the flea beetle Phyllotreta nemorum, the resistance is caused by saponins. Glucosinolates such as glucobarbarin and glucobrassicin are used as a cue for egg-laying by female cabbage white butterflies such as Pieris rapae. Indeed, the larvae of this butterfly thrive well on this plant. Diamondback moth females are also stimulated by these chemicals, but the larvae die due to the content of saponins which are apparently not sensed by the moths. This phenomenon has been tested for biological insect control: B. vulgaris plants are placed in a field and attract much of the diamondback moth egg load. As the larvae die shortly after hatching, this kind of insect control has been named "dead-end trap cropping". Distribution Native to Eurasia and North Africa, it is naturalised in many parts of North America and New Zealand as a weed. Range It is found in temperate North Africa within Algeria and Tunisia. Also in Asia, within Afghanistan, Armenia, Azerbaijan, the Caucasus, China (in the provinces of Heilongjiang, Jiangsu, Jilin and Xinjiang), Georgia, Iran, Iraq, Japan (in the provinces Hokkaido, Honshu, Kyushu, Ryukyu Islands and Shikoku), Kazakhstan, Kyrgyzstan, Mongolia, Siberia, Tajikistan, Turkmenistan and Turkey. It is also found in tropical parts Asia, such as India (- in the provinces of Sikkim, Himachal Pradesh, Jammu and Kashmir, Tamil Nadu, Uttar Pradesh and Arunachal Pradesh), Pakistan and Sri Lanka. In eastern Europe, it is found within Belarus, Estonia, Latvia, Lithuania, Moldova and Ukraine. In middle Europe, it is in Austria, Belgium, the Czech Republic, Germany, Hungary, the Netherlands, Poland, Slovakia and Switzerland. In northern Europe, in Denmark, Ireland, Sweden and United Kingdom. In southeastern Europe, within Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Italy, Montenegro, North Macedonia, Romania, Serbia and Slovenia. Lastly, it is found in southwestern Europe, it is found in France, Portugal and Spain. Habitat The plant prefers fresh or moist places, on roadsides, along rivers, in arable land, wastelands and docklands, or on the slopes and in ditches, at an altitude of above sea level. It also prefers to grow in siliceous, calcareous, sandy, alluvial and clay soils. Natural chemotypes with distinct ecology A pubescent type (the "P-type") has been described from southern Scandinavia and Russia. While this chemotype is rare in Scandinavia, it seems to be dominant in Russia according to the only survey made so far. This type has atypical chemistry and is devoid of resistance to the diamondback moth and