Parasitic behavior of Pyemotes zhonghuajia (Trombidiformes: Pyemotidae) on fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

Abstract

Fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is a destructive, migratory pest that seriously damages corn, sorghum, and other crops. The “insect killer” Pyemotes zhonghuajia (Trombidiformes: Pyemotidae) is an ectoparasitic mite of agricultural and forestry pests in China. To explore the biological control efficiency of P. zhonghuajia on S. frugiperda, we evaluated the parasitic selectivity of P. zhonghuajia on S. frugiperda of different life stages, and distribution of P. zhonghuajia on different body parts of S. frugiperda larvae and pupae, food intake of S. frugiperda larvae affected by P. zhonghuajia density, and field population dynamics of S. frugiperda in relation to the releasing population density of P. zhonghuajia. We found that P. zhonghuajia preferred 4th- to sixth-instar larvae and pupae of S. frugiperda for parasitism, and the ventral part of abdominal segments of fourth-instar larvae and the ventral part of pupal thorax for feeding. Freezing of S. frugiperda 4th instar larvae and pupae had little effect on the distribution of P. zhonghuajia on the surface of these two host stages. The parasitism of P. zhonghuajia regardless of mite population size (i.e., 5, 10, or 20 mites) could significantly decrease the cumulative food intake of fifth-instar larvae of S. frugiperda. Releasing two and three boxes (50,000 mites/box) of P. zhonghuajia significantly suppressed the field population of S. frugiperda on sorghum plants/25 m2 within 7 days. Our results show that P. zhonghuajia may be a potential biological control agent and can be used for biological control of S. frugiperda in the field.

Pest management of postharvest potatoes: lethal, sublethal and transgenerational effects of the ectoparasitic mite Pyemotes zhonghuajia on the potato worm Phthorimaea operculella

“…Previous studies report that although P. zhonghuajia females have no direct lethal effect on the mature larvae of S. frugiperda, 24 they impose sublethal effects, leading to a significant decrease in food intake at higher mite densities. 28 Such negative nonconsumptive effects reducing host feeding activity have been frequently reported in predator-prey systems. [62][63][64][65][66][67] In addition, nonconsumption effects may also alter host physiological responses, including an increase in respiration, 68,69 reduction of food assimilation efficiency [69][70][71] and reduced levels of antioxidant enzymes, 72 which increase metamorphic failure 73 and immature mortality.…”

“…In the augmentative biological control programmes, the release rate significantly affects the biological control effectiveness of pest insects, especially those from the order Lepidoptera. 21,28,61 We showed that a release rate of 10 mites/larva with an exposure duration of 24 h or one mite/ larva with an exposure duration of 72 h resulted in 100% mortality of fourth-instar larvae, while to achieve the similarly control effectiveness of PTM pupae, a higher release rate of 20 mites/pupa with an exposure duration of 72 h was required (Fig. 2).…”

“…Pyemotes zhonghuajia Yu, Zhang & He (Prostigmata: Pyemotidae) is a generalist ectoparasitic idiobiont mite, in which the adult females parasitize and prey on different immature stages of insect species in Coleoptera, Lepidoptera, Hymenoptera, Homoptera and Isoptera. [21][22][23][24][25][26][27][28][29][30][31] The females thus have the life-history traits of both parasitioids and predators. P. zhonghuajia is a viviparous species, i.e., the immature offspring develop in the mother's opisthosoma.…”

“…29 Due to their short lifecycle, high fecundity and strong toxicity to hosts, Pyemotes mites have long been considered as potential biocontrol agents, mass-produced and released to control insect pests in fields. [21][22][23][24][28][29][30][31][32][33][38][39][40][41][42][43][44] To our knowledge, only a few researchers 38,45,46 have attempted to control insect pests of storage products using Pyemotes mites, and their biological control efficiency, especially on the PTM in storages, is largely unknown.…”

“…Venom compounds including neurotoxin, dermonecrotic toxin and agatoxin gene families that are associated with toxicity have been identified in P. zhonghuajia 29 . Due to their short lifecycle, high fecundity and strong toxicity to hosts, Pyemotes mites have long been considered as potential biocontrol agents, mass‐produced and released to control insect pests in fields 21–24,28–33,38–44 . To our knowledge, only a few researchers 38,45,46 have attempted to control insect pests of storage products using Pyemotes mites, and their biological control efficiency, especially on the PTM in storages, is largely unknown.…”