S. Villareal and K.L. Heong, International Rice Research Institute, Los Baños, Philippines
Parasitism can be a difficult concept to understand and appreciate for non entomologists. There are challenges in trying to communicate the concept to farmers. In Vietnam bees are being used as surrogates in campaigns to promote ecological engineering.
Egg parasitism is important to the pest regulatory services naturally available in rice ecosystems. Often as much as 80% of the planthopper eggs are parasitized by parasitoids such as Anagrus spp. In laboratory experiments, the Anagrus female when caged with a nectar producing flower such as sesame, it lays more eggs, lives longer and has higher egg searching efficiency.
Planthoppers insert their eggs into rice stems and are protected from most predators. Only two groups of insects have the necessary “equipment” to reach these eggs. One is the mirid egg predator with a long and stiff mouth part that enables it to pierce through and suck up each egg. The other is the egg parasitoid with it long and stiff ovipositor that enables the female to pierce through the mucilage layer protecting the eggs to deposit her eggs. A video showing the search behavior of two parasitoids, Anagrus and Oligosita, is now available in YouTube.
The video will help us visualize, understand egg parasitism and appreciate the role they play in regulating BPH populations. Since these parasitoids are tiny they can be vulnerable to insecticide sprays, particularly those with high toxicity to bees.
In China, these videos may be accessed through