VL 13 Flashcards
Changing environmental factors
Urbanisation + pollution
Climate change
Land cover change
CHanging environmental factors - urbanistation + pollution
Localised temperature in cities
Lights
Sound
Water and air
Increased transportation
Ecological traps (unnatural for insect, insect will be attracted to it and die)
-> orientation, mating influenced
-> transportation also of insects, get to new places
Changing environmental factors - climate change
Increased temperatures and atmospheric CO2
Extreme weather patterns – severe drought, flooding, increased rainfall
Increasing sea levels
Changing environmental factor - land cover change
Deforestation
Agricultural land
- Monocultures
- Use of pesticides and fertilisers
Dams and draining
How is climate change affecting insects?
With 3.2°C warming, 49% of insects will lose over half of their current habitable range
Plant/prey host range may also shrink
Spring temperatures trigger emergence from diapause
20-30+ days early
Some insects already shifting to multiple reproductive cycles per year eg. bumblebees in Switzerland
Predicted effects of climate change on plant-pollinator interactions
Negative effects of competition with invasive pollinators
Land use change and fragmentation = strongest negative effects on native
pollinators
Climate induced phenological shifts
Loss of pollinator diversity, variation in pollination quality, shift in fruiting time and availability of dispersers
Phenological shifts
Phenological shift = changes in the timing of life history events relative to calendar dates
Global warming is estimated to shift plant flowering earlier
Pollinators will no longer overlap with food plants or be left with gaps
Predict that for 20-50% pollinators, up to 50% activity will fall when no food plants available
-> we are expecting, that insects will adapt, but we don’t know how long this will take and how
How is pollution affecting flower visitation?
Patches of flowers with increased diesel exhaust fumes (NOx) and ozone (at ‘safe’ air quality levels) had 80-90% less visits from pollinators
As well as 60-70% less pollinators observed in the area
Thought to be due to interference with floral scents – volatile travel distance in presence of these pollutants is reduced by 2/3
Diesel fumes also affects honeybee learning – 44% reduction in association between odour and reward
What are predicted effects on plant-herbivore interactions with increasing CO2?
Experimenally enriched atmospheric CO2:
Higher plant growth rate, but lower nutritional quality (nitrogen content)
Decrease in nitrogen based defenses eg. alkoloids
Therefore predicted 40% increase in herbivory to obtain required nitrogen
Favours plant species with alternate defenses or nitrogen fixing
Predicted effects on plant-insect interactions - temperature/drought
Increased temperature:
Faster herbivore development time
Drought stress:
Severely decreases parasitoid populations
Less active decomposers
Increased plant pathogen infection
Plants emit different volatiles while heat/drought stressed that may deter pollinators
-> for longtime drough adaptive response might be expected
How are heat waves affecting bumblebees sense of smell?
After 3 hrs exposure to 40°C, bumblebee antennae lost sensitivity to key floral scent chemicals when tested with electroantennography
This sensitivity had not returned 24hrs later
This could impact ability to locate floral resources in increasing global temperatures, and colony decline
Electrode
Evidence of robust ecosystems
Semi field trials in tropical forests:
Experimental drought did not alter seedling suceptibility to herbivory
Increased CO2 and temperature did not reduce the effectiveness of plant defence against herbivores
Semi field trials in wheat agroecosystem:
Manipulation of precipitation showed crop-herbivore-parasitoid interactions were robust between -70 to +70% precipitation
-> robustness might be better than we expect, in the lab the effect might be bigger
Pesticides
Neonicotinoids are present in the nectar and pollen of treated plants (sprayed and taken up by plant)
~94% in soil/water run off.
Slow break down, accumulate in soil,
taken up by wildflowers
Therefore banning just in flowering crops doesn’t solve problem
Honeybee and bumblebee colonies eating contaminated nectar and pollen= smaller, produce >85% less queens, lowered immune response so more susceptible to viruses, lower queen life expectancy, as well as effects on learning.
European food safety authority banned use in flower crops in 2013, all crops 2018. Neonicotinoids are still used worldwide outside of europe. Screening worldwide honey samples, 75% contain at least 1 neonicotinoid, and many 2 or 3 types
Even in Europe, farmers can apply for a derogation that gives them a temporary exemption from the ban in ‘emergency use’
There is no requirement for new insecticides coming to market to asses sublethal effects on bees or beneficial insects
Increasing populations / spread
Advantagous conditions for specific insects. Problem when invasive or damaging:
Swarms of locusts in Africa due to 400% more rainfall
Emerald ash borers, native to Asia, have established in North America and
Eastern Europe. Milder winters = spread farther north
Populations of houseflies due to more than double by 2080 due to changes in temperature, humidity and rainfall (more suitable habitat)
Mosquito spread due to increased temperatures has triggered outbreaks of dengue in France and Croatia, chikungunya in Italy and malaria in Greece in the past decade
Spread of Asian hornet (Vespa velutina) from France at nearly 50 miles a year since arriving in 2005; has established in Switzerland since 2017. Threatens viability of honeybee colonies
Factors that aid in adaptation to climate change
Mobility
Mutualisms
Diet breath
Short generation time
High fecundity (how many offspring are produced)
Thermoregulytory behaviour
Shelter / nest construction
