The effects of intercropping and mixed varieties of predators and parasitoids of cassava whiteflies (Hemiptera: Aleyrodidae) in Colombia

1989 ◽  
Vol 79 (1) ◽  
pp. 115-121 ◽  
Author(s):  
Clifford S. Gold ◽  
Miguel A. Altieri ◽  
Anthony C. Bellotti
Keyword(s):  
Natural Enemies ◽  
Cropping Systems ◽  
Cropping System ◽  
Enemies Hypothesis ◽  
Natural Enemies Hypothesis ◽  
Combined Action

AbstractCassava intercropped with cowpea in Colombia had lower numbers of Aleurotrachelus socialis Bondar and Trialeurodes variabilis (Quaintance) per leaf and per plant than did monoculture cassava. These differences persisted for up to six months after harvest of the cowpea. These results are examined in light of the natural enemies hypothesis, which suggests that natural enemies may be favoured in diversified systems, thereby reducting herbivore load. In this regard, the effects of different cropping systems on the whitefly predator Delphastus pusillus (Le Conte) and on the combined action of the parasitoids Amitus aleurodinus Haldeman and Eretmocerus aleyrodiphaga (Risbec) are discussed. D. pusillus displayed a functional responce and was more abundant in monocultures than in intercrops. Predator:prey ratios were similar between treatments and so low that predation appeared to have little impact on whitefly numbers. Parasitism levels of Aleurotrachelus socialis were not affected by crop combinations. The data suggest that the activity of the natural enemies does not explain cropping system effects on cassava whitefly populations.

scholarly journals Contribution of hardwood trees to budworm – parasitoid food web dynamics

2021 ◽  
Author(s):  
Christopher J. Greyson-Gaito ◽  
Sarah J. Dolson ◽  
Glen Forbes ◽  
Rosanna Lamb ◽  
Wayne E. MacKinnon ◽  
...  
Keyword(s):  
Food Web ◽  
Natural Enemies ◽  
Large Scale ◽  
Tree Mortality ◽  
Isotope Analysis ◽  
Balsam Fir ◽  
Mixed Stands ◽  
Enemies Hypothesis ◽  
Hardwood Trees ◽  
Natural Enemies Hypothesis

A major pest of Atlantic forests is the spruce budworm caterpillar which outbreaks every 35 years and causes large scale tree mortality. Historically, budworm management has largely ignored other species in the food web. Broadening the focus could reduce budworm outbreaks while balancing the multiple demands on our forests. However, the food web surrounding budworm including other caterpillar species that are attacked by budworm parasitoids has been relatively undersampled and under-researched. Therefore, we tested two hypotheses: the alternating hardwood-softwood parasitoids hypothesis where parasitoids attack other caterpillars on hardwoods when budworm are rare and attack budworm on balsam fir or other softwoods when budworm are plentiful, and the mixed stands natural enemies hypothesis where stands with a mixture of softwood and hardwood trees harbour greater abundances and diversity of budworm parasitoids. We tested these hypotheses using stable isotope analysis of budworm parasitoids and through community analyses of parasitoids sampled along a hardwood gradient. We found indications that parasitoids do attack caterpillars on hardwoods and budworm on balsam fir, but found mixed results for the natural enemies hypothesis. Our study highlights the importance for budworm management of understanding the dynamics of the food web surrounding budworm.

scholarly journals Meta-analysis of tree diversity effects on the abundance, diversity and activity of herbivores' enemies

2021 ◽  
Author(s):  
Alex Stemmelen ◽  
Hervé Jactel ◽  
Eckehard Brockerhoff ◽  
Bastien Castagneyrol
Keyword(s):  
Natural Enemies ◽  
Natural Enemy ◽  
Meta Analysis ◽  
Mixed Forest ◽  
Forest Tree ◽  
Tree Diversity ◽  
Enemies Hypothesis ◽  
Natural Enemies Hypothesis ◽  
Abundance And Diversity ◽  
Diversity Effects

