Ladybird Beetles

​In the Netherlands, scientists are studying the climate’s impact on the population of ladybird beetles. One type of the beetles found in the Netherlands is the two-spot ladybird. Some two-spot ladybirds have black wing covers, while others have red wing covers.

Ladybird Beetles

All insects are cold-blooded, which means they cannot maintain a constant body temperature as warm-blooded organisms do. Cold-blooded organisms must “warm up” to an ideal temperature to function at their best. The scientists hypothesize that the black two-spot ladybirds are favored in colder, less windy areas because they warm up faster than the red two-spot ladybirds. The scientists observed the percent of each type of two-spot ladybirds at different locations along the line shown in the map. The cooler, less windy conditions tend to occur in the eastern regions, away from the coast. The graph shows data collected from west to east in the years 1980–2004.

All insects are cold-blooded, which means they cannot maintain a constant body temperature as warm-blooded organisms do. Cold-blooded organisms must “warm up” to an ideal temperature to function at their best. The scientists hypothesize that the black two-spot ladybirds are favored in colder, less windy areas because they warm up faster than the red two-spot ladybirds. The scientists observed the percent of each type of two-spot ladybirds at different locations along the line shown in the map. The cooler, less windy conditions tend to occur in the eastern regions, away from the coast. The graph shows data collected from west to east in the years 1980–2004.

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The scientists wondered if changes to the climate caused a genetic response in the two-spot ladybird population. Climate information for the Netherlands from 1980 through 2010 is shown in these two graphs.

A bacterium called Rickettsia can infect female two-spot ladybird beetles. The females then pass the Rickettsia on to their offspring. The bacteria cause the male eggs to not hatch, but the Rickettsia does not affect the female offspring that inherit it from their mothers. After hatching, the offspring often eat the unhatched eggs.

Scientists studied the effects of Rickettsia by breeding a male two-spot ladybird with an uninfected female and an infected female. The table indicates some of the data the scientists collected.

Rickettsia

Ladybird beetles prey on aphids, which are small plant-eating insects that can spread diseases between plants and damage crops. Farmers tried to introduce the harlequin ladybirds to control aphid populations. For many years, the farmers’ efforts were unsuccessful, and Harlequin ladybirds could not survive in the area. In the early 1990s, the harlequin ladybirds were introduced in the Netherlands, and this time the ladybirds were able to survive and even thrive. Scientists noted that the harlequin ladybirds introduced in the 1990s preyed on two-spot ladybirds as well as aphids.

Harlequin Ladybird beetles

Harlequin ladybird beetles are another species of beetle. They were originally found in Asia. Harlequin ladybirds have multiple spots on their red wing covers and are larger in size than two-spot ladybirds.

Multiple Choice

Which statement best describes the relationship between the black two-spot beetles and climate in the Netherlands?

• A.

  The percentage of black two-spot beetles increased from west to east due to lower temperatures and less precipitation in the 1980s and early 1990s.

• B.

  The percentage of black two-spot beetles decreased from west to east due to lower temperatures and less precipitation in the late 1990s and 2000s.

• C.

  The percentage of black two-spot beetles increased from west to east due to higher temperatures and more precipitation in the 1980s and early 1990s.

• D.

  The percentage of black two-spot beetles decreased from west to east due to higher temperatures and more precipitation in the late 1990s and 2000s.

Multiple Select

Which statements explain the evolutionary impact the Rickettsia bacterium has on the population of two-spot ladybird beetles? Select the two that apply.

• A.

  The population of male two-spot ladybird beetles decreases.

• B.

  The population of female two-spot ladybird beetles decreases.

• C.

  The male two-spot ladybird beetles born to uninfected females have more food readily available than those born to infected females.

• .

  The male two-spot ladybird beetles born to uninfected females have less competition upon hatching than those born to infected females.

• E.

  The female two-spot ladybird beetles born to infected females have less competition upon hatching than those born to uninfected females.

Multiple Choice

For which organism in the food web do the harlequin and two-spot ladybirds compete?

• aphid

• grape plant

• harlequin ladybird

• soybean plant

• two-spot ladybird

Multiple Choice

Farmers tried for many years to introduce harlequin ladybirds to the Netherlands without any success until the early 1990s. During these years, some harlequin ladybirds must have experienced an important change that allowed them to be able to survive in the Netherlands when they were reintroduced there in the early 1990s.

Which statement best describes the important change and the long-term effects of that change on harlequin ladybirds?

• A.

  The change that made them better able to survive is genetic competition, and the long-term inheritance of the change by each new generation of harlequin ladybirds is natural selection.

• B.

  The change that made them better able to survive is biological evolution, and the long-term inheritance of the change by each new generation of harlequin ladybirds is genetic competition.

• C.

  The change that made them better able to survive is natural selection, and the long-term inheritance of the change by each new generation of harlequin ladybirds is biological evolution.

• D.

  The change that made them better able to survive is genetic competition, and the long-term inheritance of the change by each new generation of harlequin ladybirds is biological evolution.

Multiple Choice

Which statement describes how the harlequin ladybirds have changed the environment for the two-spot ladybirds?

• A.

  The harlequin ladybirds have become a new prey for the two-spot ladybirds, giving the two-spot ladybird a better survival chance.

• B.

  The harlequin ladybirds have become a new predator of the two-spot ladybirds, making it harder for the two-spot ladybirds to survive.

• C.

  The harlequin ladybirds have competed with the two-spot ladybirds for grape plants, but as there are plenty for both kinds of ladybirds this has not affected the survival of the two-spot ladybirds.

• D.

  The harlequin ladybirds have competed with the two-spot ladybirds for soybean plants, and the reduction in soybean plants has made it harder for two-spot ladybirds to survive.

Fill in the Blank

Use evidence to explain the survival advantages and disadvantages a red two-spot ladybird has if it is born to a female that is not infected with Rickettsia and lives on the southwestern coast of the Netherlands.

Type your answer in the space provided.

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