Posteribus Partibus Nostrarum Bracarum Volamus

Today our class had a discussion on the  experimental design of the light and trophic interactions experiment and talked a bit about the lab experiment on the local adaptation of spiders.

Below is the organized list of (almost) all the questions and ideas we had during our discussion:


pricing of lighting? 

-2 leds strips & wire (enough for 60 replicates)

-3-6 LEDs for each treatment

-Problem of too much wiring, worried about voltage drop

-Power for 24 hrs, recharge battery every other day

-Vary them with dimness with switch or adjust height of LED but would that need more wire when adding height? Voltage drop arbitrary.

-have lights far from each other; 1 battery

-Hexagonal structure of lights: why the hexagon? Because need cheaper battery, found 1 A per 7 hours how long can let it run 24 hrs. What is the max number of amps – 2 feet.

-Marshall has 5V batteries? Maybe it can work? Batteries have 2 cells (3.7) with usb port

-Are there led strips that can run in lower volt batteries? Meant to run off on battery cells. How about 9V battery?

-Illuminate area of .13 m radius=illuminance of 100 lux (4x of brightness in study)

-Can we put more replicates on bigger battery and we can have less batteries needed

-Run in parallel? Difference between series and parallel in LEDs (have 1 battery run 6 parallel in circuits)

Apparatus & Field Design

-lethal vs non-lethal pitfall traps (rather than removal it is suppression of spiders and put back other things in the pitfall trap)

Louie has Jiffy pots that expand when soaked in water

-Worrying about independence of one treatment: if we set up a field of light it will be different, we would be aggregating herbivores in local area, as long as 2m or more apart and isolated

-Dark ones are not 100% dark, it’s ok to not completely isolate treatments

-Treatments are so bright, can it influence unlit ones?

-40 replicates per treatment? Better but is it worth it? Can we do 30 instead? It would lessen a lot of the work load

-Worried about battery charging?

-How long it takes for one person to get collection?

-How much space do we have in field?

-Blocking: choose a couple of spots and have block of 30 cages set up (3 blocks with 30=10 reps of each)

-Make mesh into a cone? Some sheet with reflective surface

-Illuminating mesh sheet? Make a cone around sheet on the top half of cage

-If we have flying insects would it be blocked by the mesh?

-Mesh: increase spider substrate, light reflection?

-Goal isn’t to compare herbivory in plants, but just look at overall herbivory (randomly position plants so not one isn’t always in the mesh)

-Reflective surface on top, trapping sheet

-Have chicken wire on one side, or opening/window to reach through

-How to not disturb plants and spiders when getting pitfalls? – Go from bottom and between plants

-Trim grasses (knee high) – may be non-trivial, all grass around experiments, get disturbed within the actual cage can get grassy, use a weed wacker

-Want pitfall traps to be localized in the middle

-How long do sticky traps run?

-test overall herbivory? Do we really need to know if it’s day or night?

-Rabbits are a problem: rabbits deterred by chicken wire, they dont go after tomato leaves

-Birds pick stuff off the sticky, birds perch on cages (4 trophic levels?!)

-how to get birds out of apparatus?

-White sticky become less white with insects on it. White sticky looks like clouds/flowers illuminated during the night. Changes time at which the insect will stick. Will get aggregation of insects with sticky. Get higher counts with white stickies (Bias measure)

-Providing wind shield to get more web-building spiders to come

-Use white mesh so we can standardize everything

-White mosquito netting fabric

-Worried about sunlight destroying mesh

-Can we put cages on a slanted ground

-pitfalls on hills, put cup at slope so arthropods fall in

-take flat shovel, put terrace for trap to modify slope

-Stick to one field? We’ll get different insects = can account to it by blocking (3 blocks of 30), spread it throughout different sites

-aquatic associated spiders (near pond)

-Bring conetainer back to lab and grow them there

-Grow in greenhouse and grow them outside-wimpy; use portable fans

-Get conetainer racks

-Season will become warmer and there will be more bugs to look at

-White tarp hangs from 5 ft off ground and touches ground has hanging black light that also hangs white light things will go through the sheet

