Endophyte is a fungus Neotyphodium lolli, which lives inside ryegrass plants. It does not spread between plants, but plants grown from endophyteinfected seed will be infected. One of its eects is that it produces a range of compounds that are toxic to Argentine stem weevil Listronotus bonar- iensis, which feeds on ryegrass. AgResearch New Zealand did a study on the persistence of perennial ryegrass at four rates of Argentine stem weevil infestation. For ryegrass that was infected with endophyte the following data were observed:

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Infestation Rate Number of Ryegrass Plants (n) log (n+1) Y 0 19 2.99573 0 23 3.17805 0 2 1.09861 0 0 0.00000 0 24 3.21888 5 20 3.04452 5 18 2.94444 5 10 2.39790 5 6 1.94591 1 9 9 9 9 9 & & & 5 6 1.94591 10 12 2.56495 10 2 1.09861 10 11 2.48491 10 7 2.07944 10 6 1.94591 20 3 1.38629 20 16 2.83321 20 14 2.70805 20 9 2.30259 20 12 2.56495