Inventory and Food Web of Arthropod Fauna Associated with Lagerstroemia spp.1 in Texas

Abstract

Sustainable, effective management of crapemyrtle bark scale, Acanthococcus lagerstroemiae (Kuwana), a non-native pest from Asia, probably will include biological control. Before this strategy can be implemented it is necessary to examine relative abundance and distribution of arthropod species associated with the scale in the area targeted for biological control. In Texas, crapemyrtle ecology from two varietal groups of crapemyrtle trees (Lagerstroemia spp.) were surveyed in Tarrant and Brazos counties during six consecutive seasons in 2018-2019. A rich arthropod community was discovered. Most common predators were spiders, coccinellids, and chrysopids. Insects of the families Eriococcidae, Aphididae, and Thripidae were common herbivores on Lagerstroemia spp. Insects in the order Psocodea were consistently recovered, and numerous phytophagous and mycophagous mites also were collected. The herbivores constitute a reservoir of alternative prey for generalist predators that also might feed on A. lagerstroemiae. A seasonal Shannon index was calculated at each location. Values differed depending on season and location. A food web was constructed to illustrate direct and indirect effects of predators on A. lagerstroemiae in Texas. This approach is meant to identify gaps in species occurrence and abundance for release of natural enemies that could lead to effective and sustainable biological control. Common biological control agents such as coccinellids and chrysopids were recovered during the course of the survey. Scale predators found in previous studies such as Chilcorus cacti (L.), Harmonia axyridis (Pallas) and Hyperaspis spp. were also found in this study. This was the first study to systematically survey for A. lagerstroemiae parasitoids in the U.S., and no parasitoids of A. lagerstroemiae were recovered. This indicates a classical biological control program featuring non-native parasitoid introductions is worth investigating.