Evaluation of macadamia felted coccid (Hemiptera: Eriococcidae) damage and cultivar susceptibility using imagery from a small unmanned aerial vehicle (sUAV), combined with ground truthing

Abstract

BACKGROUND Macadamia felted coccid, Acanthococcus ioronsidei (Williams) (Hemiptera: Eriococcidae), is a significant pest of macadamia nut, Macadamia integrifolia Maiden & Betche (Protaceae), in Hawaii, and heavy infestations can kill branches, resulting in characteristic dead, copper‐colored leaves. Small Unmanned Aerial Vehicles (sUAV) or ‘drones,’ combined with spatial data analysis, can provide growers with accurate and high‐resolution detection of plant stress due to pest infestations. We investigated the feasibility of using RGB (red‐green‐blue) color images from sUAV to detect dieback caused by macadamia felted coccid infestation and compared sUAV estimates with ground‐based damage estimates (ground truthing). RESULTS Spatial analysis showed clustering of foliar damage that reflected cultivar susceptibility to macadamia felted coccid infestation, with cultivars 344 and 856 being susceptible, and cultivars 800 and 333 being tolerant. sUAV and ground‐based estimates of foliar damage were similar for the cultivar 344, but ground‐based assessments were higher than sUAV for cultivar 856, possibly due to the differences in canopy architecture and significant early dieback in the lower canopy. At foliar damage levels <10%, sUAV and ground truthing data were significantly positively correlated, suggesting sUAV may be useful in detecting early stages of macadamia felted coccid infestation. CONCLUSIONS Cultivars showed varying susceptibility to macadamia felted coccid infestation and the foliage damage appeared in clusters. sUAV was able to detect the foliage damage under high and low infestation scenarios suggesting that it can be effectively used for the early detection of infestations. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Prospects for Biological Control of Macadamia Felted Coccid in Hawaii with Metaphycus macadamiae Polaszek & Noyes, a New Encyrtid Wasp Native to New South Wales, Australia

“…Traps were replaced every month, and numbers of parasitoids and predators stuck on traps were microscopically tallied as means ± SEM of parasitoids and five species of coccinellids/trap/month/orchard during twelve months of 2015. Encarsia lounsburyi (Berlese & Paoli) (Hymenoptera: Aphelinidae), a parasitoid of male MFC, and Curinus coeruleus Mulsant (Coleoptera: Coccinellidae) were the dominant parasitoid and ladybeetle in macadamia fields, respectively, during this survey [12].…”

“…In 2014, estimates on one farm indicated that as much as half a million pounds of wet in-shell macadamia nuts were lost because of MFC. According to USDA National Agricultural Statistics Service, the highest quantity of macadamia nuts, i.e., 6879.6 hectares, is harvested in Hawaii, and the farm value for the 2017-2018 crop was estimated at USD 53.9 million [4,12,13].…”