Nectar Meals of a Mosquito-Specialist Spider

Rebecca N H Karanja,Robert R Jackson,Godfrey O Sune,Georgina E Carvell,Zipporah O Lagat,Josiah O Kuja

doi:10.1155/2012/898721

Abstract

Evarcha culicivora, an East African jumping spider, is known for feeding indirectly on vertebrate blood by actively choosing blood-carrying mosquitoes as prey. Using cold-anthrone tests to detect fructose, we demonstrate thatE. culicivoraalso feeds on nectar. Field-collected individuals, found on the plantLantana camara, tested positive for plant sugar (fructose). In the laboratory,E. culicivoratested positive for fructose after being kept withL. camaraor one of another ten plant species (Aloe vera, Clerodendron magnifica, Hamelia patens, Lantana montevideo, Leonotis nepetaefolia, Parthenium hysterophorus, Ricinus communis, Senna didymobotrya, Striga asiatica, andVerbena trivernia). Our findings demonstrate thatE. culicivoraacquires fructose from its natural diet and can ingest fructose directly from plant nectaries. However, experiments in the laboratory also show thatE. culicivoracan obtain fructose indirectly by feeding on prey that have fed on fructose, implying a need to consider this possibility when field-collected spiders test positive for fructose. In laboratory tests, 53.5% of 1,215 small juveniles, but only 3.4% of 622 adultE. culicivora, left with plants for 24 hours, were positive for fructose. These findings, along with the field data, suggest that fructose is especially important for early-instar juveniles ofE. culicivora.

Highlights

Trophic switching and feeding at more than one trophic level, often overlooked in the literature on spiders, are common themes in the evolution of arthropods [1, 2]
Using cold-anthrone tests to detect fructose, we demonstrate that E. culicivora feeds on nectar
E. culicivora tested positive for fructose after being kept with L. camara or one of another ten plant species (Aloe vera, Clerodendron magnifica, Hamelia patens, Lantana montevideo, Leonotis nepetaefolia, Parthenium hysterophorus, Ricinus communis, Senna didymobotrya, Striga asiatica, and Verbena trivernia)

Summary

Introduction

Trophic switching and feeding at more than one trophic level, often overlooked in the literature on spiders, are common themes in the evolution of arthropods [1, 2]. Many predatory heteropterans are known to feed facultatively on plant products [3, 4]. The most striking known exception is Bagheera kiplingi [5], a Central American jumping spider (Salticidae), which is almost entirely herbivorous despite cohabiting with edible ant species (Pseudomyrmex spp.). B. kiplingi feeds primarily on the Beltian bodies (specialized leaf tips) of the ant-acacia (Vachellia spp.), which dominate the ants’ diet [6,7,8]. No other spiders are known to rely as heavily on herbivory as B. kiplingi, many spiders do supplement a predatory diet with nectar taken from the floral or extrafloral nectaries of plants (e.g., [9,10,11,12])

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