Insecticide resistance. 54

A key tool for Turf Managers are Insecticides to prevent or minimize insect damage to Turfgrass, and preventing insecticide resistance is vital to continue to use these.

 

 

Globally there are over 20 different modes of action (MOA’s) available, several of which are use in the Australian turf industry.

 

Continuous use of insecticides from the same chemical grouping with the same MoA, increases the risk of resistance to that specific chemical group, and also cross-resistance to other groups.

A good example of this is the Argentine Stem Weevil.Koppenhöfer et al ¹Koppenhöfer AM, Kostromytska OS, Wu S. Pyrethroid-Resistance Level Affects Performance of Larvicides and Adulticides From Different Insecticide Classes in Populations of Listronotus maculicollis (Coleoptera: Curculionidae). J Econ Entomol. 2018 Aug 3;111(4):1851-1859. doi: 10.1093/jee/toy142. PMID: 29800225.found that with stem weevil larvae, the efficacy of cyantraniliprole, was slightly reduced against a highly bifenthrin resistant population.

Significant reductions in efficacy and no control occurred for indoxacarb against the highly resistant population, and for clothianidin, chlorantraniliprole, against the resistant and highly resistant populations.

Resistance can even develop in products that you currently don’t think will be an issue. Although no resistance was detected in the cotton bollworm or corn earworm to chlorantraniliprole in 2023-2024, in previous years there has been insecticide resistance. This is Acelepryn to you and me, so when you throw out your regular application, try and think about preventing resistance by rotating to other chemical groups!

If you use different the chemical groups that have different MoAs, this slows down the chances of resistance developing. Doing this in conjunction with certain cultural practices are the first step to slowing this down.

 

Use of Cultural Practices to Prevent Insecticide Resistance.

The use of cultural techniques to control an insect pest reduces the selection pressure from insecticides. Cultural control includes:

• The use of high endophyte sports turf seed varieties like the A-listed perennial ryegrass, Intense PRG.
• Ensuring your turf in the best possible condition, and
• Monitoring insect threshold levels.

If you are monitoring threshold levels a good mix for getting army worms, adult billbugs, or mole crickets to the surface is as follows:

In 8 L of water add 30 ml lemon scented dish washing liquid, and apply this over one square metre. Carry this out every 14 – 21 days and count how many pests emerge after treatment.

The other options is to look at Degree Day Models with a baseline temperature of 10°C.  For example, 1st adult activity of adult billbug is between 280-350 degree days. 30% adult activity is 500-624 and 70% egg hatch is between 925-1035 degree days.

 

Understand an insect or mite life cycle.

It’s essential to understand the life cycle of a turfgrass pest to better target any control methods. The best results from any insecticide or miticide in a resistance programme, should target pests when they are at their most vulnerable.

The spectrum of control of a product is also important. Many current products, are active against more than one pest, and provide multiple benefits from one application.

A good example of this is ProForce Scarlet Trio. One application for African Black beetle also gives control of mites, Argentine stem weevil, mole crickets, cutworms, armyworms and sod webworms.

 

 

The principle behind getting the best results is to apply the chemical where your target pest is. This directly impacts on the formulation you need to use, your timing, how you apply it and whether you need to water it in.

 

 

For example, if your target is in surface thatch, then irrigate an hour pre-treatment as this draws insects to the surface, and also improves movement into the soil. You can then follow up this with an appropriate amount of water or let rainfall wash it in.

 

 

 

Factors such as volatilisation, not applying enough water, hydrophobic thatch and insecticide resistance all impact on the results you get.

 

 

Insecticide molecules are much smaller than the target protein molecules they act on. These target proteins have more than one site where similar insecticides can bind.

 

The location where an insecticide binds and works, is known as the target site, and the interactions of the insecticide with that site, define its mode of action.

 

 

 

 

 

Mode of Action Classification to Manage Insecticide Resistance.

 

Varying the mode of action on insect pests is the most important tool we have to ensure we continue to control insect pests. Failing to “rotate” between different modes of action of insecticides, and to continue to use the same ones repeatedly just contributes to resistance. So look at newer options like Tetrino Insecticide and Echelon Duo as alternatives

 

 

Failure to do this just kills susceptible insects, and leaves behind those with resistance to that entire insecticide class. A good rotation strategy that uses different modes of action, slows down or avoids insecticide resistance.

 

 

If you click on the image below you can get your free insecticide resistance chart. Simply rotate between the MOA groups when you target your pests.