The natural enemies hypothesis predicts that the abundance and diversity of antagonists such as predators and parasitoids of herbivores increases with the diversity of plants, which can lead to more effective top-down control of insect herbivores. However, although the hypothesis has received large support in agricultural systems, fewer studies have been conducted in forest ecosystems and a comprehensive synthesis of previous research is still lacking. We conducted a meta-analysis of 65 publications comparing the diversity, abundance or activity of various groups of natural enemies (including birds, bats, spiders and insect parasitoids) in pure vs. mixed forest stands. We tested the effects of forest biome, natural enemy taxon and type of study (managed vs experimental forest). We found a significant positive effect of forest tree diversity on natural enemy abundance and diversity but not on their activity. The effect of tree diversity on natural enemies was stronger towards lower latitudes but was not contingent on the natural enemy taxon. Overall, our study contributes substantially toward a better understanding of the natural enemies hypothesis in forest systems and provides new insights about the mechanisms involved. Furthermore, we outline potential avenues for strengthening forest resistance to the growing threat of herbivorous insects.

scholarly journals Studies on insect diversity in jasmine (Jasminum sambac L.) ecosystem

2021 ◽  
Vol 42 (6) ◽  
pp. 1470-1477
Author(s):  
U. Pirithiraj ◽  
◽  
R.P. Soundararajan ◽  
C.G.L. Justin ◽  
V. Lakshmanan ◽  
...  
Keyword(s):  
Natural Enemies ◽  
Management Practices ◽  
Insect Pests ◽  
Cropping Systems ◽  
Cropping System ◽  
Diversity Indices ◽  
Insect Diversity ◽  
Chemical Inputs ◽  
Abundance And Diversity ◽  
Jasminum Sambac

Aim: Study was carried out to record the abundance and diversity of insects in jasmine (Jasminum sambac L.) ecosystem. Methodology: To determine insect pests, natural enemies and non-insect diversity, fortnight observations were taken from second fortnight of September'19 to March'20 on insect population at three adjacent locations. Abundance and diversity indices were computed using mean data. The management practices, presence of weeds and adjacent cropping systems were also recorded at three locations to determine the reasons for variation in the diversity of organisms. Results: A total of 3335 individuals arthropods belonging to 55 species, which included 32 species of herbivores and 23 species of natural enemies were recorded throughout the study period. Location 3 had perennial crops in the vicinity, un-weeded ecosystem with no chemical inputs. Among various diversity indices calculated, Margalef Richness Index of herbivores was higher at location 3 (1.67) than location 1 (1.17) and 2 (0.76). Interpretation: The abundance and diversity of insects in different jasmine ecosystem depends on the chemical inputs and adjacent cropping system.

Nitrate Leaching to a Shallow Mid-Atlantic Coastal Plain Aquifer as Influenced by Conventional No-Till and Low-Input Sustainable Grain Production Systems

1993 ◽  
Vol 28 (3-5) ◽  
pp. 691-700 ◽  
Author(s):  
J. P. Craig ◽  
R. R. Weil
Keyword(s):  
Management Practices ◽  
Production Systems ◽  
Cropping Systems ◽  
Cropping System ◽  
Atlantic Coastal Plain ◽  
Grain Production ◽  
Nitrogen And Phosphorus ◽  
Mineral N ◽  
Low Input ◽  
No Till

In December, 1987, the states in the Chesapeake Bay region, along with the federal government, signed an agreement which called for a 40% reduction in nitrogen and phosphorus loadings to the Bay by the year 2000. To accomplish this goal, major reductions in nutrient loadings associated with agricultural management practices were deemed necessary. The objective of this study was to determine if reducing fertilizer inputs to the NT system would result in a reduction in nitrogen contamination of groundwater. In this study, groundwater, soil, and percolate samples were collected from two cropping systems. The first system was a conventional no-till (NT) grain production system with a two-year rotation of corn/winter wheat/double crop soybean. The second system, denoted low-input sustainable agriculture (LISA), produced the same crops using a winter legume and relay-cropped soybeans into standing wheat to reduce nitrogen and herbicide inputs. Nitrate-nitrogen concentrations in groundwater were significantly lower under the LISA system. Over 80% of the NT groundwater samples had NO3-N concentrations greater than 10 mgl-1, compared to only 4% for the LISA cropping system. Significantly lower soil mineral N to a depth of 180 cm was also observed. The NT soil had nearly twice as much mineral N present in the 90-180 cm portion than the LISA cropping system.

