Colin Tann, CSIRO Entomologist, comments on the higher than usual Helicoverpa and tipworm populations being monitored this season.

Colin, can you give us an update about Helicoverpa ecology as we’re seeing a lot of moths around at the moment. It’s very early October and there are heaps of moths, what’s driving this?

This year there has been excellent breeding out in the inland regions and if anyone has had the opportunity to get out in central Australia over past years, or even this year there’s been a lot of wildflowers.

These wildflowers are excellent hosts for Helicoverpa punctigera and other species and what we’re seeing at the moment are migration flights coming across. As the hosts start to dry out in the inland regions and the temperature warms up they take to the wind and they end up over here. You get fairly poor survival but when the conditions are good you get a lot of months coming across.

So we’ve been getting a few weather changes through at the moment; is that what’s driving them?

Absolutely. They come in with the winds, they’ve even been shown to be on the jet stream sometimes. They’re lifted up with prevailing winds and they can be picked up on the radar. So this year’s obviously been a fairly successful breeding year in the inland, we haven’t been on any expeditions this year but I think it’s a fair assumption just looking at rainfall events to indicate that there’s been pretty good breeding.

What’s it going to mean to us where we’re putting cotton in the ground as we speak. What are the implications to our early season crop?

At the moment we’re doing surveys of spring crops such as chickpea, faber bean, sunflower, canola and also roadside weeds. We are picking up populations on those at the moment. If anyone sees wildflowers on the side of the road stop and have a look and you’ll probably find grubs on them. This is the first generation and we’re getting regular rainfall events (in this valley anyway) and we expect with the constant moisture to have good host availability as we keep going into warmer months, so the conditions are really good for breeding. We need to have that one generation of moths before we start thinking there’s going to be a risk to the cotton industry and it’s shaping up that we’re probably going to find quite a few months early in the season.

At the moment the life cycle of the Helicoverpa is going to be a little bit longer because things are still a little bit cooler?

Things are warming up, but certainly the cooler the conditions the slower the development of the grubs on the plant and the slower the emergence from pupation. From October on we start seeing a few Helicoverpa armigera starting to get into the system and H. puntigera moving into their second generation and so the conditions should be very nice for moth activity this year.

There are many Helicoverpa out there on weeds and spring crops at the moment because the cotton’s not really up. When are we going to see the next wave that might, hit cotton? What sort of timing is that normally or does it come in dribs and drabs?
 
It’s going to be staggered because there have been constant flights and contact activities, so I think from now on you will start seeing moth activity and the conditions are excellent for that.

November is usually a pretty good month when you get a lot of moths around and they’re going to be mixed species. People have probably been finding a lot of months around lights on buildings and they’re mixed species, they’re not all H. punctigera, so don’t panic. There’s another native species, which used to be called Neocleptria punctifera. it’s called Heliothis punctifera now and people might have been alerted to that. This insect is not that significant, it can be a pest but it usually disappears pretty quickly. It’s been migrating across and it usually beats the H. puctigera as it develops a bit quicker. There are still H. punctigera around and I’m finding them in the sampling effort we’re doing at the moment.

Would you care to make a comment about tip worm?

When you see a lot of marshmallow plants growing around the side of the road, and there’s certainly a lot this year, you can probably suggest that there’s going to be a bit of tip worm around this year and there’s been talk about Army worm as well.

I mean it’s a good season and people have got to expect it to be a higher pest year but on the other hand you’re going into crops this time of year and the beneficial populations are enormous and a lot of the stuff we’re collecting out of crops and other hosts is heavily parasitized. All our rearing effort we don’t get many moths out of it this time of the year, so the mortality is very high.

That’s pretty good news then?

That’s good news. It’s just a really good spring, we’re finding a lot of activity of insects as people are driving around at night they’ll sympathise with that some of them are bad and we just have to keep vigilant with our checking and I’m sure we’ll find H. punctigera in the system fairly frequently this year.

Further Information:
Dr Stephen Allen, Robert Eveleigh, John Marshall,  Craig McDonald, David Kelly or James Quinn