180 BR. J. ENT. NAT. HIST., 6: 1993 



Mr I. Woiwod said that this year Rothamsted Experimental Station would be 

 celebrating its 150th anniversary and would be holding open days on 4-6 June. 

 Members of the Society would be most welcome to see the work of the station, 

 including that of the insect survey team. 



Mr I. Woiwod then spoke on a new look at moths on farmland. He outlined the 

 history of the Rothamsted Insect Survey which has its origins in a moth trap run 

 on a nightly basis at Barnfield in the experimental station by C. B. Williams during 

 the 1930s and 40s. Trapping began again during the 1950s and by the mid-1960s 

 a national network of traps had been developed, many of which are run by volunteers. 

 One of the principal aims of the scheme is to build up long data runs to indicate 

 how moth populations vary from year to year. Statistical analysis of the numbers 

 of moths caught enables an index of diversity, called alpha, to be calculated, which 

 relates moth diversity to the quality of the habitat around the trap site. Mr Woiwod 

 described several trap sites within the Rothamsted estate which have been run since 

 the 1960s, including one at the original Barnfield site. The alpha number for this 

 site had declined since Williams's period of trapping, due to changes in land use, such 

 as the removal of hedges and increased use of herbicides. A woodland site, Geescroft, 

 showed comparatively little variation in its alpha number from year to year, while 

 the Allotment site showed marked differences as the surrounding land had gone from 

 cultivated allotments to arable field to weed patch and back to arable with buildings. 



Since 1990 a network of 26 Rothamsted traps has been run within the grounds of 

 the experimental station, including the four previously existing trap sites. The aim 

 of this project is to map the spatial distribution of moths across the various habitats 

 present at Rothamsted. Mr Woiwod hopes to run these traps for at least 6 years in 

 order to confirm the trends shown during the initial 3-year period. He showed a series 

 of slides of computer-generated distribution maps showing how some species seem 

 to be associated with certain habitat types. Some of the more abundant species have 

 been investigated to determine the degree of genetic variability within a species caught 

 at the various trap sites. This is done by the identification of certain enzyme systems 

 using electrophoresis equipment. Some species do show significant differences between 

 trap sites, indicating that these moths do not move far and tend to breed in relatively 

 isolated communities; other species fly freely and show little genetic variation as a 

 result. The identification of enzyme systems by electrophoresis can also be used to 

 separate difficult species of moths such as Epirrita spp. 



The diversity of moths at the 26 traps varies, with the highest alpha numbers being 

 recorded in the wooded areas and the lowest in the intensively cultivated sites. At 

 Rothamsted it has been found that the habitat within a 50-metre radius of a trap accounts 

 for 58% of the variation in the alpha number. It is hoped that the results of this survey 

 can be used to predict changes in the moth fauna when changes in land use occur, such 

 as land being taken out of cultivation for set-aside or farm woodland. 



To date 462 species of macrolepidoptera have been recorded at Rothamsted, with 

 new species still being taken. Mr Woiwod closed his talk with slides of some of the 

 more interesting species taken at Rothamsted. These included Amphipoea fucosa 

 (Frey.), A. lucens (Freyer), Celaena leucostigma (Hiibn.), Semiothisa signaria (Hiibn.) 

 and Eupithecia sinuosaha Eversmann. 



11 May 1993 



The President, Dr D. Lonsdale, announced the death of Lt. Col. Gordon 

 Eastwick-Field. 



