Thursday, April 19, 2012

Friends or Foes? Kennethiella tristosa Mites


(Image from a scanning electron microscope of
the phoretic mite Kennethiella tristosa) [7]
The phoretic mite Kennethiella tristosa attaches itself to the wasp Ancistrocerus antilope. This pair exhibits both vertical and horizontal transmission. Vertical transmission occurs when a female wasp lays an egg and the larva, or deutonymphs, leave the wasp and transmit to the egg. Horizontal transmission happens during mating from wasp to wasp [1]. Kennethiella tristosa gains a mode of transmission and housing, from a special cavity solely developed for housing mites, from the wasps without harming it.  However, it has been shown that large numbers of Kenethiella tristosa can actually become parasitic and harm the wasp.  It was observed that when large number of mites was present, juvenile wasp’s mortality rate increased by 30% [2].  According to the distribution map (from the encyclopedia of life) these mites are only found in two select areas [3]. Since the distribution is so small, these mites are rarely researched. The life cycle of these mites includes a deutonymph stage where the mites attach themselves to the propodeum of the female wasp after she has mated with an infected male. After they have attached to the wasp, they travel to a new nesting site via the females and feed in order to complete their life cycle. After reproduction, the cycle starts all over again [1] [4].

(Distribution Map for Kennethiella tristosa)[3]

Description of the Relationship:

(Life cycle of K. tristosa compared to the life cycle of A. antilope) [8]
This species of phoretic mites comes from the genus Kennethiella and the species is tristosa [1]. The second partner in this relationship comes from the genus Ancistrocerus and the species antilope. These tiny mites gain a mode of protection and transportation during their non-feeding stage of a deutonymph.  The wasps are not harmed in the process if the number of mites is kept at a manageable rate [2].  These two species exhibit commensalism where the mite obtains transportation, protection, and food while the wasp is not harmed [5].

Cost/Benefit Analysis:

Benefit for Kennethiella tristosa: The mites gain protection from the propodeum in the wasp. This area only has one function and that is to provide protection for the mites.  It also gains transportation and food.  These mites feed on the larva of the wasp and in order to finish their life cycle they must transfer to new nests with fresh larva. [1] [2]

Benefit for Ancistrocerus antilope: There is no recorded benefit thus far for the wasp in the relationship. [2]

(K. tristosa on the propodeum of the A. antilope) [6] 
Cost for Kennethiella tristosa: If there are too many mites on a single wasp, the host is killed and there are no more resources for the mites.  Therefore, they cannot finish their life cycle and produce the next generation.

Cost for Ancistrocerus antilope: If the wasp becomes too heavily parasitized, it will die.
There are no specific strategies employed by either partner in order to make contact easier.  Researchers are still uncertain as to why this commensalism relationship continues, but they have notices that the only function of this cavity in the wasp is to protect and house the phoretic mites [2].

1. Cowan, D. P. (2002, January 24). Symbiosis and mode of transfer between hosts. Retrieved from

2. Okabe, K. (2010, April). Conditional mutualism Retrieved from

3. (2010). Collection sites: world map showing specimen collection locations for kennethiella trisotosa. (2010). [Web Map]. Retrieved from

4.Gasperin, O. (2012). Behavioral ecology group. Retrieved from

5. commensalism. (2012). In Encyclop√¶dia Britannica. Retrieved from

6.Cowan, D. P. (Photographer). (2002). A male a. antilope wasp with a large cluster of k. trisetosa deutonymphs clustered on the right side of the propodeum and thorax. [Web Photo]. Retrieved from

7.Eversol, R. (Photographer). (2002). Scanning electron micrographs of k. trisetosa on a. antilope.. [Web Photo]. Retrieved from

8.Cowan, D. P. (Designer). (2002). Life cycle of k. tristosa compared to a. antilope. [Web Drawing]. Retrieved from

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