scholarly journals Influence of Organic and Conventional Farming on Grain Yield and Protein Composition of Chickpea Genotypes

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 191
Author(s):  
Michele Andrea De Santis ◽  
Michele Rinaldi ◽  
Valeria Menga ◽  
Pasquale Codianni ◽  
Luigia Giuzio ◽  
...  
Keyword(s):  
Grain Yield ◽  
Organic Farming ◽  
Cropping Systems ◽  
Negative Relationship ◽  
Cropping System ◽  
Protein Composition ◽  
2S Albumin ◽  
Sds Page ◽  
Health Quality ◽  
Water Holding

Chickpea is a key crop in sustainable cropping systems and for its nutritional value. Studies on agronomic and genetic influences on chickpea protein composition are missing. In order to obtain a deep insight into the genetic response of chickpeas to management in relation to agronomic and quality traits, a two-year field trial was carried out with eight chickpea genotypes under an organic and conventional cropping system. Protein composition was assessed by SDS-PAGE in relation to the main fractions (vicilin, convicilin, legumin, lectin, 2s-albumin). Crop response was highly influenced by year and presumably also by management, with a −50% decrease in grain yield under organic farming, mainly due to a reduction in seed number per m2. No effect of crop management was observed on protein content, despite significant differences in terms of protein composition. The ratio between the major globulins, 7s vicilin and 11s legumin, showed a negative relationship with grain yield and was found to be higher under organic farming. Among genotypes, black-seed Nero Senise was characterized by the highest productivity and water-holding capacity, associated with low lectin content. These findings highlight the importance of the choice of chickpea genotypes for cultivation under organic farming in relation to both agronomic performance and technological and health quality.

scholarly journals Combined effects of landscape composition and pesticide use on herbivore and pollinator functions in smallholder farms

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Quentin Struelens ◽  
Diego Mina ◽  
Olivier Dangles
Keyword(s):  
Smallholder Farmers ◽  
Cropping Systems ◽  
Cropping System ◽  
Landscape Composition ◽  
Pesticide Use ◽  
Combined Effects ◽  
Pollinator Abundance ◽  
New Information ◽  
Negative Impacts ◽  
Effect On Yield

Abstract Background Landscape composition has the potential to foster regulating ecosystem services such as pollination and biocontrol in temperate regions. However, most landscape studies do not take pesticide use into account even though it is the main control strategy worldwide and has negative impacts on beneficial insects. Moreover, few studies have explored these combined effects in smallholder cropping system with diverse landscapes and small cultivated fields. Methods We assessed the effect of semi-natural cover and pesticide use on pollinator and herbivore abundances and functions in 9 fields in the Ecuadorian Andes through participatory experiments with smallholder farmers. We performed a path analysis to quantify the effects of landscape and pesticide use on herbivory, pollination and ultimately yield. Results Pesticide use significantly reduced pollinator abundance but had no significant effect on pest abundance. Similarly, we found non-significant effects of landscape composition on either herbivory and pollination. The study also provides new information on understudied Andean lupine’s pests and pollinators, whose application for small farmers is discussed. Finally, we hypothesize that peculiarities of tropical smallholder cropping systems and landscapes could explain the non-significant landscape effects on insect-based processes, which calls for more research in places outside the well-studied temperate region. Conclusions Landscape composition did not show any significant effect on pest and pollinator while pesticide use decreased the abundance pollinators, but with no significant effect on yield. This study also provides information about Andean lupine reproduction and overcompensation mechanisms that could be of interest for local farmers and researchers of this understudied crop.

