scholarly journals Seasonal Changes in Population Density of Spiders in Paddy Fields, with Reference to the Ecological Control of the Rice Insect Pests

1973 ◽  
Vol 17 (4) ◽  
pp. 193-202 ◽  
Author(s):  
Shiro KOBAYASHI ◽  
Hiroaki SHIBATA
Keyword(s):  
Population Density ◽  
Seasonal Changes ◽  
Insect Pests ◽  
Paddy Fields ◽  
Ecological Control ◽  
Rice Insect Pests

scholarly journals Effects of silicon amendment on the occurrence of rice insect pests and diseases in a field test

2018 ◽  
Vol 17 (10) ◽  
pp. 2172-2181 ◽  
Author(s):  
Yong-qiang HAN ◽  
Ji-hui WEN ◽  
Zhao-pu PENG ◽  
De-yong ZHANG ◽  
Mao-lin HOU
Keyword(s):  
Field Test ◽  
Insect Pests ◽  
Pests And Diseases ◽  
Rice Insect Pests

Determination of multiple-species economic injury levels for rice insect pests

2012 ◽  
Vol 32 ◽  
pp. 150-160 ◽  
Author(s):  
K. Selvaraj ◽  
Subhash Chander ◽  
M. Sujithra
Keyword(s):  
Insect Pests ◽  
Economic Injury ◽  
Multiple Species ◽  
Rice Insect Pests

Seasonal Changes in Population Density and Vertical Distribution of prosobranch veligers in offshore Plankton at Plymouth

1973 ◽  
Vol 53 (3) ◽  
pp. 471-492 ◽  
Author(s):  
Vera Fretter ◽  
D. Shale
Keyword(s):  
Population Density ◽  
Vertical Distribution ◽  
Seasonal Changes ◽  
Littorina Littorea ◽  
Ageing Population ◽  
Age Composition ◽  
Number Of Species ◽  
Lacuna Vincta ◽  
Nassarius Reticulatus ◽  
Inshore Waters

Vertical and horizontal hauls were taken at approximately fortnightly intervals from April 1969 to April 1970 at L 3 (lat. 40° 17.7′ N, long. 4° 11.2′ W) and L 4 (lat. 50° 15′ N, long. 4° 12.5 W). Thirty-two species of prosobranch veliger were present at L 35 these larvae were not as numerous at L 4 and only 26 species were recorded. The number of species was highest in the summer: the number of veligers was highest in February. After mid October both the number of species and the abundance of veligers decreased rapidly and remained low until early February. Veligers of some species occurred later at L 3 and L 4 than in more inshore waters and these were probably individuals carried beyond tidal influences which would normally lead to settlement on the shore. They included Lacuna vincta, Littorina littorea and L. neritoides.Veligers of all ages were found at all depths. At their time of greatest abundance veligers of many species occurred maximally at 5 or 10 m, with a variable decrease towards greater depths and a sudden one towards the surface. This distribution later changed giving a proportionally greater number at greater depth. When numbers were low the larvae scattered through the water column with little or no indication of a preferred depth. An examination of the age composition of veligers of rissoids, Natica alderi, Nassarius reticulatus and Philbertia linearis from certain catches showed that the surface accumulation at the time of abundance was composed of a high percentage of young veligers: in an ageing population there was a higher percentage of larvae, especially the older ones, at greater depths, except for Nassarius reticulatus which consistently showed maximal numbers above 10 m until the larvae became scarce.

Evaluation of action thresholds for chronic rice insect pests in the Philippines. III. Leaffolders

2006 ◽  
Vol 52 (3) ◽  
pp. 181-194 ◽  
Author(s):  
J. A. Litsinger ◽  
J. P. Bandong ◽  
B. L. Canapi ◽  
C. G. Dela Cruz ◽  
P. C. Pantua ◽  
...  
Keyword(s):  
Insect Pests ◽  
The Philippines ◽  
Action Thresholds ◽  
Rice Insect Pests

Biology, status and management of rice insect pests in Nigeria

1992 ◽  
Vol 11 (5) ◽  
pp. 408-413 ◽  
Author(s):  
E.D.N. Umeh ◽  
R.C. Joshi ◽  
M.N. Ukwungwu
Keyword(s):  
Insect Pests ◽  
Rice Insect Pests

scholarly journals Analysis of physico-chemical parameters of soil and population density of Azospirillum isolates from paddy fields of Theni district, Tamilnadu

