The life cycle and parasitism of the European grasshopper mite Eutrombidium trigonum (Hermann 1804) (Prostigmata: Parasitengonae: Microthrombidiidae), a potential agent for biological control of grasshoppers (Saltatoria)

Abstract

The European grasshopper mite Eutrombidium trigonum (Hermann) lives concealed in the soil in relatively warm and xeric biotopes. The eggs and spermatophores display a moderate drought resistence. The adults, during mating and larvae leave the soil and are to be found on the soil surface. The host range of the parasitic larva is restricted to Saltatoria. The larval growth is much greater than that of other instars of E. trigonum; however, no damage or other effects on the hosts were obvious and usually the hosts survived parasitism. The active post-larval instars of E. trigonum are predatory and feed exclusively on the eggs of Acrididae. The life cycle of E. trigonum is uni- to semi-voltine and is synchronized by an obligatory diapause of the adult instar before reproduction.