Peak Population Research Articles

Seasonal incidence of TIL hawk moth, Acherontia styx (Westwood) at Raipur, C.G.

The field experiment were conducted at Research Cum Instructional Farm at IGKV, Raipur (C.G.) during kharif 2018. The til hawk moth appeared during 36th SMW i.e. 1st week of September with a mean population of 0.08 til hawk moth / plant. The peak population were 2nd week of October (41st SMW) with a mean population of 0.48 til hawk moth / plant. Thereafter, the population declined and reached to its minimum levels of 0.36 til hawk moth / plant during 3rd week of October (42nd SMW).The correlation between til hawk moth, Acherontia styx and weather parameters during kharif 2018 results indicated that the population showed significant positive correlation with maximum temperature (r = 0.692), sunshine hours (r = 0.757), while, significant negative correlation morning relative humidity (r= - 0.727) and evening relative humidity (r = - 0.674).

FRUIT FLIES (DIPTERA: TEPHRITIDAE) IN MANGO ORCHARDS IN THE MINAS GERAIS SEMI-ARID REGION*

ABSTRACT We studied the diversity and level of infestation of fruit flies in mango orchards in a semi -arid region in the state of Minas Gerais, Brazil. Surveys were conducted in orchards in the irrigated perimeter of Jaíba municipality in northern Minas Gerais, from November 2016 to November 2017. Sampling was conducted by collecting mangoes and trapping flies in McPhail traps. Of the total adult flies obtained (9,033), 8,902 specimens were Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), making it the predominant species collected in the traps (91.3%). ‘Palmer’ mango fruits were only infested with C. capitata, and showed high infestation rates (15.14 puparia kg-1 of fruit). The population peak of C. capitata coincided with the occurrence of mature mango fruits in the orchards. C. capitata was the most frequent and constant species identified in the survey and can be considered a dominant species.

Survey and Monitoring of Chinese Citrus Fly (Bactrocera minax Enderlein) in Sweet Orange Orchards of Sindhuli, Nepal

Chinese citrus fly, Bactrocera minax (Enderlein), is one of the most important pests of citrus. The pest is more problematic in the eastern part of the country, Nepal. Because of the difficulties associated with the control of this pest by chemical insecticides, farmers had experienced great losses in Sweet Orange. Therefore, a participatory field survey was conducted under farmer field conditions to assess losses and measure the efficacy of different local and recommended management options to address the problem of this pest. Study consisted of two major parts: monitoring of pest population and farmer’s survey. For monitoring three orchards were selected located at different altitude i.e. 1200 masl, 1300 masl and 1400 masl. Great Fruit fly Bait (25% protein hydrolysate and 0.1% abamectin) in McPhail traps were used for monitoring. Monitoring was done in every 7 days interval and lures were changed in every 15 days for the effectiveness. Only 18.3% farmers were using protein bait for the management of fruit fly. B. minax had peak population intensity at May and was found decreasing after June so the management practices should be adopted before June to prevent the loss by fruit fly. However, for best effective control attention for monitoring and management procedures has to take place throughout the life cycle of the insect.

Effectiveness of population density as natural social distancing in COVID19 spreading

Recently, many countries have decided to reopen gradually and some of them have thought that social distancing has not had a significant effect. In our study, a new view of the importance of social distancing to prevent the spread of coronavirus has been presented in terms of the relationship between peak day and peak period and population density of nine countries. Data for nine different countries in different coronavirus situations have been analyzed. The analysis process was applied by using three programs, namely; WebPlotDigitizer, WSxM and Origin. The results provide evidence of the effectiveness of social distancing by calculation of the effect of population density on coronavirus infection. That was applied by two stages, the first one by determination of two different groups of countries depending on the rate and range of coronavirus spread. These two groups were countries with developed and developing COVID19 which lead to calculate the peak day and the period times of developed groups. Then, analysis of that data with population density was evaluated to indicate there are significant effects of population density on peak day and peak period times which explain the importance of social distancing between people to manage and control that. The results showed that there are increasing in peak day and peak period times with increasing the population density.

