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1. Honey bees require minerals for a complete diet. However, minerals from flowers can be inadequate in concentration and composition. Therefore, honey bees may drink 'dirty water' from natural sources such as puddles. Some research has attempted to simulate this through honey bee bioassays, but to date, these have tested minerals individually, not as mixtures as would occur in nature. Here, for the first time, we use honey bees in bioassays in which a range of mineral mixtures are presented together in choice experiments.2. Six minerals (NaCl, KCl, CaCl 2 , MgCl 2 , NH 4 Cl, and KH 2 PO 4 ) were used in mixtures to simulate different mineral stoichiometries, which may occur in 'dirty water', such as puddles, from which honey bees often drink. Based on the honey bee mineral tolerance ranges from the literature, these mixtures were offered in aqueous solutions at low, medium, high, and mixed molar concentrations. Deionised water and sucrose were neutral and positive controls, respectively. Petri dishes were set up in containers in a laboratory. Twenty worker honey bees (Apis mellifera L.) were placed into each container and observed for drinking behaviour for 1 h.3. Honey bees preferred the mixed molar treatment comprising a high Na:K ratio, a medium molarity of NaCl and a low molarity of the other minerals. This novel finding suggests that mixed mineral 'dirty water' should be investigated on a larger scale with multiple hives in the field and highlights the importance of stoichiometrically balanced honey bee diets.

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The tomato/potato psyllid (TPP), Bactericera cockerelli (Hemiptera, Triozidae), is an adventive psyllid in New Zealand that is a major pest of solanaceous crops and a serious threat to growers in the glasshouse industry. Worldwide, evaluation of potential biological control (BC) agents is normally conducted using single species and this is the case with some potential BC agents for TPP. However, the idea that multiple species can act synergistically remains largely untested so that is the aim of the current work, which is funded by Tomatoes New Zealand. The introduced parasitoid Tamarixia triozae is a BC agent of TPP that attacks mainly late instars. It lives for just 1 day when provided with water but can live up to 11 days (and consume more pests) when nectar in the flowers of buckwheat (Fagopyrum esculentum) is provided. In addition, another potential BC agent, the mirid bug Engytatus nicotianae, prefers young nymphal instars, while the ladybird Cleobora mellyi is voracious and consumes all instars. We are testing combinations of these species to understand the potential for synergies between and within trophic levels for better biological control.

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