Lady beetles are beneficial to the environment due to their suppression of aphids, scale insects, thrips, mites and other plant pests. In a laboratory experiment we studied the efficiency of the larvae of two-spotted lady beetle (Adalia bipunctata Linnaeus) at controlling two types of aphids (Aphididae) namely green apple aphid (Aphis pomi de Geer) and black bean aphid (Aphis fabae Scopoli). The experiment was set up at three different temperatures (15, 20, and 25 °C) and at 75 % relative humidity. The aphids and the larvae of two-spotted lady beetle were placed in plastic Petri dishes, which were then put in a growth chamber. The larvae of two-spotted lady beetle were fed with aphids. In three consecutive days, we counted the aphids to determine if they had multiplied or been eaten by the larvae of two-spotted lady beetle. We discovered that the two-spotted lady beetle larvae prefer the green apple aphids at the temperature of a 20 ºC, as after three days an average of only 63.3 aphids from the total of 100 remained. Regarding the black bean aphids, we discovered that the second day at the temperature of 20 ºC the number of specimens increased to an average of 112.7. At a temperature of 15 °C we found that after three days the total of 100 green apple aphids had been reduced to 71,7 aphids, whereas as to the black bean aphids an average of 95,5 specimens remained. We also observed that at the temperature of 25 °C after three days an average of 73.3 green apple aphids remained and as to the black bean aphids, an average of only 71 was left.
|
