Chapter 14 Flashcards
(33 cards)
biological control
use of natural enemies to decrease pest population. makes pest less abundant and damaging
natural enemy
any organism that controls the abundance of another
examples of biological controls
invasive weeds - herbivores
invasive insects - insectivore
crop pests - pest predators
what do biocontrols solve/prevent
pests develop resistance to chemicals, target pest resurgence, emergence of secondary pests, few pesticides available (banned quickly), costly to use chemicals, human health and environmental concerns
good biocontrol characteristics
adapted to environment of pests, host specific, abundant, high per capita growth rate, doesn’t drive itself and pest to extinction
non target impacts
unintended impact on species other than pest (doesn’t solve pest)
rabbit example of biocontrol
rabbits released, population increased out of control, virus introduced, kept population at more manageable size
pricey pear biocontrol
introduced for fencing, spread quickly, out of control, introduced moth that eats it, kept it under control
biocontrol chronology
- pest introduced
- pest exponential growth
- biocontrol species introduced
- pest and biocontrol coexist at low population sizes
how do predators and prey coexist
population sizes of each oscillate/change together -
predator eat a lot prey, prey decreases, predators have less food, predator decreases, prey has less predators, prey increase, predator eat a lot of prey
how can predator/prey interaction cause metapopulation
predators locate prey, drive down prey population, surviving prey recolonize somewhere else (prey refuges), until predator finds again
what does Lotka Volterra model show
predator-prey oscillations
dN/dt=rN
shows exponential prey pop. growth due to no predators
dN/dt=rN-cNP
shows how prey population is reduced by predator
dN/dt=rN-cNP
what do variables mean
r = #individuals added/per individual in population c = prey capture rate
what does rN represent and why
represents births
because it considers the amount of individuals added to population per individual and the population size
what does cNP represent and why
deaths
because it considers prey capture rate, predator density, and the population size
dP/dt=-mP
what does this represent
predator density with no prey - causes decrease
what does m represent
mortality rate
dP/dt = acNP-mP
what does this represent
predator denisty depending on rate of capture (c) and rate of prey converted to energy by predator (a)
what does mP and acNP represent and why
mP = deaths - because it considers morality rate and amount of predators acNP = births - because it considers capture rate, energy conversion rate, population, and amount of predators
what happens to prey population when dN/dt=0
prey population is stable/constant (dN/dt=0)
what happens to equation with rate=0
(0=rN-cNP)
change to make equal to P
N=N
rN=cNP
r=cP
P=r/c
why is prey population stable with dN/dt=0?
growth rate=0
-prey stable bc there is no increase or decrease in growth
