The black-bean aphid Aphis fabae bears populations of coccoid symbiotic bacteria Buchnera spp. at 2.0-3.2 x 10(7)cells mg(-1)aphid mass and rod-shaped secondary symbionts of uncertain taxonomic affiliation at 0.1-0.6 x 10(7)cells mg(-1)aphid mass. Buchnera provides essential amino acids, supplementing the poor supply in the aphid diet of plant phloem sap. Comparison of the performance of A. fab...

Antagonistic coevolution between hosts and parasites can result in negative frequency-dependent selection and may thus be an important mechanism maintaining genetic variation in populations. Negative frequency-dependence emerges readily if interactions between hosts and parasites are genotype-specific such that no host genotype is most resistant to all parasite genotypes, and no parasite genoty...

أوضحت نتائج التجربة المختبرية لتقدير الكفاءة النسبية لمعاملات المستحضرات الفطرية في مكافحة نوعين من حشرات المَن هما Aphis gossypii و fabae أن المستحضر الفطري Lecanicillium muscarium هو الأكثر كفاءة باقي المستخدمة الدراسة وهي , Isaria fumosorosea Beauveria bassiania acridum Metarhizium إذ بلغت النسبة المصححة للموت بعد 7 أيام المعاملة لحوريات مَن القطن 92.8 % وللبالغات 88.78 حين كانت الباقلاء الأسو...

Much has been learned of the kinematics and aerodynamics, the metabolism and even the sensory and nervous physiology of insect flight from observations on tethered specimens, preferably in a wind tunnel or on a roundabout to provide a relative wind simulating that created by free flight (Pringle, 1957). Such devices were developed to a high pitch of refinement by Weis-Fogh (1956) for locusts an...

coccinellids play a major role in aphid control. hippodamia variegata goeze is an aphidophagous predator of worldwide distribution that could be found in different parts of iran. one of the criteria for evaluating the efficiency of a predator is its response to change in prey population density (functional response). the functional responses of males and females of hippodamia variegata were stu...