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Title: Effects of Sheep-Dip Disposal on Terrestrial Invertebrates
Author: Environment Agency
Document Type: Monograph
Annotation: Environment Agency Project ID:EAPRJOUT_1449, Representation ID: 499, Object ID: 2603; Environment Agency Project ID:EAPRJOUT_1637, Representation ID: 564, Object ID: 2744
Abstract:
This study, into the effects of sheep dip disposal on terrestrial invertebrates, was initiated as a response to a change in disposal policy and has been jointly funded by the Environment Agency, English Nature and the Countryside Council for Wales. The 1998 Groundwater Regulations required the majority of dip to be disposed to farmland. However, little information was available on the effects of disposal on soil invertebrates and the possible consequences for their bird predators. The present study aimed to assess the significance of organophosphate and synthetic pyrethroid dip disposal in upland terrestrial habitats, especially in relation to bird populations, and to provide guidelines for best practice. A questionnaire was used to make a preliminary survey of dip disposal practice on 42 hill farms on or adjacent to SSSIs. These areas support breeding waders and it is possible that significant decreases in soil invertebrate densities could have adverse effects on the birds. The survey exposed a wide variety of practices and considerable deviation from the recommended procedures in many cases. The effects of sheep dip disposal were further investigated by sampling paired disposal and control sites on a subset of the surveyed farms. Invertebrate abundance was estimated by taking soil samples, followed by Berlese extraction (or hand sorting for worms), pitfall trapping and suction sampling. Comparisons of total, sedentary and active invertebrate species densities were made between control and disposal sites; active species being more likely to recolonise an area rapidly after disposal. Spiders, bugs and ground beetles were identified to species and multivariate analysis was carried out on the pitfall samples of spiders and ground beetles. Sampling the farm sites indicated that variables, other than the application of pesticide, influenced the densities and species composition of the invertebrate communities. However, invertebrate densities on disposal sites were significantly lower than on control sites in 7 out of 15 cases and the multivariate analysis indicated significant effects of dip disposal on carabid, but not spider, species composition six months after application. Density reductions were greatest on areas that had been used for dip disposal over many years. An experimental site was set up on an area of rough pasture on 10 x 10 m plots in a aLatin-squarea design. OP and SP were applied at full made-up dip strength and at the recommended 1:3 dilution, allowing comparison of the effects of the two insecticides under more controlled conditions than on the farms. The same sampling methods were used as on the farm sites and densities of all invertebrate groups, except linyphiid spiders and carabids (the latter showed increases) were significantly reduced on the disposal plots on one or more sampling occasion after application. The invertebrates living above the soil surface, taken by suction sample, showed the most severe and consistent reductions. Densities were lower on both OP and SP plots, at both dilutions, than on the controls at both 20 and 40 days after application. A second Latin square experiment on more productive inby pasture, was used to determine the effects of disposal on during 2002. Again, densities of all invertebrate groups were significantly reduced on the disposal plots on one or more sampling R and D TECHNICAL REPORT P2-250/1/7/TR i occasion after application. Additional sampling for Collembola on the treated plots showed significant reductions 20 days after treatment application, indicating possible consequences for larger carnivorous invertebrates for which smaller invertebrates are an essential food source. A small-scale laboratory study of the effects of dip application to tipulid larvae showed that both OP and SP dips were toxic to larvae introduced 17 days after application with possible persistence to 133 days. A risk assessment, based on the results, suggests that spring disposal should not be undertaken on areas where there are young wader chicks. Small chicks are restricted in movement and could suffer from food reduction in their immediate area. As there is also the possibility of poisoning by contaminated prey, there should be no disposal during the wader breeding season in areas where there is a high likelihood of the presence of nesting birds. In autumn, disposal on improved ground should be avoided. These areas often have high tipulid densities and are used as a resource by adult waders when they arrive in the uplands in spring. Tipula paludosa, which is the predominant species, has an annual cycle and, from September onwards, young larvae will be vulnerable in the soil. R