WHEATLAND--Jack Gilbert, according to this story, stood between his walnut trees with outstretched arms, trying to catch spray from the crop-duster swooping overhead. Normally, it is not a good idea to stand beneath a working agricultural plane. But it was perfectly safe in this case, because out of nozzles under the wings came not chemical pesticides, but eggs bearing bugs. Very tiny bugs. Good bugs.
Like the pesticides they're replacing, these good bugs will, the story says, kill pesky bugs. The hope is that they will save walnut farmers money and save a walnut eater from the distasteful experience of opening a wormy nut.
Farmers have been deploying beneficial insects for years, but only now is it becoming feasible to use them on a grand scale. This summer, walnut growers from Tehama to Tulare counties have contributed 12 plots for a test project in aerially dispatching a parasitic wasp against a pest called codlingmoth.
When Gilbert, the orchard owner, tried to catch an egg for curiosity's sake, it took several passes of the crop-duster before what looked like a speck of black dust landed in his palm. Though you could hardly see them, pilot Russ Stockerhad distributed 3 million eggs onto 15 of Gilbert's acres. Using a single-seat Cessna Ag-Wagon, the job took all of 10 minutes.
Before Stocker worked out a method to drop bugs by air, local growers and researchers who wanted to try this wasp had to hand-staple cards of eggs to the tree leaves.
Sprayed from above, the eggs stick to the leaves in a solution of guar gum, a common thickener found in foods such as ice cream. Adult wasps lay their eggs in the eggs of codling moth. The moth larva is the proverbial worm in the apple. Besides apples, codling moth larvae also feast on walnuts. The wormy bugs bore into the husks, gobble the meat and leave droppings behind.
By making the codling moth egg a nursery for its own young, the parasitic
wasp effectively kills the pest before it hatches as a destructive worm.
What Stocker rains onto the walnut trees are the eggs of grain moths that
were parasitized by wasps in an insect factory in Canada. After spraying,
the wasps emerge to produce their own young, attacking codling moth eggs
to do so.
Scientists and agricultural engineers have been working for years on ways of distributing beneficial insects en masse. It's not common to find commercial crop-dusters taking a crack at it, and so far the wasp egg spraying is only being tested on walnuts.
Carolyn Pickel,an integrated pest management adviser for the University
of California Cooperative Extension in Yuba City and a consultant on the
project was quoted as saying, "What happens in research is, people develop
it to a certain level, and it never gets out. If it hadn't been for Russ,
we wouldn't have had this (aerial) system."