Laboratory investigation on two-spotted lady beetle (Adalia bipunctata [L.], Coleoptera, Coccinellidae) in controlling of two aphid (Aphididae) species

Polonice so za okolje ter za ljudi koristne živali, ker zatirajo listne uši, kaparje, resarje, pršice in nekatere druge škodljivce. V laboratorijskem poskusu smo preučevali učinkovitost ličink dvopike polonice (Adalia bipunctata Linnaeus) pri zatiranju dveh vrst listnih uši (Aphididae), in sicer zelene jablanove uši (Aphis pomi de Geer) in črne fižolove uši (Aphis fabae Scopoli). Poskus smo izvajali pri treh temperaturah, 15, 20 in 25 °C, ter pri 75 % relativni zračni vlagi. Uši in ličinke dvopike polonice smo namestili v plastične petrijevke, ki smo jih položili v rastne komore. Ličinke dvopike polonice smo hranili z listnimi ušmi. V treh zaporednih dneh od nastavitve smo šteli listne uši, da bi ugotovili, ali so se uši namnožile ali pa so jih pojedle ličinke dvopike polonice. Ugotovili smo, da ima ličinka polonice večjo preferenco do zelene jablanove uši pri temperaturi 20 saj °C je po tretjem dnevu od 100 uši ostalo povprečno le 63,3. Pri črni fižolovi uši pa smo ugotovili, da se je pri temperaturi 20 °C v drugem dnevu štetja število osebkov povečalo na povprečno 112,7. Pri temperaturi 15 °C smo ugotovili, da je po tretjem dnevu štetja od 100 zelenih jablanovih uši ostalo samo še povprečno 71,7, pri črni fižolovi uši pa je ostalo povprečno 95,5 uši. Ugotovili smo tudi, da je pri zelenih jablanovih ušeh po tretjem dnevu pri temperaturi 25 °C ostalo povprečno 73,3 osebkov, pri črni fižolovi pa le povprečno 71 osebkov.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