2019 ◽  
Vol 11 (1) ◽  
pp. 88-93
Author(s):  
Uma Devi S. ◽  
Muthuchelian K.
Keyword(s):  
Electrical Conductivity ◽  
Population Density ◽  
Chemical Analysis ◽  
Phosphorus Content ◽  
Paddy Fields ◽  
Chemical Parameters ◽  
Physico Chemical ◽  
Study Results ◽  
Water Holding ◽  
Range Of Values

The rhizosphere region of eight different paddy field areas of Theni district was studied for their physico-chemical analysis of soil and the population density of Azospirillum sp. The study results showed range of values of pH (7.4-7.9), bulk density (1.13g/cm3 -1.60g/cm3), water holding capacity (34.31% - 18.25%), electrical conductivity (1.31 – 1.11), organic carbon (0.93% - 0.71%) . The macronutrient values namely total nitrogen (1.72% - 0.78%), phosphorus content (0.177% - 0.122%) and potassium (1.364% - 1.273%) were observed. Also micronutrients of various paddy fields like Zn (0.9% - 0.5%), Cu (2.3% - 1.7%), Fe (10.9% -8.2%), Mn (6.7% - 5.2%) were recorded, whereas the values of available macronutrients namely nitrogen (295kg/ha - 223kg/ha), phosphorous (89Kg/acre - 49kg/acre), potassium (790kg/acre - 490kg/acre) were noted. The Azospirillum population density was highest in Chinnamanur (192 x105 CFU/g) and lowest in Royyanpatti (91 x105 CFU/g). Thus through this work we were able to isolate and identify novel high yielding Azosprillium sp from paddy fields of Theni district.

scholarly journals BIOLOGI DAN TRANSFORMASI BELALANG KEMBARA LOCUSTA MIGRATORIA MANILENSIS MEYEN (ORTHOPTERA: ACRIDIDAE) PADA BEBERAPA TINGKAT KEPADATAN POPULASI DI LABORATORIUM

2005 ◽  
Vol 5 (1) ◽  
pp. 24-31
Author(s):  
Hamim Sudarsono ◽  
Rosma Hasibuan ◽  
Damayanti Buchori
Keyword(s):  
Population Density ◽  
Insect Pests ◽  
Control Strategies ◽  
Locusta Migratoria ◽  
Feeding Activity ◽  
Laboratory Population ◽  
Migratory Locust ◽  
Green House ◽  
Cage Size ◽  
Locusta Migratoria Manilensis

Biology and Transformation of the Migratory Locust Locusta migratoria manilensis Meyen (Orthoptera: Acrididae) at Several Laboratory Population Density Levels.  The migratory locust, Locusta migratoria manilensis Meyen (Orthoptera: Acrididae) is one of insect pests in Indonesia that undergoes a unique polymorphic biology.  The locust develops a transformation phase which is triggered mainly by high population density.  Its recent outbreaks in several regions of Indonesia cause major concern and control strategies must be developed to strengthen control efforts in the future. Its unique polymorphic phenomenon, therefore, must be investigated thoroughly for the basis of management of the outbreak.  Due to its agility and its long range flying ability, the most realistic technique to study behavioral and morphological change of the locust is in controlled condition at a laboratory or a green house facility. The experiment was aimed to study effects of colony densities on the biology and transformation process of the migratory locust.  More specifically, the experiment was to study effects of population density on the feeding activity, mortality rate, and the ratio of F/C and E/F of the migratory locust L. migratoria manilensis.  The population densities were simulated in colonies at 2, 5, 10, 20, dan 30 couples per cage (cage size: 45x45x90 cm) reared in a green house. Results of the experiment show that, in general, higher densities of the migratory locust colonies tended to feed more rigorously than those of the less dense colonies.  The locust remained in solitary phase at the density of 2-5 couples per cage whereas the transient phase occured at the density of 10-20 couples per cage.  The colonies transformed to gregarious stage when their densities were 30 couples per cage or higher.  Mortality percentage tended to be higher at colonies with higher density, especially for the third instar of the migratory locust. 

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