Rice insect pests and their natural enemies complex in direct seeded and transplanted rice (Oryza sativa) of Chidambaram areas of Cuddalore, India

Rice is the cereal grain that feeds half the planet. Rice fields are economically important as well as ecologically valuable. Rice fields are one of the biggest ecosystems that can be found in the tropics, including diverse insect pests and their natural enemies. In this view, rice varieties were sown in experimental plots of Faculty of Agriculture, Annamalai University, Chidambaram. The values are found significant at 5% level. To monitor the pest and natural enemies by using net sweeping and yellow pan trap method was used. The results showed that the maximum number of yellow stem borer was observed in the direct-seeded rice variety of CR Dhan 209 (7.33) and the leaf folder population was maximum in the direct-seeded rice variety of CR Dhan 204 (7.33). The peak population of grasshopper and green leafhopper was recorded in the transplanted rice variety of CR Dhan200 (11.33), CR Dhan 209 (8.00). The values were found significant at 5% level. The maximum number of Braconidae was observed in direct-seeded rice variety of CR Dhan 205 (3.66), and Ichneumonidae was recorded the highest number of direct-seeded and transplanted rice in the variety of CR Dhan 202 (3.00). The peak population of Trichogrammatidae was recorded in direct-seeded rice of CR Dhan 207 (3.66). The presence of Platygastridae was high in the transplanted rice variety of CR Dhan 201 (8.66), respectively. Among the rice ecosystems, more insect pests and crop damage were noticed in direct-seeded rice more than the transplanted rice.

Population dynamics of cabbage aphid, Brevicoryne brassicae L. (Homoptera: Aphididae) in relation to weather factors on major brassica crops in central rift valley of Ethiopia: baseline studies for the management of the pest

Cabbage aphid, Brevicoryne brassicae L. is a major pest of cruciferous crops all over the world. The population dynamics of the pest is highly influenced by weather factors. A field study was carried out in 2018/19 at Debre Zeit Agricultural Research Center (DZARC) to determine the role of weather factors on cabbage aphid population dynamics. Four brassica crops namely Ethiopian Kale, head Cabbage, Cauliflower and Broccoli were planted on two different dates at fifteen days interval. Results revealed that, maximum aphid population of 164.7 ± 2.93 and 70.2 ± 2.64 aphid/ inch2 leaf area were recorded on the date 15/12/2018, on late planted kale and head cabbage crops, respectively. The highest mean infestation for all tested crops (22.77aphids/inch2 leaf area) was observed on late planted crops as compared to 0.82 aphids/inch2 leaf area on early plantings. Accordingly, early planted crops were 96.4% safer than late planted crops for aphid infestations. Correlation analysis showed that, the maximum temperature had a significant influence on aphid population specifically on kale crop (r = 0.676, p = 0.032). Although, the relative humidity, minimum and average temperature, rainfall and wind speed has shown none significant correlation with aphid population growth. There was variation in aphid population, crop preference and infestation peak in relation to weather factors. In general, during the experiment higher aphid population was observed on kale crop when the maximum temperature and relative humidity were < 26.750C and 72%, respectively. This study provided information on time of initial infestation and also the peak activity of the particular insect in relation to temperature. Therefore, the population peak timing reported in this study (45th SMW) is useful as a critical infestation period for scheduling cabbage aphid management practices.

Moving toward Net-Zero Emissions Requires New Alliances for Carbon Dioxide Removal

The 1.5°C target will require removing at least some of the carbon dioxide (CO2) previously emitted. Knowledge on how this can be done has been increasing, though barriers remain concerning governance, policy, and acceptability. For the 26th session of the Conference of the Parties (COP26) to move beyond an academic debate on CO2 removal (CDR), a broader alliance of research and policy communities, industry, and the public is needed.