and D TECHNICAL REPORT P2-250/1/7/TR ii CRYNODEB GWEITHREDOL Dechreuwyd yr astudiaeth hon ynghylch effaith gwaredu dip defaid ar greaduriaid diasgwrn cefn mewn ymateb i newid yn y polisi gwaredu ac feai hariannwyd ar y cyd gan Asiantaeth yr Amgylchedd, English Nature a Chyngor Cefn Gwlad Cymru. Yn Rheoliadau DAMicro Daear 1998 roedd raid i fwyafrif y dip gael ei waredu i ffermdir. Fodd bynnag, ychydig iawn o wybodaeth oedd ar gael ynghylch effaith y gwaredu ar greaduriaid di-asgwrn cefn yn y pridd aar canlyniadau posib o ran eu hysglyfaethwyr sef yr adar. Anelir yr astudiaeth bresennol tuag at asesu arwyddocAd dip organoffosffad a pyrethroid synthetig ar gynefinoedd yn yr ucheldir, yn arbennig mewn perthynas A phoblogaeth yr adar, ac er mwyn darparu canllawiau ar gyfer arfer da. Defnyddiwyd holiadur i wneud yr arolwg rhagarweiniol ynghylch yr arferion wrth waredu dip ar 42 o ffermydd mynydd sydd ar, neuan gyfagos i SoDdGA. Maear ardaloedd hyn yn cynnal rhydwyr syan bridio ac maean bosib y gallai lleihad yn y creaduriaid di-asgwrn cefn yn y pridd, gael effaith andwyol ar yr adar. Dangosodd yr arolwg amrywiaeth eang o arferion ac mewn sawl achos gwyriad sylweddol oddi wrth y gweithdrefnau a gymeradwyir. Archwiliwyd effaith gwaredu dip ymhellach drwy samplu safleoedd gwaredu a safleoedd rheoli ar is-set oar ffermydd a arolygwyd. Amcangyfrifwyd bod digonedd o greaduriaid di-asgwrn cefn drwy gymryd samplau oar pridd, gan ddilyn hyn A thyniad Berleses (neu ddidoli am bryf genwair A llaw), sampl pydew a samplu drwy sugno. Gwnaed cymariaethau o gyfanswm y rhywogaethau sefydlog, gweithredol yn y safleoedd rheoli a gwaredu; roedd rhywogaethau gweithredol yn llawer mwy tebygol o ail-gytrefu ardal yn fuan ar Al gwaredu. Dynodwyd pryf copyn, bygiau, a chwilod fel rhywogaethau a gwnaed dadansoddiad aml-amrywedd ar y samplau pydew o bryf copyn a chwilod. Nododd samplau safleoedd y ffermydd bod newidynnau oni bai am daenu pla laddwyr, yn dylanwadu ar ddwyserdd a chyfansoddiad rhywogaethau cymunedauar creaduriaid di-asgwrn cefn. Fodd bynnag, roedd dwysedd creaduriaid di-asgwrn cefn ar safleoedd gwaredu yn sylweddol yn As nag ar safleoedd rheoli yn 7 oar 15 achos, a nododd y dadansoddiad aml-amrywedd effaith arwyddocaol gwaredu dip ar gyfansoddiad rhywogaethau carabid chwe mis ar Al ei daenu, ond nid pryf copyn,. Roedd y lleihad dwysedd mwyaf ar ardaloedd a ddefnyddiwyd am sawl blwyddyn ar gyfer gwaredu dip. Sefydlwyd safle arbrofol ar ardal o borfa fras ar rannau 10x10 fel cynllun aSgwArLladina. Taenwyd dip OP a SP ar ei gryfder llawn ac ar y gwanhad a argymhellir sef 1:3, gan alluogi cymharu effaith y ddau bryfleiddiad dan amodau a reolwyd, yn well nag ar y ffermydd. Defnyddiwyd yr un dulliau samplu ar un neu fwy achlysur ar Al taeniad ar safleoedd y ffermydd, a lleihaodd holl grwpiau y creaduriaid di-asgwrn cefn yn sylweddol ar y mannau gwaredu, oni bai am bryf copyn linyphiid a carabid (dangosodd yr olaf gynnydd). Y creaduriaid di-asgwrn cefn a oedd yn byw uwchben arwyneb y pridd, a gymerwyd A sampl sugno ddangosodd y lleihad mwyaf difrifol a chyson. Roedd dwysedd yn llai ar y mannau OP a SP, ar y ddau wanhad, nag ar y ddau reolydd, a hynny 20 a 40 niwrnod ar Al y taeniad. R and D TECHNICAL REPORT P2-250/1/7/TR iii Defnyddiwyd ail arbrawf sgwAr Lladin ar borfa mwy cynhyrchiol i benderfynu ar effaith y gwaredu yn ystod 2002. Unwaith eto, ar achlysur un sampl neu fwy, lleihawyd dwysedd yr holl grwpiau o greaduriaid di-asgwrn cefn yn arwyddocaol ar y mannau gwaredu. Dangosodd samplu ychwanegol am Collembola ar fannau a daenwyd leihad mewn 20 niwrnod, gan nodi canlyniadau posibl ar gyfer y creaduriaid di-asgwrn cefn mwy, y maear creaduriaid di-asgwrn cefn llai yn ffynhonnell bwyd hanfodol iddynt. Ar raddfa fechan yn y labordy, dangosodd astudiaeth ar effaith taenu dip ar tipulid larfa bod dip OP a SP yn wenwynig i larfa a gyflwynwyd 17 niwrnod ar Al y taeniad ac roedd parhad posibl i hyd at 133 diwrnod i hyn. Awgryma asesiad o beryglon, yn seiliedig ar y canlyniad, na ddylid gwaredu dip yn y gwanwyn ar ardaloedd lle mae cywion ifanc rhydwyr. Mae cywion bychain yn rhwystredig mewn symudiad, a gallent ddioddef o ddiffyg bwyd yn eu hardal gyfagos. Gan fod posibilrwydd o wenwyno gan ysglyfaeth a ddifwynwyd, ni ddylid gwaredu yn ystod tymor bridio y rhydwyr mewn ardaloedd syan debygol o gynnal adar syan nythu. Yn yr hydref dylid osgoi gwaredu ar dir wedi ei wella. Yn aml mae gan yr ardaloedd hyn ddwysedd tipulid uchel ac feau defnyddir fel ffynhonnell i rydwyr aeddfed pan gyrhaeddant oar ucheldir yn y gwanwyn. Mae gan Tipula paludosa syan rywogaeth bwysig, gylch blynyddol, ac o fis Medi ymlaen, bydd larfa ifanc yn hawdd iaw niweidio yn y pridd. R and D TECHNICAL REPORT P2-250/1/7/TR iv CONTENTS EXECUTIVE SUMMARY i CRYNODEB GWEITHREDOL 1.
Publisher: Environment Agency
Subject Keywords: Disposal; Wildlife; Invertebrates; Sheep; Nature conservation; Birds; Impacts
Extent: 159
Permalink: http://www.environmentdata.org/archive/ealit:4683
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