Agricultural scientists investigated two methods for controlling the population of red spider mites (Tetranychus urticae) on tomato plants in a commercial vertical farm.
In the first method, they sprayed the plants with a chemical organophosphate acaricide.
In the second method, they introduced a predatory mite (Phytoseiulus persimilis) as a biological control agent.
They recorded the percentage of the mite population remaining every 5 days over a period of 25 days. The results are shown in the table below:
Time after treatment (days)Acaricide treatment (%)Biological control treatment (%)010010051255108221530102065625923\begin{array}{c|c|c} \text{Time after treatment (days)} & \text{Acaricide treatment (\%)} & \text{Biological control treatment (\%)} \\ \hline 0 & 100 & 100 \\ 5 & 12 & 55 \\ 10 & 8 & 22 \\ 15 & 30 & 10 \\ 20 & 65 & 6 \\ 25 & 92 & 3 \end{array}Time after treatment (days)0510152025Acaricide treatment (%)100128306592Biological control treatment (%)10055221063Explain the changes in the percentage of the mite population remaining over the 25-day period when treated with the chemical acaricide.
Give two advantages of using biological control (predatory mites) rather than chemical acaricide to control the pest population.
Describe a method that could be used to estimate the population of mites on the tomato plants in the vertical farm.
74 exam-style questions on Edexcel IGCSE Biology Food production. Each one has a worked solution and a mark scheme showing where the marks go.