Background: Ladybird beetles (Coleoptera: Coccinellidae) are abundant predatory species in many agroecosystems, are valued for their biological pest control functions, and have been recommended as test species for studies supporting the assessment of non-target effects of insect-resistant Bt crops. Although insecticidal Bt proteins are known to be highly specific against target pests, some recent laboratory studies reported putative toxic effects of Bt proteins on ladybird species. While such studies have been criticised because of methodological shortcomings or inconsistencies, they cast doubt on the insecticidal spectrum of activity of some Bt proteins. Performing a systematic review that synthesises all existing evidence on this controversial topic may help to resolve the remaining scientific uncertainties. The review question to be addressed by the systematic review is the following: Are ladybird beetles (Coleoptera: Coccinellidae) affected by Bt proteins expressed in genetically modified insect-resistant crops? The systematic review will focus on studies performed under controlled environmental conditions. Methods: An extensive literature search will be conducted to identify the articles relevant to the review question. A wide range of electronic bibliographic databases, the internet search engine Google Scholar, and websites of specialized organizations will be searched. Citation searching, reference list-checking and searching of key journals will also be performed. The relevance of the identified articles will be assessed against a set of pre-defined eligibility criteria, following a two-step approach. In the first step, title and abstract (or summary) will be screened, whilst in the second step the full text of all remaining articles will be assessed by two members of the review team. All relevant studies will be subjected to an appraisal of external (generalisability) and internal (risk of bias) validity. Data from the selected studies will be extracted and synthesised in a narrative report. If a sufficient number of datasets generated with comparable experimental setup is available, statistical meta-analyses will be conducted on a range of comparisons and including sensitivity analyses.
