BIOALLIES

BIOALLIES

Post # 21

Donald A. Windsor

When a parasite uses another parasite as a tool, what do you call it? A “biotool”? A “biohenchman”? A “bioenforcer”? A “bioally”? I prefer “bioally”.

Consider the amazing case of a parasitic wasp laying its eggs in a lady beetle; then using a virus to convert the beetle to a robotic, zombie-like protector of the resulting wasp pupae.

The parasitic wasp is Dinocampus coccinellae. The host is the lady beetle Coleomegilla maculata. The bioally is a Dinocampus coccinellae paralysis virus DcPV. The life cycle is described by Dhailly et al (1).

Wasp lays an egg in the beetle. Egg hatches and larva develops within the beetle.

Larva emerges 3-weeks later and pupates, spins its cocoon between the beetle’s legs.

The beetle remains static and trembles, protecting the cocoon from predators.

Adult wasp emerges. Sometimes the beetle host recovers.

The guarding behavior of the host beetle is attributed to the DcPV in the beetle’s brain. This virus infects the oviduct cells of the wasp and is transmitted with the wasp egg into the host beetle.

Lacewing fly larvae (Neuroptera) are among the natural predators of this wasp’s pupae (2-3).

This complexity can be depicted as: H + Pw + Pv ====> HPwPv ====> HPv + Pw

I do not know what happens to the virus in the beetle’s brain.

This parasitic team of wasp and virus shows how a biological interaction between a host and a parasite has not just 2 participants, but 3. Four, if the causative predator driving its evolution is included.

I am now investigating how high the number of participants in a basic host-parasite interaction can go. What is the maximum level of complexity that has ever evolved?

References cited:

1. Dheilly, NM ; Maure, F ; Ravallec, M ; Galinier, R ; Doyon, J ; Duval D ; et al. Who is the puppet master? Replication of a parasitic wasp-associated virus correlates with host behaviour manipulation. Proceedings of the Royal Society of London B Biological Sciences 2015; 282: 20142773: 1-10.

2. Libersat, Frederic ; Kaiser, Maayan ; Emanuel, Stav. Mind control: how parasites manipulate cognitive functions in their insect hosts. Frontiers in Psychology 2018 May; 9: article 572: 1-6.

3. Maure, Fanny ; Brodeur, Jacques ; Droit, Anais ; Doyon, Josee ; Thomas, Frederic. Bodyguard manipulation in a multipredator context: Different processes, same effect. Behavioural Processes. 2013 October; 99: 81-86.

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