Abstract Culicoides biting midges (Diptera: Ceratopogonidae) are responsible for the transmission of a large number of pathogens to livestock and wild animals. In this study the presence of the genus, using light traps based at four different sites within the National Zoological Gardens of South Africa, was investigated during 2002-2004. In total, 37species were recorded, including large numbers of Culicoides irnicola Kieffer, 1913, which is responsible for the transmission of economically important arboviruses in South Africa, Europe, Middle and Far East. These results are discussed with reference to the wider Culicoides fauna in the Onderstepoort area of South Africa, their vector competence as well as biosecurity at the National Zoological Gardens.

Didymosphenia geminata is a diatom that has been accidentally introduced to New Zealand's South Island rivers. It has grown to bloom conditions in all rivers it inhabits, which has caused impacts to the river systems, loss in recreation value, and economic losses. The pathways and vectors of dispersal are difficult to control and hence it continues to spread throughout the South Island. Laboratory experiments assessed the survivability of D. geminata in different environmental conditions, a range of combinations of light availability, temperature and moisture. Experiments in the field were based in the Waitaki River to determine growth rates of D. geminata. D. geminata is growing in a greater range of temperature and light conditions than previously recognised. In cool to cold conditions with a little water this diatom can survive up to 1500h, the colder temperatures also increase survivability in the dark. However, D. geminata has reduced survivability in warm, damp conditions, up to 60h. In the Waitaki River D. geminata is attaining biomass of 2.51mg mm-2 over six weeks during summer. This high biomass is causing a change in biotic and abiotic conditions. Longevity of survival and the range of conditions in which it can survive increases the risk of spread throughout New Zealand and the world. There are considerable problems with invasive species and international trade. Policies aiming to reduce international invasions due to trade are becoming more prevalent as the consequences of invasion are more obvious and costly. New Zealand has been able to implement polices in the last decade that has reduced the number and variety of incursions. However these policies did not stop D. geminata arriving. This shows that even with the best policies species can invade fragile ecosystems. Central and local government policies surrounding management of invasive aquatic species were reviewed. Central and local government policies were developed to reduce the spread of D. geminata, however they are not effective as the diatom is still dispersing. Further research is required to elucidate means of dispersal in New Zealand, in particular the importance of dispersal by animals compared with that by humans, and the importance of continuing international dispersal.

A total of 4,778 cows from 179 herds were tested for antibodies to N. caninum using a commercially availableELISA. Neospora caninum herd-level seroprevalence ranged from 25.0% to 75.9% (a herd was considered positive with ¡Ý 2 cows testing positive). The true cow prevalence was estimated as 5.2% (95% CI= 4.6 ¨C 5.8). ¡°Pre-calving use of dry lots¡±, ¡°separation of cow-calf pair from other cows after calving¡±, ¡°use of standing water in summer¡±, ¡°use of running water in winter¡±, ¡°feeding heifers with manure handling equipment¡±, ¡°abortion and stillbirths left for canids¡± and ¡°number of sightings of wild canids per year¡± (categorized into three categories: less than 10 times per year, 11¨C 25 times per year, and greater than 26 times per year) were positivelyassociated with herd serological status. However, ¡°washing boots between visits to livestock farms¡± was negatively associated with serological status. These 8 variables were included in a multivariable logistic regression model. Province and herd size were considered potential confounders and kept in the model regardless of significance. Only 4 variables remained significant in the final model.Risk factors associated with prevalence included the use of dry lots/corrals as pre-calving area (OR=2.8; 95% CI =1.3 ¨C 6.2), the use of natural standing water in summer (OR=3.2; 95%CI=1.31 ¨C 8.0), and leaving abortions/stillbirths for dogs or wild canids (OR=2.5; 95%CI=1.0 ¨C 5.9). As the frequency of sighting coyotes and foxes increased so did herd seroprevalence to N. caninum. Risk factors suggested the likely role of horizontal transmission in the transmission of N. caninum in these beef cow-calf herds. Beef herd managers might consider biosecurity practices such as preventing the access of wild canids to fetuses and stillbirths thereby preventing pasture contamination and controlling contamination of water source with oocyst of N. caninum thereby reducing chances of infection. Aherd was considered positive for Bovine leukemia virus (BLV) if ¡Ý 1 animal tested positive.Estimates of cow-level seroprevalence was 1.01% (95% CI= 0.73% ¨C 1.29%) while herd seroprevalence was 12.4% (95% CI= 7.57 ¨C 17.23). Potential risk factors examined for BLV transmission included the use of blade or surgical castration without disinfection between animals, using gouger and saw dehorning methods, multi-use of common rectal sleeve between cows without disinfection and the use of communal pasture where mating occurred. No associations existed between potential risk factors and