L14 Climate and abundance

Question 1

Fancy word for coldblooded

Answer 1

Poikilotherm - body temp varies directly with surroundings. Temp directly affects survival, reproduction and development

Question 2

How do bumble bees and locusts regulate their body temperature?

Answer 2

Bumblebees - produce heat by vibrating wings

Locusts bask in sun

Question 3

trend of temperature affecting development?

Answer 3

U shaped, optimum at about 30 degrees C.
Cooler development slows and also higher.
If reaches a lower threshold, development is suspended - base temperature.
Large gap between base temp and lower lethal temp. Small gap between upper temp threshold and higher lethal temp.

Question 4

what is a thermal window?

Answer 4

range between lower lethal temp and higher lethal temp).

Varies between species.

Question 5

Why is it important to know life processes in detail

Answer 5

Different optimum and thresholds for each process eg. Reproduction, growth and survival.
Need to know these processes in detail to see how temp change will affect physiology.

Question 6

What are day degrees?

Answer 6

A thermal unit which allows you to predict the length of lifecycle of the insect.

Question 7

How do you calculate day degrees?

Answer 7

1. Find out how long it takes to complete the lifecycle at different temperatures. - makes curve downwards as temp increases
   2.Convert this data into rate, using 1/time. This gives a straight line.
   Extrapolate line down to where it crosses the x axis, this makes the base temperature.
2. Calculate day degrees required -
   Day degrees = (ambient-base temp) x No. days at base temp
   This gives you a value which has to be reached to complete development.
3. Can then rearrange equation to find how many days at different ambient temperatures.

Question 8

Why would day degrees be useful?

Answer 8

Can apply to lifecycles of pest species to time exactly when to use fertiliser, to avoid continuous fertiliser use and pollution.
eg. Cabbage root fly - Delia radicum maggots hatch and burrow into roots and tubers. Use knowledge of lifecycle and day degrees to model and predict when maggots will hatch, and time pesticide use exactly.

Question 9

describe a pest outbreak which was preceded by periods of rainfall

Answer 9

Swetnam and Lynch 1993 - Studies tree rings to which years had attack of Western spruce budworm. Saw correlation btw years of high rainfall and budworm attack. Causes huge devastation of forests.

Question 10

How are outbreaks of African armyworm initiated?

Answer 10

Devastating pest in E africa.
in years of reasonable rainfall, virus has a high survival rate. Caterpillars are not resistant to virus and plenty of food.
Drought is damaging to the virus and allows caterpillar populations to flourish and achieve outbreak.
In periods of drought and virus has low survival, allowing caterpillar outbreak.
Correlation between rainfall and caterpillar outbreaks was so tight they could make a model able of predicting outbreaks.

Question 11

What causes population blooms of Chrysomya megacephela and why is it significant?

Answer 11

Fish dried on beach in sun in S India as away of preserving it. Overnight, Latrine fly can lay 200 eggs each in the fish, maggots hatch and eat all the fish. By morning, all that is left are the maggots in the sand.
Studied climate, found temp very constant, and rainfall started in May and very heavy for a few months.
Fly pop decreases when dry, and population booms when rain starts. Whole beach covered in flies overnight.
Potential for disease transmission is huge at this level of abundance.

Question 12

What must be considered when studying climate niche

Answer 12

many climatic factors, eg humidity, temperature and wind.

Question 13

study of microclimate impacting insects

Answer 13

Blowfly - Lucilia, in SE england.
Placed sticky target every 10m in field, and counted number of flies, and measures humidity, wind and temp.
Microclimates varied, and found correlation between humidity and fly abundance. built map of microclimate and abundance, found highest along S facing edge of field.
Fly is damaging to livestock, so can tell farmers where in fields there are less flies.

Question 14

How has macroclimate affected distribution of Mosquitos?

Answer 14

Mosquito, Aedes aegypti.
Tropical and semi tropical distribution. Important vector of yellow fever and other viruses.
Temps below 10 degrees C are lethal to adults and larvae. Distribution is sharply limited by latitude and temperature.

Question 15

What are 4 ways insects can avoid adverse conditions?

Answer 15

Diapause
Quiescence
Supercooling
Dispersal

Question 16

How do diapase and quiescence differ?

Answer 16

They are a state of arrested development
Diapause occurs before adverse conditions occur. eg Lucilia flies produce generation of Larvae that will go into ground and into diapause before photoperiod decreases in winter.
Quiescence is initiated by adverse conditions. As conditions improve, the leave quiescence. Facultative and short term.

Question 17

What is supercooling

Answer 17

Secretion of glycerol into cells to survive low temperatures.
Elm bark beetle freezes at -7 degrees, byt with glycerol can withstand -9.