PEI and some of the Original Metal-Heads

Posted on August 22, 2013 by BIObus Crew

This has been my second time in Prince Edward Island National Park, and although the national park is small (only 20km²) it has some of the most beautiful salt-water beaches I have ever seen. Being an avid traveler I have been to many beaches, ranging from working on isolated beaches in Costa Rica to living in Surfers Paradise where there are upwards of two million visitors a year. PEI boasts a perfect combination of having enough space to set up your towel at peak hours and space to play games without getting in people’s way, while still having the reassurance of hired lifeguards. Just like the advertisements for PEI National Park depict, there are epic views of gorgeous sand dunes topped with billowing emerald green dune grasses on one side, and the sloping fine sand on the other. Although the beaches are a definite draw to most tourists, the park also hosts some nice trails that are enriched with information on ecosystems and historical events. These trails are also home to many interesting insects- and this week we found an ichneumonid wasp!

Ichneumonid wasp collected in Prince Edward Island National Park

Despite being a relatively shy insect, ichneumonid females have a very aggressive appearance. The one that we found had a well-defined waist and a long stinger-like appendage at the end of her abdomen. The stinger is actually an ovipositor that the female uses to insert her eggs into the ground or trees depending on the species of wasp. Ichneumonids are parasitoid wasps; this means they require a host to develop from egg to larvae, and possibly many moults before they become an adult. To do this the female has to detect where the host insects are living, get her ovipositor into the insect or its larva and then deposit her eggs inside of the host. This often requires her to detect the location of host larvae inside of tunnels inside trees through the bark! In some cases the tip of the ovipositor is tipped with ionized zinc or manganese help it drill through wood. For all of these insects, getting into the tree and developing into adulthood is only half of the journey. After moulting into an adult, the ichneumonid must then find a way to exit the tunnels of her host. To do this, they often have to chew their way out of the tree using mandibles that are also tipped with ionized metal.

Next week we are visiting our final park of the season — Kouchibouguac here we come!

Jill

Black & Yellow

Posted on August 18, 2013August 22, 2013 by BIObus Crew

Another quick week has gone by and we’re on the road again from Kejimkujik to Prince Edward Island. Famed for its mosquitos, clear night skies and Mi’kmaq origins, Kejimkujik National Park did not fail to impress. In an act of sublime timing and luck we were able to arrive in one of Canada’s most ideal spots for night sky viewing during the incredible Perseid meteor shower. For three days the sky was periodically streaked with ephemeral cosmic lights and we soaked up every bit of it we could. Our days were filled with frogs, deer, the occasional snake and of course many an arthropod.

Agriope aurantia female consuming her Orthopteran prey — *Agriope aurantia* female consuming her Orthopteran prey

One arthropod in particular caught my interest: an arachnid, the Black and Yellow Garden Spider, Argiope aurantia. We had just about completed one of our hand collection events at the Farmlands trail (hand collecting is when we travel down a path and manually collect arthropods along the way) and came into a clearing where a farm once stood. In a lone bush among the tall grass that now dominated the clearing was the strikingly large Argiope aurantia, where it carefully maintained and monitored its web. The web was also the final destination for a number of unfortunate grasshoppers and flies.

As is true with many spiders, there is a distinct sexual dimorphism observable in the relative size of the males and females. The A. aurantia I photographed was clearly a female with a body length well over an inch; their male counterparts are often three times smaller than the female. The distinct yellow markings against black background on the abdomen remain conserved between the sexes, making for a relatively easy identification.

Note the distinctive markings on the abdomen and the white, hairy cephalothorax.

A female Black and Yellow Garden Spider will spend the majority of her life within a small range, generally staying within her web for the entire summer where she will eat, mate and lay eggs. The smaller male will construct his web either within or adjacent to the female’s web. There is no ambiguity to the male’s purpose in this relationship, after he mates he will die and potentially be consumed by the female. The female will lay thousands of eggs within several sacs encased in layers of silk. She will spend the remainder of her summer and life protecting the eggs; eventually she will die come the frost. The eggs will overwinter and emerge the next year.

Despite the size and intimidating appearance, these spiders pose no threat to humans. They have a large range with populations in Canada, the United States, Mexico and Central America.

-Forest

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