How do RGT18 Alkaloids Compare to Other Endophytes?
Traditionally, most New Zealand pastures contained the endophyte now referred to as ‘Standard’ endophyte, which includes the alkaloids Peramine, Lolitrem B, and Ergovaline. While Standard endophyte provides some benefits, it also has negative impacts on livestock. Novel endophytes offer insect protection while being safer for animals.
For ryegrass, endophyte options can be roughly divided into two groups:
Endophytes containing one or a combination of the following alkaloids: Peramine, Lolitrem B, and Ergovaline. Some endophytes have varying concentrations of all three alkaloids, while others, like AR1, contain only Peramine.
Implications of these alkaloids:
- Peramine: Increases plant protection from Argentine stem weevil (ASW) and Pasture mealy bug. It is non-toxic to animals.
- Lolitrem B: Is toxic to Argentine stem weevil larvae At high concentrations, it can negatively affect livestock, particularly causing ryegrass staggers, with the most pronounced effects in summer and autumn.
- Ergovaline: Offers increased protection against Black beetle feeding and moderate resistance to root aphids. It can constrict blood vessels and may contribute to heat stress in cows under certain conditions, although this has not been proven in New Zealand.
Endophytes composed of alkaloids called “Janthritrems”: These can provide increased tolerance against a wide range of insects, including Black beetles, Root aphids, Pasture mealy bug, Argentine Stem Weevil, and Porina.
While Janthritrems can potentially cause ryegrass staggers, RGT18 has undergone a number of independent trials that show the risk of ryegrass staggers is significantly less than the AR37 control, making it very safe for livestock while still offering excellent pest protection. RGT18 should not be used where grazing may include deer or horses.
