Chemical ecology of Cyclocephala forsteri (Melolonthidae), a threat to macauba oil palm cultivars (Acrocomia aculeata, Arecaceae)

Abstract

The environmental unsustainability of African oil palm crops is a growing worldwide concern, and the macauba palm in tropical Southern America surges as the most viable substitute for the production of first‐generation biodiesel as a renewable fuel. Large‐scale cultivation of the macauba palm, however, is bound to suffer a major setback due to the fast emergence of a florivorous pest threat, Cyclocephala forsteri, a scarab beetle species that can severely reduce fruit yield. Like other congenerics, female and male C. forsteri are night‐foraging and driven in large numbers to macauba palm inflorescences by specific volatile organic compounds. In the present study, we assessed the kairomonal cues involved in this plant–florivore interaction and their potential application in selective pest management strategies. Headspace samples of the floral fragrance of macauba palms at our study site in Central Brazil were largely dominated by 4‐methylanisole (>97% relative amount), which along with the minor constituents 2‐isopropyl‐3‐methoxypyrazine and 2‐sec‐butyl‐3‐methoxypyrazine triggered electroantennographic responses from both female and male C. forsteri. Field behavioural assays evidenced that beetles of this species were exclusively attracted to scented traps baited with 4‐methylanisole. Increased total scent discharge attained with an ultrasonic piezoelectric diffuser has positively influenced attractiveness efficiency of the trapping setup. 4‐Methylanisole is hereby identified as yet another volatile kairomone involved in highly selective attraction of potential pest florivorous cyclocephaline scarabs associated with economically exploitable palms and should be viewed as a key element in short‐term integrated management plans for the cultivation of the macauba palm in South America.

Acrocomia spp.: neglected crop, ballyhooed multipurpose palm or fit for the bioeconomy? A review

“…In the field of plant propagation, somatic embryogenesis from leaf tissues has recently been introduced, contributing to the understanding of the embryogenesis process (Meira et al 2019). Other publication adding relevant information for crop management includes an evaluation of acrocomia's root system (Moreira et al 2019), studies of potential pests, e.g., Raoiella indica and Cyclocephala forsteri (Maia et al 2020;Souza et al 2020), a model to estimate bunches weight (Malaquias et al 2019), and the validation of a prototype for harvesting by mechanical vibration (Grupioni et al 2020). Carbon sequestration in cultivated acrocomia and potential carbon credit generation were assessed for the first time (Moreira et al 2020b).…”

“…Despite there being no evidence of pests or diseases in commercial plantations of acrocomia (César et al 2015;Colombo et al 2018), potential threats have been identified in a number of studies, contributing to the planning of integrated pest management during cultivation and post-harvest. These threats include phytophagous scarabs that feed on flowers and roots, the red palm mite, lethal yellowing disease caused by phytoplasma bacteria, fungal pathologies, and seed predator insects that attack mature fruits (Guatimosim et al 2012;Maia et al 2018Maia et al , 2020Pereira et al 2014;Ramos et al 2001;Roca et al, 2006;Souza et al 2020;Zuart-Macías et al 1999). Based on agricultural practices, around 10 kg ha −1 agrochemicals including pesticides and herbicides are applied during the first year of establishment and 2.2 kg ha −1 per year after the fifth year (Evaristo et al 2018).…”

Identification and field verification of an aggregation pheromone from the white-spotted flower chafer, Protaetia brevitarsis Lewis (Coleoptera: Scarabaeidae)

“…4-Methylanisole has also been reported in the flowers of phytelephantoid palms ( Arecaceae ) 29 and Cymbopetalum brasiliense 30 , and was inferred to be well perceived by various insects, especially pollinators 28 . In the inflorescences of the macauba palm, the dominant floral fragrance was identified as 4-methylanisole (> 97% relative amount), which showed exclusive attractiveness to a florivorous chafer, Cyclocephala forsteri 31 . In this study, we found that 4-methylanisole showed significant attractiveness to the WSFCs, a Cetoniinae species.…”

“…It is well documented that flower-derived 4-methylanisole attracts flower-visiting insects, including various kinds of bees and beetles 28 , 29 , 31 . This means that traps baited with 4-methylanisole could capture pollinators in the field.…”

Chemistry, biosynthesis and biology of floral volatiles: roles in pollination and other functions

“…Thereof, 156 was also attractive to florivorous Cyclocephala forsteri , and the two pyrazines to another florivorous cyclocephaline beetle, Aspidolea bleuzeni . 238 The acuri palm ( Attalea phalerata ) releases almost exclusively methyl acetate ( 158 ) to attract its putative main beetle pollinators ( Mystrops spp., Nitidulidae; Andranthobius spp., Curculionidae) and this communication channel is exploited by non-pollinating florivorous beetles, such as palm borers ( Paratenthras martinsi , Cerambycidae; Parisoschoenus sp., Belopoeus sp. ; Curculionidae).…”