Effectiveness of Net Traps and Clove Oil in Controlling Large Black Chafers Beetle (Holotrichia parallela ) in Organic Pear Orchards

유기재배 배 과수원에서 그물망과 정향유 처리가 큰검정풍뎅이 방제에 미치는 영향

Abstract

The purpose of this study was to investigate whether leaf damage in pear orchards caused by large black chafer beetles can be controlled through net traps and clove oil treatment. In June 2017, we measured large black chafer beetle population density and leaf damage rates in two orchards, located in Boseong and Hampyeong, under three treatments: net, net plus clove oil, and control. In order to evaluate the effect of net position on the adult beetles, nets were placed outside the orchard and along the upper and lower parts of a horizontal trellis. The adult beetle population density was 20.4 to 34.7% lower in the net alone treatment, and 21.1 to 38.1% lower in the combined net and clove oil treatment than in the control. The adult beetle population density was 10.9-14.4 times higher outside the orchard and 5.1 to 9.1 times higher in the upper parts of the horizontal trellis than in the lower parts of the horizontal trellis. Leaf damage under both the net only and net plus clove oil treatments was significantly lower than that in the control at both sites. Therefore, intensive net installation around orchards may be a practical organic alternative to prevent leaf damage caused by large black chafer beetles.

본 연구는 배 유기재배 과수원에서 그물망과 정향유물을 처리하였을 때 큰검정풍뎅이에 의한 잎 피해를 예방할 수 있는지 확인하고자 수행되었다. 2017년 6월 하순에 보성과 함평의 배 과수원에서 그물망, 그물망 + 정향유, 무처리구 등 3처리구를 두고 큰검정풍뎅이 밀도와 잎 피해율을 조사하였다. 또한 그물망 설치 위치를 달리하여 과수원 외부, 평덕시설의 상부, 평덕시설의 하부에 그물망을 설치하여 포획된 성충 개체수를 계수하였다. 그 결과 그물망 처리구에서 20.4~34.7%, 그물망 + 정향유 혼합처리구에서 21.1~38.1% 수준으로 무처리구보다 낮은 성충수가 포획되었다. 또한 그물망 설치위치에 따른 포획 개체수는 수관하부 설치구 대비 과수원 외곽은 10.9~14.3배, 수관 상부는 5.1~9.1배로 더 많이 포획되었다. 처리구별 잎 피해율을 조사 한 결과 두 지역 모두 무처리구와 비교하여 유의적으로 그물망, 그물망 + 정향유 처리구에서 잎 피해율이 낮았다. 따라서 큰검정풍뎅이에 의한 잎 피해를 예방하기 위해 그물망을 외곽에 처리하는 것이 실용적 대안이라고 판단된다.

Fig. 1. Picture of the outer side of a pear orchard (A) and trellis training system—upper (B) and lower (C) position, installed in different treatments.

Fig. 2. Damage severity levels in pear leaves (Pyrus pyrifolia nets. Nakai) according to the leaf’s damage area: (A) level 1, 1-20%; (B) level 2, 21-40%; (C) level 3, 41-60%; (D) level 4, 61-80%; and (E) level 5, >81% of the leaf’s sectional area.

Fig. 3. Large black chafer beetle (Holotrichia parallela) caught by nets.

Fig. 4. Seasonal fluctuation in adult Holotrichia parallela numbers captured in nets and using clove oil in Hampyeong (A) and Boseong (B). Vertical bars indicate ± standard errors (n = 3). Different lowercase letters above each bar indicate significantly different means, as determined by Duncan’s multiple range tests.

Fig. 5. Seasonal fluctuation in adult Holotrichia parallela numbers captured according to net trap treatment positions in Hampyeong (A) and Boseong (B). Vertical bars indicate ± standard errors (n = 3). Different lowercase letters above each bar indicate significantly different means, as determined by Duncan’s multiple range tests.

Fig. 6. Leaf damage (rate of damage) observed under different treatments in two organic pear orchards. (A) Hampyeong, (B) Boseong. Different lowercase letters above each bar indicate significantly different means as determined by Duncan’s multiple range tests.