1 markThe Helicoverpa punctigera (native budworm) caterpillar is a major insect pest for Cicer arietinum (chickpeas). Reduction to crop yield and seed quality occurs when the larvae density reaches 10 to 20 per m2. The larvae primarily cause damage to the leaf surface area, flower buds and fruiting bodies and are classified into 4 instars (sizes); very small (VS) - 1 to 2 mm, small (S) - 4 to 7 mm, medium large (ML) - 8 to 23 mm and large (L) - 24 to 30+ mm. The smaller instars prefer foliage, however it is the larger instars (greater than 8 mm), who prefer the pods, that cause the most economical damage. Farmers regularly monitor their arietinum crop to determine when insecticides are required to control the H.punctigera.
The monitoring involves beating the plants to determine the mean number of larvae per metre row and making observations of the type of damage.
Identify the feeding site on the C.arietinum that has the least percentage of feeding by larvae smaller than 8 mm.
1 markCalculate the difference between the percentage of feeding by larvae less than and greater than 8 mm, on C.arietinum leaves.
1 markSuggest a reason for the preference of the small larvae feeding on the leaves.
1 markPest management is economically and environmentally important to farmers. Insecticides can be costly, insect resistance can develop and broad-spectrum insecticides can cause beneficial insects (e.g. pollinators) to be killed when applied. Scientists have been researching the most appropriate method to manage pests of chickpea crops. They have genetically engineered C.arietinum plants with the bacterium Bacillus thuringiensis (Bt), which results in the plants releasing a toxin that kills insects that ingest it. Scientists have also been developing synthetic pyrethroids (e.g. 
-Cypermethrin) that H.punctigera currently have a low resistance to.
In this study, scientists explored four different pest management methods over one growing season. The graphs below represent data from the experiments undertaken.
State which pest control management method was most successful in controlling larvae less than 8 mm prior to pod development.
1 markSuggest why Bt C.arietinum appear to be more effective at controlling the larger larvae of H.punctigera.
3 marksCompare the effectiveness of the three methods used in limiting the damage caused by H.punctigera, prior to pod development and during pod development.
3 marksUsing all the data provided, evaluate the hypothesis that the most sound pest management method is a combination of using a synthetic pyrethroid (-Cypermethrin) on a genetically engineered (Bt) chickpea crop.
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