Oxygen demand and behavior of the rice midge Cricotopus bicinctus Meigen 1818 (Diptera: Chironomidae)
2002
Szito, A.
Cricotopus bicinctus Meigen is one of the most important rice pests of flooded rice culture in Hungary. It damages young rice leaves on the water surface. An experiment was conducted to test the assumption that the behavior of the larvae is influenced by their oxygen demand, which in turn explains why they become common rice pests. In laboratory experiments, mature larvae started to move toward the water surface after the optimum of about 10.9 mg dm¯³ of dissolved oxygen was reached in the water. The same behavior was observed with younger larvae at 3.7 mg dm¯³. The LC50 value was 2.7 mg dm¯³ and the LC100 value was 1.8 for mature larvae and 1.2 mg dm¯³ for young larvae. The mature larvae had a high oxygen demand, whereas the younger larvae were more tolerant of oxygen deficiency. The oxygen content of the water is considerably lower near the mud surface, especially at night or ar daybreak, which makes C. bicinctus larvae move toward the water surface. Rice leaves present both a substrate and food for the larvae, together with the overgrowth of algae and bacteria. In this way, the originally polyphagous C. bicinctus larvae become rice pests.
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Эту запись предоставил International Rice Research Institute