Tarantula Hawk Wasp

So I was recently looking through my pictures from the Tropical Terrestrial Biology class trip to Costa Rica, when I came across the picture I took of a wasp with large orange wings dragging a limp large bodied tarantula into a hole. The picture was taken in the middle of our group project on trafficking patterns of Atta cephelotes, when a girl in our group who had something against insects to begin with was almost landed on by giant pile of entwined flying insect. She screamed and swatted, then finally jumped away and immediately called us over because of what she was witnessing. As we squatted to look closer at what was happening we were amazed that the tarantula was still moving slightly, but was obviously paralyzed from the venomous wasp sting. The wasp left the spider for a minute as it unburied the entrance to a den in the ground which we had inadvertently covered as we stood taking times and measurements less than a meter away around the ant path.

The reaction our teacher had to the picture is still vivid in my mind, as he was astonished and jealous that we saw such a seemingly rare incident, considering he had been doing the trip for 30+ years and had never seen it. Turns out we had watched a Tarantula Wasp (Pepsis formosa) sting and paralyze a tarantula, which it was dragging back to its lair where it would lay a single egg the abdomen of the spider (Cazier and Mortenson, 1964, Punzo and Garman, 1989). The wasp then seals the lair, and soon enough the egg hatches and the larva consumes the spider from the inside out (Evans and Yoshimoto, 1962).

I know that P. formosa is not a true parasite as we have studied in class, but instead a parasitoid, or an organism which spends most but not all of its life stages inside another organism (also it eventually kills the host). I have chosen to do research for this article on this parasitoid because I do not know if I will have another chance to write about it, and I also want to share its awesome behaviors and life styles with the class and late night internet suffers alike.

Cazier, M. A. M. Mortenson. 1964. Bionomical observations on tarantula hawks and their prey

(Hymenoptera: Pompilidae). Ann. Ent. Soc. Amer. 57: 533–541.

Evans, H. E. C. M. Yoshimoto. 1962. The ecology and nesting behavior of the Pompilidae (Hymenoptera)of the United States. Misc. Publ. Ent. Soc. Amer. 3: 67–120.

Punzo, F. B. Garman. 1989. Effects of encounter experience on the hunting behavior of the spider wasp, Pepsis formosa (Hymenoptera: Pompilidae). Southwest. Nat. 34: 513–518

Babesia microti Life Cycle

Babesia microti is a blood parasite that infects humans using ticks as insect vectors.  It is important to understand the lifecycle of Babesia microti in order to prevent infection.  The life cycle begins when a tick takes a blood meal from a mouse or other small mammal and introduces sporozoites form in to the host (Leiby, 2011).  The sporozoites then enter the hosts’ erythrocytes, or red blood cells, and reproduce by budding, a type of asexual reproduction.  This process yields both male and female gametes.  The tick then takes another blood meal and ingests the gametes.  Once inside the tick the gametes transform in to sporozoites.  Sporozoites are the infective stage to humans so when a tick containing sporozoites takes a blood meal from a human they will become infected.  Inside the human host Babesia microti is able to cycle between the merozoite form and the trophozoite form inside the blood.  Both the trophozoite and the merozoite forms are diagnostic stages to humans, or when the disease will start showing symptoms.  When Babesia microti multiplies within the human the symptoms of the disease will become more and more apparent (Becker et al, 2009).  Once Babesia microti has infected a human it can no longer infect any other host.  The only way to spread the disease after a human has been infected is through blood transfusions.  

Symptoms of this parasite will usually become apparent between 1 and 9 weeks after transmission has occurred.  Some of the minor symptoms include fever, headache, chills, and muscle pain (Leibly, 2011).  However in some individuals the symptoms can be more serious, causing premature breakdown in blood cells known as hemolytic anemia.  Many people who become infected are able to tolerate the symptoms but the parasite can have serious consequences on elderly, young children, and people who are already immune-compromised (Leibly, 2011).  These individuals risk facing respiratory failure, hemolysis, blood pressure instability, and myocardial infarctions. 

Studying the life cycle and symptoms of Babesia microti are important to preventing its transmission.  One of the main problems this parasite poses is that it can be transmitted through blood transfusions and is more complicated to screen for than other blood illnesses (Liebly, 2011).  Understanding the symptoms and lifecycle of this parasite can help with diagnostic testing and lead to more accurate blood screening.

Leibly, D. A.2011. Transfusion-Transmitted Babesias. Clin. Microbiol. Rev. 24:14-28.

Becker, C. A. M., A. Bouju-Albert, M. Jouglin, A. Chauvin, and L. Malandrin. 2009. Natural transmission of zoonotic Babesia spp. by Ixodes ricinus ticks. Emerg. Infect. Dis. 15:320-322