scholarly journals Population dynamics and parasitism rate of leafhopper species (Hemiptera: Cicadellidae) in maize (Zea mays L.) crop

2021 ◽  
Vol 12 (2) ◽  
pp. 448-457
Author(s):  
Atilla Atmaca ◽  
Mehmet Mamay ◽  
Çetin Mutlu
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Management Practices ◽  
Zea Mays L ◽  
Egg Parasitoid ◽  
Pesticide Use ◽  
Effective Management ◽  
Parasitism Rate ◽  
Maize Crop ◽  
Beneficial Insect

Maize is an important crop in Turkey that is infested by various leafhopper species during the whole season. Monitoring population dynamics and parasitism rate of these species would help to devise effective management practices. This study determined population dynamics of four leafhopper species, i.e., Zyginidia sohrab Zachvatkin, 1947, Empoasca decipiens Paoli, 1930 and Psammotettix striatus (Linnaeus, 1758) in second maize crop. Similarly, population dynamics and parasitism rate of egg parasitoid (Anagrus atomus) of these leafhopper species was also studied through July to November 2018 in Akçakale, Harran and Haliliye districts of Şanlıurfa province, Turkey. Population density of all species significantly varied among studied districts with the highest density of A. atomus recorded on 7 September with 30 adults/trap in Haliliye district. The parasitism rate on Z. sohrab eggs was 78% in Akçakale, 82% in Harran and 63% in Haliliye district. It was followed by E. decipiens with 18% in Akçakale, 14% in Harran and 32% in Haliliye. The highest population density of Z. sohrab was recorded on 21 September in Akçakale (4328 adults/trap), Harran (3920 adults/trap) and Haliliye (4592 adults/trap). Similarly, E. decipiens had the highest (1216 adults/trap) population density on 10 August in Harran, 12 October (368 adult/trap) in Akçakale and 17 August (2184 adults/trap) in Haliliye. Population dynamics of leafhoppers and their egg parasitoid coincided with each other. The parasitism rate was lower than other provinces in Turkey which is owed to high pesticide use in Şanlıurfa province. Therefore, chemical control should be decided by considering population development of beneficial insect species.

Effects of hybrids, population densities, fertilization and irrigation on grain corn (Zea mays L.) in Quebec

1992 ◽  
Vol 72 (4) ◽  
pp. 1163-1170 ◽  
Author(s):  
B. C. Liang ◽  
A. F. MacKenzie ◽  
M. Remillard
Keyword(s):  
Zea Mays ◽  
Population Density ◽  
Management Practices ◽  
Zea Mays L ◽  
Plant Population ◽  
Population Densities ◽  
Clay Loam Soil ◽  
Eastern Canada ◽  
Corn Production ◽  
Loam Soil

The increase in area for corn production in eastern Canada has stimulated the search for improvements in corn management practices to obtain higher yields. The purpose of this study was to investigate the effects of maize (Zea mays L.) hybrids, plant population density, rates of fertilization and irrigation on grain yield. A field experiment was conducted on a Chicot sandy clay loam soil in Quebec from 1984 to 1986. Corn attained grain yields of 10.9–15.2 Mg ha−1. These yields were attained only when all management inputs were at optimum levels. No single hybrid was superior over the 3-yr-period. High plant population densities, if not accompanied by other inputs, decreased yields. In moist, cooler years, effects of management factors were reduced, and only high plant population densities seemed to increase production. High rates of fertilization increased yields only when other management levels were high.Key words: Population density, irrigation, fertilization, hybrid, Zea mays, grain

scholarly journals Impact of combine releases of the egg parasitoid, Trichogramma euproctidis (Girault) and the entomopathogenic nematode, Heterorhabditis bacteriophora to control Tuta absoluta (Meyrick) in tomato greenhouses in Egypt

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
D. Adly ◽  
Gehan M. Nouh
Keyword(s):  
Biological Control ◽  
Population Density ◽  
Management Practices ◽  
Entomopathogenic Nematode ◽  
Heterorhabditis Bacteriophora ◽  
Egg Parasitoid ◽  
Tuta Absoluta ◽  
Leaf Miner ◽  
Pest Species ◽  
Biological Control Agents

AbstractIn greenhouses, tomato plants are subject to attack by several pest species. The present study aimed to investigate the compatibility of releasing the egg parasitoid, Trichogramma euproctidis (Girault) (Hymenoptera: Trichogrammatidae), and the entomopathogenic nematode, Heterorhabditis bacteriophora, strain HP88 against the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in commercial tomato greenhouses (Cherry and Bushra varieties) at winter plantation of 2018–2019 in Egypt. Three commercial plastic greenhouses were used. The first plastic greenhouses were treated by the two tested biological control agents (BCG), the second sprayed by certain recommended pesticides (PG), and the third used for control. Pheromone traps were used for monitoring the appearance of T. absoluta moths. The combined use of T. euproctidis and H. bacteriophora resulted to reduce the population density of the T. absoluta gradually until the end of the season in BCG. In the 17th week of treatments by T. euproctidis and H. bacteriophora, the population density of T. absoluta was estimated as leaf mines/plant (0.8 and 1.26 mines/leaf, in Cherry and Bushra varieties, respectively) in BCG. Also, in the 17th week of treatments by recommended pesticides, the population density of T. absoluta reached 12.73 mines/leaf and 18.33 mines/leaf, in CG. Early use of pesticides, by the appearance of T. absoluta infestation, could not suppress its population density that continued to increase until the end of the season in PG. Results revealed that the combination of the tested biological control agents against T. absoluta is recommended to be a main part in pest management practices in tomato greenhouses.