Seasonal diversity of soil microarthropods in two different vegetable plots of Aligarh-India

Soil microarthropods are intimately linked with health and fertility of soil as well as plant productivity. In India, despite their rich faunal diversity, information on soil microarthropods diversity and interactions with variety of edaphic factors is extremely limited. The present study is carried out to observe seasonal diversity of soil microarthropods in two different vegetable plots in Aligarh. The two vegetable plots chosen in this study where predominantly Tomato (Lycopersicom esculentum) and Brinjal (Solanum melongena, family-Solaneceae) have been grown and sapling has been sown in April when plants attained a height of approximately 6″. The samples collected randomly from a depth of 5 cm. @ of four samples per month for a period of 1 year. All microarthropods extracted with the help of Tullgren funnel apparatus. Among soil microarthropods collected, Collembolans have highest average monthly density (15.20 inds./sample) in brinjal plot and greatest abundance (18.7 inds./sample) in tomato plot. A highly significant negative correlation observed between Collembolans population with reference to soil temperature (r = – 0.867, P 0.05). Neutral pH level preferably influences the Collembolans as well as Acarina (mites). Peak population buildup of Collembola and Acarina was found in spring, and winter months, whereas sharp decline in summer months was observed. Therefore, this study clearly establishes the fact that habitat difference as well as edaphic factors play important roles in buildup of soil microarthropods population.

Path analysis of environmental factors affects the population dynamics of American bollworm, Helicoverpa armigera (Hubner) lepidoptera-noctuidae in cotton

The path analysis of environmental factors affects the population dynamics of American Bollworm (ABW), Helicoverpa arecmigera (Hubner) Lepidoptera –Noctuidae was assessed at the Jawharlal Nehru Krishi Vishwa Vidhyalaya, Cotton Research Station, Khandwa M.P. The perusal of data on the population of American bollworm, Helicoverpa armigera revealed that the pest was first come into view in the 28th SMW i.e. Ist week of July and remained active till 51st SMW (III week of December). The peak population level was observed during 35th SMW i.e. Ist week of September. The weather condition prevailed during the peak population viz. maximum temperature, minimum temperature, morning relative humidity, evening relative humidity, sunshine hours, wind velocity, rainfall and rainy day were 34.11°C, 25.49°C, 76.54%, 39.56%, 8.29 hours per day, 6.94 kmph, 18.50 mm and 0.50 days respectively. The simple correlation studies between American bollworm eggs population and weather factors revealed that the ABW Eggs population had a significant positive correlation with minimum temperature. The multiple regression computed with eleven parameters as independent variables and ABW population as dependent variables was as follow Y=72.7571.401X1+0.027X2+0.276X3+0.048X4+0.056X5+1.517X6-0.052X7-1.413X8-0.624X9+2.657X10-0.945X11 (R2=0.772). The Path coefficient analysis revealed that minimum temperature had positive and high direct effect on ABW egg population, followed by spider, morning relative humidity and green lacewing respectively.

The Seasonal Abundance of Immature Stages of the Cabbage Worm, Pieris rapae L. on Cabbage Crop in Beni Suef Governorate, Egypt

In recent years the number of cabbage worm Pieris rapae has increased in Beni Suef Governorate, and they have threatened the vegetative growth of cabbage crop, especially in the newly reclaimed areas. That study was conducted during the 2017/18 – 2018/19 seasons respectively. Results obtained revealed that there are two distinct peaks for each eggs, larvae and pupae stages per year on cabbage plants. The immature stages covered the entire period of sampling from August 2017, till April 2018 on the cabbage plant. The first peak of egg Population was recorded on November 6 2017 and another smaller peak on mid of March 2018. The maximum larval Population (770 larvae) appeared on November 13, 2017 another smaller peak (450 larvae) on beginning April 2018. Pupal population exerted two periods of abundance On the 22 November, 2017 the highest numbers of pupae were recorded and another smaller peak on mid-April 2018. We can point out that the first and second peak of these stages in 2018/19 came about one to two weeks after the previous season 2017/18. The results also showed that there were statistically significant differences between the number of immature stages and the seasons of the year in cabbage fields. The cabbage sown in autumn season was severely attacked by this pest, followed by spring season. Autumn insect population was about 2-3 folds of winter population. Knowledge of the seasonal abundance of the immature stages is of great valuable to help in planning a control program against this target pest.

