Nutritional benefits of intraguild predation and cannibalism among generalist and specialist phytoseiid mites

Abstract

Summary1. Intraguild predation and cannibalism are common among predaceous phytoseiid mites (Acari, Phytoseiidae) but the nutritional benefits gained by these processes are poorly understood.2. The study reported here addressed the questions of whether cannibalism and intraguild predation provide different nutritional benefits and whether the ability to utilise cannibalism and intraguild predation is linked to the diet specialisation of phytoseiid mites. Specialists tested werePhytoseiulus macropilis,Galendromus occidentalis, andNeoseiulus longispinosus;generalists tested wereAmblyseius andersoni,Neoseiulus cucumeris, andNeoseiulus fallacis.3. All generalists and the specialistP. macropiliswere able to complete juvenile development with both con‐ and hetero‐specific prey. Juvenile development of generalists was shorter with heterospecific prey than with conspecific prey, whereas development of the specialistP. macropilisdid not differ between prey types. Only a fewN. longispinosusandG. occidentalis, both specialists, reached adulthood by cannibalism but none reached adulthood by intraguild predation.4. All generalists were able to sustain oviposition by intraguild predation.Neoseiulus cucumerisandA. andersonilaid more eggs with heterospecific prey than with conspecific prey, whereasN. fallacishad similar oviposition rates with both prey types. No specialist sustained oviposition by intraguild predation or cannibalism.5. Overall, generalists gained equal or more nutritional benefits by intraguild predation than by cannibalism and were able to utilise phytoseiid intraguild prey as an alternative food source. Specialists gained equal or more nutritional benefits from cannibalism than from intraguild predation. For specialists, con‐ and hetero‐specific phytoseiids may be considered only a supplemental food.