Abstract
Biological control against mushroom fly, Lycoriella mali, was performed by using Bacillus thuringiensis subsp. israelensis Bti-D and Bti-U, isolated from dead mushroom fly in oyster mushroom houses. Control values of the bacterial strains Bti-D and Bti-U against L. mali in bottle culture of oyster mushroom were 74.4% and 64.2%, respectively, and the value in small tray culture were 75.8% and 56.8%, respectively. In the experiment to develop the mass, cheap media for Bti-D and Bti-U isolates, the Biji broth (bean curd residue, called Biji in Korean language) was selected as a culture medium for an inexpensive and mass cultivation by the measurement of optical density of the two bacteria grown in the different media tested. Insecticidal effect of the formulation contained different ingredients that were prepared by using the Bti-D strain cultured in the Biji broth was tested in tray and bottle culture of oyster mushroom. The WCS formulation that contained corn starch as bio-gel (86.4%) was more effective to control the mushroom fly than living cells (69.1%) in bottle culture of oyster mushroom. Moreover, insecticidal effect of the WCS formulation was improved when water of pH 8 was used for dilution of the formulation. Effect of the WCS formulation using water of pH 8 and chemicals, Zuron (dimillin) W.P. on the control of mushroom fly and the productivity of oyster mushroom was investigated in tray culture of oyster mushroom. The Zuron W.P. was more effective to control the mushroom fly than the WCS formulation. However, compared with no treatment, the productivity of the mushroom treated with the WCS formulation was improved than that of the mushroom with Zuron W.P.
국내 느타리버섯 재배지의 버섯파리 사충으로부터 분리하여 버섯파리 유충에 높은 독성을 나타낸 Bacillus thuringiensis subsp. israelensis Bti-D와 Bti-U 균주를 이용하여 느타리 버섯파리에 대한 생물학적 방제효과를 검정한 결과, 느타리버섯 병재배시는 Bti-D와 Bti-U의 방제가가 각각 74.4%와 64.2%이었으며, 소형상자재배시는 75.8%와 56.8%였다. Bti-D와 Bti-U의 제제화를 위한 대량배양용 염가배지를 개발하기 위하여 배지종류별 세균증식량을 OD를 측정하여 비교한 결과, 2균주 모두 비지배지에서 가장 높았다. 두 균주 중 방제효과가 더 높은 Bti-D 균주를 비지배지에서 대량배양하여 몇 종류의 수화형 미생물 살충제를 만들고 느타리버섯 병재배와 상자재배에서 방제효과를 검정한 결과, 병재배에서 bio-gel로서 옥수수전분을 이용하여 만든 WCS 제제의 방제가가 86.4%로 가장 높았으며, 생균처리의 69.1%보다도 효과적이었다. 또한, 이 WCS 제제를 살포하기 위하여 희석할 때 pH 8로 보정된 물을 사용할 경우에는 방제가가 93.2%로 제고되었다. 상자재배에서는 pH 8로 보정된 물을 사용한 WCS 제제와 화학살충제인 주론수화제의 방제효과와 버섯수량에 미치는 영향을 동시에 비교하였는데, WCS 제제 처리시 방제가는 74.3%로서 주론수화제 처리시 92.2% 보다 낮았다. 그러나 버섯수량 비교에서는 WCS 제제를 처리할 경우 무처리나 주론수화제 처리에 비해 수량이 증가되었다.
