Lecture 18 Flashcards
clearing land for agriculture has resulted in what?
envr cost & not sustainable
What do beneficial insects need to complete their life cycles? (6) Do crops have all of these things?
Overwintering sites
Alternative prey/hosts
Nectar or pollen resources
Moderated microclimates
Host plants
Aggregation sites – protection
NO
why is it important to study landscape ecology of an insect?
determines what insects will be present in the crop
what’s around the crop will determine what insects will be present
landscape
area that is spatially heterogeneous in at least one factor of interest
patch
SA that differs from its surroundings in nature or appearance
fragmentation
breaking up of habitat or cover type into smaller, disconnected parcels
cover type
category within a classification scheme defined by the user that distinguishes among the different habitats ecosystems or vegetation types on landscape
what enables the differentiation b/w the diff patches within the landscape?
cover type
what restricts insects from moving among patches?
habitat fragmentation
what are the 2 ways of measuring what’s in a landscape?
composition & configuration
composition
proportion of diff habitats that occur within a landscape
habitat richness & diversity
configuration
have the same composition but can be connected or fragmented
habitat connectivity & fragmentation
complex landscapes have significantly: (7)
o 1 – Higher % of deciduous forests
o 2 – Lower % area cover by crops
o 3 – Smaller fields
o 4 – Wider field borders
o 5 – Taller vegetation in the border
o 6 – Richness of tree species in the border
o 7 – Higher % of trees/shrubs in the border
describe the diet of true armyworms
generalist, attack several crops
how are true armyworms controlled?
by natural enemies
Meterous communis
generalist endoparasitoid mainly on Noctuidae
solitary
alternative hosts
Glyptapanteles militaris
generalist endoparasitoid mainly on Noctuidae
gregarious
alternative hosts
what is the main diff b/w Glyptapanteles militaris & Meterous communis?
Glyptapanteles militaris mainly feeds on grasses & forbs
higher % of parasitism in ______ than in ______
comlex
simple
how are melon aphids controlled?
by many natural enemies
what habitats benefit the natural enemies of melon aphids? (6)
% area of:
Alfalfa o Cucurbits o Other crops o Native vegetation o Riparian vegetation o Grassland
Do we benefit from predators arriving early to the crops?
YES! Delaying the arrival of predators impacted the aphid population growth
what is the most important vegetation in determining the survival rates of aphids?
alfalfa
decres survival = incres in alfalfa
how do you enhance natural enemy impacts?
incers flowering species
Select diff species that may be possible to place at the sites of the fields or close to it that have these flowering plants so at diff times of the season they provide the nectar & pollen to provide them with enough E to move into crops
how do complex landscapes affect beneficial insects?
by providing resources from non-crop habitats
natural enemies _____ their abundance in complex habitats
increase
pes suppression in complex landscapes is _____
higher
