Twinkies for Roger

Today was a day of exciting progress for the monarch stripes project! The main things we accomplished today:

  • Split into two teams (team Asclepias for milkweed work, team Lespesia for tachinid shenanigans)
  • Planted lots of milkweed!
  • Practiced tethering our first fly!!!
  • Talked about tachinid catching/rearing/sexing
  • Reconvened to discuss our progress & future plans for Friday

At the start of class, we divvied ourselves up into teams Asclepias and Lespesia depending on our natural talents & inclinations for either plant- or insect-rearing. Team Asclepias went with Louie to the greenhouse, milkweed seeds in hand, to get tons of planting done. With many hands working together, they filled several trays successfully & rejoined the main group with time to spare!

Our milkweed babies… soon-to-be monarch food, hopefully!

Team Lespesia had some great discussions about tachinid biology & how we might find, trap, rear, sex, and eventually use them in our research trials. We came up with 4 main methods for trapping: using the 2 light traps provided by Eliza, sweep-netting, rearing out of caterpillars collected in the field, and baiting with sentinel Spodoptera exigua. For all of these, we decided that our best collecting locations will likely be in sunny spots near agricultural crops that spods normally like (cabbage, beets, other tasty leafy vegetables). Here’s a list of prime Lespesia-finding spots we thought of:

  • The ecological garden/student farm
  • Dome garden
  • The arboretum
  • UC Davis good life garden
  • Plant science edible food gardens

Hopefully we can capture enough L. archippivora from these places, using several different methods, to start a colony.

We also discussed issues with sexing and rearing. The rearing seemed straightforward enough, as outlined by some of the literature on L. archippivora we’ve read – all we’d really need are small pop-up bug tents (multiple containers > one big container for disease-control purposes), sugar-protein diet for the adults, and spods for females to lay their eggs on. However, sexing may prove to be more difficult. So far, we’ve yet to find any easy morphological characters that clearly distinguish males from females. We did wonder if perhaps a behavioral assay – presenting a spod and seeing which flies try to parasitize it – might be the most efficient way, as females seem to be quite aggressive egg-layers once they’re ready! In general, more research still needs to be done to determine if there are any easier sexing methods.

Our adorable mascot Roger, brought in by Annaliese (pre-tethering)

One especially exciting development today was that we were able to practice our tethering methods on a real fly! Louie and Elizabeth had already fiddled around with the UV epoxy before class, and found that it worked great for connecting superfine fishing line to small bits of paper – but a living insect was the real test. Luckily, Annaliese managed to find a tachinid and bring it into class just in time! We named them Roger and proceeded to put them in to fridge for 5 minutes to slow them down just enough…

Once they had “chilled out” a bit, Elizabeth put a dot of UV epoxy on the thorax, stuck it to a length of fishing line, and cured it for ~30 seconds with a UV flashlight. And it worked!!

Just walkin’ my fly… or… flyin’ my fly?
Rewarded for being a good sport with twinkie crumbs. Yum!

Roger did great on the leash (despite almost escaping) and the UV epoxy bond held up perfectly! This method seems very promising for various parasitism & landing assays in the future. However, we will have to consider whether our tachinids will react normally to stimuli on the tether, and make sure that the leash doesn’t impede their locomotion.

When team Asclepias returned from planting, we further discussed rearing/housing plans for our various insects & investigated Louie’s lab to see some options. We found lots of small plastic containers with mesh tops, some mesh boxes, and huge pop-up tents! For spods, we thought it would be good to rear them in the small containers first and then move them to bigger housing as adults. We also decided to raise the spods and monarchs separately.

Finally, we talked about what we might do for Friday:

  • Option A (Good Weather):
    • Figure out what Spodoptera exigua looks like and make an ID cheat sheet
    • Go out and look for caterpillars on campus or the west Davis community garden
    • Make diet for spods (possibly with the “expired” powder), maybe try to make diet for tachinids
    • Find produce that hasn’t been sprayed, perhaps through the UC Davis fruits & nuts department
  • Option B (Rainy Weather):
    • Catch up on the require reading list
    • Find a paper on sexing Lespesia archippivora
    • Do the same indoor activities as above (make ID cheat sheet, test out making diet)

Special shoutout to Roger for this Tuesday’s blog post – while they may be in the freezer now, they’ll always be in our heart…

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