Planthoppers Can Change Wings From Short to Long

The brown planthopper is a tiny insect, about the size of a sesame seed that threatens the rice crops of Asia each year. These insects hang onto the stalks of the rice plants and siphon the sap from them with their sucking mouthparts. This causes the plants to turn yellow and to dry up, known as hopper burn. Large numbers of the brown planthopper can lead to the destruction of thousands of acres of rice, which is the primary source of food for approximately half of the world’s population. In order to do this these insects have a developed a strategy, which involves the wing length of the brown planthopper.

When the conditions in a rice field are stable the juvenile planthoppers develop wings that are short. Short winged planthoppers cannot fly, but produce offspring fairly quickly. A short winged female can lay more than 700 eggs in her lifetime. However, as the fall approaches and the days shorten and temperatures drop these insects start to develop longer wings. This allows them to fly into new rice fields in search of food. Previously scientists did not understand how the cooler temperatures and the shorter days caused the insects to shift from short winged to long winged or which hormones were involved, but a new study by Duke University reveals new information on the topic.

The study involved using a technique called RNA interference or RNAi. As a result of this technique genes for two different insulin receptors were able to be silenced. The effects that doing this had on the animals’ wings were then measured. In the past scientists had believed that all insects have only one insulin receptor, but it was discovered that the brown planthopper has two.

The researchers silenced the first insulin receptor and the planthopper nymphs developed into adults with short wings. Silencing the second insulin receptor caused the nymphs to develop into long winged adults. The scientists pushed their research even farther and were able to determine that the long winged form of the planthopper is the default form. However, the secretion of a certain type of insulin due to changes in temperature and day length causes the second insulin receptor to inactivate the first insulin receptor and short winged planthoppers develop. Essentially, the second insulin receptor interferes with the first and shuts down the signal.

The implications of the study could be numerous, but as of yet it is too early to tell if these findings could lead to techniques for controlling these insects. Scientists have discovered this mechanism in other planthopper species and hope to determine if insulin plays a similar part in other insects with flying and flightless forms.

To me this is astounding that these insects have evolved in such a way. It is really interesting to think that these insects have evolved such mechanisms to survive. It seems so complex and rather ingenious of these organisms, but I also think it is excellent that scientists have discovered how they are able to change from form to form. Hopefully, in the future researchers will be able to find a way to stop these insects from invading the rice fields and destroying the crops. It is exciting to think how far science has come and what can happen with the new information these studies are providing. 

Link to Article: http://www.sciencedaily.com/releases/2015/03/150318145422.htm

Additional Links: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/insects/item/planthopper

http://entomologytoday.org/2015/03/18/planthopper-wing-lengths-controlled-by-two-insulin-receptors/