climate change and pest interaction
TRANSCRIPT
Yogesh Wagh 2015-21-013
Plant Physiology
Long Term and Short Term Projection of Climate Change on Crop Pest Interaction
Introduction Changes in climate may trigger changes in-
Geographical distribution, Increased overwintering, Changes in population growth rates, Increases in the number of generations,Changes in crop-pest synchrony, Changes in interspecific interactions, Pest biotypes, Activity and abundance of natural enemies, Species extinction, Increased risk of invasion by migrant pests and efficacy of crop
protection technologies
Climate change will also reduce the effectiveness of-Host plant resistance, Transgenic plants, Natural enemies, Biopesticides, Synthetic chemicals for
pest management
introduction…
Higher temperatures and longer growing seasons could result in increased pest population
Pest infestations often corresponds with changes in climatic conditionsSuch as early or late rains, drought, or increases in humidity,
which can reduce yields
Climate change have increased pesticide use due to presence of diseases and pestsA 2.4 to 2.7-fold increase in pesticide use by 2050
introduction…
Insects are poikilothermic animals A poikilotherm : Is an organism whose internal
temperature varies considerably
They are highly sensitive to their surrounding climate particularly the temperature
introduction…
Increased temperature Insects are stenotherms (cold-blooded), sensitive to
temperature
Higher temperature increase rates of development and with less time between generations20C temperature increase insects experience one to five
additional life cycles per seasonEg. Cabbage maggot, Onion maggot, European corn
borer, Colorado potato beetle
Warmer winters -Reduce winterkill and consequently induce increased insect
populations It cause delay in onset and early summer may lead to faster
termination of diapauses in insects
Reproductive rate- Rising temperatures will lengthen the breeding season and
increase the reproductive rate raise the total number of insects attacking a crop and
subsequently increase crop losses
increased temperature…
Natural enemy
Parasitoids depend on a series of adaptations to the ecology and physiology of their hosts
According to a survey of over 1700 species, 50% of these wild species are already affected
Even a mid-range climate warming scenario predicts that 15% to 37% of the species may become extinct by 2050
Parasitism could be reduced if host populations emerge and pass through vulnerable life stages before parasitoids emerge
The tritrophic interactions between plants, herbivorous insects, and their natural enemies (predators, parasitoids, and pathogens)
Coevolutionary process specific to a particular environment and relatively stable climatic conditions
natural enemy…
These tritrophic interactions are affected by climatic changes in diverse ways
natural enemy…
Effect of Changing Precipitation onInsects
Precipitation whether optimal, excessive or insufficientKey variable that affects crop-pest interactions
Warmer environment has a tendency to hold more water, it results in more intense and frequent rainfallsSmall body-sized insects may be physically dislodged from the
host plant by heavy rainfallOften more of a problem during dry seasons when the
mortality factor is missing
Drought stress sometimes brings increased insect pest outbreaks
Drought can change the physiology of host species, leading to changes in the insects that feed on them
Cool, wet conditions can also bring on severe insect infestations, although excessive soil moisture may drown out soil-residing insects
precipitation on insects…
Increase in the frequency of flooding of fields could tend to suppress some soil dwelling insect populations
Eg. cranberry fruit worm and other cranberry insect pests
precipitation on insects…
Most fungi which are known to cause various diseases in insects (entomopathogens)
Fungal pathogens of insects are favoured by high humidity Lengthen periods of high humidity and reducing insect pest
populationsEg. Wet northern California
winter, the fungal pathogen (Pandora neoaphidis) causes catastrophic mortality to pea aphid
precipitation on insects…
CO2 would increase canopy size and density of plants
Produce high biomass and microclimates may become more conducive for foliar pathogensEg. Rusts, Mildews, Leaf spots and Blights
Effect of Rising CO2 on Insects
Insect pests could occur through indirect effects on host biochemical composition i.e. Increased simple sugars in the leaves
Greenhouse and lab studies have shown that high CO2 atmosphere increase C:N ratioInsects respond to this ratio by increasing their feeding in
order to fulfill their metabolic needs for nitrogen
effect of rising co2 on insects…
Climate change on Pollination Climate change impact pollination by altering-
The geographic ranges Plant phenologiesDaily activity patterns of their pollinators Mutualistic interactions
Miscellaneous Certain pesticides like Pyrethroids, Organophosphates
and especially the Biopesticides being highly thermo unstable degrade faster at higher temperature
These products to be less or not effective in pest control, necessitating frequent insecticide applications for effective control
Transgenic crops
Interactions among factors
Host
Disease Triangle
Pathogen
Environment Climate change
Temperature CO2
Precipitation
Pathogen change Genetic shiftMovement
Host change Variety
Cultural practice Chemical practice
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