scholarly journals Effects of difference in vegetation management of ridges on the population density of rice bugs and natural enemies

2012 ◽  
Vol 38 (1) ◽  
pp. 240-243
Author(s):  
Hidehiro INAGAKI ◽  
Minoru ICHIHARA ◽  
Kazuo MATSUNO ◽  
Chieko SAIKI ◽  
Shou YAMAGUCHI ◽  
...  
Keyword(s):  
Population Density ◽  
Natural Enemies ◽  
Vegetation Management

The Life System of Cardiaspina Albitextura (Psyllidae), 1950-74.

1975 ◽  
Vol 23 (4) ◽  
pp. 523 ◽  
Author(s):  
LR Clark ◽  
MJ Dallwitz
Keyword(s):  
Population Density ◽  
Natural Enemies ◽  
Average Rate ◽  
The Other ◽  
Population Densities ◽  
Insect Abundance ◽  
Complete Development ◽  
Rate Of Increase ◽  
Adverse Weather ◽  
Survival And Reproduction

In 1958-63 and 1964-71 the life systems of four kinds of test-forming psyllid that coexist on Eucalyptus blakelyi were investigated intensively in a comparative study of insect abundance. This paper deals mainly with C. albitextura, which was kept under observation from 1950 to 1974. (The others were two species of Glycaspis, Spondyliaspis sp, and Creiis costatus.) The results indicate that the differences in maximal abundance reached by the four kinds of psyllid are mainly the outcome of differences in their ability tg utilize the leaves of the host plant as a source of food, C. albitextura being much more effective than the other species. For the latter, it appears that the principal environmental determinant of abundance was the number of feeding places where nymphs could survive long enough to complete development. That number varied according to foliage and weather. C. albitextura also differed from the other species by having its population densities held for long periods far below the levels at which the food supply would be limiting, by restrictions imposed upon reproduction by adverse weather and foliage conditions (the latter being due partly to poor synchronization between the emergence of adults in spring and the occurrence of foliage attractive for oviposition), and by high mortalities due to natural enemies. The life system of C. albitextura lacks an element that can stabilize abundance at low population densities, but adverse environmental influences usually limit the rate of increase greatly when abundance is low. The magnitude of the average rate of increase to high levels of population density, and the length of time for which high average densities are maintained, depend upon the frequency with which favourable conditions of weather, foliage and predation combine to promote both survival and reproduction.

scholarly journals Kepadatan Populasi Wereng Coklat (Nilaparvata lugens, Stal.) dan Musuh Alaminya Pada Berbagai Varietas Padi di Bantul Yogyakarta

2021 ◽  
Vol 1 (2) ◽  
pp. 45-48
Author(s):  
Darmawan Suryo Sudarsono
Keyword(s):  
Population Density ◽  
Natural Enemies ◽  
Rice Field ◽  
Brown Planthopper ◽  
Nilaparvata Lugens ◽  
Resistant Variety ◽  
Local Varieties ◽  
Hybrid Variety ◽  
Nilaparvata Lugens Stål

A research to observe the population density of brown planthoppers (Nilaparvata lugens, Stal.) and their predator and parasitoid natural enemies has done on the rice field in Bantul regency of Yogyakarta. The research was conducted to observe the hoppers and its natural enemies on three local varieties and one superior brown planthoppers resistant variety of rice. The three local varieties of rice were Rejosari, Sri Kuning, and Sri Ayu, while the hopper resistant variety was IR 64. The observation were replicated three times. The result showed that population of brown planthoppers in the three local varieties of rice were higher than in the resistant IR 64 hybrid variety. The population of predators and parasitoid were relatively high in order to control the development of brown planthopper population. The predator Lycosa sp. and the parasitoids Anagrus sp.  were commonly found in the ecosystem.

Natural Enemies of the Gypsy Moth (Lepidoptera: Lymantriidae) in a low Population Density

2014 ◽  
Vol 35 (2) ◽  
pp. 117-127 ◽  
Author(s):  
Urwa Alalouni ◽  
Gabriela Lobinger ◽  
Martin Schädler ◽  
Roland Brandl
Keyword(s):  
Population Density ◽  
Gypsy Moth ◽  
Natural Enemies

Status of biological control in vegetation management in forestry

1993 ◽  
Vol 23 (10) ◽  
pp. 2023-2031 ◽  
Author(s):  
George P. Markin ◽  
Donald E. Gardner
Keyword(s):  
Biological Control ◽  
Natural Enemies ◽  
Plant Pathogens ◽  
Native Plants ◽  
Mass Rearing ◽  
Vegetation Management ◽  
New Agents ◽  
Promising Alternative ◽  
Alternative Approach ◽  
Target Plant

Biological control traditionally depends upon importing the natural enemies of introduced weeds. Since vegetation management in forestry has primarily been aimed at protecting economic species of trees from competition from other native plants, biological control has been of little use in forestry. An alternative approach to controlling unwanted native plants, supplementing their existing complex of natural enemies with introduced insects found attacking closely related plants, is being used on rangeland, but is not recommended for forestry. New agents will not remain restricted to the location where they are released, but will spread and would eventually affect the target plant throughout its entire range, including areas where it might be desirable. A more promising alternative is manipulating one or more insects or diseases that already attack the undesirable plants. Many plant pathogens naturally associated with a particular plant species are highly virulent and specific to only the target plant. Mass producing these pathogens and applying them with conventional spray systems is being used in agriculture and is being considered for forestry. Other methods of manipulation, such as mass rearing insects and releasing them to attack the undesirable plant or manipulating populations of the insect predators that naturally suppress phytophagous insects of a target plant, are discussed.

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