Population Build-up Research Articles

Rapid Range Expansion of a Marine Ectotherm Reveals the Demographic and Ecological Consequences of Short-Term Variability in Seawater Temperature and Dissolved Oxygen.

AbstractThe distributions of marine ectotherms are governed by physiological sensitivities to long-term trends in seawater temperature and dissolved oxygen. Short-term variability in these parameters has the potential to facilitate rapid range expansions, and the resulting ecological and socioeconomic consequences may portend those of future marine communities. Here, we combine physiological experiments with ecological and demographic surveys to assess the causes and consequences of sudden but temporary poleward range expansions of a marine ectotherm with considerable life history plasticity (California market squid, Doryteuthis opalescens). We show that sequential factors related to resource accessibility in the core range-the buildup of large populations as a result of competitive release and climate-associated temperature increase and oxygen loss that constrain aerobic activity-may drive these expansions. We also reveal that poleward range expansion alters the body size-and therefore trophic role-of invading populations, with potential negative implications for socioeconomically valuable resident species. To help forecast rapid range expansions of marine ectotherms, we advocate that research efforts focus on factors impacting resource accessibility in core ranges. Determining how environmental conditions in receiving ecosystems affect body size and how body size is related to trophic role will help refine estimates of the impacts of future marine communities.

Efficacy of Indigenous Crude Plant Extracts against Rice Weevil, Sitophilus oryzae L. 1763 (Coleoptera: Curculionidae)

Rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae) is a widely distributed and major insect pest of rice that causes considerable losses to both husked and unhusked rice grains. Plant-based pesticides are alternative to synthetic pesticides in managing stored product pests owing to their severe hazardous effects. Thus, locally available plant leaf crude extracts i.e., neem (Azadirachta indica A. Juss 1830), turmeric (Curcuma longa L. 1753), and mint (Mentha longifolia L. Huds. 1762) were investigated at 2 % (w/w) concentration against S. oryzae in unhusked and husked rice. Adult mortality was recorded at 24, 48 hours, and seven days after the application whereas, population build-up was recorded at 1-, 2-, and 3-months intervals. Overall and grain weight loss was also recorded at the end of the experiment. In husked and unhusked rice, the highest mortality percentage was observed in turmeric powder (93.30 %) and neem (80.00 %), respectively. In comparison to plant extracts, relatively higher population growth of S. oryzae was recorded in control husked and unhusked rice. At the end of the 3rd month, the highest and lowest population in husked rice grains was recorded in control (70.67 ± 3.18) and turmeric treatments (18.00 ± 2.65), respectively, whereas control and neem treatments exhibited the highest (83.67 ± 3.28) and lowest (39.67 ± 2.33) populations in unhusked rice. The lowest grain weight loss in husked and unhusked rice was recorded in turmeric (9.33 %) and neem (16.67 %), respectively. Thus, turmeric and neem extracts should be investigated on large scale under commercial warehouses for the management of S. oryzae in husked and unhusked rice.

Ground-truthing predictions of a demographic model driven by land surface temperatures with a weed biocontrol cage experiment

Herbivorous insects play important roles in agriculture as pests or as weed biological control agents. Predicting the timing of herbivore insect population development can thus be of paramount importance for agricultural planning and sustainable land management. Numerical simulation models driven by temperature are often used to predict insect pest population build-up in agriculture. Such simulation models intend to use station-derived temperatures to drive the development of the target insect, although this temperature may differ substantially from that experienced by the insect on the plant. To improve the estimations, it has been suggested to replace air temperature in the model by land surface temperature (LST) data. Here, we use a numerical simulation model of insect population dynamics driven by either air temperature (combined with atmospheric temperature soundings) or land surface temperature derived from satellites to predict the population trends of the leaf beetle Ophraella communa, a potential biological control agent of Ambrosia artemisiifolia in Europe. For this, we conducted an extensive field experiment that included caged O. communa populations at five sites along an altitudinal gradient (125–1250 m a.s.l.) in Northern Italy during 2015 and 2016. We compared our model predictions using air or land surface temperature with observed beetle population build-up. Model predictions with both air and land surface temperatures predicted a similar phenology to observed populations but overestimated the abundance of the observed populations. When taking into consideration the error of the two measurement methods, the predictions of the model were in overlapping timeframes. Therefore, the current model driven by LST can be used as a proxy for herbivore impact, which is a novel tool for weed biocontrol.

