste under climate change scenario. Being sources of nutrients and secondary chemicals/metabolites for herbivorous insects, the variation in foliar soluble nutrients and functional components of tea plants resulting from CO2 enrichment will further affect the herbivorous insects' occurrence and feeding ecology. In this study, the tea aphid, Toxoptera aurantii was selected as the phloem-feeding herbivore to study the effects of elevated CO2 on foliar soluble nutrients and functional components of tea seedlings, and the population dynamics of T. aurantii. The results indicated that elevated CO2 enhanced the photosynthetic ability and improved the plant growth of tea seedlings compared with ambient CO2, with significant increases in net photosynthetic rate (+20%), intercellular CO2 concentration (+15.74%), leaf biomass (+15.04%) and root-to-shoot ratio (+8.08%), and significant decreases in stomatal conductance (−5.52%) and transpiration rate (−9.40%) of tea seedlings. Moreover, elevated CO2 significantly increased the foliar content of soluble sugars (+4.74%), theanine (+3.66%) and polyphenols (+12.01%) and reduced the foliar content of free amino acids (−9.09%) and caffeine (−3.38%) of tea seedlings compared with ambient CO2. Furthermore, the relative transcript levels of the genes of theanine synthetase (+18.64%), phenylalanine ammonia lyase (+49.50%), s’-adenosine methionine synthetase (+143.03%) and chalcone synthase (+61.86%) were up-regulated, and that of caffeine synthase (−56.91%) was down-regulated for the tea seedlings grown under elevated CO2 relative to ambient CO2. In addition, the foliar contents of jasmonic acid (+98.6%) and salicylic acid (+155.6%) also increased for the tea seedlings grown under elevated CO2 in contrast to ambient CO2. Also, significant increases in the population abundance of T. aurantii (+4.24%–41.17%) were observed when they fed on tea seedlings grown under elevated CO2 compared to ambient CO2. It is presumed that the tea quality and taste will be improved owing to the enhanced foliar soluble nutrients and functional components of tea seedlings under the climate change scenario, especially on account of the rising atmospheric CO2 concentration, while the climate change may exacerbate the occurrence of tea aphid, T. aurantii, despite the enhanced secondary defensive chemicals manifested by the CO2 enrichment.

Field Studies on the Natural Role of the Predator Chrysoperla carnea (Steph.) Attacking Aphids in a Mixed Orchard Containing Pear and Plum Trees, with Evaluating the Possibility of Using Pheromone Traps against the Peach Fruit Fly, Bactrocera zonata (Saunders).

The present study was carried out to record the population density of two aphids' species (the cotton aphid Aphis gossypii on pear trees and the mealy plum aphid Hyalopterus pruni on plum ones) and the green lacewing predator Chrysoperla carnea, which occurred in a mixed orchard containing both trees, during season 2019, in Qalubia Governorate. The obtained data showed that the occurrence of aphids' species on pear and plum trees covered the whole four months of study (March-June, 2019). Aphids' populations were the highest in their numbers, during the two months April and May 2019, on both the two trees species. The results indicated also that, the existence periods of aphids' individuals on both pear and plum trees were the same as those recorded in case of the predator C. carnea. A field experiment was performed by putting pheromone traps on plum trees (during the fruiting season from the second half of May to the first half of July, 2019). Highest total number of the peach fruit fly Bactrocera zonata males was recorded in pheromone traps during the first half of June, 2019 (when using one or two pheromone capsules on the same glued sheets, on the same plum tree). Generally, the lacewing predator C. carnea can be massed reared in the laboratory and released for controlling aphids on pear and plum trees and/or other fruit trees that are subjected to attack by the two aphids' species. Besides, the pheromone traps can be used against the peach fruit fly B. zonata on plum trees and/or fruit trees that suffer from pest attack. The uses of either C. carnea and/or pheromone traps can be applied with other available safe control methods, in the frame of Integrated Pest Management (I.P.M.) programs, for protecting man heath and the surrounding environment from pollution.

Population, Fluctuation of Aphid on the different Wheat Varieties from Larkana District

The present investigation has been carried on the population fluctuation of aphids on the different wheat varieties i-e TD-1, Benazir, Tj-83, QS-4, NIAamber from larkana district. Triticium astivum (wheat) is considered very important food crop in Pakistan including Sindh. This crop is attacked by numbers of insect including aphids, which is responsible for reduction of its yield. The occurrence of aphid has been started in the month of January and its peak infestation was observed during mid March when wheat crop was fully grown. During the present study significant large numbers of specimens were collected from the different varieties of wheat. The collected material was sorted out in to two species viz: Rhopalosiphum padi (L.), Schizaphis graminum (Rondani). During this study it was noted that TD-1 was significantly affected by R.padi and S.gramium as compare to other tested varieties. It was observed that aphid reached peak point in mid February on leaves then in the end of February aphids started shifting from leaves to ears and their population start to decline in month of April.

