Evidence for Food as a Limiting Resource in the Life Cycle of Tiger Beetles (Coleoptera: Cicindelidae)

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Abstract
Using an assemblage of tiger beetles in SE Arizona, USA, as test organisms, the potential for food as a limiting resource in each of the life cycle stages was determined. Laboratory experiments established at what levels food quantity affected adults and larvae. Adult females at low feeding levels produced significantly fewer eggs and larvae than females at high feeding levels. Larvae at low feeding levels took significantly longer to pass through all three larval stages, and their pupae and emergent adults were significantly smaller than those individuals raised at higher feeding levels. Large adults survived longer than small adults when deprived of food. Small adult females produced fewer eggs and larvae at low feeding levels than larger conspecific females at the same feeding levels. Field observations established that the feeding levels of wild larvae and adults in several habitats over five years was lower than the level which produced maximum offspring and survival in the laboratory, except on permanent pond edges where food was abundant. Year to year fluctuations in food availability indicated that food in some habitats was more likely limiting in some years than others.