In late summer we often see bugs migrating into strawberry crops as the plants they have been living on start to dry down.
We tend to use the term “bug” to mean any insect, or even an arachnid like a spider, but entomologists mean something much more specific. Technically, a “bug” is an insect that’s in the family homoptera (like aphids) or hemiptera (like mirids). Both families have a straw-like mouth that they stick into their food and suck up the contents of the cells. Also, they’re the type of insect that go through unwinged “nymph” stages on their way to adulthood, but don’t have a larvae like a caterpillar or a maggot.
A grower recently sent of the photo above of black bugs on a fruit, hoping that they were good guys like stethorus beetles (predators like ladybirds). Nope, unfortunately not in this case. These are nymphs of Green Veggie Bug, which look quite different than the adults which (true to their name) are green.
One of the characteristics of bug feeding (both nysius and green veggie bug) is that when they suck, they spit back a bit of saliva. If they were sucking on a ripe fruit and it is eaten immediately it will taste horrible and bitter, but the nasty taste dissipates after some hours.
We don’t have great solutions for bugs in strawberries. They’re not easy to kill with soft chemistry, so we end up pulling out the harder chemistry in the arsenal, which isn’t compatible with a predator IPM program.
The Lighter Touch program, of which Strawberry Growers New Zealand is a member, is looking for solutions for green veggie bug in sweet corn. The first step in the green vegetable bug project involves two field trials in Gisborne of two biological compounds and four synthetic insecticides, which will be applied and compared to the industry standard. SGNZ will get the results of these trials, which will inform our next steps for bugs in strawberries.
New Zealand is not the only country with bug problems in strawberries. The UK has three species that cause them grief, and have developed a repellent that smells like the bugs’ alarm pheromone. We currently have a small amount of product to trial in NZ, in the hopes that our species of pestiferous bugs are also repelled.
In fact, even understanding which species bother strawberries in NZ is a challenge. To date we have received samples from Nelson and Hawke’s Bay. Nelson’s sample was easily identified as Nysius huttoni. The Hawke’s Bay sample is trickier as it contains more than one species, and identification to species level is still under way. More samples are needed from strawberry farms—please mail to Molly Shaw at Berryworld (C/O Plant and Food Lincoln, 74 Gerald Street, Lincoln, 7608).
Notes for NZ Berry Growers 