Effect of abiotic factors on seasonal incidence of mites on pear trees in Amritsar region

A survey of mites was conducted on pear trees in Amritsar region from February 2018 – November 2019 at three different locations. Three species of phytophagous mites belonging to the family Tetranychidae and Tenuipalpidae and five species of predatory mites of Phytoseiidae, Stigmaeidae and Cunaxidae were recorded from Khalsa College Amritsar, Guru Nanak Dev University and Government garden/nursery (Attari) locations. Among the three locations, maximum mite population was observed at Attari with dominant incidence of Tetranychidae and least of Cunaxidae. The incidence of the mites increases with increase in temperature and was highest during hot dry summer season. Population started decreasing due to rains in monsoon season. However, the mite population was completely absent during cold winter season. The highest peak of mite population was recorded at maximum temperature of 42°C and minimum of 25°C with no rainfall. There was significant positive correlation of mite abundance with temperature and negative correlation with rainfall at all the three locations. The coefficient of determination of all the mites with abiotic factors had significant contribution in regulating the mite population.

Bio-efficacy of insecticide, Cyclaniliprole 100 DC against gram pod borer, Helicoverpa armigera Hubmer. Infesting chickpea

The present investigation was conducted at Ariculture Research Station, Hanumanamatti, University of Agricultural Sciences, Dharwad during rabi Season. Gram pod borer Helicoverpa armigera larval population was observed from vegetative stage of the crop. The peak population of gram pod borer were observed from flowering stage. The new insecticide molecule Cyclaniliprole 100 DC different dosages Viz., 30,35 and 40 g a.i./ha gave significantly highest in reduction of larval population compared to Chlorantraniliprole 18.5 SC @ 25 g a.i./ha and Novaluron 10% EC @ 75 g a.i./ha without causing any significant effect on natural enemies. The highest yield was obtained from Cyclaniliprole 10% DC @ 40 g a.i /ha treated plots (13.25 q/ha) which was statistically at par with the treatment of Cyclaniliprole 10% DC @ 35 g a.i/ha, Chlorantraniliprole 18.5 SC @ 25 g a.i./ha and Cyclaniliprole 10% DC @ 30 g a.i./ha (12.92, 12.80 and 11.71 q/ha, respectively).

The biology and ecology of pine aphid, Eulachnus tuberculostemmatus (Hemiptera: Aphididae) and its demographic responses to environmental changes

Abstract Eulachnus tuberculostemmatus (Hemiptera: Aphididae) is the most abundant aphid species attacking pine trees in Isfahan, Iran. Population fluctuations of this species and its natural enemies were studied on Pinus brutia var. eldarica by weekly sampling. Its fertility‐life table parameters were determined in the field in spring and summer 2016. Furthermore, effects of different temperatures (15, 20, 25, and 30 °C) and irrigation regimens (well irrigated, moderately and highly drought‐stressed) on its performance were investigated in the laboratory. The aphid population reached its peak abundance between 11 April and 23 May. Also, a minor peak was observed between mid‐November and mid‐December. During the survey, no sexual morphs were observed. Most fertility‐life table parameters of E. tuberculostemmatus were found to be significantly higher in spring than in summer. Aphids reared at 20 and 25 °C had a significantly higher net reproductive rate, intrinsic rate of increase and finite capacity for increase compared to those reared at 15 and 30 °C. Also, the aphid performed significantly better on highly drought‐stressed trees, due to higher survival rate, female adult longevity and fecundity. Population peaks of the four Coccinellidae predators Adalia bipunctata, Hippodamia variegata, Propylea quatuordecimpunctata and Coccinella septempunctata coincided with that of the aphid.