-Yellow sticky traps: bias from yellow

-Moths confused about flashlight, instead of flying into sheet land on shrub nearby, get distracted and land on unlit areas

-Mariah saw moth dumped all eggs near light (happens more often later in season when they’re about to die)

Lab Study

-Heiling where spiders prefer to put their webs (naive spiders)

-Do for urban and rural spiders

-Prediction: urban spiders we’ll see this preference

-What types of spiders used for lab study? : salticid (diurnal) , lycosid (mostly nocturnal) , gnaphosid

-build silk retreats, keep them in one place over 24 hours see evidence of where they’re resting and where they’re present

-Hard to collect web-building spiders? – use spiders from pitfall

-Local adaptation in ground spiders

-Ballooning by web spiders

-Start point one light one dark, spider could perceive light or dark tunnel

-How to account for no natural light in lab setting – leave by window and have the light always on (see it where is the most)

-Assay: behavior at night, choice of going to the light

-Keep in black box

-Keep them in the rhythm, natural light for the cycle

-Don’t confuse light for the day

-Box with mesh and a little LED on one side

-Choice experiment: kept in day and night and expose them during the night with artificial light

-Clear box, with door opening to non-lit or lit

-Why not take the initial choice of the spiders? What is the point of looking at 5 minutes later?

-Chamber that they can move in between, where they end up after they explored

-Extended assay: could provide additional, can’t look at where it is in

-clear box: tally how many times they went into the light and dark

(5 mins) but what if they have different periodicity

-Instead use time lapse cameras to monitor spider activity

-Do spiders perceive red light as dark?

-Trap plate (?): powdered graphite, mineral oil ethanol (grey paint to paint onto surface, measure footprints (See where you see marks of tiny spider feet)

-Cursorial spiders would move between the two

-How about we train for spiders to have a preference for light-conditioning spiders

-You can strengthen preference

-Pitfall trap in urban areas

-Raise naive spiders (test to see if it genetic)

-Is there evolutionary preference for light rather than learned? Is there a difference between rural and urban spiders? 

-If rural prefers light can say its genetic

-What is rural? Some areas actually still have light (Stebbins is really dark)

-Consider maternal effects from the eggs

-Conditioning: Can you teach them that light means food? Dark means food? Teach them to switch prey

-Plasticity experiment is an actual experiment because you’re manipulating prey

-Be hard to retrain spider than it is to train them from spider infancy

-Ask question about ability to reverse behavior than is it a plastic behavior?

-Wolf spiders: in both urban and rural environments, hunt mostly at night

-Joel help us with spider identification?

Why can’t you use 1 species for lab study? It is much easier.

-Problems with Pseudoreplication?

-Learned preferences: learning literature on bees evolve to be social, communicate info, play soccer (Lots of salticid social experiments)

Main Concerns with Lab Study

1) what species would we use?

-can you identity

-are you going to structure them by stage (can you compare juveniles vs adults)

-can you get enough spiders to isolate a stage

2) how would you measure preference

-people be here at midnight?

-time lapse camera

3) can you get naive spiders, rear them in a constant environment?

-rear them as early as possible (egg to whatever stage you want them)

4) plasticity/conditioning

-local adaptation study: fancy observations

-no manipulation


tl;dr: In the end, we decided that we should focus on the field experiment first and then decide if the lab study is feasible. However we also recognized that we should not completely give up thinking about the lab study either because it can provide us with some important implications. Also thank you to all the people who volunteered this weekend to start planting the seeds! Let us know how that goes!

Like Albert Einstein said, “If we knew what it was we were doing, it would not be called research, would it?” Continue the good work everyone and keep those creative thoughts flowing!

Tentative Schedule: 

1:40-1:50 pm Updates from seed planting volunteers and malaise trap group

1:50-4:15 pm Work on building apparatus

4:15-4:30 pm Next steps


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