Just phoresy? Reduced lifespan in red palm weevils Rhynchophorus ferrugineus

Invasive species usually act as carriers of their associated organisms like parasites and symbionts. This phenomenon has also occurred with the recent colonization of the red palm weevil, Rhynchophorus ferrugineus, in the Mediterranean area: this introduced pest is strictly associated with several species of mites (mainly belonging to the suborder Uropodina). In this paper, we document the high rate of infestation of Central and Southern Italian red palm weevil populations by the mite Centrouropoda almerodai. This mite species was found in all five investigated regions and infested the large majority of individuals (from 57 to 95%) by settling preferentially under the first pair of wings. Although this mite–weevil association is usually considered as a phoretic relationship, i.e. without impact on hosts, our study revealed that infested individuals have a significantly reduced lifespan (by one-third) in comparison with those not infested. Our study provides evidences that C. almerodai imposes a cost on its carrier host, at least under laboratory conditions, leading us to believe that the R. ferrugineus– C. almerodai relationship is also not phoretic in the wild

Captura de Rhynchophorus palmarum L. (Coleoptera: curculionidae) em armadilhas iscadas com o feromônio de agregação e compostos voláteis de frutos do abacaxi Trap catches of Rhynchophorus palmarum L. (Coleoptera: curculionidae) baited with its aggregation pheromone and volatile compounds from pineapple

O objetivo deste trabalho foi determinar os índices de captura de Rhynchophorus palmarum em armadilhas iscadas com o feromônio de agregação, 6-metil-2(E)-hepten-4-ol (rincoforol), associado a toletes de cana-de-açúcar, a pedaços de frutos do abacaxi e a seis compostos voláteis isolados de frutos do abacaxi. Os compostos voláteis do abacaxi são caracterizados por uma mistura de ésteres metílicos e etílicos, sendo o octanoato de metila e o octanoato de etila os mais abundantes. As armadilhas iscadas com o rincoforol associado a toletes de cana-de-açúcar e as iscas com rincoforol associado a pedaços de abacaxi não apresentaram diferenças significativas no número de besouros capturados. No entanto, ambas apresentaram índices de captura superiores àquelas em que o rincoforol foi utilizado em associação com voláteis do abacaxi. Não se observaram efeitos significativos do local e época de captura, nem no número de machos e de fêmeas capturados.<br>The aim of this work was to investigate the capture of Rhynchophorus palmarum in traps baited with its aggregation pheromone, 6-methyl-2(E)-hepten-4-ol (rhynchophorol), in association with sugar cane, pieces of pineapple fruit, and six volatile compounds from pineapple. A mixture of methyl and ethyl esters, being methyl octanoate and ethyl octanoate the most abundant, characterizes the volatile compounds from pineapple fruits. Traps baited with rhynchophorol in association with sugar cane and those baited with rhynchophorol in association with pieces of pineapple, showed no significant differences in the number of trapped weevils. However, both traps caught significantly more weevils, than those baited with rhynchophorol in association with pineapple volatiles. There were no significant effects from place and time or in the number of male and female weevils trapped

Structure, chirality, and field testing of a male-produced aggregation pheromone of Asian palm weevilRhynchophorus bilineatus (Montr.) (Coleoptera: Curculionidae)

4-Methyl-5-nonanol is a male-produced aggregation pheromone of the Asian palm weevil,Rhynchophorus bilineatus (Montr.). The pheromone was identified by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectrometric (MS) analyses of male-and female-produced volatiles. Analyses by GC-EAD and GC-MS of weevil-produced and stereoselectively synthesized isomers of 4-methyl-5-nonanol on a Cyclodex B column, which separated isomers with baseline resolution, revealed that only (4S,5S)-4-methyl-5-nonanol is EAD active and produced by the males. In field experiments in Papua New Guinea, (4S,5S)-4-methyl-5-nonanol and a racemic mixture of disatereoisomers of it enhanced attraction of male and female weevils to sugarcane-baited traps. (4S,5S)-4-Methyl-5-nonanol is also an aggregation pheromone of two other Asian palm weevils.R. ferrugineus (Oliv.) andR. vulneratus (Panz.). The stereoisomeric mixture of 4-methyl-5-nonanol is currently used to manage populations ofR. bilineatus in Papua New GuineaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigaciones en Productos Naturales (CIPRONA

Ethyl propionate: Synergistic kairomone for african palm weevil,Rhynchophorus phoenicis L. (Coleoptera: Curculionidae)

Small trunk pieces of a freshly felled 10-year-old oil palm,Elaeis quineensis (Jacq.), were placed in a modified Nalgene desiccator, and volatiles captured for six days on Porapak Q. Gas chromatographic (GC) analysis of Porapak-Q-trapped volatiles with both flame ionization (FID) and electroantennographic detection (EAD) using male or femaleR. phoenicis antennae revealed several EAD-active compounds. They were identified as: ethyl acetate, ethyl propionate, isobutyl propionate, ethyl butyrate, and ethyl isobutyrate. In field experiments in the La Me Research Station, Côte d'Ivoire, ethyl propionate (50 mg/24 hr) but not all esters combined (50 mg/24 hr each) significantly increased capture ofR. phoenicis in pheromone-baited (3 mg/24 hr) traps. One kilogram of 1- to 3-day-old palm tissue was significantly more effective than ethyl propionate in enhancing pheromone attraction. Superior attraction of palm tissue may be attributed to additional as yet unknown semiochemicals. Alternatively, release rates and/or ratios of synthetic volatiles differed from those of palm tissue at peak attraction.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigaciones en Productos Naturales (CIPRONA