seropositivity to BLV because the number of herds testing positive to BLV were too few to find any association. However, management practices observed in this study may have the potential to transmit infections. Lapses in biosecurity practices identified were addition of new animals to the herds(73.7%, 132/179), the use of communal grazing (24.0% (43/179) of herds using with 28% (12/43) using more than one communal pasture where mating occurred(93%, 40/43) with bulls from other herds. During communal grazing, contact herds ranged between 1 and 25 (mean = 7.4). Large herds (¡Ý111) animals were more likely to use communal pasture compared to medium sized or small herds (¡Ü46) (P<0.01). Domestic and wild canids had access to stored grain in 19% (34/179) of herds. The odds of wildlife gaining access to stored gain is twice as high (OR=2.37, P<0.02) in western Canada compared to eastern Canada. Purebred herds were less likely to be fed on the ground compared to cross-bred herds (P<0.03). Herds from western Canada administered more feedstuffs on the ground compared to herds from eastern Canada (P<0.01). Large herds were more likely to store feedstuffs outdoors compared to small herds (P<0.01). Herds from western Canada were more likely to store their feedstuffs outside compared to herds from eastern Canada (P<0.01). The odds of not removing surface manure from maternity pens was almost three times (OR=2.98, P<0.01) in herds from western Canada compared to eastern Canada. 78.7% (140/179) of herds disposed ofmanure by spreading on surface ground. 52% (93/179) of herds borrowed manure contaminated equipment from other producers for use on their farms. Thirty three percent (53/179) of herds performed breeding soundness examinations in breeding bulls and 9.5% (17/179) of herds performed trichomonas testing on breeding bulls. Large herds were more likely to co-mingle cows and heifers during the breeding season (P<0.01) compared to small herds. Cow-calf pair separation from other cows after calving occurred more in large herds compared to medium sized or small herds (P<0.01). The odds of using maternity pen as hospital pen was twice in western compared to the eastern Canada (OR=2, P=0.04). Sixty percent (107/179) of herds used the same area for calving and winter-feeding. Herds from western Canada were more likely to use the same area for calving and winter feeding compared to herds from eastern Canada (P<0.01). Forty-one percent (73/179) of herds used hospital pens as maternity pens during calving season. 35.8% (64/179) of herds transported animals to veterinary clinic for treatment. In nine percent (16/179) of herds visitors or outside employees changed their boots, and in18% (32/179) visitors washed their boots. Eighty two percent (146/179) of herds dehorned cattle, of which 74% (109/148) used non-bloodless methods. Of herds using non-bloodless dehorning methods, 28.4% (31/109) disinfected dehorning equipment between animals. 73.7% (132/179) of herds reported castrating animals, of which 32.6% (43/132) used surgical castration method. Of herds using surgical castration method, 81.4% (35/43) disinfected surgical equipment between animals. 12.2% (22/179) of herds disinfected or used new needles between animals when injecting drugs or vaccines. Thirty five percent (63/179) of herds changed sleeves between animals when performing rectal examinations.Over twenty nine percent (29.6%, 53/179) of herds left abortions for dogs and coyotes while 27.4% (49/179) of herds left stillbirths for dogs and coyotes.The risk of adding calves persistently infected (PI) with Bovine Viral Diarrhea (BVD) virus exists with 13% (23/179) of herds adding unweaned beef calves and 18.4% (33/179) adding weaned beef calves without pre-purchase testing.PI calves are known for shedding large amounts of BVD virus and spreading BVD virus infection in beef herds. BVD virus vaccination may compensate for exposure to the virus in a cowherd by mitigating the risk of fetalinfection; however, the timing of vaccination is essential to offer protective immunity. BVD virus vaccine administered during pregnancy check may not protect the fetus against BVDV infection.There is likelihood of infection in-utero resulting in immunotolerant fetus persistently infected (PI) with BVDV and carried to term. This may occur if calf was infected in-utero before 125 days of gestation. Herds in this study administered BVD virus vaccination to breeding cows prior to breeding (60%, 118/179), during pregnancy check (28%, 50/179), and at other times (6%, 11/179). In replacement heifers, BVD vaccination was administered prior to breeding (79%, 142/179), during pregnancy check (13.4%, 24/179), and at other times (7.3%, 13/179).Herds vaccinating breeding cows for BVD virus were 63.1% (113/179), of which 29.1% (52/179) used modified live vaccine and 34.1% (61/179) used killed vaccine. Herds vaccinating replacement heifers for BVD were sixty percent (107/179), of which 25.1% (45/179) used modified live virus vaccine and 34.6% (62/179) used killed vaccine. The role ofthe veterinarianis essential in educating producers on what constitute risky practices and how to mitigate such risks. Approach to mitigating risks may not necessarily be the same for all cow-calf herds; it must be tailored to each production unit. Initial risk assessment will identify what constitutes risky management practices, after which sound mitigation measure are designed to address such risks. On-farm biosecurity practices needs approach within the framework of risk assessment and periodic review for effectiveness.

