Peculiarities of development of the bird cherry aphid rhopalosiphum padi (l.) Feeding on cereals

Bird cherry aphid Rhopalosiphum padi (L.) is a common pest of grain crops. To control its harmfulness, there is a great necessity in a reliable method to estimate aphid abundance and spread in the field and to fulfil screening of resistant accessions for feeding in vegetation. The flight behavior patterns or selection of hidden sites by wingless insects within plants, as well as the wing emergence of offspring on cereal grasses, have been poorly studied, although they are important for aphid reproduction and harmfulness. The purpose of the current study was to optimize methodological approaches to estimating R. padi abundance due to its specific topical distribution and wing emergence. The field study and model trials have identified the features of R. padi’s topical distribution that had been overlooked. There has been shown that aphid can remain below the soil surface when feeding on wheat (the variety ‘Leningradskaya 6’) and 10 species of cereal grasses during the period of ‘tillering-early stem formation’. Their maximum abundance was 18.7 % on wheat (field) and 25.8 % on multiflora ryegrass (Tarquin) (model trials). There has been found that one of the causes of such migrations may be tactile stimuli, as a result of which the “hidden” number of insects in model trials (touching with a brush) has increased on average from 6.0 to 11.5 %. This feature should be taken into account when assessing R. padi population density. The current work has characterized the wing dimorphism of aphids and the role of both summer morphotypes in plant damage. The use of winged females to screen for plant suitability for aphid feeding poses challenges because of their flight activity. There has been found that female wing manipulations, which simulate the “crowding effect” and increase wing emergence of offspring through prenatal transgenerational transmission of relevant signals, distort the estimation results and cannot be used.