Factors determining local and seasonal variation in abundance of Harmonia axyridis (Coleoptera: Coccinellidae) in Central Europe

To determine the causes of the variation in the seasonal dynamics of Harmonia axyridis (Pallas) in Central Europe, numbers of adults and larvae of this invasive species were recorded on trees (Acer, Betula, Tilia) throughout the growing seasons from 2011 to 2016. Each year beetles were collected every two weeks, using a standardized sweeping method. The seasonal dynamics was expressed as plots of abundance (number of individuals per 100 sweeps) against time (Julian day) and these plots (seasonal profiles) were compared in terms of their size (area under the seasonal profile curve), range, timing and height of the mode (maximum abundance). Timing and size of seasonal profiles varied among hostplants, years and sites. Abundance of larvae paralleled aphid occurrence and peak abundance of adults followed that of larvae 10 to 20 days later. Population dynamics before and after the peak were determined by dispersal. Adults arrived at sites before the start of aphid population growth and persisted there long after aphid populations collapsed. The abundance of H. axyridis decreased from 2011 to 2013 and then increased, achieving the previous levels recorded in 2015 and 2016. The variation in seasonal profiles revealed that H. axyridis, in terms of its response to environmental conditions, is a plastic species and this flexibility is an important factor in its invasive success.

Population dynamics of aphid species in Korean seed potato cultivation area over four decades

AbstractThe world's climate is changing. This can affect agricultural insects and the damage they cause by altering their ecology, behavior and habitats. Aphids are emerging as an indicator of climate change, and they are a good model for understanding these environmental changes, especially based on their migratory behavior. In this study, the occurrence of aphids in a seed potato field in Pyeongchang, Korea, was monitored daily using a yellow water pan trap from 1977 to 2017. During these 40 years, the annual migration fluctuations of the aphids were analyzed, with particular focus on four species known to vector potato viruses, Aphis gossypii, Aulacorthum solani, Macrosiphum euphorbiae, and Myzus persicae. It was found that, as time goes by, the start point of spring migration in these aphid species was getting earlier while the peak in autumn migration gradually moved to the winter season. Moreover, the annual total number of collected aphids increased by 3.74 times during the 40 years. Together with a mean annual temperature increase of 1.03°C in Pyeongchang over the past four decades, there is a potential threat of expansion in the distribution of aphid species. Therefore, we carefully hypothesized that this temperature change could influence the aphid's population changes in the Korean peninsula. This information can be used in an integrated aphid management program in seed potato cultivation.

Landscape structure alters the abundance and species composition of early-season aphid populations in wheat fields

Agricultural landscape composition is reported to have effects on the occurrence of natural enemies in fields, but the responses of herbivorous pests to landscape features have rarely been studied. Our previous landscape-level study in northern China found that natural enemies had no significant effects on the population growth of wheat aphids at the colonization stage. Hence, we hypothesised that the initial aphid population in wheat fields may largely depend on immigration events from other habitats. In this study, we investigated the effects of landscape pattern on wheat aphid abundance and species composition at the colonization stage by surveying population densities of different aphid species along a landscape gradient. We found that noncrop habitats such as woodlots, fallow lands and vegetation around dwellings or wetlands in the landscape all had positive correlations with aphid abundance in wheat fields because they provided a source for aphid colonization. More specifically, the proportion of woodlots, fallow lands, dwellings, and other crops increased the abundance of Rhopalosiphum padi (L.), and the existence of water and dwellings in an agricultural landscape facilitated the occurrence of Sitobion avenae (Fabricius). Likewise, the abundance of Schizaphis graminum (Rondani) in wheat fields was found to be significantly promoted by the presence of water. The habitats around water and dwellings usually provide the overwintering sites for the aphids. Furthermore, wheat production acreage had a significant negative correlation with the abundance of R. padi, S. avenae and S. graminum. Landscape characteristics had a significant effect on the species composition of wheat aphids. Our study suggests that noncrop habitats in a landscape enhance aphid occurrence at the population colonization stage, and differences in overwintering host plants among aphid species may be responsible for the differing responses of the abundance of different aphids to landscape variables, which greatly altered aphid population composition across different landscapes. These results highlight the need for taking landscape effects on the pest itself into consideration when designing landscape-level pest management strategies.