ORIGINAL PAPER Giovanni Benelli & Barbara Conti & Rita Garreffa & Marcello Nicoletti Received: 20 November 2013 /Accepted: 27 November 2013 /Published online: 13 December 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Industrial plant-borne by-products can be sources of low-cost chemicals, potentially useful to build eco-friendly control strategies against mosquitoes. Neem cake is a cheap by-product of neem oil extraction obtained by pressing the seeds of Azadirachta indica . Neem products are widely used as insecticides since rarely induce resistance because their multiple mode of action against insect pests and low-toxicity rates have been detected against vertebrates. In this research, we used field bioassays to assess the effective oviposition repellence of neem cake fractions of increasing polarity [n - hexane (A), methanol (B), ethyl acetate (C), n- butanol (D), and aqueous (E) fraction] against Aedes albopictus, currently the most invasive mosquito worldwide. These fractions, al- ready characterized for low nortriterpenoids contents by HPLC analyses, were analyzed for their total content by HPTLC, highlighting striking differences in their chemical composition. Field results showed that B, A, and C tested at 100 ppm exerted higher effective repellence over the control (71.33, 88.59, and 73.49 % of ER, respectively), while E and D did not significantly deter A. albopictus oviposition (17.06 and 22.72 % of ER, respectively). The highest oviposition activity index was achieved by A (−0.82), followed by C (−0.63), and B (−0.62). Lower OAIs were achieved by D (−0.14) and E (−0.09). On the basis of our results, we believe that A, B, and C are very promising as oviposition deterrents against the arbovirus vector A. albopictus since they are proved as rich in active metabolites, cheap, and really effec- tive at low doses. Introduction The neem tree, Azadirachta indica Juss. (Meliaceae), is a fast growing evergreen tree native of India (National Research Council 1992), nowadays worldwide distributed, owing to its multipurpose utility and increasing economic importance. Although its seeds contain more than 100 biologically active compounds, attention was so far focused on the oil and its limonoid (nortriterpenes) constituents (i.e., azadirachtin, nimbin, nimbidin, and nimbolides) in consideration of their insecticide effects. Interestingly, many formulations deriving from neem seeds showed antifeedancy, fecundity suppression, ovicidal and larvicidal activity, growth regulation, and repellence against a great number of different insects also at very low dosages (Dua et al. 2009; Egho et al. 2012). For instance, the concentrate extract of neem seeds [e.g., Alpha-Biocare (Düsseldorf, Germany)] is really effective against a huge range of pests of medical and veterinary im- portance (Semmler et al. 2010), including Ixodes and Rhipicephalus ticks, house dust mites, cockroaches (Blatta, Blattella , and Gomphadorhina ), raptor bugs (Triatoma ), cat fleas, bed bugs (Schmahl et al. 2010), biting and bloodsucking lice (Al-Quraishy et al. 2011; Al-Quraishy et al. 2012; Abdel- Ghaffar et al. 2012; Mehlhorn et al. 2012), Sarcoptes scabiei De Geer mites infesting dogs (Abdel-Ghaffar et al. 2008), poultry mites (Abdel-Ghaffar et al. 2009; Locher et al. 2010), and beetle larvae parasitizing the plumage of poultry (Walldorf et al. 2012). Neem-based products rarely induce resistance since their multiple mode of action against insects. Insect growth regulatory activity of neem-borne molecules Electronic supplementary material The online version of this article (doi:10.1007/s00436-013-3725-4) contains supplementary material, which is available to authorized users. G. Benelli (*) : B. Conti : R. Garreffa Department of Agriculture, Food and Environment, University of Pisa, via del Borghetto 80, 56124 Pisa, Italy e-mail: benelli.giovanni@gmail.com M. Nicoletti Department of Environmental Biology, University Sapienza of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy Parasitol Res (2014) 113:933–940 DOI 10.1007/s00436-013-3725-4 Shedding light on bioactivity of botanical by-products: neem cake compounds deter oviposition of the arbovirus vector Aedes albopictus (Diptera: Culicidae) in the field MiteStop® developed by the university spin-off company