scholarly journals Effects of conservation agriculture on productivity and Economics of maize-wheat based cropping systems in midwestern Nepal

2019 ◽  
Vol 17 (1) ◽  
pp. 49-63
Author(s):  
K Pariyar ◽  
A Chaudhary ◽  
P Sapkota ◽  
S Sharma ◽  
CB Rana ◽  
...  
Keyword(s):  
Grain Yield ◽  
Cropping Systems ◽  
Cropping System ◽  
Conservation Agriculture ◽  
Crop Productivity ◽  
Conventional Tillage ◽  
Net Income ◽  
Zero Tillage ◽  
Higher Plant ◽  
Equivalent Yield

The effects of two tillage methods (zero tillage and conventional tillage), two residue managements (residue kept and residue removed) and two levels of cropping system (maize + soybean and sole maize) were studied over 3 years (2015-2017) at Dailekh district of Nepal. Arun-2 and Puja were the varieties of maize and soybean used respectively, followed by winter wheat. The results revealed that the maize + soybean system had significantly higher plant population and ear population (34.83 thousands ha-1 and 34.35 thousands ha-1, respectively), grains per row (37.1), ear length (16.6 cm) and 20.5% higher grain yield as compared to sole maize. The highest maize equivalent yield (7.92 t ha-1) was recorded in maize + soybean as compared to the lower grain yield equivalent (7.06 t ha-1) in sole maize. Zero tillage accounted relatively higher benefits (high net income and B:C ratio) as compared to conventional tillage. The residue kept plot resulted significantly higher B:C ratio (2.41) than the residue removed (2.11) and the maize + soybean recorded 82.5% greater B:C ratio compared to sole maize. Net annual income was significantly higher in zero tillage, residue kept and maize + soybean system (NRs. 223072.00, 222958.00 and 269016.00 ha-1 respectively). Such combinations are recommended for Dailekh district of Nepal to have profitable crop productivity. SAARC J. Agri., 17(1): 49-63 (2019)

Resource use efficiency in a cotton-wheat double-cropping system in the Yellow River Valley of China

2020 ◽  
Vol 56 (3) ◽  
pp. 422-439
Author(s):  
Guoping Wang ◽  
Yabing Li ◽  
Yingchun Han ◽  
Zhanbiao Wang ◽  
Beifang Yang ◽  
...  
Keyword(s):  
Resource Use ◽  
Yellow River ◽  
Cropping Systems ◽  
Cropping System ◽  
River Valley ◽  
The Yellow River ◽  
Resource Use Efficiency ◽  
Yellow River Valley ◽  
Double Cropping ◽  
Use Efficiency

AbstractThe cotton-wheat double-cropping system is widely used in the Yellow River Valley of China, but whether and how different planting patterns within cotton-wheat double-cropping systems impact heat and light use efficiency have not been well documented. A field experiment investigated the effects of the cropping system on crop productivity and the capture and use efficiency of heat and light in two fields differing in soil fertility. Three planting patterns, namely cotton intercropped with wheat (CIW), cotton directly seeded after wheat (CDW), and cotton transplanted after wheat (CTW), as well as one cotton monoculture (CM) system were used. Cotton-wheat double cropping significantly increased crop productivity and land equivalent ratios relative to the CM system in both fields. As a result of increased growing degree days (GDD), intercepted photosynthetically active radiation (IPAR), and photothermal product (PTP), the capture of light and heat in the double-cropping systems was compared with that in the CM system in both fields. With improved resource capture, the double-cropping systems exhibited a higher light and heat use efficiency according to thermal product efficiency, solar energy use efficiency (Eu), radiation use efficiency (RUE), and PTP use efficiency (PTPU). The cotton lint yield and biomass were not significantly correlated with RUE across cropping patterns, indicating that RUE does not limit cotton production. Among the double-cropping treatments, CDW had the lowest GDD, IPAR, and PTP values but the highest heat and light resource use efficiency and highest overall resource use efficiency. This good performance was even more obvious in the high-fertility field. Therefore, we encourage the expanded use of CDW in the Yellow River Valley, especially in fields with high fertility, given the high productivity and resource use efficiency of this system. Moreover, the use of agronomic practices involving a reasonably close planting density, optimized irrigation and nutrient supply, and the application of new short-season varieties of cotton or wheat can potentially enhance CDW crop yields and productivity.

