Population Structure of Topshells (Trochus Niloticus) in Saparua Island, Central Moluccas-Indonesia

Lola snail (Trochus niloticus) is one of the largest sea snails that live in coral reefsat Indo Pacific region and Indonesia including Saparua Island, the province of Moluccas. In a few recent years, the exploitation of lola snails has been increasing, so that the population of lola snails in nature decreases.. The yield of lola snail in Saparua Island and in the archipelagos of Banda from 1979 until 1992 showed a decrease from around 4 tons of dry shells to only around 0.25 tons. Furthermore, this research was aimed to estimate the size structure, age structure, and the sex ratio of lola snails population in Saparua Island, the regency of Central Moluccas. The sampling of lola snails used transects strip method. Each transect was 100 m long and 2 m wide, which were divided into 10 segments of 10 m x 2 m. Transect was laid perpendicular to the coast line started from the lowest fall of the tides to the coast. The Bhattacharya method was applied for data analysis. The frequency distribution of shell diameter revealed that lola snails in Saparua Island consisted of nine size classes and two different age classes, which indicated that the population of lola snails in Saparua Island had two periods of spawning. Finally, from this research it could be concluded that the sex ratio of lola snail was 1:1

Biologi Lalat Sciarid, Bradysia Ocellaris (Diptera : Sciaridae), Serangga Hama pada Pertanaman Jamur Tiram

Bradysia ocellaris Comstock is an important insect pest of oyster mushroom at Bandung. Eggs are oval, 0.44 ± 0.12 mm in length, 0.26 ± 0.08 mm in width, and translucent. Larvae are worm-like, legless, translucent, and capsule distinctive black. Larvae consist four instars. Pupae are obtectate, 2040 ± 0.22 mm in length, and 0.69 ± 0.10 mm in width. Adults are small, females 2.58 ± 0.28 mm and males 2021 ± 0.28 mm in length. Life cycle is 16 -6 26 days. Larvae feed on media, mycelia and fruit bodies. Lalat Bradysia ocellaris Cumstock merupakan hama penting pada pertanaman jamur tiram di Bandung. Telur serangga berbentuk lonjong, berukuran panjang 0,44 ±0,12 mm, lebar 0,26±0,08 mm dan berwarna Bening. Larva berbentuk seperti cacing, tidak bertungkai, berwarna Bening dan kapsul kepala jelas berwarna hitam. Larva terdiri dari empat instar. Pupa obtektat, berukuran panjang 2,40±0,22 mm dan lebar 0,69±0,10 mm dan berwarna kuning coklat. Tipe pupa obtektat. Lalat dewasa berukuran relatif kecil, panjang tubuh dewasa betina 2,58±0,288 mm dan dewasa jantan 2,21±0,28 mm. Siklus hidup 16-26 hari. Larva serangga hidup dengan cara memakan media jamur, miselia dan tubuh buah jamur

Analisis Spasiotemporal Populasi Lalat Sciarid pada Budidaya Jamur Tiram

Sciarid fly (Bradysia ocellaris Comstock) population growth and its distribution in the mushroom house was studied. Insects were collected using sticky yellow traps laid on 21 stations in the house over 18 weeks. At the first time, insects population was low. After that, insect population grew and reached at a maximum level in the 8th week. In subsequent weeks, insect population fluctuated. In the other hand, insect population dispersal also occured in the house. Based on spatiotemporal analysis using contour map and semivariogram analysis, insect population showed aggregation pattern, in a small group is called subpopulation. This was related to biological characters of insect such as eggs oviposition in mass and short flights