نتایج جستجو برای: larval density

تعداد نتایج: 433688  

Journal: :حفاظت گیاهان 0
(مقاله کوتاه پژوهشی)مهرداد عمواقلی طبری حسن قهاری

abstract the effect of different larval density of chilo suppressalis walker was evaluated through 2006-2008 on rice infestation in controlled condition of the cages. the results indicated that there were significant effects between dead hearts, white heads and crop yield. the highest dead hearts and white heads were related to the treatment of 32 larvae per m2 and the lowest ones were obtained...

Journal: :modares journal of medical sciences: pathobiology 2006
alireza bolandnazar mohammad said dayer ezzatdin javadian alieh moosavi ivanaki

aim: this study investigates the intraspecific competition, for food and density amongst larvae of anopheles stephensi (main malaria vector in south iran). material & methods: the effects of 4 selected food quantities (1x,2x,4x,6x) and 5 larval densities (0.1 to 3 larva/cm2) were tested individually or in combination on 7 biological indexes of the vector and the results were statistically ...

Journal: :نامه انجمن حشره شناسی ایران 0
r. hosseini a. a. sahragard kh. madahi

searching efficiency (a') (attack rate) and handling time are two major components of natural enemies’ functional response and are usually used to evaluate their effectiveness. the age-specific searching efficiency of aphidoletes aphidimyza (rondani) was studied during its larval stage. the experiment was conducted in terms of age-specific functional response to the varying density (5, 1...

The larval community of coral reef fishes in the Red Sea was studied in coastal and offshore sites to determine the effects of the exposure to waves and currents and the distance from the shore in structuring the larval fish community. Plankton sampling from inshore and offshore sites and the exposed and sheltered sides of the reefs resulted in the collection of 2048 larvae representing 49 diff...

Journal: :دانش گیاه پزشکی ایران 0
سید علی اصغر فتحی گروه گیاه پزشکی، دانشگاه محقق اردبیلی، اردبیل، ایران

the tomato leafminer, tuta absoluta (meyrick), is one of the most important pests of tomato, solanum lycopersicum l., in iran. in this research, natural enemies diversity of t. absoluta and proportion of predators or parasitoids density to moth eggs or larvae density on five tomato cultivars including super strain b, super chief, mobil, korral, and early urbana y were studied in an experimental...

The larval community of coral reef fishes in the Red Sea was studied in coastal and offshore sites to determine the effects of the exposure to waves and currents and the distance from the shore in structuring the larval fish community. Plankton sampling from inshore and offshore sites and the exposed and sheltered sides of the reefs resulted in the collection of 2048 larvae representing 49 diff...

2015
Matthew Schrader Benjamin J. M. Jarrett Rebecca M. Kilner

Studies of siblings have focused mainly on their competitive interactions and to a lesser extent on their cooperation. However, competition and cooperation are at opposite ends on a continuum of possible interactions and the nature of these interactions may be flexible with ecological factors tipping the balance toward competition in some environments and cooperation in others. Here we show tha...

2003

Density dependence is the major process keeping the sizes of natural populations within bounds. In organisms with complex life cycles, the stage at which density dependence occurs and whether it occurs in one or several life stages have important consequences for the dynamics of their populations. I manipulated density of pool frogs (Rana lessonae) during the aquatic larval and the terrestrial ...

2009

1. Hosts experiencing frequent variation in density are thought to benefit from allocating more resources to parasite defence when density is high (‘densitydependent prophylaxis’). However, high density conditions can increase intra-specific competition and induce physiological stress, hence increasing host susceptibility to infection (‘crowding-stress hypothesis’). 2. We studied monarch butter...

Journal: :Journal of vector borne diseases 2011
Albert O Mala Lucy W Irungu

BACKGROUND & OBJECTIVES The study was undertaken to characterize factors influencing differential productivity of Anopheles gambiae complex mosquitoes at larval habitats in a rural village in western Kenya. METHODS Longitudinal larval sampling was done using an area sampler for 3 months. Emerged adults were identified to species level morphologically using taxonomic keys and to sub-species by...

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