Phaedon cochleariae (F.) performance on different crucifer varieties with different glucosinolate profiles

The mustard leaf beetle, Phaedon cochleariae (F.) (Coleoptera: Chrysomelidae), is a serious insect pest of cruciferous crops, known especially in Europe. Feeding performances of P. cochleariae on six varieties of crucifer crops (Sinapis alba, Flata and Litember; Raphanus sativus, Münchener Bier and Runder Schwarzer Winter; and Brassica chinensis, Joi Choi and Black Behi) was investigated. The larval performance, measured by weight increase within seven days, was significantly different among six cultivars. The highest larval weight increase observed was on the B. chinensis cultivars with the lowest GS contents, followed by R. sativus and S. alba cultivars. Furthermore, a better larval performance co-insisted with the presence of indolyl and aliphatic GS in cultivars like B. chinensis and R. sativus and was poor on mustard cultivars with aromatic GS. Similar to the weight increase observation, the oviposition performance of P. cochleariae adult beetle was also investigated on three varieties: S. alba: Litember, R. sativus: Muinchener Bier, and B. chinensis: Joi Choi. The female P. cochleoriae laid significantly different numbers of eggs within three days on the different cultivars of crucifers. The highest number of eggs was laid on the B. chinensis cultivar Joi Choi, followed by the radish and mustard cultivars Muinchener Bier and Litember, respectively. Differential oviposition behaviour of P. cochleariae on the different varieties might be explained by their different GS profiles and the dominating group of GS. Indolyl GS, which are abundant in B. chinensis, may have a more stimulatory effect on the oviposition of P. cochleariae than aromatic and aliphatic GS.