Onion Germplasm Possesses Lower Early Season Thrips Numbers

Onion is one of the most valuable vegetable crops in the US. Onion thrips were identified as one of the main threats to the US onion industry. An integrated approach, including host plant tolerance, is required. For this study, four New Mexico State University breeding lines, along with two thrips-attractive cultivars, were evaluated for their attractiveness to thrips. In addition, this study observed thrips population dynamics throughout the growing season and the relationship between onion plant size and thrips attractiveness. The experiment was designed as a randomized complete block design with three blocks, each containing four replications. Thrips-infested bulbs were used to ensure the presence of thrips and thrips-attractive plants were used to ensure equal thrips distribution throughout the field. Ten plants were randomly selected from each plot and thrips and leaf numbers were counted multiple times through the growing season. Plants of NMSU breeding lines were observed to have fewer thrips, be more tolerant to thrips pressure and produce more leaves and larger bulbs than thrips-attractive entries. Early in the growing season, leaf number was not a determining factor in thrips population dynamics. The larger bulb weights of the breeding lines allowed them to maintain their market value. A delay in thrips population buildup in plants of the breeding lines may result in the critical threshold for spraying for thrips being reached later in these lines. This would potentially allow for fewer pesticide applications by growers, increasing growers’ profits and ensuring a more environmentally friendly approach to plant production.

Field evaluation of the entomopathogenic fungi enriched with organic amendments against Holotrichia consanguinea Blanchard (Coleoptera: Scarabaeidae) infesting groundnut crop

BackgroundWhite grubs are highly polyphagous and most destructive soil pests inflicting damage to a groundnut crop that causes economic yield losses in commercial groundnut production in India. In this study, potential of the two entomopathogenic fungi (EPF) viz., Metarhizium anisopliae (Metchnikoff) Sorokin and Beauveria bassiana (Balsamo) Vuillemin enriched with organic amendments like neem cake, castor cake, vermicompost and poultry manure was evaluated to manage buildup of white grub population in groundnut crop.ResultsResults showed that the plot treated with soil application of vermicompost @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha showed the least amount of plant mortality due to white grub which was at par with castor cake @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha and neem cake @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha which showed only 1.74, 2.00 and 2.24% plant damage, respectively. Plots treated with vermicompost @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha had the fewest (0.19) white grubs per one meter row length. Based on highest pod yield, net realization and net gain, the treatment with soil application of vermicompost @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha was found most effective treatments for the management of white grub in groundnut.ConclusionsResults indicated that M. anisopliae supplemented with various organic amendments, such as vermicompost, castor cake, and neem cake can be commercialized as a healthy alternative to minimize the use of synthetic pesticides in groundnut crops for white grub management.

Organic maize and bean farming enhances free-living nematode dynamics in sub-Saharan Africa

Despite their important ecological roles for soil health and soil fertility, free-living nematodes (FLN) have received relatively limited research attention. The present study evaluated the community structure and diversity of FLN in a field setting. The experiments were conducted in on-farm and on-station field plots sown to maize (Zea mays) and beans (Phaseolus vulgaris) under four cropping practices. These farming systems included organic (compost and biopesticide use), conventional (synthetic fertilizer and pesticide applications), farmer practice (organic and synthetic amendments) and a control (non-amended plots). Nineteen genera of free living nematodes, belonging to bacterivores, fungivores, omnivores and predators were recorded. Among these, bacterivores (Cephalobidae and Rhabditidae) were the most dominant group in the organic systems when compared to the conventional and control systems. Farming systems influenced the abundance and diversity of free living nematodes, with the organic farming system having higher values of maturity, enrichment and structural indices than other farming systems. This would indicate greater stability in soil health and improved soil fertility. This implies that the organic farming systems play a key role in improving the biodiversity and population buildup of FLN, compared with other systems. Our study helps to improve our understanding of how farming systems influence soil biodynamics, while studies on the longer-term effects of organic and conventional farming systems on the build-up or reduction of free living nematodes for improved ecosystem services are needed.

