Bollworms are insect pests that feed on cotton plants. They can be controlled by natural predators such as parasitic wasps and assassin bugs.
Draw a food chain showing the relationship between cotton plants, bollworms, and parasitic wasps.
A biologist wanted to compare the ability of these two different predators to control bollworms. Parasitic wasps were released on day 0 into one cotton field (Field A), and assassin bugs were released into a different cotton field (Field B).
The table below shows the results:
Time\multicolumn2c∣Field A\multicolumn2cField B\cline2−5(days)Bollworms per m2Wasps per m2Bollworms per m2Assassin bugs per m20500155101544905038090848511015017012450180101401612024053020023012002402253900\begin{array}{c|c|c|c|c} \hline \textbf{Time} & \multicolumn{2}{c|}{\textbf{Field A}} & \multicolumn{2}{c}{\textbf{Field B}} \\ \cline{2-5} \textbf{(days)} & \textbf{Bollworms per } \text{m}^2 & \textbf{Wasps per } \text{m}^2 & \textbf{Bollworms per } \text{m}^2 & \textbf{Assassin bugs per } \text{m}^2 \\ \hline 0 & 500 & 15 & 510 & 15 \\ 4 & 490 & 50 & 380 & 90 \\ 8 & 485 & 110 & 150 & 170 \\ 12 & 450 & 180 & 10 & 140 \\ 16 & 120 & 240 & 5 & 30 \\ 20 & 0 & 230 & 120 & 0 \\ 24 & 0 & 225 & 390 & 0 \\ \hline \end{array}Time\cline2−5(days)04812162024\multicolumn2c∣Field ABollworms per m250049048545012000\multicolumn2cField BWasps per m21550110180240230225Bollworms per m2510380150105120390Assassin bugs per m215901701403000Use the information in the table to answer the following:
Suggest two reasons why parasitic wasps might be a better biological control agent to use than assassin bugs.
Suggest one reason why assassin bugs might be a better biological control agent than parasitic wasps.
Other than predation, name two biotic (living) factors that may affect bollworm numbers.
Name two abiotic (non-living) factors that may affect bollworm numbers.
20 exam-style questions on Edexcel IGCSE Biology Feeding relationships. Each one has a worked solution and a mark scheme showing where the marks go.