Effects of Controlling the Pine Needie Gall Midaes by Salicylic Acid Content in Needles of Some Pinus spp.

소나무류(類) 침엽내(針葉內)의 salicylic acid에 의한 솔잎혹파리의 방제효과(防除效果)

The frequency of gall formation by pine needle gall midges ranged from 35% to 40% in both P. densiflora and P. thunbergii species. However, there was no indication of gall development from larva on both P. virgiana and P. rigida species suggesting that some specific compounds might play role in preventing gall formation of larva. The susceptible species to pine needle gall midges including P. densiflora and P. thunbergii contained a little salicylic acid under the free phenolic compound conditions while the resistant species against such insects including P. virginiana and P. rigida species contained about 37ppm to 50ppm of salicylic acid. Thus, this compound might have important roles in insect resistance. The contents of internal salicylic acid in the needles of susceptible pines increased from 9.5ppm to 20.6ppm after direct external irrigation of salicylic acid solution and flour treatment on roots. As a result, the frequency of gall formation decreased dramatically 17~19 times lower when compared with that of control. According to our results, the application of salicylic acid for effective prevention against insect damages should be performed before hatching eggs. The frequency of gall formation in the hybrid pines of P. thunbergii(susceptible) and P. virginiana(resistant) showed approximately 24% as average value of those in both species. In the case of specific individuals, it ranged from 2.8% to 11.5% in hybrids of both species. Therefore, effective production of insect resistant pines can be obtained through hybrids by crossing between susceptible and resistant species including P. thunbergii and P. virginiana by increasing internal salicylic acid contents of the needles.

소나무, 해송의 솔잎혹파리 충영형성율(蟲廮形成率)은 35~40%이나 버지니아소나무, 리기다소나무에는 산란(産卵)은 하나 충영(蟲廮)이 형성(形成)되지 않으므로 침엽내(針葉內)에 솔잎혹파리에 대한 저항성물질(抵抗性物質)이 존재(存在)함을 알 수 있었다. 솔잎혹파리의 감수성(感受性) 수종(樹種)인 소나무, 해송의 침엽내(針葉內) free phenol상태의 salicylic acid는 소량(小量) 함유(含有)되어 있으나 내충성(耐蟲性) 소나무인 버지니아소나무, 리기다소나무에는 37~50ppm이 함유(含有)되어 있어 salicylic acid는 솔잎혹파리에 대한 저항성물질(抵抗性物質)로 추정(推定)된다. 솔잎혹파리에 감수성(感受性) 수종(樹種)인 소나무와 해송에 salicylic acid의 용액(溶液)을 관수(灌水) 혹은 분말(粉末)을 뿌리에 주어 침엽내(針葉內) salicylic acid의 함량(含量)을 높여 줌으로써 무처리구(無處理區)에 비하여 충영형성율(蟲廮形成率)을 17~19배(倍)로 감소(減少)시킬 수 있었다. Salicylic acid에 의한 솔잎혹파리의 방제(防除)는 유충(幼蟲)이 알에서 부화(孵化)하기 전(前)에 처리(處理)하는 것이 효과적(效果的)이며, 해송과 버지니아소나무 교잡종(交雜種)의 충영형성율(蟲廮形成率)은 양친수종(兩親樹種)의 중단수치(中間數値)인 24%이나 교잡종중(交雜種中) 선발(選拔)한 개체(個體)에 따라 2.8%, 11.5%의 충영형성율(蟲廮形成率)을 나타내므로 침엽내(針葉內)salicylic acid의 함량(含量)에 의해서 솔잎혹파리에 대한 내충성(內蟲性) 개체(個体)를 선발(選拔)할 수 있을 것으로 기대된다.