A total of 4,778 cows from 179 herds were tested for antibodies to N. caninum using a commercially availableELISA. Neospora caninum herd-level seroprevalence ranged from 25.0% to 75.9% (a herd was considered positive with ¡Ý 2 cows testing positive). The true cow prevalence was estimated as 5.2% (95% CI= 4.6 ¨C 5.8). ¡°Pre-calving use of dry lots¡±, ¡°separation of cow-calf pair from other cows after calving¡±, ¡°use of standing water in summer¡±, ¡°use of running water in winter¡±, ¡°feeding heifers with manure handling equipment¡±, ¡°abortion and stillbirths left for canids¡± and ¡°number of sightings of wild canids per year¡± (categorized into three categories: less than 10 times per year, 11¨C 25 times per year, and greater than 26 times per year) were positivelyassociated with herd serological status. However, ¡°washing boots between visits to livestock farms¡± was negatively associated with serological status. These 8 variables were included in a multivariable logistic regression model. Province and herd size were considered potential confounders and kept in the model regardless of significance. Only 4 variables remained significant in the final model.Risk factors associated with prevalence included the use of dry lots/corrals as pre-calving area (OR=2.8; 95% CI =1.3 ¨C 6.2), the use of natural standing water in summer (OR=3.2; 95%CI=1.31 ¨C 8.0), and leaving abortions/stillbirths for dogs or wild canids (OR=2.5; 95%CI=1.0 ¨C 5.9). As the frequency of sighting coyotes and foxes increased so did herd seroprevalence to N. caninum. Risk factors suggested the likely role of horizontal transmission in the transmission of N. caninum in these beef cow-calf herds. Beef herd managers might consider biosecurity practices such as preventing the access of wild canids to fetuses and stillbirths thereby preventing pasture contamination and controlling contamination of water source with oocyst of N. caninum thereby reducing chances of infection. Aherd was considered positive for Bovine leukemia virus (BLV) if ¡Ý 1 animal tested positive.Estimates of cow-level seroprevalence was 1.01% (95% CI= 0.73% ¨C 1.29%) while herd seroprevalence was 12.4% (95% CI= 7.57 ¨C 17.23). Potential risk factors examined for BLV transmission included the use of blade or surgical castration without disinfection between animals, using gouger and saw dehorning methods, multi-use of common rectal sleeve between cows without disinfection and the use of communal pasture where mating occurred. No associations existed between potential risk factors and seropositivity to BLV because the number of herds testing positive to BLV were too few to find any association. However, management practices observed in this study may have the potential to transmit infections. Lapses in biosecurity practices identified were addition of new animals to the herds(73.7%, 132/179), the use of communal grazing (24.0% (43/179) of herds using with 28% (12/43) using more than one communal pasture where mating occurred(93%, 40/43) with bulls from other herds. During communal grazing, contact herds ranged between 1 and 25 (mean = 7.4). Large herds (¡Ý111) animals were more likely to use communal pasture compared to medium sized or small herds (¡Ü46) (P<0.01). Domestic and wild canids had access to stored grain in 19% (34/179) of herds. The odds of wildlife gaining access to stored gain is twice as high (OR=2.37, P<0.02) in western Canada compared to eastern Canada. Purebred herds were less likely to be fed on the ground compared to cross-bred herds (P<0.03). Herds from western Canada administered more feedstuffs on the ground compared to herds from eastern Canada (P<0.01). Large herds were more likely to store feedstuffs outdoors compared to small herds (P<0.01). Herds from western Canada were more likely to store their feedstuffs outside compared to herds from eastern Canada (P<0.01). The odds of not removing surface manure from maternity pens was almost three times (OR=2.98, P<0.01) in herds from western Canada compared to eastern Canada. 