Photophysiology response of non-calcifying microalgae Chaetoceros sp. on increasing anthropogenic carbon dioxide and temperature

Increased use of fossil fuels, land use change, and deforestation, causing an increase in carbon emissions in the atmosphere, is estimated to 4.1 ± 0.1 GtC year−1, it lowers the pH in the oceans, causing ocean acidification which affects the productivity of calcifying and non- calcifying phytoplankton. The study was conducted to analyze the photophysiology response of non-calcifying microalgae Chaetoceros sp on increasing anthropogenic carbon dioxide and temperature. There were 3 levels of CO2 concentration, and temperature was tested (385 ppm, 750 ppm, 1000 ppm CO2 and temperature of 30°C, 32°C and 34°C) with the factorial pattern. The results showed that increasing CO2 concentration affected the growth of daily population, peak population, the rate of cell growth, and chlorophyll content of Chaetoceros sp. The highest population growth and chlorophyll content occurred at 385 ppm CO2 and 32°C, population decreased with increasing CO2 concentration and temperature. Increasing carbon dioxide and temperature significantly affected on decrease of Chaetoceros sp productivity.

Seasonal incidence of fall army worm, Spodoptera frugiperda (Smith) infesting maize crop at Raipur (Chhattisgarh)

The field experiment were conducted at Research Cum Instructional Farm at IGKV, Raipur (C.G.) during kharif 2018, to know the seasonal incidence of fall army worm, Spodoptera frugiperda infesting maize crop. Fall army worm, Spodoptera frugiperda appeared during 37th SMW i.e. 2nd week of September with a mean population of 0.12 larva/plant. The peak population were observed in the fourth week of September with a mean population of 0.56 larva/plant. Thereafter, the population declined gradually and reached to a minimum level of 0.16 larva/plant during 4th week of October (42nd SMW). The correlation between fall army worm, Spodoptera frugiperda and abiotic parameters during kharif 2018 results indicated that the population demonstrated a significant positive correlation with maximum temperature (r=0.586).

Investigation on the Natural Enemies of Jute Yellow Mite and Their Performances and Seasonal Incidence

The jute yellow mite Polyphagotarsonemus latus constitutes one of the major pests of jute crop in Bangladesh. The objective of this work was to investigation on the natural enemies of jute yellow mite. The investigation on the natural enemies of jute yellow mite were studied in the laboratory of Bangladesh Jute Research Institute during March 2011 to September 2013. As many as six predators of jute yellow mite viz, Predatory mite, Thrips, Minute pirate bug, Lady bird beetle, Mirid bug and Spider were collected and identified. The predation rate of the predatory mite Amblyseius sp. showed an average of 8.8 jute yellow mite per hour in laboratory condition. Predatory mite reached the peak on the 20th June. The highest population was 25 predatory mite/25 leaves. The population of predatory mite declined sharply in the 1st week of July. The nymph and adult of Scolothrips consumed an average of 15.4 and 20.10 yellow mite per hour. Scolothrips sp reached its peak population on 30th June and declined occurred in the 1st week of July. Both nymph and adult stage of Orius sp. predate 24.5 and 21 jute yellow mite respectively. The highest number of Minute pirate bug 20 was recorded at 30th June. Both the grubs and adults of lady bird beetle predate on all the stage of yellow mite. Grub was found as voracious feeder showing a predation efficiency of 35 per hour. The highest and lowest number of Ladybird beetle was recorded on 25th June and 5th May respectively. The highest 15 Mirid bug was recorded at 30th June. An unidentified species of spider was found to consume yellow mite.

Does stump removal reduce pine weevil and other damage in Norway spruce regenerations? – Results of a 12-year monitoring period