Mucuna deeringiana (Bort) Merr. vs. the corm weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae), in plantains

1969 ◽  
Vol 89 (3-4) ◽  
pp. 201-210
Author(s):  
Amparo Salazar ◽  
Alberto Pantoja ◽  
Juan Ortiz
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Management Practices ◽  
Production Costs ◽  
Cosmopolites Sordidus ◽  
Adult Density ◽  
High Population Density ◽  
Population Densities ◽  
Insect Density ◽  
The Relationship

The effect of the legume Mucuna deeringiana on Cosmopolites sordidus population dynamics and damage was studied in two planting systems: intercropping with mucuna and mucuna as green mulch before establishing the plantain. The relationship between C. sordidus adult density and larval damage was also studied. The presence of M. deeringiana affected the incidence of C. sordidus.The data suggest that C. sordidus adults are attracted by M. deeringiana, but additional studies are needed to better understand the relationship between the legume and the insect. The presence of M. deeringiana did not affect plantain height, stem diameter, or sucker production if the legume was eliminated four months after planting. However, management practices to establish and cultivate the legume increased production costs. Although C. sordidus population densities were low during most of the year, a high population density was recorded from November to January. A second population explosion was recorded between June and August. The highest insect density recorded was 3.5 insects per trap.

scholarly journals Epidemiology of African Swine Fever and Its Risk in Nepal

2021 ◽  
Vol 12 (3) ◽  
pp. 580-591
Author(s):  
Deepak Subedi ◽  
Suman Bhandari ◽  
Saurav Pantha ◽  
Uddab Poudel ◽  
Sumit Jyoti ◽  
...  
Keyword(s):  
Viral Infection ◽  
Management Practices ◽  
Viral Infections ◽  
African Swine Fever ◽  
Illegal Trade ◽  
Effective Management ◽  
Pork Industry ◽  
Wild Pigs ◽  
The World ◽  
The Government

African swine fever (ASF) is a highly contagious viral infection of domestic and wild pigs with high mortality. First reported in East Africa in the early 1900s, ASF was largely controlled in domestic pigs in many countries. However, in recent years ASF outbreaks have been reported in several countries in Europe and Asia. The occurrence of ASF in China, the largest pork producer in the world, in 2018 and in India, the country that surrounds and shares open borders with Nepal, has increased the risk of ASF transmission to Nepal. Lately, the pork industry has been growing in Nepal, overcoming traditional religious and cultural biases against it. However, the emergence of viral infections such as ASF could severely affect the industry's growth and sustainability. Because there are no effective vaccines available to prevent ASF, the government should focus on preventing entry of the virus through strict quarantine measures at the borders, controls on illegal trade, and effective management practices, including biosecurity measures.

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

PREDATION BY INSECTS AND SPIDERS INHABITING COLONIAL WEBS OF HYPHANTRIA CUNEA

1972 ◽  
Vol 104 (8) ◽  
pp. 1197-1207 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Population Dynamics ◽  
Nova Scotia ◽  
North America ◽  
Population Density ◽  
New Brunswick ◽  
Numerical Response ◽  
Initial Number ◽  
Hyphantria Cunea ◽  
The North ◽  
The Mean

AbstractThe number of predators inhabiting nests of Hyphantria cunea Drury was recorded annually for 13 years in four areas in New Brunswick and two areas on the coast of Nova Scotia. The most common groups were the pentatomids and spiders, which sometimes reproduced within the nests, but the mean number per nest was low in relation to the number of H. cunea larvae in the colonies. The rate of predation on fifth-instar larvae was low. Small or timid predators appeared to prey largely on moribund larvae or small saprophagans during the principal defoliating instars of H. cunea.No relationship could be detected between the number of larvae reaching the fifth instar and the number of predators in the colony; nor could any functional or numerical response of the predators to either the initial number of larvae per colony or the population density of colonies be found. It is concluded that the influence of the nest-inhabiting predators is small and relatively stable, and may be treated as a constant in the development of models to explain the population dynamics of H. cunea.H. cunea is a pest in parts of Europe and Asia, where it has been accidentally introduced from North America. The introduction to other continents of the North American predator, Podisus maculiventiis (Say), is discussed briefly.

