Symbionts and arthropods – potential implications for biological control

Most arthropod species live in association with numerous bacteria. Their interactions can have different outcomes. While some bacteria are crucial for their host’s survival, others are facultative and their presence can have a negative, positive or neutral effect on the nutrition, reproduction or survival of their host. Some endosymbionts (such as Wolbachia for example) are known as reproduction manipulators. Vertically transmitted, these bacteria developed several strategies (such as parthenogenesis induction, cytoplasmic incompatibility) to increase the transmission of infected females in their host population, in comparison to un-infected females. Another way to ensure its propagation is to become crucially needed by its host. By protecting their host against natural enemies such as hymenopteran parasitoids, nematodes, entomopathogenic fungi, bacteria or viruses, endosymbionts achieved this goal. Endosymbionts may then greatly influence biological control programs. These influential house mates may not only affect the rearing of beneficial arthropods (by altering their reproduction mode) but also influence their interactions with target crop pest species (by inducing resistances for example). This paper explains how endosymbionts may influence biological control and provides practical examples and a protocol to follow to identify problems associated to their presence.