Adaptive dynamics of earhead bugs in different genotypes of sorghum under abiotic factors

Based on preliminary screening, ten sorghum genotypes were selected on the basis of head bugs infestation and grain damage rating by visual observation method and replicated thrice in a plot size of 3 metre row length. The population build-up of sorghum earhead bugs was low with mean of 18.9 bugs/5 panicles in resistant genotypes as compared to susceptible ones (66.20 bugs/panicles) and minimum temperature, relative humidity of morning and evening hours were negatively correlated while, maximum temperature and sunshine hours were positively correlated with head bug population build-up in sorghum crop. It is inferred that sorghum earhead bugs did not preferred some sorghum varieties with certain morphological as well as biochemical plant characters which in the end reflects in the population build-up of sorghum earhead bugs.

Effect of meteorological parameters and natural enemies on population dynamics of rose aphid, Macrosiphum rosae L. under mid hills of Himachal Pradesh, India

The study revealed that the rose aphid first appeared in 8th standard meteorological week (SMW) and attained the first peak on 10th SMW, when maximum and minimum temperatures were around 20.5 and 5.9 (°C), respectively and morning relative humidity was 62.50% during both the years. The second mean population build-up was observed on 36th SMW and the population fluctuated between 37th to 52nd SMW and peak population was recorded on 51st SMW (29.05 aphids/shoot), which declined to 1.48 aphids/shoot on 52nd SMW during both years. The rose aphid population was significantly negatively correlated with Tmax (r = -0.453**) and Tmin (r = -0.572**); whereas relative humidity (morning and evening) and rainfall showed a nonsignificant negative correlation with the rose aphid population. The stepwise regression analysis of rose aphid population with weather parameters showed that the maximum temperature contributed 20.50% variation in rose aphid population followed by morning relative humidity (17.90%) and minimum temperature (12.70%). The difference between coefficient of multiple determination (R2) and adjusted R2 was less, indicating that the abiotic variables (Tmax: 0.017; Tmin: 0.030) have a significant effect on the rose aphid population. Hence, this study gives information on abiotic and biotic factors that naturally suppress the rose aphid, which helps develop management strategies against M. rosae in the mid-hills of Himachal Pradesh, India.

Ecological assessment of soil mite communities in diverse fodder production systems of semi–arid central India

The agrarian community of North West region of Bundelkhand in Central India is mainly dependent on livestock rearing and related activities. In order to support the livestock-based economy of the area, a number of fodder and pasture development schemes are promoted by government of India. The hypothesis is that various such systems due to change in land management and vegetation pattern; may affect soil structure and native soil biota. This study presents ecological assessment of soil mite communities in selected fodder production systems in this geographical region. Mites, the most diversified among soil biota are considered effective bio-indicators of soil conditions. So, in this study, their community structure, seasonal abundance were closely monitored and analyzed in different fodder-based land utilization schemes viz., natural grasslands, cultivated pastures (Cenchrus ciliaris + Stylosanthes hamata), pure tree stands of Albizia amara, silvipstures (tree + grass) and fodder crop cultivation. Mites were represented by 44 families under 4 suborders. Most dominant groups (families) observed were Tarsenomidae,Caligonellidae, Gamasellus,Dermanyssoidea, Scheloribetidae, Epilohmanniidae, Oppiidae, Galumnidae, Perlohmanniidae, Orobatulidae and Hydrozetidae. Peak population buildup was recorded in the month of August. Diversity was low in annual fodder cultivation system and bare land situations. Perennial fodder production systems namely, open tree stand of Albizia amara, natural grassland, improved pastures and silvipasture systems supported higher diversity of mite fauna. Greater soil mite diversity in such carefully designed perennial systems indicate that such systems might ecologically sound and would achieve long term fodder sustainability for the region.

