scholarly journals Impacts of agrochemical intensification on the assembly and reassembly of a mainland-island model metacommunity

2021 ◽  
Author(s):  
Rodolfo Mei Pelinson ◽  
Bianca Rodrigues Strecht ◽  
Erika Mayumi Shimabukuro ◽  
Luis Cesar Schiesari
Keyword(s):  
Community Structure ◽  
Rainy Season ◽  
Isolation By Distance ◽  
Single Pulse ◽  
Temporary Pond ◽  
Species Dispersal ◽  
Crop Fields ◽  
Predatory Insect ◽  
Spatial Isolation ◽  
Predatory Insects

ABSTRACTMany lentic aquatic environments are found embedded in agricultural fields, forming complex metacommunity structures. These habitats are vulnerable to contamination by agrochemicals, which can differentially affect local communities depending on the intensity and variability of species dispersal rates. We conducted a field experiment to assess how agrochemical intensification simulating the conversion of savannas into managed pastures and sugarcane fields affects freshwater community structure at different levels of spatial isolation. We constructed forty-five 1,200-L artificial ponds in a savanna landscape at three distances from a source wetland (30 m, 120 m, and 480 m). Ponds were spontaneously colonized by aquatic insects and amphibians and treated with no agrochemicals (‘savanna’ treatment), fertilizers (‘pasture’ treatment), or fertilizers and a single pulse of the insecticide fipronil and the herbicide 2,4-D (‘sugar cane’ treatment) following realistic dosages and application schedules. The experiment encompassed the entire rainy season. ‘Pasture’ communities were only slightly different from controls largely because two predatory insect taxa were more abundant in ‘pasture’ ponds. ‘Sugarcane’ communities strongly diverged from other treatments after the insecticide application, when a decrease in insect abundance indirectly benefitted amphibian populations. However, this effect had nearly disappeared by the end of the rainy season. The herbicide pulse had no effect on community structure. Spatial isolation changed community structure by increasing the abundance of non-predatory insects. However, it did not affect all predatory insects nor, surprisingly, amphibians. Therefore, spatial isolation did not change the effects of agrochemicals on community structure. Because agrochemical application frequently overlaps with the rainy season in many monocultures, it can strongly affect temporary pond communities. Ponds embedded in pastures might suffer mild consequences of fertilization by favoring the abundance of few predators through bottom-up effects. Ponds in sugarcane fields, however, might experience a decline in the insect population, followed by an increase in the abundance of amphibians tolerant to environmental degradation. Furthermore, we found no evidence that isolation by distance can change the general effects of chemical intensification, but future experiments should consider using real crop fields as the terrestrial matrix since they can represent different dispersal barriers.

scholarly journals Top predator introduction changes the effects of spatial isolation on freshwater community structure

2019 ◽  
Author(s):  
Rodolfo Mei Pelinson ◽  
Mathew A. Leibold ◽  
Luis Schiesari
Keyword(s):  
Community Structure ◽  
Dispersal Limitation ◽  
Interspecific Variation ◽  
Trophic Levels ◽  
Predatory Fish ◽  
Macroinvertebrate Communities ◽  
Local Conditions ◽  
Freshwater Habitats ◽  
Spatial Isolation ◽  
Predatory Insects

AbstractThe importance of local selective pressures on community structure is predicted to increase with spatial isolation when species favored by local conditions also have higher dispersal rates. In freshwater habitats, the introduction of predatory fish can produce trophic cascades because fish tend to prey upon intermediate predatory taxa, such as predatory insects, which indirectly benefits herbivores and detritivores. Similarly, spatial isolation is known to limit predatory insect's colonization rates more strongly than of herbivores and detritivores, thus generating similar effects. Here we tested the hypothesis that the effect of introduced predatory fish on macroinvertebrate community structure increases across a gradient of spatial isolation by conducting a field experiment where artificial ponds with and without fish (the Redbreast Tilapia) were constructed at three different distances from a source wetland. Overall results show that fish do reduce the abundance of predatory insects but have no effect on the abundance of herbivores and detritivores. Spatial isolation, however, does strengthen the trophic cascade caused by dispersal limitation of predatory insects, but only in the absence of fish. More importantly, macroinvertebrate communities with and without fish tend to diverge more strongly at higher spatial isolation, however, this pattern was not due to an increase in the magnitude of the effect of fish, as initially hypothesized, but to a change in the effect of isolation in the presence of fish. We argue that as spatial isolation increases, suitable prey, such as predatory insects become scarce and fish increases predation pressure upon herbivores and detritivores, dampening the positive effect of spatial isolation on them. Our results highlight the importance of considering interspecific variation in dispersal and multiple trophic levels to better understand the processes generating metacommunity structures.

