Licorice strips enhance predator‐mediated biological control in China's cotton crop

Abstract

BACKGROUND Habitat management such as field‐ or farm‐level diversification can conserve arthropod natural enemies, enhance biological pest control and lower (or suspend) insecticide use in agricultural crops. These approaches however have been underexploited to manage the aphid Aphis gossypii in cotton cropping systems of Xinjiang, China. In this study, we investigated whether the presence of licorice (Glycyrrhiza uralensis) at the field edge benefits generalist predator abundance and aphid biological control in local cotton crops. RESULTS Field trials during 2020 and 2021 showed that licorice strips enhanced the in‐field abundance of generalist predators (primarily ladybeetles) 2.2–4.3 fold during early season, i.e. initial growth before A. gossypii peak infestation pressure. During peak outbreak conditions in July, treatment fields with licorice strips experienced a respective 17.5–61.2% lowered aphid density and 12.3–14.6‐fold higher predator‐to‐aphid abundance ratio (PAR) than control fields. In late season (aphid decline phase) of either year, cotton fields with licorice strips also attained a respective 4.7–9.9 fold higher PAR. Exclusion cage assays quantitatively assessed predator‐mediated A. gossypii biological control and the relative contribution of licorice strips. The biocontrol services index (BSI) was 2.8 times (2020) and 1.4 times (2021) higher at 5 m distances from the licorice strip as compared to control fields. CONCLUSION Licorice strips in the immediate vicinity of cotton fields benefit generalist arthropod predators and improve aphid biological control throughout the cotton cropping season. These findings help to integrate habitat management within integrated pest management (IPM) frameworks in the biggest cotton production region of China. © 2022 Society of Chemical Industry.

Volatiles from essential oils of three Lamiaceae plants repel the winged cotton aphid, disturb its feeding behavior and reduce its fecundity

“…However, these plants support a diverse population of natural enemies of aphids, such as ladybeetles. 76,77 By using repellent substances to drive Aphis gossypii onto these plants, we provide prey for these natural enemies and promote their population increase, possibly contributing to control of the Aphis gossypii population. Consequently, we believe that use of repellents to manage Aphis gossypii in cotton fields should promote regional management of Aphis gossypii.…”

Plant volatiles mediate Aphis gossypii settling but not predator foraging in intercropped cotton

“…Intercropping regularly lowers herbivore abundance and lifts numbers of invertebrate predators or parasitoids, as evidenced in peanut × maize, 38 onion × cabbage, 39 wheat × mungbean, 40 and wheat × rape systems. 41 It is commonly assumed that enhanced plant diversity translates in higher natural enemy numbers, [42][43][44][45] yet empirical work in different systems yields rather inconsistent patterns. In cotton systems, different intercrops reduce Aphis gossypii infestation pressure 46 enhanced (crop) diversity or by providing (food, non-food) resources to resident natural enemies.…”

Intraguild Predation of Hippodamia variegata on Aphid Mummies in Cotton Field

“…The predatory ladybeetle community mainly includes Hippodamia variegata (Goeze), Propylaea quatuordecimpunctata (Linnaeus), Oenopia conglobata (Linnaeus), Coccinella tredecimpunctata Linnaeus, and Stethorus punctillum Weise. Survey results of field population density showed that H. variegata was abundant in cotton fields in many areas of Xinjiang [ 18 , 19 , 20 ], and was a dominant predator [ 21 , 22 ]. Regarding aphid parasitoids in the cotton fields of Xinjiang, the population dynamics and parasitism rate of aphids have been investigated and the composition of the aphid parasitoid community has been determined (65% primary parasitoids, 35% hyperparasitoids).…”