Influence of weather variables on whitefly population build-up and progression of okra yellow vein mosaic virus disease

Influence of weather variables on whitefly population build-up and progression of okra yellow vein mosaic virus disease

Pests associated with two brassicaceous oilseeds and a cover crop mix under evaluation as fallow replacements in dryland production systems of the northern Great Plains

Abstract Identifying pests associated with novel crops is important for forecasting impacts on their production and determining if they could be reservoirs of pests moving over onto cash crops. We carried out preliminary pest surveys in two bioenergy crops, carinata (Brassica carinata Alexander Braun (Brassicaceae)) and camelina (Camelina sativa (Linnaeus) Crantz (Brassicaceae)), and a cover crop mix under evaluation to replace fallow in rotations with wheat. Insect pests were sampled in each of the three crops over two years. Crucifer flea beetles, Phyllotreta cruciferae Goeze (Coleoptera: Chrysomelidae), dominated the pest complex associated with carinata and the cover crop mix, comprising more than 70% of the insects sampled. In contrast, the pest complex associated with camelina was dominated (40–91%) by generalist Lygus spp. (Heteroptera: Miridae). Crucifer flea beetles were 200–1000 times more abundant in carinata than in camelina, suggesting that they could be a serious pest of carinata. Camelina, in contrast, appears less likely to be attacked by, or serve as a reservoir for, crucifer flea beetles. Future work to assess feeding damage and population buildup of pests in these crops is needed to determine impacts on their production and the extent to which they may be reservoirs of canola pests over broader spatial scales.

Climate-Based Modeling and Prediction of Rice Gall Midge Populations Using Count Time Series and Machine Learning Approaches

The Asian rice gall midge (Orseolia oryzae (Wood-Mason)) is a major insect pest in rice cultivation. Therefore, development of a reliable system for the timely prediction of this insect would be a valuable tool in pest management. In this study, occurring between the period from 2013–2018: (i) gall midge populations were recorded using a light trap with an incandescent bulb, and (ii) climatological parameters (air temperature, air relative humidity, rainfall and insulations) were measured at four intensive rice cropping agroecosystems that are endemic for gall midge incidence in India. In addition, weekly cumulative trapped gall midge populations and weekly averages of climatological data were subjected to count time series (Integer-valued Generalized Autoregressive Conditional Heteroscedastic—INGARCH) and machine learning (Artificial Neural Network—ANN, and Support Vector Regression—SVR) models. The empirical results revealed that the ANN with exogenous variable (ANNX) model outperformed INGRACH with exogenous variable (INGRCHX) and SVR with exogenous variable (SVRX) models in the prediction of gall midge populations in both training and testing data sets. Moreover, the Diebold–Mariano (DM) test confirmed the significant superiority of the ANNX model over INGARCHX and SVRX models in modeling and predicting rice gall midge populations. Utilizing the presented efficient early warning system based on a robust statistical model to predict the build-up of gall midge population could greatly contribute to the design and implementation of both proactive and more sustainable site-specific pest management strategies to avoid significant rice yield losses.

Influence of Abiotic Factors on Population of Aphid Complex and Its Coexisting Natural Enemies in Mustard Agroecosystem

A field experiment was conducted to determine the population build-up of mustard aphid and their natural enemies in relation to abiotic factors at TCA, Dholi during the Rabi season of 2018-19 and 2019-20 respectively. The incidence of mustard aphid started in the 2nd and 3rd SMW of 2019 and 2020 respectively and reached maximum in 8th SMW in both the years. However, the predatory activity of coccinellids, syrphid larvae and spiders were started from 3rd SW with their peak activity at 3rd and 4th week of February in both the years. Mustard aphid population exhibited positive correlation with maximum temperature (0.347 & 0.543), minimum temperature (0.317 & 0.152) and negative correlation with relative humidity (-0.083 & -0.479) during 2019 & 2020 respectively and rainfall (-0.35) during 2020. However, natural enemies viz., coccinellids, syrphid larvae and spiders exhibited positive correlation with Tmax, Tmin, rainfall and negative correlation with RH in both the years.

