Both beetles and moths have been found, at least as larvae, in all stages of the flowering and fruit process.
Collecting the fruits at these different stages involves some difficult procedures, including:
- Climbing the tree and cutting branches bearing fruit, or using ropes to shake fruit off.
- Collecting falling fruit using fruit traps set under the trees, keeping fruit from different trees separate wherever possible.
- Keeping the fruit sealed in bags to prevent insects escaping before examination.
Rearing Larvae
To better identify the insect predators, fruit may be stored to allow the insects inside to reach maturity. Care must be taken to avoid damp and the chance of escape, as some beetles may be less the 1mm in size.
Once beetles emerge they should not be killed immediately as their internal organs, vital for identification, take approximately 2 – 3 days to harden. Beetles should be collected into tubes of 70% ethyl alcohol for study.
Moths should be killed immediately, and micropinned with the wings spread.
Sampling fruit
Once collected, fruit should be sampled at random to determine if insect damage is present. This is done by cutting into the bud or fruit to see inside.
Care must be taken to avoid over or under-estimation of infestation. Photographing or preserving specimens is the most reliable way of assessing the infestation rate.
Reasons for uncertainty:
- Although usually there is one larva per fruit in beetle and moths, numerous individuals may be present or they may move between fruits, depending on the species.
- Trees may selectively abort fruit containing insects leading to over-estimates of infestation in fallen fruit.