Alfalfa weevil (Hypera postica) is the most problematic pest in Wyoming alfalfa fields. One of the reasons this pest is so tricky for producers to manage, is because infestations can be highly variable and difficult to predict. They can be very problematic in some years and fields, and not at all in others. As a result, producers have the difficult task of deciding if, how, and when to manage for weevil. Continue reading
Allison speaking. The relationship between aphids and parasitoid wasps has been of a lot of interest to us here, as the wasps that kill weevils by using them as hosts for their young to eat (from the inside out!) may benefit from having aphids around for the honeydew they provide. It can be an important sugary food source to many bees, ants and wasps in the order Hymenoptera. Another hypothesis we have is that flower nectar may also play an important role in a parasitic wasp’s diet. But how important to successful weevil parasitism is wasp nutrition? Would the size of aphid populations have any effect on the size of weevil populations through this indirect relationship?
Besides alfalfa weevil, alfalfa producers deal with a number of other pest insects like lygus (stay tuned for more on these critters!) and aphids. In focus groups conducted with Wyoming alfalfa growers over the past two years, it became clear that there was some confusion about what sort of damage aphids can cause to alfalfa, the types of aphids found in WY alfalfa fields, and how to manage them.
As a result we decided to put together a fact sheet with some information about aphids in alfalfa. Continue reading