Influence of Weed Management Practices and Crop Rotation on Glyphosate-Resistant Horseweed (Conyza canadensis) Population Dynamics and Crop Yield-Years III and IV

Weed Science ◽  
2009 ◽  
Vol 57 (4) ◽  
pp. 417-426 ◽  
Author(s):  
Vince M. Davis ◽  
Kevin D. Gibson ◽  
Thomas T. Bauman ◽  
Stephen C. Weller ◽  
William G. Johnson
Keyword(s):  
Population Dynamics ◽  
Crop Rotation ◽  
Crop Yield ◽  
Cover Crops ◽  
Weed Management ◽  
Management Practices ◽  
Plant Density ◽  
Crop Yields ◽  
Management Systems ◽  
No Till

Horseweed is an increasingly common and problematic weed in no-till soybean production in the eastern cornbelt due to the frequent occurrence of biotypes resistant to glyphosate. The objective of this study was to determine the influence of crop rotation, winter wheat cover crops (WWCC), residual non-glyphosate herbicides, and preplant application timing on the population dynamics of glyphosate-resistant (GR) horseweed and crop yield. A field study was conducted from 2003 to 2007 in a no-till field located at a site that contained a moderate infestation of GR horseweed (approximately 1 plant m−2). The experiment was a split-plot design with crop rotation (soybean–corn or soybean–soybean) as main plots and management systems as subplots. Management systems were evaluated by quantifying in-field horseweed plant density, seedbank density, and crop yield. Horseweed densities were collected at the time of postemergence applications, 1 mo after postemergence (MAP) applications, and at the time of crop harvest or 4 MAP. Viable seedbank densities were also evaluated from soil samples collected in the fall following seed rain. Soybean–corn crop rotation reduced in-field and seedbank horseweed densities vs. continuous soybean in the third and fourth yr of this experiment. Preplant herbicides applied in the spring were more effective at reducing horseweed plant densities than when applied in the previous fall. Spring-applied, residual herbicide systems were the most effective at reducing season-long in-field horseweed densities and protecting crop yields since the growth habit of horseweed in this region is primarily as a summer annual. Management systems also influenced the GR and glyphosate-susceptible (GS) biotype population structure after 4 yr of management. The most dramatic shift was from the initial GR : GS ratio of 3 : 1 to a ratio of 1 : 6 after 4 yr of residual preplant herbicide use followed by non-glyphosate postemergence herbicides.

Risk-management practices for effective management of risk in research universities

2020 ◽  
pp. 51-58
Author(s):  
M.S.M. Ariff ◽  
N. Zaidin ◽  
N.Z. Salleh ◽  
R. Md. Nor ◽  
M.N. Som ◽  
...  
Keyword(s):  
Risk Management ◽  
Research Universities ◽  
Management Practices ◽  
Effective Management ◽  
Management Of Risk

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole Microtus Montanus

2005 ◽  
Vol 29 ◽  
pp. 49-51
Author(s):  
Alita Pinter
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Population Density ◽  
Climatic Factors ◽  
Small Rodents ◽  
Microtus Montanus ◽  
Small Measure ◽  
Long Term Studies

A variety of hypotheses has been proposed to explain multiannual fluctuations in population density ("cycles") of small rodents (for reviews see Finerty 1980, Taitt and Krebs 1985). Doubtless, such cycles - known since antiquity (Elton 1942) - result from an interaction of a multitude of factors. However, the inability of extant hypotheses, alone or in combination, to explain the causality of cycles rests in no small measure with the fact that long-term studies of the phenomenon are notoriously uncommon.

Population dynamics and production of a brine shrimp, Parartemia zietziana Sayce (Crustacea : Anostraca), in two salt lakes in westren Victoria, Australia

1977 ◽  
Vol 28 (4) ◽  
pp. 417 ◽  
Author(s):  
R Marchant ◽  
WD Williams
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Temperature Stress ◽  
Brine Shrimp ◽  
Dry Weight ◽  
Salt Lakes ◽  
Confidence Limits ◽  
Length Frequency ◽  
Population Densities ◽  
The Mean

Quantitative samples of P. zietziana were taken monthly for two years from Pink Lake and Lake Cundare. Shrimps were usually contagiously distributed. To reduce error, samples were stratified resulting in confidence limits of 40-50% for the mean population density. Despite this variability, stable trends emerged, and variation was not so great as to mask significant differences. Length-frequency analyses distinguished cohorts; a regression was established between length and dry weight, enabling growth to be estimated from samples. By combining growth with population densities in Allen curves, production was computed. In Pink Lake and Lake Cundare mean pro- duction was 11.3 and 1.0 g dry weight m-2 year-1 respectively. Generally there were two or three generations per year, but time and extent of recruitment were not predictable. Each generation suffered continuous mortality, the death of young shrimps accounting for most of the production. This mortality remains unexplained; there are no significant predators and salinity and temperature stress would occur only during summer.

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