Convert to organic farming
Overall effectiveness category Awaiting assessment
Number of studies: 9
Background information and definitions
In conventional farming, a wide range of chemicals are commonly applied for pest control or fertilization, but these can have lethal or sub-lethal effects on farmland wildlife, including butterflies and moths (Russell & Schultz 2010, Schultz et al. 2016). Organic farming is an agricultural system that excludes the use of synthetic fertilizers and pesticides, and relies on techniques such as crop rotation, composting and biological pest control to maintain soil fertility and prevent pest outbreaks.
This action includes studies where there has been a complete cessation of chemical applications across an entire farm or substantial farmed area. For studies on a general reduction of multiple or unnamed chemicals, either without cessation or across a smaller area, see “Reduce fertilizer, pesticide or herbicide use generally”. For studies on the reduction or cessation in use of a specific, named chemical, see “Restrict certain pesticides or other agricultural chemicals”.
Russell C. & Schultz C.B. (2010) Effects of grass-specific herbicides on butterflies: an experimental investigation to advance conservation efforts. Journal of Insect Conservation, 14, 53–63.
Schultz C.B., Zemaitis J.L., Thomas C.C., Bowers M.D. & Crone E.E. (2016) Non-target effects of grass-specific herbicides differ among species, chemicals and host plants in Euphydryas butterflies. Journal of Insect Conservation, 20, 867–877.
Supporting evidence from individual studies
A replicated, paired, site comparison study in 2003–2004 on 24 arable farms in Scania, Sweden (Rundlof & Smith 2006) found that organic farms had a higher abundance and species richness of butterflies and burnet moths than conventional farms in intensively farmed but not more diverse landscapes. In intensively farmed landscapes, both the abundance (1.7 individuals/50 m) and species richness (0.9 species/50 m) of butterflies and burnet moths on organic farms were higher than on conventional farms (abundance: 0.4 individuals/50 m; richness: 0.3 species/50 m). However, in more diverse landscapes, the abundance (4.5 individuals/50 m) and species richness (1.6 species/50 m) of butterflies and burnet moths on organic farms were not significantly different from conventional farms (abundance: 3.6 individuals/50 m; richness: 1.4 species/50 m). Twelve arable farms with >50% of land under EU-subsidized organic management in 2002 and 12 conventional farms of similar size, crop type and landscape features, were selected. Farm pairs were 3–8 km apart. Six pairs of farms were in diverse landscapes (15% arable land, 19% pasture, small fields), and six pairs were in intensively farmed landscapes (70% arable land, 3% pasture, large fields). From June–August 2003 and May–August 2004, butterflies and burnet moths were surveyed 5–6 times/year along 400–750 m routes along cereal field boundaries. Individuals occurring 5 m into the crop and in adjacent 2-m uncultivated margins were counted.Study and other actions tested
A before-and-after study in 1994–2006 on a mixed farm in Oxfordshire, UK (Taylor & Morecroft 2009) found that following adoption of the Environmentally Sensitive Areas scheme, including stopping the application of fertilizers, herbicides and pesticides, the abundance and species richness of large moths and some species of butterfly increased. After Environmentally Sensitive Area management began, the total abundance (1,000–1,450 individuals) and species richness of large moth species was higher than before (800–1,250 individuals, richness data not presented). One of the five most abundant moth species (lunar underwing Omphaloscelis lunosa) and five of 23 butterfly species (meadow brown Maniola jurtina, brown argus Aricia agestis, common blue Polyommatus icarus, small copper Lycaena phlaeas and red admiral Vanessa atalanta) increased in abundance after the change in management. However, two butterfly species became less abundant (green-veined white Pieris napi and large white Pieris brassicae, data presented as model results). Overall butterfly abundance and species richness increased over the entire monitoring period, but the increase did not just happen after the management change. In 2002, the farm entered the Environmentally Sensitive Areas agri-environment scheme, and fertilizers, herbicides and pesticides were no longer used. Additionally, the proportion of grassland increased, and the total number of livestock dropped from 180 cows and 1,000 sheep to 120 cows and 850 sheep. Butterflies were monitored weekly from April–September on a fixed 3.6 km transect divided into 13 sections. Moths were monitored nightly from dusk to dawn using a light trap in a fixed position in the middle of the farm.Study and other actions tested
A replicated, site comparison study in 2001 on 16 arable farms in Ontario, Canada (Boutin et al. 2011) found that organic farms had a similar abundance and species richness of macro-moths to conventionally managed farms. On organic farms, the total abundance (51–418 individuals/trap) and species richness (8–26 species/trap) of moths were not significantly different to on conventional farms (abundance: 40–359 individuals/trap; richness: 9–21 species/trap). However, more species of the family Notodontidae were found in organic than conventional farms (data not presented). Of 126 species collected only once, 91 were found on organic farms compared to 35 on conventional farms (statistical significance not assessed). See paper for species results. Eight organic farms had no chemical inputs for at least three years. Eight conventional farms had chemical fertilizers and herbicides applied. From June–September 2001, macro-moths were sampled on six nights/site. Each night, one fluorescent UV black-light funnel trap was set halfway along a hedge, and one was set ~50 m away in the middle of the adjacent crop field. Two organic and two conventional farms were sampled each night, and all sites were sampled within five nights every two weeks.Study and other actions tested
