Hornets possess long-lasting olfactory memories

Abstract

The ability of animals to learn and remember is an important adaptation for coping with environmental changes. The fitness benefits provided by these cognitive skills, in conjunction with social behaviours, contribute to the success of social insects. How these abilities are shared among the different castes and the long-term persistence of memory are now being elucidated in diverse systems, work that should shed light on general principles underlying cognitive evolution. Here, we provide the first evidence of olfactory learning and long-term olfactory memory in all three castes of an Asian hornet, Vespa velutina. Using the first proboscis extension reflex assay developed for hornets or wasps, we found that all hornet castes could learn and remember odours associated with a food reward. Moreover, long-lasting memory was retained without significant decay in gynes (virgin queens) and drones even up to 30 days (workers did not survive for 30 days). Drones learned and remembered simple odorant molecules and gyne sex pheromone with equal facility. These results increase our understanding of the outstanding cognitive abilities of social insects and suggest the likely importance of long-lasting memory in different castes of the same species.

Assessment of the In Vivo and In Vitro Release of Chemical Compounds from Vespa velutina

“…Heneicosane (C 21 ) was identified as a cuticular hydrocarbon in both V. velutina [3] and V. crabro [26] and as a volatile defence in the hive environment [27]. Heptacosane (C 27 ) has been studied in V. velutina as a semiochemical rec-ognized by sensory neurons within the basiconic sensilla of the hornet [16]. This compound and nonadecane (C 19 ), are recognized by V. velutina when it is released by S. tuberosa for the dispersal of its seeds [23].…”

“…identified nonanal as a volatile aliphatic odorant using the single sensillum extracellular recording (SSR) technique in V. velutina. Furthermore, olfactory learning and long-term olfactory memory in the Asian hornet were tested using gynes of V. velutina, which responded significantly to nonanal [16]. This olfactory response to nonanal has also been studied in the relationships of Apis cerana with the Asian hornet [17].…”

“…Finally, 9-Octadecenoic acid (oleic acid) has been studied as a chemical component derived from the glands of Hymenoptera as from the mandible glands of V. crabro [48] or as chemical secretion of the sternal glands of Polistes social wasps [49]. Volatile aliphatic odorants [10] Alarm pheromone [50] Trail pheromone [22] Sex pheromone [16] Decanal --3.8 4.7…”

De Novo Transcriptomic Resources in the Brain of Vespa velutina for Invasion Control

“…Based on sequence homology, 33,245 unigenes were categorized into 56 functional groups in the GO database ( Figure 3). The three main categories were biological process, cellular component, and molecular function, and they had the following occupancy: "cellular process" (18,198; 54.74% of 33,245); "cell part" (10,515; 31.63% of 33,245), and "binding" (15,543; 46.75% of 33,245) ( Figure 3). In addition, a total of 17,971 unigenes were assigned appropriate KOG clusters (Figure 4).…”

“…Several groups have been working on the identification of sex pheromones [11][12][13] and chemicals [14] to develop specific traps. Hornet behavior [4,[15][16][17] and olfactory systems [13,18,19] are areas of active research for developing control strategies, but little is known about the molecular level characteristics of Vespa velutina. Although molecular markers, such as mitochondrial DNA sequences [20][21][22] and microsatellites [23], have already been used to identify Vespa velutina samples [24] and define their distribution area [25,26], molecular-genomic tools are rarely used for hornet control.…”