Acta Tropica 146 (2015) 81–88 Contents lists available at ScienceDirect Acta Tropica jo ur nal home p age: www.elsevier.com/locate/actatropica Nectar protein content and attractiveness to Aedes aegypti and Culex pipiens in plants with nectar/insect associations Zhongyuan Chen, Christopher M. Kearney ∗ Department of Biology, Baylor University, One Bear Place #7388, Waco, TX 76798, USA a r t i c l e i n f o Article history: Received 11 November 2014 Received in revised form 4 March 2015 Accepted 7 March 2015 Available online 16 March 2015 Keywords: Nectar Bait Mosquito control Oral toxicity Imbibition a b s t r a c t We chose five easily propagated garden plants previously shown to be attractive to mosquitoes, ants or other insects and tested them for attractiveness to Culex pipiens and Aedes aegypti. Long term imbibition was tested by survival on each plant species. Both mosquito species survived best on Impatiens walleriana, the common garden impatiens, followed by Asclepias curassavica, Campsis radicans and Passiflora edulis, which sponsored survival as well as the 10% sucrose control. Immediate preference for imbibition was tested with nectar dyed in situ on each plant. In addition, competition studies were performed with one dyed plant species in the presence of five undyed plant species to simulate a garden setting. In both preference studies I. walleriana proved superior. Nectar from all plants was then screened for nectar protein content by SDS–PAGE, with great variability being found between species, but with I. walleriana producing the highest levels. The data suggest that I. walleriana may have value as a model plant for subsequent studies exploring nectar delivery of transgenic mosquitocidal proteins. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Nectar is a metabolic expenditure borne by plants to modulate insect behavior. While floral nectar is used to attract pollinators, extrafloral nectar is produced on nectary organs located on the petioles and leaf edges of plants in order to attract aggressive insects such as ants to protect the plant from herbivores (Grasso et al., 2015). Mosquitoes capitalize on these plant/insect associa- tions by using nectar as an energy source and imbibe both floral and extrafloral nectar (Foster, 1995). With this in mind, we searched the literature to identify plant species with nectar/insect associations that might be tested for attractiveness to mosquitoes. Our end goal is to identify a plant species which could serve as a transgenic model system to study the delivery of mosquito toxin or pathogen control proteins expressed in the nectar. A prime example of such a modu- latory protein would be the Cry proteins from Bacillus thuringiensis israelensis, which show toxicity specific to mosquitoes and other Nematocera (Boisvert and Boisvert, 2000). The success of attractive toxic sugar baits (ATSB) in the field provides the rationale for exploring nectar delivery of mosquitoci- dal proteins. Nectar and other sugar sources are the main source of energy for male mosquitoes, and females typically cannot live long exclusively on blood, drawing much of their energy from ∗ Corresponding author. Tel.: +1 254 710 2131. E-mail address: chris kearney@baylor.edu (C.M. Kearney). sugar sources (Foster, 1995). The two notable exceptions to this are females of the endophilic species Anopheles gambiae (Fernandes and Briegel, 2005) and Aedes aegypti (Mostowy and Foster, 2004; Nayar and Sauerman, 1975a,b), which can survive on blood alone, though sugar sources critically enhance egg laying and longevity. In fact, the highly blood-dependent Anopheles sergentii (Theobald) had 250 times the vectorial capacity for malaria transmission in females from an oasis with a rich supply of nectar from Acacia trees compared to mosquitoes from a sugar-poor oasis (Gu et al., 2011). Furthermore, an 86% reduction of An. gambiae females was achieved with toxic sugar baits at an outdoor test site (Müller et al., 2010a). At the control site without pesticide, 56% of the female mosquitoes had imbibed dyed bait (male results similar). Effective outdoor adult mosquito control using attractive toxic sugar baits has also been demonstrated for Aedes albopictus (Skuse) (Revay et al., 2014) and Culex pipiens (Müller et al., 2010b). The selection of a plant species is a critical first step in developing a model nectar delivery system. The ideal plant would be attractive to mosquitoes, induce imbibition of nectar, have robust nectar pro- tein expression, and be relatively easy to transform and propagate. Unfortunately, almost all plants species noted in the literature as being attractive to mosquitoes have no published transformation protocols. Conversely, nectar proteins have been studied exten- sively only in the Nicotiana (tobaccos) (Park and Thornburg, 2009), which also include many easily transformed species, but these species are not attractive to mosquitoes (e.g., note data herein for Nicotiana benthamiana). Thus, we broadened our selection criteria http://dx.doi.org/10.1016/j.actatropica.2015.03.010 0001-706X/© 2015 Elsevier B.V. All rights reserved.