STUDY REGARDING THE APHIDOFAGOUS FAUNA STRUCTURE IN THE PEACH ORCHARDS FROM CONSTANTA COUNTY IN 2020

2020 ◽  
Vol 13 ◽  
pp. 110-114
Author(s):  
Andrei Chiriloaie-Palade ◽  
Mădălina Radulea ◽  
Gheorghe Lămureanu ◽  
Ștefan Ion Mocanu ◽  
Maria Iamandei
Keyword(s):  
Myzus Persicae ◽  
Management System ◽  
Green Peach Aphid ◽  
Aphid Species ◽  
Insect Species ◽  
Essential Component ◽  
Intensive Use ◽  
Predatory Insect ◽  
Predatory Insects ◽  
Aphid Populations

"The cosmopolitan aphid species Myzus persicae is a key pest of peach orchards in south and southeastern Romania. The phenomenon of resistance induced by the intensive use of insecticides is a matter of concern for farmers and protectionists, making necessary integrated measure for the control of this pest. Conservation of natural enemy’s populations is an essential component of any management system proposed for pest aphids. The aim of the study was to determine the structure of predatory insects associated with Myzus persicae populations in peach orchards. The research was carried out in three orchards from two localities from Constanta County, in peach plantations with Springcrest variety aged 7, 11 and 12 years. As a result of this study, there were determined a total of 15 predatory insect species belonging to eight systematic families: Coccinellidae, Chrysopidae, Hemerobiidae, Syrphydae, Cecidomyiidae, Panorpidae, Nabidae and Forficulidae, which naturally contribute to the reduction of the green peach aphid populations. "

scholarly journals The Connectivity of Nutrient Ratios on The Abundance of Phytoplankton Population In Jakarta Bay

2020 ◽  
Vol 147 ◽  
pp. 02012 ◽  
Author(s):  
Tumpak Sidabutar ◽  
Endang S. Srimariana
Keyword(s):  
Community Structure ◽  
Strong Correlation ◽  
Rainy Season ◽  
Mesh Size ◽  
Nutrient Ratios ◽  
Phytoplankton Abundance ◽  
Phytoplankton Population ◽  
Very High

The frequency of algal bloom’s event has been increased in Jakarta Bay, recently. Most of the bloom events were tend to be reoccurred after the rainy season. The research was conducted from 2008 until 2015 to study the linkage of nutrients and the ratios on the growth of the phytoplankton population. Collecting samples were conducted using a canonical plankton net of 20 µm mesh size, 125 cm length and 30 cm diameter of the opening mouth. The results of the study showed that the concentration of phosphate in the waters ranged from 0.01-12.5 µg/l (average 4.58 µg/l) and nitrate ranged from 0.01-15.89 µg/l (average 0.72 µg/l). The N/P ratio during the study ranging from 0.2 up to 45.4. High ratios of nutrients were mostly recorded in 2010 where the overall abundance of phytoplankton is very high. There is a strong correlation of N/P ratio with the community structure or composition of the phytoplankton population. The variability of phytoplankton abundance appears to be related to nutrient ratios of nitrate and phosphate.

scholarly journals Susceptibility of pine stands to bark stripping by chacma baboons Papio ursinus in the Eastern Highlands of Zimbabwe

2009 ◽  
Vol 55 (6) ◽  
pp. 389-395 ◽  
Author(s):  
C.A.T. Katsvanga ◽  
L. Jimu ◽  
J.F. Mupangwa ◽  
D. Zinner
Keyword(s):  
Rainy Season ◽  
Predictor Variables ◽  
Bark Stripping ◽  
Conservation Areas ◽  
Papio Ursinus ◽  
Crop Fields ◽  
Pine Trees ◽  
Chacma Baboons ◽  
Level Of Significance ◽  
Eastern Highlands

