The year of the sugarcane aphid

Aphids are very small insects and some people might wonder what kind of threat a small insect could pose. Well, 2015 has been a stark example; sorghum production has suddenly become a very expensive endeavor. The sugarcane aphid made some kind of genetic switch to sorghum in recent years and has been a devastating pest in Texas since 2013. It reached the High Plains late in 2014, too late to do much damage. However, it arrived here in June of 2015 and most of my summer has been devoted to trying to stop this pest.

This aphid, like many aphids, is born pregnant and gives birth to live young. Thus the progeny begin birthing live young in 4-5 days. This reproductive potential means that populations can double in just a few days. Aphid colonies expanded and it is not long before thousands of aphids cover the bottom of sorghum leaves and extract plant juices. The aphids then excrete honeydew, a thick sugary substance that coats the leaf below and causes it to glisten in the sun. Aphids extract a huge number of calories from plants and kill leaves, and this in turn leads to significantly reduced grain yield. My trials indicate a 76 - 80% yield loss if insecticides are not used. In some cases the aphids lead to no grain yield, and it is torture to walk a field and realize that the grower had a significant investment but would not have any harvestable yield. To add to the problem the honeydew is pretty much like Karo Syrup and it may make it very difficult for a combine to harvest the sorghum kernels in fields that did yield. In August there were billions of winged aphids migrating from fields, and cars along the interstate would run through these clouds. Drivers suddenly found their windshields coated with aphids and they had to pull over and scrape them off before they could continue. Almost every sorghum field on the Texas High Plains had very high and damaging numbers of aphids.

Agricultural research requires detailed planning going in to spring and there is very little room to alter the schedule. This year, however, the magnitude of the sugarcane aphid threat caused many of us to shelve our carefully made plans and put all efforts toward blunting the effects of this pest. But that's what we do; the agricultural community comes first.

A sugarcane aphid colony with winged adults.

And a few days later.