Good question! Until recently it was DDVP in semi-closed traps (not the delta-type, of course) but since DDVP was not re-registered in Europe I do not think there is any insecticide that could be generally used. Volatile pyrethroids have been tested by my ex-colleague Miklós Tóth but they do not seem to work (inactive? deterrent?). In some cases (traps for wasps) water w/detergent might work. Do you have any suggestion? 

For some insects, contact insecticide such as deltamethrin might work. However, there is a need for easy application of it in the trap - like impregnated plastic plates to place in the traps.

You say "might work". Any experimental evidence? I have worked with tsetse flies where fabric targets are impregnated w/deltamethrin and this has been thoroughly  studied (also for malaria nets, obviously; see my presentations on this site. But usinf pieaces of commercial household pyrethroid sticks / paltes with moths we did not get what we expected (w/Miklós Tóth, unpublished, I beileve). For practical / economic and safety reasons impregation of cardboard and plastic trap walls were opted out. (See Csalomon familiy of traps).

http://www.csalomontraps.com

With Medfly, in our "Steiner" trap, we tested pieces of cardboard impregnated with deltamethrin and it works fine and as good as the DDVP. Deltamethrin is also used against the olive fly. But other then these fruit flies, I wonder what kind of alternative were developed to the DDVP in the world.

BTW, what about DDVP-plugs. Are these acceptable as an alternative for the liquid DDVP (as these may be used ONLY in insect traps)?

Yes, flies are very different from moths... I am not sure about the global situatio of DDVP but it cannot be sold in te EU. Of course if one applies to exemption it could be possible though uneconomical. And this is an environmental / "green" issue as well.One does not want to work with a 'possible human carcinogen' to make a formulation just for a couple of hundred /thousand traps. For research, OK but not for commercial reason. Unless there is a zika-vector-like situation alternative 'kill' solutions should be sought for.

Hi Yoav, 

Even banned in all EU, in Spain DDVP is still allowed only as plugs in Steiner-like traps, when applied by registered professionals and only for citrus and olive crops (some regions had also this extension for pear and apples). This is a special extension of use from UE, limited to march-october period. This extension should be asked for approval for each Spanish region governments in a yearly basis. 

During the rest of the year, another alternatives are also available, like the one explained with deltamethrin but in this case with cypermethrin in cardboards within the trap (KILLDISC(R) from SANSAN).  This pyrethroid had better results in killing than deltamethrin. Also Deltamethrin covered trap-covers are being used (from PROBODELT). 

But in some regions of Valencia, citrus growers prefer liquid based traps (STARCE from Biagro or CERATRAP by BioIberica), just by cost, as the dry-traps require also the attractants plus the insectice.

Almost all these companies had equivalent traps for olive fruit fly and drosophila suzukii. And other pest insects that are killed in the same way. 

Hope this helps Yoav,

Beatriz  

Thank you Istvan and Beatriz, very helpful answers

(though I wouldn't wait for a zika-vector-like solution... :)

Anyway, I wonder what is the situation with that respect in the America's (both North- and South-)