Although impacts of intensive forest harvesting practices such as removing logging residue and stumps for bioenergy on forest ecosystem has been extensively studied, no information is available about the long-term effects of stump harvesting on the health status of young Norway spruce stands. In the present study, we surveyed damage caused by the large pine weevil (Hylobius abietis L.) and other causal agents as well as the height growth of the Norway spruce seedlings for 12 years in stump-harvested and non-harvested experimental plots. The overall effect of stump harvesting combined with mounding on the health and survival of spruces was positive: 70% of spruce seedlings in stump-harvested plots were spared any damage, while 58% of seedlings remained undamaged in undisturbed control plots. The positive effect of stump removal and mounding on tree health was mainly due to reduced pine weevil damage. In all, 14.8 and 24.6% of spruce seedlings were gnawed by pine weevil in stump-harvested and control plots, respectively. In stump-harvested plots, pine weevil damage was slighter and lasted for a shorter time than in control plots. In addition, damage caused by Hylastes spp., black root beetles, was significantly less on stump-harvested plots. By contrast, vole damage was most frequent in stump-harvested plots during the population peak when the vole density was exceptionally high. Irrespective of whether stumps were harvested or not, stump roots provided a source of Heterobasidion inoculum in the next spruce regeneration. During this early stage of stand development only a few spruce seedlings were killed by Heterobasidion root rot and there were neither temporal nor quantitative treatment-related differences between the treatments. From the third year onwards the height growth of undamaged seedlings was more rapid in stump-harvested than non-harvested plots. Our results suggest that the overall risk of damage in young Norway spruce stands can be reduced by stump harvesting. Thus, stump harvesting and mounding seem to decrease the need for supplementary planting, which reduces regeneration costs that represent a considerable financial investment for a forest owner.

Seasonal incidence and management of red cotton bug (Dysdercus koenigii) infesting Bt cotton under Red lateritic zone of West Bengal

A field study was undertaken in the Institutional Research Farm, Institute of Agriculture, Visva-Bharati, Sriniketan to evaluate the seasonal incidence and population variation of red cotton bug with respect to weather conditions and its insecticidal management during kharif, 2018-19. Experiments were conducted in a Randomized Block Design (RBD) with three replications having nine different insecticidal treatments including one untreated control. Red cotton bug population was recorded from Second week of August and continued till harvest with a peak population Peak population at Second week of November. Multivariate correlation studies showed that the red cotton bug population was significantly positively correlated with Temperature Gradient and significantly negatively correlated with Relative Humidity and Rainfall. Among the different insecticides tested combination of Imidacloprid 6% + Lambda Cyhalothrin 4% SL @ 500 ml/ha proved most effective and giving 71.14% and 94.84% pest population reduction in two consecutive treatment imposition.

Subnational disparities in EU law use: exploring the GEOCOURT dataset

ABSTRACT We present a new dataset compiling the geographic coordinates of the entire universe of courts that have passed on cases to the European Court of Justice over the lifetime of the European Union. The GEOCOURT Dataset allows the exploration of spatial disparities and clustering effects across time, member states and tiers of courts. Exploration of our new dataset reveals that involvement in the preliminary ruling procedure tends to be concentrated in a relatively small subset of regions within member states, often the region hosting the country's capital. We also consider several regional attributes associated with Article 267 use, which point out avenues for future research. Controlling for country and region fixed effects, we show that peak courts, GDP, population and capital along with with indicators of economic well-being and integration in cross-border trade are positively associated with referral propensity.

Spatial variation in breeding phenology at small spatial scales: A stochastic effect of population size

AbstractSpatial variation in phenology can occur at small spatial scales over which individuals can disperse or forage within one generation. Previous studies have assumed that variations in phenological peaks are caused by differences in abiotic environmental characteristics. However, environments should generally be similar among local habitats over small spatial scales. When the local population size is small, the phenological peak of the local population should be strongly affected by the variation in timing expressed by individuals. If a regional population consists of small local subpopulations (e.g., a metapopulation), the stochastic processes regulated by population sizes may explain the spatial variation in phenology. In this study, we quantitatively evaluated the extent of the spatial and annual variations in the breeding phenology of the forest green tree frog, Rhacophorus arboreus habiting a small area (&lt;10 km2). The spatial variation in phenological peaks among 25 breeding sites was large over 6 years. This spatial variation was not explained by differences in air temperature or water depth. Randomization tests revealed that a large portion of the spatial variation could be explained by differences in population size, without considering site‐specific factors. Annual variations in phenological peaks tended to be greater for smaller populations. These results imply that the stochastic process might have caused the spatial and annual variations in the phenological peaks of R. arboreus observed in the study region. Understanding spatiotemporal variation in phenology determined by stochastic process would be important to better predict interspecific interactions and (meta)population dynamics at small spatial scales.