78.7% (140/179) of herds disposed ofmanure by spreading on surface ground. 52% (93/179) of herds borrowed manure contaminated equipment from other producers for use on their farms. Thirty three percent (53/179) of herds performed breeding soundness examinations in breeding bulls and 9.5% (17/179) of herds performed trichomonas testing on breeding bulls. Large herds were more likely to co-mingle cows and heifers during the breeding season (P<0.01) compared to small herds. Cow-calf pair separation from other cows after calving occurred more in large herds compared to medium sized or small herds (P<0.01). The odds of using maternity pen as hospital pen was twice in western compared to the eastern Canada (OR=2, P=0.04). Sixty percent (107/179) of herds used the same area for calving and winter-feeding. Herds from western Canada were more likely to use the same area for calving and winter feeding compared to herds from eastern Canada (P<0.01). Forty-one percent (73/179) of herds used hospital pens as maternity pens during calving season. 35.8% (64/179) of herds transported animals to veterinary clinic for treatment. In nine percent (16/179) of herds visitors or outside employees changed their boots, and in18% (32/179) visitors washed their boots. Eighty two percent (146/179) of herds dehorned cattle, of which 74% (109/148) used non-bloodless methods. Of herds using non-bloodless dehorning methods, 28.4% (31/109) disinfected dehorning equipment between animals. 73.7% (132/179) of herds reported castrating animals, of which 32.6% (43/132) used surgical castration method. Of herds using surgical castration method, 81.4% (35/43) disinfected surgical equipment between animals. 12.2% (22/179) of herds disinfected or used new needles between animals when injecting drugs or vaccines. Thirty five percent (63/179) of herds changed sleeves between animals when performing rectal examinations.Over twenty nine percent (29.6%, 53/179) of herds left abortions for dogs and coyotes while 27.4% (49/179) of herds left stillbirths for dogs and coyotes.The risk of adding calves persistently infected (PI) with Bovine Viral Diarrhea (BVD) virus exists with 13% (23/179) of herds adding unweaned beef calves and 18.4% (33/179) adding weaned beef calves without pre-purchase testing.PI calves are known for shedding large amounts of BVD virus and spreading BVD virus infection in beef herds. BVD virus vaccination may compensate for exposure to the virus in a cowherd by mitigating the risk of fetalinfection; however, the timing of vaccination is essential to offer protective immunity. BVD virus vaccine administered during pregnancy check may not protect the fetus against BVDV infection.There is likelihood of infection in-utero resulting in immunotolerant fetus persistently infected (PI) with BVDV and carried to term. This may occur if calf was infected in-utero before 125 days of gestation. Herds in this study administered BVD virus vaccination to breeding cows prior to breeding (60%, 118/179), during pregnancy check (28%, 50/179), and at other times (6%, 11/179). In replacement heifers, BVD vaccination was administered prior to breeding (79%, 142/179), during pregnancy check (13.4%, 24/179), and at other times (7.3%, 13/179).Herds vaccinating breeding cows for BVD virus were 63.1% (113/179), of which 29.1% (52/179) used modified live vaccine and 34.1% (61/179) used killed vaccine. Herds vaccinating replacement heifers for BVD were sixty percent (107/179), of which 25.1% (45/179) used modified live virus vaccine and 34.6% (62/179) used killed vaccine. The role ofthe veterinarianis essential in educating producers on what constitute risky practices and how to mitigate such risks. Approach to mitigating risks may not necessarily be the same for all cow-calf herds; it must be tailored to each production unit. Initial risk assessment will identify what constitutes risky management practices, after which sound mitigation measure are designed to address such risks. On-farm biosecurity practices needs approach within the framework of risk assessment and periodic review for effectiveness.