Abstract The aim of this study was to determine the susceptibility, intensity and distribution of pine trees to bark stripping by chacma baboons Papio ursinus in three plantations in the Eastern Highlands of Zimbabwe. The number of plots/ha, stripped trees/plot and stripped trees/ha was recorded during the pre-rainy, rainy and post-rainy seasons from August 2006 to May 2007. During data collection, altitude, aspect, season and other site predictor variables (e.g., roads and fire traces, water points, indigenous vegetation conservation areas, crop fields, human settlements, wattle scrubs, rocky areas, open grasslands, earlier stripped sites and roost sites) were recorded for each plot in association with selected predictor variables within plantation estates. Data on the number of stripped plots/ha, stripped trees/plot and stripped trees/ha were analysed as dependent variables using the Generalised linear Model (GLM) through SPSS version 15 (2006) to determine which predictor variables were significantly related to bark stripping. Differences between means were tested using Bonferroni tests with a 5% level of significance. Our findings show that bark stripping of pine trees by baboons occurred at all altitudes and aspects. Overall, the number of bark stripped trees/ha did not significantly vary by season. The number of bark stripped plots/ha was lower during the pre-rainy season than the rainy season, whereas the number of bark stripped trees/plot was higher during the pre-rainy than the rainy season. Bark stripping of pines occurred more often in the vicinities of areas with abundant food and water.

Soil macrofauna diversity and population dynamics in Indian Himalayan agroecosystems

Soil Research ◽  
2020 ◽  
Vol 58 (7) ◽  
pp. 636
Author(s):  
Madhuri Pant ◽  
G. C. S. Negi ◽  
Pramod Kumar
Keyword(s):  
Soil Fertility ◽  
Rainy Season ◽  
Soil Depth ◽  
Soil Macrofauna ◽  
Crop Fields ◽  
Β Diversity ◽  
Top Soil ◽  
Himalayan Mountain ◽  
Irrigated Wheat ◽  
Taxonomic Groups

Soil macrofauna diversity in Himalayan mountain agroecosystems has received negligible attention despite people’s dependence on soil fertility that determines crop yield for their sustenance. This study was carried out with the objective to determine differences in soil macrofauna taxonomic groups and abundance with soil depth (0–30 cm) in irrigated and non-irrigated wheat and rice crops of two dominant Himalayan mountain agroecosystems. At both the sites, a total of 11 macrofauna groups and 23 families were recorded. Macrofauna population across both crop seasons for non-irrigated fields was significantly greater (P < 0.05) than in irrigated fields. Macrofauna population significantly differed (P < 0.001) with soil depth and significantly declined with increasing soil depth (P < 0.001). The top soil (0–10 cm depth) contributed over 80% of the total macrofauna population. Macrofauna diversity in non-irrigated fields (H′ = 2.10) was greater than in irrigated fields (H′ = 1.86), but β diversity was greater in irrigated fields (1.67 vs 1.76). The two agroecosystem types significantly differed (P < 0.05) with soil depth and crop season. On the basis of presence or absence, the macrofauna groups were categorised as (i) present in soil year-round but exhibiting high density during warm and wet rainy season and (ii) present in soil only during the warm and wet rainy season. The non-irrigated fields had greater abundance of Coleoptera, Dermaptera, Hemiptera and Isoptera than the irrigated fields. This study highlights that the Himalayan mountain crop fields host a rather diverse and abundant macro-invertebrate community that should be efficiently used to promote soil fertility.

scholarly journals KELIMPAHAN DAN KEANEKARAGAMAN SPESIES SERANGGA PREDATOR DAN PARASITOID Aphis gossypii DI SUMATERA SELATAN

2011 ◽  
Vol 11 (1) ◽  
pp. 57-68
Author(s):  
Riyanto Riyanto ◽  
Siti Herlinda ◽  
Chandra Irsan ◽  
Abu Umayah
Keyword(s):  
Species Diversity ◽  
Rainy Season ◽  
Aphis Gossypii ◽  
Dry Season ◽  
Predatory Insects

 This study was aimed to analysis abundance and species diversity of predatory insects and parasitoid of Aphis gossypii from lowland and highland areas of South Sumatra.    Survey of was conducted in 11 vegetable centers of  South Sumatra.  The results showed that 20 species of predatory insects and 3 species of parasitoids were found from the survey. The predatory insects consisted of 15 species of coccinellid beetles, two species of syrphids, and  one species of chamaemyiid, mantid and staphylinid.  Parasitoid found were 2 species of Aphidiidae (Diaretiella rapae and Aphidius sp.) and a species of Aphelinidae (Aphelinus sp.).  The highest abundance of the predator was found in Soak (42.61 larvae and adults) and the highest abundance of the parasitoid was found in Talang Buruk (25.99 adults).  The highest species diversity of the predator and the parasitoid were found in Soak (15 species and H’= 0.94) and in Talang Buruk (2 species and H’ = 0.27), respectively.  Abundance and species diversity of the predators and parasitoids were higher in the dry season than those in rainy season. Thus, the abundance and species diversity of the predators and parasiotids were higher in the lowland than highland areas in South Sumatra, while the seasons affected the abundance and species diversity of the predators and parasitoids.