Population buildup of whitefly, Bemisia tabaci (Gennadius) on parthenocarpic cucumber in relation to weather parameters under protected environment in Punjab

Population buildup of whitefly, Bemisia tabaci (Gennadius) on parthenocarpic cucumber in relation to weather parameters under protected environment in Punjab

Epidemiology of Nosema spp. and the effect of indoor and outdoor wintering on honey bee colony population and survival in the Canadian Prairies.

The epidemiology of Nosema spp. in honey bees, Apis mellifera, may be affected by winter conditions as cold temperatures and differing wintering methods (indoor and outdoor) provide varying levels of temperature stress and defecation flight opportunities. Across the Canadian Prairies, including Alberta, the length and severity of winter vary among geographic locations. This study investigates the seasonal pattern of Nosema abundance in two Alberta locations using indoor and outdoor wintering methods and its impact on bee population, survival, and commercial viability. This study found that N. ceranae had a distinct seasonal pattern in Alberta, with high spore abundance in spring, declining to low levels in the summer and fall. The results showed that fall Nosema monitoring might not be the best indicator of treatment needs or future colony health outcomes. There was no clear pattern for differences in N. ceranae abundance by location or wintering method. However, wintering method affected survival with colonies wintered indoors having lower mortality and more rapid spring population build-up than outdoor-wintered colonies. The results suggest that the existing Nosema threshold should be reinvestigated with wintering method in mind to provide more favorable outcomes for beekeepers. Average Nosema abundance in the spring was a significant predictor of end-of-study winter colony mortality, highlighting the importance of spring Nosema monitoring and treatments.

Modeling of aphid complex and its associated natural enemies in rapeseed-mustard in relation to climatic factors


 Effect of climatic factors on population build-up of aphid complex of rapeseed-mustard viz. mustard aphid, Lipaphis erysimi (Kaltenbach), cabbage aphid, Brevicoryne brassicae (Linnaeus), and green peach aphid, Myzus persicae (Sulzer) and associated natural enemies (coccinellids, syrphids and a parasitoid, Diaeretiella rapae M’Intosh) was studied at Experimental Farm of CSK HPKV Palampur over a period of three years. Correlation coefficients indicated that the temperature favoured build-up of aphid population and their natural enemies while rainfall exerted negative impact. The population of coccinellids was negatively correlated with the population of L. erysimi and M. persicae while, positive correlation with B. brassicae was observed. On the other hand, population of syrphids was found to be positively correlated with aphid population. Predictive model using stepup regression analysis revealed that a weak relation in aphid population was attributed by weather parameters particularly minimum, maximum temperature and bright sunshine hours. Regression analysis revealed that 89 per cent variation in parasitization by D. rapae was attributed by minimum and maximum temperature, rainfall, relative humidity and bright sunshine hours.

Influence of meteorological parameters on population build-up of brinjal shoot and fruit borer, Leucinodes orbonalis Guenee in Assam

Influence of meteorological parameters on population build-up of brinjal shoot and fruit borer, Leucinodes orbonalis Guenee in Assam

Evaluation of biorational pesticides against Bemisia tabaci Gennadius and Amrasca biguttula biguttula Ishida and its impact on natural enemies population in cowpea ecosystem