The objective of this dissertation is to extend the use of spatial predictive modelling for use by biosecurity agencies to help prevent the introductions of new and emerging invasive plants (i.e., pests). A critical review of international and national policy instruments found that they did not effectively articulate how spatial predictive modelling could be incorporated into the biosecurity toolbox. To determine how spatial predictive modelling could be extended I modelled the potential distribution of Tamarix and Lythrum salicaria in Prairie Canada using a genetic algorithm. New seasonal growth data was used to interpolate a growing degree-day’s risk surface for L. salicaria. Models were developed using suites of predictive variables as well as different data partitioning methods and evaluated using different performance measures. Expert evaluation was found to important in final model selection. The results indicated that both invasive plants have yet to reach their potential distribution in Prairie Canada. The spatial models can be used to direct risk-based surveillance efforts and to support biosecurity policy decisions. The results of this dissertation conclude that spatial predictive modelling is an informative tool that needs to be incorporated into the biosecurity toolbox. A phytosanitary standard is proposed to guide toolbox development.

The objective of this dissertation is to extend the use of spatial predictive modelling for use by biosecurity agencies to help prevent the introductions of new and emerging invasive plants (i.e., pests). A critical review of international and national policy instruments found that they did not effectively articulate how spatial predictive modelling could be incorporated into the biosecurity toolbox. To determine how spatial predictive modelling could be extended I modelled the potential distribution of Tamarix and Lythrum salicaria in Prairie Canada using a genetic algorithm. New seasonal growth data was used to interpolate a growing degree-day’s risk surface for L. salicaria. Models were developed using suites of predictive variables as well as different data partitioning methods and evaluated using different performance measures. Expert evaluation was found to important in final model selection. The results indicated that both invasive plants have yet to reach their potential distribution in Prairie Canada. The spatial models can be used to direct risk-based surveillance efforts and to support biosecurity policy decisions. The results of this dissertation conclude that spatial predictive modelling is an informative tool that needs to be incorporated into the biosecurity toolbox. A phytosanitary standard is proposed to guide toolbox development.

Didymosphenia geminata is a diatom that has been accidentally introduced to New Zealand's South Island rivers. It has grown to bloom conditions in all rivers it inhabits, which has caused impacts to the river systems, loss in recreation value, and economic losses. The pathways and vectors of dispersal are difficult to control and hence it continues to spread throughout the South Island. Laboratory experiments assessed the survivability of D. geminata in different environmental conditions, a range of combinations of light availability, temperature and moisture. Experiments in the field were based in the Waitaki River to determine growth rates of D. geminata. D. geminata is growing in a greater range of temperature and light conditions than previously recognised. In cool to cold conditions with a little water this diatom can survive up to 1500h, the colder temperatures also increase survivability in the dark. However, D. geminata has reduced survivability in warm, damp conditions, up to 60h. In the Waitaki River D. geminata is attaining biomass of 2.51mg mm-2 over six weeks during summer. This high biomass is causing a change in biotic and abiotic conditions. Longevity of survival and the range of conditions in which it can survive increases the risk of spread throughout New Zealand and the world. There are considerable problems with invasive species and international trade. Policies aiming to reduce international invasions due to trade are becoming more prevalent as the consequences of invasion are more obvious and costly. New Zealand has been able to implement polices in the last decade that has reduced the number and variety of incursions. However these policies did not stop D. geminata arriving. This shows that even with the best policies species can invade fragile ecosystems. Central and local government policies surrounding management of invasive aquatic species were reviewed. Central and local government policies were developed to reduce the spread of D. geminata, however they are not effective as the diatom is still dispersing. Further research is required to elucidate means of dispersal in New Zealand, in particular the importance of dispersal by animals compared with that by humans, and the importance of continuing international dispersal.