scholarly journals iHSD Mill Efficacy on the Seeds of Australian Cropping System Weeds

2017 ◽  
Vol 32 (2) ◽  
pp. 103-108 ◽  
Author(s):  
Michael J. Walsh ◽  
John C. Broster ◽  
Stephen B. Powles
Keyword(s):  
Moisture Content ◽  
Crop Production ◽  
Production Systems ◽  
Cropping Systems ◽  
Cropping System ◽  
High Efficacy ◽  
Weed Seed ◽  
Rigid Ryegrass ◽  
Mill Speed ◽  
Wheat Chaff

AbstractIn Australia, widespread evolution of multi-resistant weed populations has driven the development and adoption of harvest weed seed control (HWSC). However, due to incompatibility of commonly used HWSC systems with highly productive conservation cropping systems, better HWSC systems are in demand. This study aimed to evaluate the efficacy of the integrated Harrington Seed Destructor (iHSD) mill on the seeds of Australia’s major crop weeds during wheat chaff processing. Also examined were the impacts of chaff type and moisture content on weed seed destruction efficacy. Initially, the iHSD mill speed of 3,000 rpm was identified as the most effective at destroying rigid ryegrass seeds present in wheat chaff. Subsequent testing determined that the iHSD mill was highly effective (>95% seed kill) on all Australian crop weeds examined. Rigid ryegrass seed kill was found to be highest for lupin chaff and lowest in barley, with wheat and canola chaff intermediate. Similarly, wheat chaff moisture reduced rigid ryegrass seed kill when moisture level exceeded 12%. The broad potential of the iHSD mill was evident, in that the reductions in efficacy due to wide-ranging differences in chaff type and moisture content were relatively small (≤10%). The results from these studies confirm the high efficacy and widespread suitability of the iHSD for use in Australian crop production systems. Additionally, as this system allows the conservation of all harvest residues, it is the best HWSC technique for conservation cropping systems.

Diversity of Root Bacteria from Peanut Cropping Systems

2004 ◽  
Vol 31 (2) ◽  
pp. 86-91 ◽  
Author(s):  
D. T. Gooden ◽  
H. D. Skipper ◽  
J. H. Kim ◽  
K. Xiong
Keyword(s):  
Fatty Acids ◽  
Biological Control ◽  
Gas Chromatography ◽  
Cropping Systems ◽  
Cropping System ◽  
Critical Research ◽  
Chromatography Analysis ◽  
Rotation System ◽  
Gas Chromatography Analysis ◽  
Peanut Production

Abstract Rhizobacteria play an important role in sustainable agriculture via plant growth and biological control of pests in a number of ecosystems. Understanding the interactions of crop rotation and rhizobacteria on peanut production is a critical research need. Development of a database on the rhizobacteria obtained from continuous and rotational fields of peanut was initiated in 1997 and terminated in 2000. Peanut was planted in monoculture for 4 yr. In rotational plots, peanut, cotton, corn, and peanut were planted in sequence. Rhizobacteria were isolated from the roots of crop plants grown in a Norfolk soil near Florence, SC. These isolates were identified by composition of fatty acids from gas chromatography analysis (GC/FAME). Arthrobacter and Bacillus were the major genera from non-rhizosphere soils. At initiation of this study in July 1997, the plots selected for continuous peanut had more diversity in rhizobacteria than those plots selected for rotation. In July 2000, rhizobacteria diversity was greater from peanut roots in the rotation cropping system than continuous peanut. Even though rhizobacteria diversity was greater in the rotation system, higher peanut yields were recorded in the continuous peanut system in 2000. Burkholderia spp. were always isolated from the peanut and other crop rhizospheres at each sampling date.

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