Preferensi Makan Rayap Tanah Schedorhinotermes javanicus Kemner (Isoptera: Rhinotermitidae) terhadap Kayu Tusam (Pinus merkusii Jungh. et de Vriese)

Abstract

Rayap tanah Schedorhinotermes javanicus Kemner (Isoptera: Rhinotermitidae) dikenal sebagai salah satu spesies rayap perusak kayu terpenting di Indonesia selain Coptotermes sp. Sebaran geografis spesies rayap tersebut di Indonesia cukup luas dan telah ditemukan menyerang bangunan gedung maupun perkebunan. Namun demikian, perilaku penyerangannya pada kayu dan bangunan gedung, termasuk preferensi makannya belum banyak dilaporkan. Suatu penelitian lapang telah dilakukan untuk menganalisis preferensi makan rayap tanah S. javanicus terhadap kayu tusam (Pinus merkusii Jungh. et de Vriese) di lapangan dan beberapa faktor ekologis yang terkait. Sebanyak 30 kayu umpan yang terbuat dari kayu tusam (kadar air ±15 %) berukuran 2 x 2 cm arah tranversal dan 2 x 46 cm arah longitudinal dikubur di lapngan (titik kordinat 6°33’26.43’’S 106°43’44.99’’E, ketinggian 192 Mdpl). Jarak antar kayu umpan pada arah memanjang (baris) adalah 30 cm, sedangkan pada arah melebar (kolom) adalah 60 cm. Satu, dua, dan tiga bulan sejak penguburan kayu umpan, kehilangan berat kayu umpan dan konsumsi kayu umpan oleh rayap S. javanicus ditelaah. Spesimen rayap tanah yang menyerang kayu umpan juga dikoleksi untuk keperluan identifikasi. Disamping itu, karakteristik tanah (kandungan c-organik, tekstur, dan pH tanah) dan cuaca (suhu harian, kelembapan udara harian serta intensitas cahaya harian) di tapak pengujian dicatat. Hasil penelitian menunjukkan bahwa S. javanicus sangat aktif menyerang kayu umpan. Hal itu tercermin dari tingginya kehilangan berat (35,03%) dan konsumsi kayu umpan (38,78 g) oleh S. javanicus. Bahkan serangan rayap tersebut pada kayu umpan telah terjadi sejak bulan pertama pengujian. Kehilangan berat kayu umpan setelah satu, dua, dan tiga bulan pemaparan di tapak pengujian masing-masing mencapai 13,54%, 16,38%, dan 35,03%. Dengan perkataan lain laju kehilangan berat kayu umpan rata-rata 76,41%/bulan. Sementara itu, konsumsi kayu umpan oleh S. javanicus setelah satu, dua, dan tiga bulan pemaparan di tapak pengujian masing-masing mencapai 14,9 g, 18,25 g, dan 38,78 g. Tingginya kehilangan berat dan konsumsi kayu umpan tersebut menunjukkan bahwa rayap tanah S. javanicus memiliki preferensi makan yang tinggi terhadap kayu tusam. Penelitian juga mengungkapkan bahwa karakteristik tanah (pH, kandungan C-organik, dan tekstur) serta cuaca (suhu dan kelembapan udara serta intensitas cahaya) di tapak pengujian sesuai untuk mendukung kehidupan koloni S. javanicus.

The subterranean termite Schedorhinotermes javanicus Kemner (Isoptera: Rhinotermitidae) is known as one of the most important wood destroying termites in Indonesia along with Coptotermes sp. The geographical distribution of these termite species in Indonesia is quite wide and have been found attacking buildings and plantations. However, their attacking behavior on wood and buildings, including their feeding preference, has not been widely reported. A field study was conducted to determine the palatability of S. javanicus on tusam wood (Pinus merkusii Jungh. et de Vriese) in the field and some related ecological factors. A total of 30 bait woods made of tusam wood (water content ±15%) measuring 2x2 cm in the transverse direction and 2x46 cm in the longitudinal direction were buried in the field (coordinate point 6°33'26.43''S 106°43'44.99' 'E, altitude 192 masl). The distance between the bait wood in the longitudinal direction (row) was 30 cm, while in the wide direction (column) was 60 cm. One, two, and three months after burial of bait wood, weight loss of bait wood and wood consumption by termites S. javanicus were studied. The specimens of subterranean termites that attack bait wood were also collected for identification purposes. In addition, soil characteristics (c-organic content, texture, and soil pH) and weather (daily temperature, daily humidity and daily light intensity) at the test site were recorded. The results showed that S. javanicus was actively attacking bait woods. This was reflected in the high weight loss (35.03%) and wood consumption (38.78 g) by S. javanicus. Even the termite attack on bait wood has occurred since the first month of testing. The weight loss of bait wood after one, two, and three months of exposure at the test site reached 13.54%, 16.38%, and 35.03%, respectively. In other words, the average weight loss rate of bait woods was 76.41%/month. Meanwhile, the wood consumption by S. javanicus after one, two, and three months of exposure at the test site reached 14.9 g, 18.25 g, and 38.78 g, respectively. The high weight loss and wood consumption of bait woods indicated that the S. javanicus had a high feeding preference on tusam wood. The study also revealed that soil characteristics (pH, C-organic content, and texture) as well as the weather (temperature, humidity, and light intensity) at the experimental site were suitable for the life of S. javanicus.