scholarly journals Struktur Komunitas dan Kelimpahan Fitoplankton dan Zooplankton pada Musim Penghujan di Zona Intertidal Pantai Selatan Yogyakarta

2021 ◽  
Vol 24 (2) ◽  
pp. 167-176
Author(s):  
Ratih Ida Adharini ◽  
Namastra Probosunu
Keyword(s):  
Community Structure ◽  
Environmental Conditions ◽  
Water Samples ◽  
Low Temperatures ◽  
Intertidal Zone ◽  
Rainy Season ◽  
Diversity Index ◽  
South Coast ◽  
Wet Season ◽  
Dominance Index

Plankton is an organism that plays an important role as a water food reserve, which is influenced by environmental conditions. This study aims to determine the community structure, abundance and biodiversity of phytoplankton and zooplankton in the intertidal zone of south coast of Yogyakarta during the rainy season. The research was conducted at Pantai Drini, Kukup, and Sundak of Gunungkidul District during December 2016 - February 2017. Sampling was conducted on three observation stations in the intertidal zone of Drini Beach, Kukup, and Sundak twice a month. The water samples were taken with plankton nets number 25, then were fluidized in 4% formalin and stored at low temperatures. The results showed diversity index of plankton in Kukup Beach in January at 1.86 while the lowest value in February at Sundak Beach was 0.87. The highest plankton abundance in January at Sundak Beach was 900 individu L-1 while the lowest value in December at Kukup Beach was 217.8 individu L-1. Based on the diversity index of Shannon-Wiener, intertidal coast waters of Yogyakarta in wet season is categorized as moderate, and dominance index is categorized  as low. Plankton merupakan organisme yang berperan penting sebagai cadangan makanan perairan dan dipengaruhi oleh kondisi lingkungan. Penelitian ini bertujuan untuk mengetahui struktur komunitas, kelimpahan dan keanekaragaman plankton pada zona inertidal pantai selatan Yogyakarta selama musim penghujan. Penelitian dilakukan di Pantai Drini, Kukup, dan Sundak Kabupaten Gunungkidul selama bulan Desember 2016 – Februari 2017. Pengambilan sampel dilakukan pada tiga stasium pengamatan di zona intertidal Pantai Drini, Kukup, dan Sundak setiap dua minggu. Sampel air diambil dengan jaring plankton nomor 25, kemudian sampel plankton difiksasi dalam formalin 4% dan disimpan pada suhu rendah. Hasil penelitian menunjukan indeks keanekaragaman jenis plankton tetinggi di Pantai Kukup pada bulan Januari sebesar 1,86 sedangkan nilai terendah pada bulan Februari di Pantai Sundak sebesar 0,87. Kelimpahan plankton tertinggi pada bulan Januari pada Pantai Sundak sebesar 900 individu L-1 sedangkan nilai terendah pada bulan Desember di Pantai Kukup yaitu 217,8 individu L-1. Berdasarkan indeks keanekaragaman Shannon-Wienner maka indeks keanekaragaman di pantai selatan Yogyakarta tergolong rendah-sedang dengan indeks dominansi tergolong rendah.

Nematode community structure in crop fields near Yamuna in Faridabad, Haryana

2017 ◽  
Vol 2 (02) ◽  
pp. 210-215
Author(s):  
Shikha Ahalavat ◽  
Ashok Kumar Chaubey
Keyword(s):  
Community Structure ◽  
Nematode Community ◽  
Parasitic Nematodes ◽  
Agricultural Fields ◽  
Plant Parasitic Nematodes ◽  
Crop Fields ◽  
Plant Parasitic

A survey of agricultural fields near Yamuna in Faridabad, Haryana was conducted to study the diversity and community structure of the soil inhabiting nematodes. A total of 32 genera belonging to 7 orders and 22 families were recorded. In terms of abundance, order Tylenchida was most abundant while in terms of number of genera, order Rhabditida was most frequent. Out of 32 genera, 10 viz., Pratylenchus, Psilenchus, Helicotylenchus, Hemicriconemoides, Hoplolaimus, Meloidogyne, Rotylenchulus, Tylenchorhynchus, Hirschmanniella, Xiphinema belonged to plant-parasitic nematodes. Overall Meloidogyne was the most abundant among all the nematode genera.

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