Exploiting trap type and color for monitoring the macadamia felted coccid Acanthococcus ironsidei (Williams) and associated parasitic wasps in macadamia orchards in Hawai’i

Authors: Acebes-Doria, Angelita; AIGBEDION-ATALOR, PASCAL - University Of Hawaii

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2025
Publication Date: 2/2/2025
Citation: Acebes-Doria, A.L., Aigbedion-Atalor, P. 2025. Exploiting trap type and color for monitoring the macadamia felted coccid Acanthococcus ironsidei (Williams) and associated parasitic wasps in macadamia orchards in Hawai’i. Insects. 16:149. https://doi.org/10.3390/insects16020149.
DOI: https://doi.org/10.3390/insects16020149

Interpretive Summary: Macadamia felted coccid (MFC) is an invasive pest of macadamia in Hawaii, affecting tree health and causing yield losses. Monitoring options are limited to using double-sided sticky tapes which can be cumbersome and impractical for large orchards. Alternative trapping options are needed; and thus, field trials were conducted to evaluate the efficacy of using sticky card (vs sticky tapes) and assess sticky card colors (yellow, lime green, dark green, and white) for monitoring MFC, and parasitoids associated with macadamia orchards in Hawai’i. Trials were conducted at two commercial orchards at two separate trapping periods. Results showed that sticky cards captured MFC immatures and adult males, while the double-sided sticky tapes captured only crawlers. Trap color did not have significant effects on the captures of MFC male adults at both sites, while captures of crawlers on sticky cards were lowest on the dark green sticky traps at one site. The captured parasitoid species showed different levels of attraction to color; however, yellow, lime green and dark green colors are shown to be effective for monitoring Encarsia lounsburyi, a known parasitoid of MFC. These results provide useful practical implications for improved monitoring of MFC crawlers, male adults and its associated natural enemies.

Technical Abstract: Acanthococcus ironsidei (Williams) (Hemiptera: Eriococcidae) is an invasive pest of macadamia, Macadamia integrifolia in Hawai’i, causing death to macadamia trees and decreased nut productivity. Monitoring relies on wrapping double-sided sticky tapes over tree branches to trap dispersing crawlers (i.e., mobile immature), but this is tedious for growers especially in large orchards. From September to November 2022 and December 2022 to February 2023, at two commercial macadamia orchards on Hawai’i Island, the use of colored sticky cards was assessed for improved monitoring of A. ironsidei and investigate the Hymenopteran parasitoid complex that inhabit macadamia canopies. At each study site, four different colored sticky cards: yellow, lime green, dark green, and white were placed on the lower canopy of five trees, and in each tree a transparent double-sided sticky tape was deployed. At bi-weekly intervals, sticky cards were replaced and re-randomized on each tree, and the double-sided sticky tapes were replaced. Results showed that sticky cards captured both A. ironsidei crawlers and (winged) adult males while the double-sided sticky tapes captured only crawlers. Trap color did not have significant effects on the captures of A. ironsidei male adults at both sites, while captures of crawlers on sticky cards were lowest on the dark green sticky traps at one site. The captures of A. ironsidei male adults on white sticky traps were generally correlated with the number of crawlers captured in the double-sided sticky tapes. The parasitoid complex captured had disparities in attraction to color; however, yellow, lime green and dark green colors are shown to be effective for monitoring Encarsia lounsburyi (Berlese & Paoli), a parasitoid of A. ironsidei. These results provide useful practical implications for improved monitoring of A. ironsidei crawlers, male adults and its associated natural enemies.