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Xanthophylls are key constituents of semi‐synthetic diets for continuous breeding of Pieris brassicae without food plant
Author(s) -
Kayser H.
Publication year - 2012
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/j.1439-0418.2011.01657.x
Subject(s) - biology , xanthophyll , sinigrin , pieris brassicae , lutein , pieridae , larva , carotenoid , botany , food science , glucosinolate , brassica
Abstract Semi‐synthetic or fully artificial diets are well established in culturing laboratory insects on a large scale. In Pieris brassicae L. (Lepidoptera: Pieridae), a published semi‐synthetic diet supplemented with sinigrin, a chemical label of cruciferous plants, is well accepted by the larvae but the adults fail to produce offspring; continuous breeding, therefore, requires the addition of cabbage powder to the diet. We set out to identify essential substances to eliminate the need for cabbage in our long‐term mass culture. The studies revealed that the dietary difference, which becomes most evident at the adult stage only, is because of a severe lack of carotenoids in the cabbage‐free version. This was uncovered in larvae, fed cabbage‐supplemented diet, that respond to blue light of sufficient intensity by high cuticle melanization on pupation; larvae fed the carotenoid‐deficient sinigrin‐supplemented diet fail to respond in this way. Males were found to be more sensitive than females to blue light in this respect. The essential substance mediating this photo response was found to be lutein and/or zeaxanthin, two abundant xanthophylls of green leaves. β‐Carotene was only marginally active. These xanthophylls are known to serve as precursors to the synthesis of 3‐hydroxyretinal, the exclusive visual chromophore of lepidopteran insects; retinal, derived from β‐carotene, is not (substantially) used by these insects. In conclusion, the absence of flying and mating activity in the adults from the sinigrin diet may indicate visual deficiency owing to a lack of a specific structural class of carotenoids in the larval food. Our results enabled us to formulate a semi‐synthetic diet that allows continuous mass rearing of P. brassicae without cabbage at any stage including oviposition. In addition to the key constituents sinigrin and xanthophylls, this superior diet includes tryptophan, as methyl ester, and α‐tocopherol.