Biological control of wasps

Press, 3 February 1981, Page 18

Biological control of wasps

Parasites' which attack wasp larvae are being .studied by the Entomology Division of the Department of Scientific'and Industrial Research. The division hopes to find a means of biological control against wasps. German- wasps were; in-,-troduced to New -ealand by accident in packing materials from the northern hemisphere during the Second World War. They found conditions' to their liking; ? and spread-rapidly. ; •■/■' The new study is being carried out by Entomology Division.' to' investigate the . life cycles and habits of /o.f//.wasps,// with?// assistance from the Commonwealth- .• Institute •. of./--..

Biological Control. Wasps can be . a problem to beekeepers; robbing weak hives towards the end of the season, causing thousands of dollars worth of lost production • a-year.--; Wasps are also a nuisance to holidaymakers, and can be dangerous to people who are allergic to their stings. Orchard! sts do not like wasps . either because; they damage over-ripe fruit and can ; be an • annoyance to pickers. The Entomology Division recently received from America some parasites of a wasp, which is related to the . German wasp established .-here,- , A New Zealand scientist

has been successful in handling the parasite under laboratory conditions and has developed techniques for breeding it under control. If the present search for suitable parasites in Europe is successful, then these techniques will be used to rear German wasp parasites introduced from Europe. These pararitij are what is ca’led “host-specific” — they will not attack species other than their normal host — so there is no danger of them becoming a problem to beekeepers. They attack the cocooning larvae and developing pupae in the wasp nest, preventing a build-up of wasp numbers and restricting the size of the colony, . .

The conditions which proved so congenial to the German wasp' — New Zealand’s mild winters — ■ could well prove suitable for the parasites to multiply faster than they do in their original habitat.

When these new parasites have been checked for freedom from diseases or imported enemies, and when the scientists are satisfied that they will not harm native New Zealand .species or insects beneficial to man, the parasites may. be tested in the field. Careful monitoring of the results could then show whether it will be possible to reduce wasp, numbers by.these. natural means.