Task: Question Answering
Input (English): Passage: Wildlife photographer Pickett Smith is taking photographs of the local flora and fauna as he canoes through a swamp surrounding an island containing the affluent mansion estate of the wealthy and influential Crockett family. Also evident throughout the swamp are numerous indicators of pollution, which Pickett believes are connected to pesticide use on the island plantation. After Clint Crockett accidentally tips over Smith's canoe, he and his sister Karen escort Smith to the family mansion where he meets the entire Crockett family. The grouchy, wheelchair-bound patriarch Jason intends on spending the next day enjoying both the 4th of July and his own birthday celebrations uninterrupted. Due to the mutual dislike of the fauna around the mansion, Jason sends a man named Grover to spray pesticide in order to get rid of the frogs. Pickett later discovers Grover's corpse covered in snakebites in the swamp not far from the house. Despite this warning, Jason continues with his celebrations the next day.
Early next morning, Michael Martindale sets out to check on a possible downed telephone line. He accidentally shoots himself in the leg and is rendered immobile by strange white moss hanging down from the surrounding trees. Tarantulas descend from the branches and kill him. 
Back on the estate, Jason's sister, Iris Martindale sends her son, Kenneth into the greenhouse to collect flowers for a centerpiece. As he gathers the flowers, he fails to notice dozens of tokay geckos entering behind him. The geckos swarm over the stacked shelves, knocking over numerous jars of poisonous chemicals, and the resulting toxic gas asphyxiates him.
Seeing the danger posed by the animals, Pickett suggests that everyone should leave the island, but Jason is adamant that nothing will ruin his birthday. 
Question: How did Iris's son die?
Output (English): toxic gas asphyxiates him.