that the virus must be insect-specific. Invertebrates do not produce antibodies by the lymphocyte-based adaptive immune system that is central to vertebrate immunity, but they are capable of effective immune responses. Phagocytosis was first observed in invertebrates, and this and other innate immune responses are important in immunity to viruses and other pathogens. The hemolymph of invertebrates contains many soluble defence molecules, such as hemocyanins, lectins, and proteins, which protect these animals against invaders. The health of the honey bee has been important to human societies for centuries. Like all invertebrates, the honey bee (Apis mellifera) is susceptible to many viral infections, and their numbers have dramatically declined around the world. These bees often suffer infestations of varroa mites, which are vectors for deformed wing virus, as a result, this virus has become one of the most widely distributed and contagious insect viruses on the planet. The virus causes stunted wings and as a result, the infected bees are unable to leave the hive and forage for nectar. Symptomatic bees have a severely reduced life-span of less than 48 hours and are often expelled from the hive by other bees. Bees are crucial to the survival of humans, along with producing honey, they pollinate plants that contribute up to one third of the food we eat, and their dramatic decline is a grave concern. Baculoviruses are among the best studied of the invertebrate viruses. They infect and kill several species of agricultural pests, and as natural insecticides, they have been used to control insect populations in Brazil and Paraguay such as the velvet bean caterpillar (Anticarsia gemmatalis), a pest of soy beans. Viruses are an attractive alternative to chemical pesticides because they are safe to other wildlife and leave no residues. Viruses can also change the behaviour of their insect hosts to their own advantage. A baculovirus of the gypsy moth (Lymantria dispar) makes their caterpillars climb to the tops of trees where they die. In doing so, they release a shower of millions of progeny viruses that go on to infect more caterpillars. References Bibliography Animal virology