Watch this whiteboard animation with drawings by myself and animated by Corine Feenstra, videojournalist at WUR. It was made for my Dies Natalis talks #WUR100 (see post March 21, 2018).

A butterfly female lays her eggs on the lower side of the leaf (shot 1). The female carefully glues the eggs onto the leaf surface with the help of a secretion released from the ovipositor (shot 2). With some plants these eggs develop to caterpillars without the plant noticing it (shot 3). After a couple of days the caterpillar emerges (shot 4-6), and often first feeds on the egg shell (shot 7) before it starts to feed on the plant. Many caterpillars can eat whole plants (shot 8). Some plants have developed a way to prevent eggs from hatching (shot 9-10). Those plants can recognize the egg upon deposition often by the egg glue between the egg and the plant (shot 11). We have been showing that the egg glue itself contains molecules that trigger an egg-killing cell necrosis, called hypersensitive-like response resembling disease resistance responses. Probably, the egg molecules (EAMPs) bind to plant receptors on the plasma membrane (shot 12). After the molecules bind to the receptors, the latter become activated (shot 13) and trigger a cascade of reactions and molecules that migrate through the cell and induce it to respond. The cell responds with the expression of certain defence genes (shot 14) that eventually lead to the necrosis (shot 15-17). So far, we neither know the nature of the egg molecules nor which receptors or genes are involved that lead to egg-killing. The necrosis and maybe some chemicals produced lead to the egg shrivelling and sometimes falling off the plant (shot 18). Instead of being eaten the plant can nicely grow and reproduce – if no other invaders are attacking her (shot 19).