Sains Malaysiana 53(1)(2024): 1-10 http://doi.org/10.17576/jsm-2024-5301-01 Molluscicidal Activity of Entomopathogenic Fungus, Metarhizium anisopliae (Hypocreales: Clavicipitaceae) against Golden Apple Snails, Pomacea canaliculata (Architaeniglossa: Ampullariidae) (Aktiviti Moluskisid Kulat Entomopatogen, Metarhizium anisopliae (Hypocreales: Clavicipitaceae) terhadap Siput Gondang Emas, Pomacea canaliculata (Architaeniglossa: Ampullariidae)) MOHAMAD IKMAL HAKIM ALLAHUDIN 1 , ANIS JAZLEENA SYAFIQAH ANN JAISOFI 1 , MA NYUK LING 1 , THILAHGAVANI NAGAPPAN 1 , AZIZ AHMAD 1 , NG LEE CHUEN 2 & WAHIZATUL AFZAN AZMI 1,* 1 Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia 2 Faculty of Fishery and Food Science, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia Received: 6 March 2023/Accepted: 5 January 2024 ABSTRACT Golden Apple Snails (GAS, Pomacea canaliculata) is known in Malaysia as one of the world’s worst invasive pest species, wreaking havoc on paddy fields by lowering rice yield dramatically. Farmers now employ chemical molluscicides to eliminate GAS, but these are expensive and have serious health and environmental consequences. Biological control agent using entomopathogenic fungus is preferred over chemical molluscicides to control GAS because it is non-toxic, environmentally friendly and cost-effective. This study is aimed to investigate the molluscicidal activity of an entomopathogenic fungus, Metarhizium anisopliae towards GAS adults and eggs. M. anisopliae conidia were subsequently produced into four concentrations (3×10 4 , 3×10 5 , 3×10 6 , and 3×10 7 conidia/mL) and tested against adults and eggs GAS. The median lethal time (LT 50 ) for the concentration of 3×10 7 took 5 and 3 days to kill 50% of GAS adults and inhibited 50% of eggs from hatching, respectively. Physiological analysis was also conducted on both GAS adults and eggs. The skin of infected individuals became white and opaque, while internal organs such as the pulmonary sac, digestive tract, and hepatopancreas were visibly destroyed. The colour of GAS eggs turned pale after M. anisopliae infestation and resulted in non-viable eggs. This research shows that M. anisopliae is an effective biological control agent for GAS and has the potential to be used as a targeted bio-molluscicide for GAS management. Keywords: Biopesticide; entomopathogenic fungus; Golden Apple Snail; Pomacea canaliculate; sustainable agriculture ABSTRAK Siput Gondang Emas (GAS, Pomacea canaliculata) dikenali di Malaysia sebagai salah satu spesies haiwan perosak paling bahaya yang mendatangkan bencana kepada sawah-sawah padi dengan mengurangkan hasil tuaian padi secara dramatik. Pesawah kini menggunakan racun moluska kimia untuk menghapuskan GAS, akan tetapi cara ini agak mahal dan mendatangkan kesan yang serius kepada kesihatan dan persekitaran. Kaedah kawalan biologi menggunakan kulat entomopatogen lebih diutamakan berbanding racun moluska kimia bagi mengawal GAS kerana ia tidak toksik, mesra alam dan berkesan kos. Penyelidikan ini bertujuan untuk mengkaji aktiviti moluskisid bagi satu kulat entomopatogen, Metarhizium anisopliae, terhadap siput dewasa dan telur GAS. Konidia M. anisopliae kemudiannya dihasilkan kepada empat kepekatan (3×10 4 , 3×10 5 , 3×10 6 , dan 3×10 7 konidia/mL) dan diuji ke atas siput dewasa dan telur GAS. Tempoh masa maut median (LT 50 ) bagi kepekatan 3×10 7 untuk membunuh 50% siput dewasa dan menghalang 50% telur GAS daripada menetas, masing-masing mengambil masa 5 dan 3 hari. Analisis fisiologi juga telah dijalankan bagi kedua-dua siput dewasa dan telur GAS. Kulit individu yang dijangkiti menjadi putih dan legap, manakala organ dalaman seperti kantung pulmonari, saluran penghadaman dan hepatopankreas kelihatan hancur. Warna telur GAS bertukar menjadi pucat setelah dijangkiti M. anisopliae dan mengakibatkan telur-telur itu tidak berdaya hidup. Kajian ini menunjukkan bahawa M. anisopliae merupakan satu kaedah kawalan biologi yang berkesan untuk GAS dan berpotensi disasarkan sebagai bio-moluskisid untuk pengawalan GAS. Kata kunci: Kulat entomopatogen; pertanian mampan; Pomacea canaliculata; racun perosak bio; Siput Gondang Emas