The whitefly (Bemisia tabaci Gennadius) and leafhopper (Amrasca biguttula biguttula Ishida) are two major sucking pests causing considerable damage in cowpea production. Considering the negative impact of chemical pesticides on food safety, environment, and human welfare; an eco-friendly approach is aimed at utilizing naturally derived products for effective management of the aforesaid pests and maintain ecological balance. The present study was performed under field conditions to evaluate the performance of five naturally derived components [water plant extracts viz. chili (Capsicum annum), garlic (Allium sativum L.), and neem (Azadirachta indica A. Juss.) along with cow urine in three different combinations, two formulated entomopathogenic fungi (Metarrhizium anisopliae and Beauveria bassiana) along with one positive (Imidacloprid) and negative (water) control. The study was designed in RCBD with three replications for the years 2019 and 2020, respectively. Combined application of neem, chili, garlic, and cow urine extracts (NCGC) at 10% w/v had the highest population reduction of whitefly (0.09 & 0.10 per three leaves) and leafhopper (0.03 & 0.04 per three leaves) over both standard controls after two round of application in the year 2019 and 2020, respectively. Natural enemies (coccinellids) population was drastically reduced in positive control whereas the population build-up strengthened in all other treatments including negative control. Cowpea treated with NCGC produced a higher economic yield (1.54 Mg ha−1) than those of other treatments. The study suggests that NCGC is an effective biorational based technology for sustainable management of whitefly and leafhopper in cowpea cropping system with ensuring food safety and eco-friendly approach. This novel finding can be integrated with an integrated pest management program for diverse cropping systems.

Species Composition, Abundance, and Seasonal Dynamics of Perilla Seed Bugs (Heteroptera: Lygaeidae) in Weeds and Perilla Fields in Korea.

Perilla seed bugs (Nysius sp.) are considered to be the emerging pests causing nutritional and yield losses in perilla and cereal crops. A survey of perilla seed bugs on weeds and perilla crops was conducted over the course of 2 yr in Korea to determine the species composition, abundance, and seasonal dynamics of perilla seed bugs. Three species of Heteroptera (Nysius plebeius, Nysius hidakai, and Nysius inconspicuus), nymphs of Nysius species, and several parasitoid species were collected from weeds and perilla crops. Nysius hidakai was the most abundant perilla seed bugs. In 2019, adult perilla seed bugs, nymphs of perilla seed bugs, and parasitoid species were more abundant in weed species than in perilla crops. An early peak with a greater number of adult perilla seed bug (N. hidakai) was observed in weeds in 2020. However, an identical peak with a similar number of perilla seed bug (N. hidakai) was found in perilla crops in both years. Peak perilla seed bugs densities were observed in the 4th week of June, 2020 in weeds. Parasitoid species from Aphidiidae (1), Braconidae (11), Eulophidae (7), Figitidae (5), Ichneumonidae (7), Platygastridae (1), and Pteromalidae (5) subfamilies were collected. Perilla seed bugs seem to be a serious and increasingly important pest in several field crop species including perilla crops grown on the southern Korean peninsula. Monitoring and early detection of insect species are vital to predicting seasonal colonization and population build-up of perilla seed bugs on perilla crops from a climate change perspective, and essential for developing appropriate management techniques. Thus, continuous monitoring of perilla seed bugs in alternative weed hosts is needed to protect perilla crops from perilla seed bug infestation.

G × E interaction, biochemical characterization and SSR marker analysis of eggplant (Solanum melongena) for shoot and fruit borer resistance

Brinjal or Aubergine or Eggplant, one of the top ten growing vegetables incurs serious crop losses due to shoot and fruit borer from season to season especially under high humidity leading to population buildup reducing the crop yield up to 60–70%. This present investigation was carried out during 2018–19 at Annamalai University, Tamil Nadu, India using 36 genotypes and landraces to identify stable genotypes of eggplant with high yield and resistance to shoot and fruit borer. The genotypes were also characterized using eleven SSR markers, where three were not amplified. The AMMI and GGE biplot analyses have shown the significant contribution of genotypic variation over the environments and their interaction. AMMI and GGE analysis revealed that ICO361838 was the most stable genotype for fruit yield per plant, whereas ICO-354749 and ICO-427008 were stable for the trait shoot borer infestation. The resistant lines had the highest total phenol, polyphenol oxidase and ascorbic acid content but total sugar content was lowest in these lines. The identified genotypes can be further utilized in breeding for resistance and the selection can also be done on the basis of these biochemical parameters. However, the SSR markers utilized were not informative enough and for marker assisted selection a greater number of primers should be added.