Living organisms, including insects, have developed a complex array of physiological and behavioral mechanisms allowing them to cope with biotic and abiotic challenges. Under natural circumstances they are readily capable to make ‘predictions’ and consequently can adjust their physiology and behavior to ‘anticipate’ the expected changes. The compilation of predictions provide a fine tuning to prepare for would-be conditions allowing them to react at the right time by the best set of available physiological, behavioral ‘answers’. The attained internal harmony of the organism is the best option what an individual may achieve. Among insects, the most significant controller of rhythms is light and its changes, while temperature, humidity, food availability and population densities are also important. Rhythmic events at individual and population levels may be grouped as follows: development, dormant, reproductive, behavioral, metabolic cycles and polymorphism. The periodic changing of light and biological events related to this provides the most elaborate model. The main elements are: photoreception; clock mechanism measuring day and/or night length; photoperiodic counter including memory to accumulate information; neuroendocrine effector mechanisms regulating relevant physiological processes. A description of elements and an inventory will be provided of respective hormones, neuropeptides which are notably taking part in controlling events.
Flour from grains originating from plants infected artificially with cereal aphids were analyzed for glutenin and gliadin and total protein content, using Size Exclusion HPLC. Wheat plants were caged at the beginning of stem elongation. Cages were treated with 0.1 % methyl parathion. One week later, the caged plants were artificially infected with 5 aptera individuals of
Metopolophium dirhodum, Diuraphis noxia, Sitobion avenae
. It was found that aphid infection had significant effect on the glutenin and gliadin content, the total protein content and the gliadin/glutenin ratio. Both the glutenin and gliadin content was significantly higher in the seeds harvested from aphid infected plants. However, the gliadin/glutenin ratio was significantly lower in wheat flour prepared from aphid infected plants than in those from uninfected control. The most significant decrease in gliadin/glutenin ratio was caused by
M. dirhodum, D. noxia, S. avenae
infection followed by
at high-abundance. As the gliadin/glutenin ratio was significantly lower in flours made from aphid infected wheat seeds, it may be suggested, that aphid feeding results in decreased bread making quality of wheat flour.
Authors:P. Makleit, A. Nagy, S. Veres, and A. Fónagy
The concentration (in mg kg–1 fresh weight) of two main hydroxamates, 2,4-dihydroxy- 7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), and their temporal changes were simultaneously investigated using HPLC analysis in the leaves and roots of five Pioneer® maize (Zea mays L.) hybrids to select hybrids with higher hydroxamate contents. Although significant differences were found among hybrids in leaves, youngest leaves and roots, none of them showed unambiguously higher hydroxamate contents. However, the age of the organs and the plants significantly affected hydroxamate content. DIMBOA content of leaves decreased with increasing organ and plant age. DIBOA content varied among the hybrids, but generally decreased in the initial phase and then increased. In the roots, DIMBOA content decreased during the 21-day study and although DIBOA content did not show a clear temporal tendency, differences among hybrids were detected. According to current results, hydroxamate content temporally decreases in hybridspecific patterns, which should be considered when establishing a proper sampling time frame.