On biocontrol and SWD management strategies: It is a general recommendation in the IPM SWD management literature to collect and destroy SWD-infected berries before the SWD larvae and pupae in those berries can complete their development to adults.
This makes good sense in the absence of other, non-chemical control strategies. However, adding possible biocontrol organisms will change the considerations on this SWD management practice.
For example, the recently USDA/APHIS approved predator wasp Ganaspis brasiliensis, (discussed above) reproduces by infecting SWD larvae that are developing in the fruit. So eliminating those SWD-infected fruit would be counterproductive to establishing effective biocontrol via G brasiliensis.
Similarly, the commercially available Steinernema feltiae (Sf) - a beneficial nematode predator -reproduces inside SWD larvae and pupae developing on the ground. So any removal of SWD-infested fruits would reduce population growth for the Sf predator.
…but for the small berry patch home gardener, still the great unknown: Gambling that the wasp or nematodes will dominate the SWD cycle in any one year, or having the patience to wait multiple years.
An aside: SWD-infected cameberries can be identified by multiple collapsed drupelets and a mushy overall feel to the fruit without ever seeing the larvae.
When raspberries are infested with SWD larvae, they become soft and wet. I look at the inside of the ripest berries and if they look wet, they get tossed into the killing bucket. As an urban gardener, I think that most of the fruit flies are coming from outside of my small garden; and my actions won’t have much effect on the parasitic wasp population (if they are actually present). Besides the SWD larvae, any infested raspberries become breeding sites for picnic beetles, which are still abundant in my garden; so, I make it a point to gather all damaged and fallen fruit as early as possible and kill whatever pests are present.
I’ve been growing raspberries in this location for over 35 years; the picnic beetles arrived sometime more recently than 25 years ago. I don’t remember when they first appeared, but they became more abundant after SWD fruit flies arrived. I don’t use any pesticide sprays on the raspberries.