Peculiar Parasitoids

Fascinating yet rather repulsive are the parasitoids I am studying. Yesterday, whilst picking my way through rotten kawakawa leaves and caterpillar frass (poo) I came across this one sick looking caterpillar. It was floundering around, still alive at the bottom of the pot next to a wasp cocoon. This indicated to me that this caterpillar had previously been injected with wasp eggs, the eggs had hatched out inside the caterpillars body, where the wasp larvae proceeded to eat the caterpillars internal organs and then burst out of it's side to go into pupation. Shockingly this half eaten caterpillar had enough of its vital organs remaining to enable it to carry on living. A behaviour that's rather typical amongst parasitoid species. Amazing.



Anyhow, I thought I'd put up a shot to show you the evidence, the black hole near the rear is where the parasitoid emerged and the wiry ovoid is the wasp pupae.

Completing Caterpillar Collections

All caterpillars are now obtained, photographed and safely stored away in controlled temperature rooms in individual containers. They are photographed, as below to enable me to establish at which stage of development (instar) the caterpillars were at when collected. As caterpillars grow and shed their skin, their heads grow and by measuring the widths of their heads, I can tell whether they are first (0.3mm), second (0.6mm), third (0.9mm), 4th (1.25mm) or fifth instar (1.5mm).



The forest remnant that I was working on yesterday was undulating and rather unstable underfoot. We managed to do well getting the samples down from a steep slope, over a river bed, through brambles but as we scrambled up the last slippy valley side I lost my footing and thumped to the ground landing on a number of the Petri-dishes containing the caterpillars. Not ideal. Luckily no caterpillars were harmed although they did proceeded to loop out from their labelled containers, march out of my collecting belt and get completely mixed up whilst crawling round my top. We managed to catch some of them yet unfortunately I could not tell which caterpillars came from which plants. Still, I should be able to analyse parasitism rates for the site still. Not all bad news.

Anyway, to celebrate finishing the second stage of my fieldwork we decided to go and see some of the other wildlife in the area, the enigmatic Hectors dolphins. Apparently they are the world’s smallest, rarest marine dolphins and in going swimming with them I got to fulfil a childhood dream and contribute funds towards ensuring their survival.

Long Days of Summer

Long day today, 5am start at Uni preparing the glasshouse for a new experiment. Last Autumn I collected kawakawa fruit from the Banks Peninsula, germinated the seedlings and now these young plants have transformed into one meter tall semi-mature trees. Result.





Now, I am taking these plants as well as some others donated from a nursery in Auckland and a Master’s project in Nelson, and packing them away in insect-proof mesh (a.k.a. curtain off-cuts!)



Now that the plants are all self- enclosed it is time to add a single caterpillar. These are moth larvae that I have collected from my field sites whilst surveying and in giving them their own plant I should be able to analyse how much they eat in their lifetime. I plan to place a number of caterpillars collected from Auckland on plants grown from Nelson and Banks Peninsula to see if herbivory rates change (and vice versa). This may indicate how species interactions may differ as insects move into new habitats. Anyhow, time for me to stop for the day, I have to have some energy to collect the last group of caterpillars in Akaroa tomorrow.

I'm back (for a while).

Phew, so sorry for the lack of updates but I’ve been tied up with an intensive period of fieldwork. Now I’m back in Christchurch after travelling almost 7000km in and around the North Island and I’m being kept busy feeding the caterpillars I’ve collected, all 1055 of them!
So the last couple of weeks have been packed full of bush bashing, insect showers, land owner liaisons, photography, camping adventures and plenty of travelling.

Although undertaking your own research can be rather stressful at times it is also a lot of fun and rewarding when it is successful. Of course it never always does run exactly to plan; with swooping falcons bullying us out of the forest, rain drenching specimens and data-loggers going missing it’s never dull in the field… I’ll post a few more tit-bits in-between the feeds…

...in the mean time check out the pic of the cats in their pots.