Percentage of Dinocampus coccinellae cocoons eaten by larval green lacewing, Chrysoperla carnea, when parasitoid cocoons were exposed alone, covered by a dead ladybird (Coleomegilla maculata), or attended by a living ladybird. Probabilities were obtained using the Fisher exact test, ***p , 0.0001. Numbers refer to sample sizes (from Maure et al 2011).
Parasitoid cocoons alone or sheltered with a dead ladybird suffered significantly more predation by lacewing larvae that did those protected by living ladybirds, supporting the hypothesis that the parasitoids manipulate the ladybird's behaviour to their own advantage, effectively converting them into their own bodyguards. The ladybird protective colours made little difference, although these are thought to protect against bird, not insect, predators.
Presumably, there must be a cost to the larvae to manipulate the ladybird. She must left the ladybird alive and produce chemicals to make it into her bodyguard. Maure and coworkers also tested this, by measuring the relationship between the ladybird lifespan once the parasite emerged and the survival and fecundity of the parasite. Their results show a significant negative correlation between the ladybird lifespan - 25% survived the parasitoid emergence - and the number of mature eggs the parasitoids had in their bodies after emergence as adults. This suggest that indeed there is a cost to making your host into a bodyguard. Overall, though, it must compensate the parasite to shield itself with the live ladybird in terms of predator avoidance.
ReferenceMaure F, Brodeur J, Ponlet N, Doyon J, Firlej A, Elguero E, & Thomas F (2011). The cost of a bodyguard. Biology letters PMID: 21697162