Lygaeus (Spilostethus) equestris L. (Het.: Lygaeidae), a sunflower pest
1991
Horvath, Z. | Bujali, G. (Bacsalmasi Napraforgotermelesi Rendszer (Hungary))
Lygaeus equestris overwinters among plant residues in the soil in the imago form. In early spring the imagos continue feeding to maturity on the weeds Carduus acanthoides L., C. mutans L., Onopordum acanthium L., Centaurea spp. and Asclepias syriaca. The number of eggs per female depends on how well fed the female is, the type of host plant, the temperature and other ecological factors. The temperature has a decisive effect on the duration of embryonic development and on the intensity of larva emergence. The 1st larval generation appears in late May or early June and the last in mid-October. In Hungary, L. equestris has 4-5 generations a year. Where it feeds, germ-destroying fungi appear on sunflower. A total of 20-25 imagos per inflorescence leads to an average 13 o/o reduction in the germination ability of sunflower. Although previously L. equestris was considered to cause damage only on the edges of the fields, it may also be found in their middle. As a result of the damage, there is an increase in the linoleic acid content of the achenes, which has a deleterious effect on storability. The only known natural enemy of L. equestris is the ichneumon fly Elomya lateralis.
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