A replicated, site comparison study in 2009 on 60 arable farms in Uppland and Scania, Sweden (Jonason et al. 2012) found that organic farms had a higher abundance and species richness of butterflies and day-flying moths than conventional farms. Data were not presented. Forty organic and 20 conventional farms (>2 km apart) were selected. Organic farms had been under organic management for 1–25 years. From June–August 2009, butterflies and burnet moths (Zygaenidae) were surveyed 5–6 times on three transects/farm. One 250-m transect was located along an uncropped margin of a cereal field, and two 50-m transects ran perpendicular to the margin into the field.Study and other actions tested
A replicated, site comparison study in 2010 in 18 arable farms in south-east Sweden (Jonason et al. 2013) found that recently established organic farms had a higher abundance and species richness of moths than older organic farms or conventional farms. On farms which had been managed organically for up to six years, the abundance (357 individuals) and species richness (26 species) of moths was higher than on farms which had been managed organically for over 15 years (abundance: 48 individuals; richness: 11 species) and on conventionally managed farms (abundance: 50 individuals; richness: 12 species). Twelve species of moth were associated with new organic farms (see paper for details), but no species were associated with old organic or conventional farms. Six farms had been in organic management for ≤6 years, six had been in organic management for 15–23 years, and six were still managed conventionally. In early August 2010, moths were sampled for four consecutive days using three bait traps/farm. Traps were placed 50 m apart along one 1.5–3-m-wide, >300-m-long, uncropped field margin/farm, 1.7 m above ground, and baited with sugar saturated red wine.Study and other actions tested
A replicated, site comparison study in 2009–2011 in 133 mixed farms in the Central Plateau, Switzerland (Stoeckli et al. 2017) found that organic farms had a similar abundance and species richness of butterflies to conventional farms. On organically managed farms, both the abundance and species richness of butterflies was similar to conventionally managed farms (data presented as model results). Of 133 farms (17–34 ha, 13–91% arable crops), 42 were managed organically, and 91 were managed conventionally. All farms contained “Ecological Compensation Areas” under agri-environment schemes. From May–September 2009–2011, butterflies were surveyed six times on 10–38 transects/farm, totalling 2,500 m/farm. Each transect ran diagonally through a single crop or habitat type, with all available crops and habitats represented. All visits to a farm were completed in a single year, and the species richness was summed across all visits. Total abundance of butterflies was calculated from the number recorded in each habitat, and the availability of each habitat across the farm.Study and other actions tested
A replicated, site comparison study in 2015 on seven arable farms in Germany (Sybertz et al. 2017) found that field margins next to organically managed fields had more butterfly species than field margins next to conventionally managed fields. On margins next to organically managed fields, there were more butterfly species than on margins next to conventionally managed fields (data presented as model results). Overall, 143–542 butterflies of 8–25 species were recorded on each organic farm, and 217–446 butterflies of 10–16 species were recorded on each conventional farm (statistical significance not assessed). Five farms (80–700 ha) were managed organically, and two farms (58–260 ha) were managed conventionally. From June–August 2015, butterflies were surveyed six times along 10 permanent, unsprayed and uncropped arable field margins (≥1 m wide, 50–250 m long) on each farm.Study and other actions tested
A replicated, site comparison study in 2015–2017 on 19 mixed farms in Scania, Sweden (Carrie et al. 2018) found that organic farms had more consistent butterfly species richness across the farm than conventional farms. Across three field types, butterfly species richness was more consistent on organic than on conventional farms (data presented as model results). However, the consistency of butterfly species richness within a single field type throughout the summer, and between years, was similar on organic and conventional farms. On each of 10 organic and nine conventional farms, three fields were surveyed: a cereal field, a grass ley (rotational, sown, improved grassland), and a semi-natural grassland. From May–August 2015–2017, butterflies were surveyed five times (two weeks apart) along two 100-m transects/field.Study and other actions tested
A replicated, paired, site comparison study in 2017 in four farms in Hualien County, Taiwan (Yen et al. 2018) found that organic farms had a similar abundance and species richness of butterflies to conventional farms. On organic farms, the abundance (287 individuals/ha) and species richness (11 species/farm) of butterflies was not significantly different from that on conventional farms (abundance: 191 individuals/ha; richness: 9 species/farm). Within a National Park, 39 ha of farmland remained in production and farmers were encouraged to convert to organic farming. In each of two areas, one organic and one conventional farm were selected (number of years since conversion to organic not given). Farms were 250–3,200 m apart. From May–September 2017, butterflies were surveyed once/month along 150-m transects at each farm (number not specified).Study and other actions tested