Phuah Chuan Hun, manager of the plantation in East Kalimantan, Indonesian Borneo, and his employee Widiantoro paid two men to kill the primates, prosecutors claimed.
They and the two alleged killers, Imam Muhtarom and Mujianto, face five years each in jail if found guilty of the charge of killing endangered species.
Prosecutor Suroto told the court: "The two men were paid one million rupiah (£70) for each orangutan and 200,000 rupiah (£14) for other monkeys.
"The two used a 4.5-millimetre calibre airsoft gun to shoot the orangutans out of trees before their six hunting dogs chased them."
The prosecutor claimed Muhtarom and Mujianto would then club the orangutans with rocks or wooden sticks before binding their corpses and taking photographs as evidence.
Right to left, Malaysian Phuah Chuan Hun sits next to Indonesian Widiantoro, Imam Muhtarom and Mujianto during their trial in Tenggarong, East Kalimantan
Indonesian men on trial for slaughtering primates for pest control at palm oil plantationIndonesian men on trial for slaughtering primates for pest control at palm oil plantation