Made available in DSpace on 2014-06-11T19:30:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2004Bitstream added on 2014-06-13T18:59:54Z : No. of bitstreams: 1 borges_srt_me_botfmvz.pdf: 543954 bytes, checksum: e9db7a1524342c6af1adf4f74190eb56 (MD5) / Universidade Estadual Paulista (UNESP) / O objetivo do presente trabalho foi o de avaliar os níveis de biossegurança, nos anos de 2001 à 2003, na totalidade das 10 (dez) granjas de reprodutores suínos (GRSC) do Estado de São Paulo certificadas pelo Ministério da Agricultura (MAPA) de acordo com os critérios de pontuação e resultados de provas e testes diagnósticos legalmente estabelecidos. Para o estudo da biossegurança, foram conferidos pontos (variando de 0 a 2) para cada critério (distancia em relação a outras unidades de criação, densidade de rebanhos num raio de 3,5 km, granjas fornecedoras de matrizes para reposição do plantel, distância entre a rodovia que transporta suínos, isolamento da granja (cerca e cinturão verde, controle de visitas, existência de quarentenário, origem da ração, transporte da ração). Foram realizadas 6.297 provas sorológicas para Peste Suína Clássica (2.023), Doença de Aujeszky (2.001), Brucelose (2.085), Leptospirose (188) e 1.001 testes de reação alérgica para tuberculose. Relativamente à biossegurança, 4 (quatro) granjas foram qualificadas com nível A, 5 (cinco) granjas como nível B e 1 (uma) granja com nível C. Relativamente aos resultados de provas e testes de diagnóstico, apenas 1 granja do nível A apresentou testes positivos para leptospirose no primeiro ano de certificação e a partir desta data passou a vacinar seus animais contra leptospirose à semelhança das demais 9 granjas devida à endemicidade da doença. Dentre as de nível B, uma granja apresentou animais infectados com M. avium e em uma granja de nível C foram detectados animais positivos para M. avium e brucelose no quarentenário. Estes resultados indicam necessidade de aprimoramento das medidas de biossegurança no tocante à prevenção e/ou controle de roedores sinantrópicos, de aves de vida livre e aquisição de animais de granjas também GRSC, porém, de nível igual ou superior. / The aim of this research is the evaluation of biosafety levels during the period from 2001 to 2003, in a total of 10 swine breeder farmers located in São Paulo state - Brazil and certificated by the Ministry of Agriculture according to scores and diagnostic tests legally established. For this purpose, each variable scored in 0 to 2 were: distance from other swine farms; herds density in 3,5Km ray area; breeder supplier farms; distance from road for swine transportation; farm isolation; control of visitors; installation for animal quarantine; ration origin and transportation. There were performed 6,297 diagnostic tests for Classical Swine Fever (2.023) - Aujeszky disease (2.001), Brucellosis (2.085), Leptospirosis (188) and 1.001 alergic tests for tuberculosis. As a result of biosafety, 4, 5 and 1 farms were scored respectively as A, B and C levels. For diagnostic tests, only one farm of level A had positive animals for Leptospirosis in the first year of certification and since then all the animals were vaccinated against leptospirosis, as the others 9 did due to the endemicity of this disease. In one farm among those of level B, it was diagnosed the presence of M. avium and in one farm of C level it was detected M. avium and in the quarantine station was diagnosed brucellosis. These results points up the need for improving the biosafety measures related to rodents and free life avian prevention and/or control and selection of GRSC breeder supplier farms with equal or higher biosafety level.

No

Biosecurity is one of the main mechanisms used to protect and mitigate the introduction of non-indigenous species. Effective biosecurity requires a knowledge and understanding of pathways and vectors along which invasion can occur. This study contributes to our knowledge and understanding of possible biosecurity risk factors in the Antarctic by identifying potential vectors for invasive species in the pathway between New Zealand and the Antarctic. The Antarctic has important indigenous terrestrial and marine, plant and animal species, all of which contribute to the food chain in Antarctica and the Southern Ocean. This study seeks to contribute some baseline data about pathways and vectors between the two regions and the implications for the biosecurity of both. An assessment of some of the risks associated with human activities within the Antarctic region, including the traffic of people and goods to and from the area, are the focus of this thesis. Current biosecurity practices with regard to personnel, shipping containers, and fresh produce are examined and where appropriate, recommendations to alleviate any detected risks are made. The results of the research indicate a significant volume of seed and plant material being unintentionally transported to Antarctica. The most striking finding was the presence of seeds in new clothes, which have previously been assumed not to be vectors. The presence of seeds in soil samples in Antarctica suggests that seeds have probably already been transported to Antarctica. Presently the climate in Scott Base seems to prevent non-indigenous species from becoming established. However, with the increases in temperature being experienced in Antarctica, this may not always be the case, therefore greater attention to biosecurity legislation and its implementation is required.