Development of the Mass-rearing Technique for a Predatory Mite Stratiolaelaps scimitus (Acari: Laelapidae) Using the Double Box System

이중상자 시스템을 이용한 뿌리이리응애(Stratiolaelaps scimitus)의 대량생산 방법

Abstract

A mass-rearing method for a soil-dwelling predatory mite Stratiolaelaps scimitus (Womersley) was developed using the double box system. The rearing box consists of two, outer (22 L, $54{\times}36{\times}18cm^3$) and inner (6.5 L, $31{\times}22{\times}11cm^3$), plastic boxes. Inner box was filled with chaff (rice husks) which is used as the shelter of the predatory mites. Outer box contained 1 L of water and the inner box, then covered with a lid. This system prevents the predatory mites from escaping as well as keeping moisture of the shelter. In addition, Tyrophagus putrescentiae (Schrank), as prey mites of S. scimitus, was reared on the rice bran as a food source using the same double box system. The both mites were reared at $25{\pm}1^{\circ}C$, $60{\pm}10%$ relative humidity condition. The prey mites were provided once a week. The density of predatory mites increased three times for four weeks and the final population was approximately 120,000 individuals/box (4 L). This is a simple mass-raring technique of S. scimitus and helpful for the biological control of soil pests.

토양해충의 포식성 천적인 뿌리이리응애[Stratiolaelaps scimitus (Womersley)]를 이중박스 시스템을 활용하여 대량생산할 수 있는 방법을 개발하였다. 사육상자는 외부(22 L, $54{\times}36{\times}18cm^3$) 및 내부(6.5 L, $31{\times}22{\times}11cm^3$)로 구성된 플라스틱상자이다. 내부상자에는 뿌리이리응애의 은신처 역할을 하는 왕겨(4 L)를 담았다. 외부상자에는 물을 1 L 채우고 그 위에 내부상자를 넣고 외부상자 덮개를 덮었다. 이 시스템은 포식성응애의 탈출을 막고 은신처의 습도를 유지할 수 있다. 천적의 먹이원으로서 긴털가루응애[Tyrophagus putrescentiae (Schrank)]를 쌀겨에 사육하였으며, 뿌리이리응애와 마찬가지로 2중상자에서 증식시켰다. 천적응애상자에 주 1회 먹이응애를 제공하면서 $25{\pm}1^{\circ}C$, 상대습도 $60{\pm}10%$ 조건에서 사육하였다. 뿌리이리응애의 밀도는 4주에 3배로 증가하였으며 최종적으로 약 12만 마리/상자(4 L)였다. 이 방법은 간단한 뿌리이리응애 대량사육기술로서 토양해충의 생물적 방제에 큰 도움이 될 것으로 판단한다.

Fig. 1. Double box for rearing Stratiolaelaps scimitus. Both Tyrophagus putrescentiae (A) and Stratiolaelaps scimitus (B) were reared in the double rearing box. Both Tyrophagus putrescentiae (C) and Stratiolaelaps scimitus (D) can get out of the inner box but were dead by drowning to water of outer box. Rearing boxes were kept in the rearing room at the conditions of 25 ± 1℃ and 60 ± 10% Relative humidity (E).

Fig. 2. The adult female of Stratiolaelaps scimitus. Whole body of the adult female (A), dorsal shield tapering sharply after level of setae S2 (B), palp apotele with two subequal tines (C), and postanal (po) and paranal (pa) setae subequal in length (D).

Fig. 3. The moisture contents of the culture media (chaff) within the inner box of Stratiolaelaps scimitus. The moisture content of chaff was determined at interval of two days for four weeks using the hay moisture tensiometer. Data represent the mean ± SE of three replicates.

Fig. 4. The density of Stratiolaelaps scimitus in the double rearing box. One ml of chaff culture media from the rearing box was transferred into an A4 white copy paper and counted the density of Stratiolaelaps scimitus under the microscope. Data represent the mean ± SE of five replicates.

Table 1. Density of Tyrophagus putrescentiae and Stratiolaelaps scimitus

Table 2. Estimated populations of Tyrophagus putrescentiae and Stratiolaelaps scimitus in the double rearing box

Table 3. Estimated amount of Tyrophagus putrescentiae required in the double rearing box for rearing Stratiolaelaps scimitus