Pheromone-based Mating and Aggregation in the Sorghum Chafer, Pachnoda interrupta

Abstract

Adults of the sorghum chafer, Pachnoda interrupta Olivier (Coleoptera: Scarabaeidae: Cetoniinae), form aggregations during the mating period in July, but also in October. The beetles aggregate on food sources, e.g., Acacia spp. trees or sorghum with ripe seeds, to feed and mate. During the mating season, field trapping experiments with live beetles as bait demonstrated attraction of males to unmated females, but not to mated females or males, indicating the presence of a female-emitted sex pheromone. Unmated females combined with banana (food source) attracted significantly more males and females than did unmated females alone. Other combinations of beetles with banana were not more attractive than banana alone. Thus, aggregation behavior appears to be guided by a combination of pheromone and host volatiles. Females and males were extracted with hexane during the mating period, and the extracts were compared by using GC-MS. In a field trapping experiment, 19 compounds found only in females were tested, both singly and in a mixture. Traps baited with one of the female-associated compounds, phenylacetaldehyde, caught significantly more beetles than any other treatment. However, the sex ratio of beetles caught in these traps did not differ from that of control traps and it is possible that other components may be involved in the sex pheromone signal. Furthermore, traps baited with a mixture of all 19 compounds attracted significantly fewer beetles than did phenylacetaldehyde alone.

Response of Odorant Receptors with Phenylacetaldehyde and the Effects on the Behavior of the Rice Water Weevil (Lissorhoptrus oryzophilus)

“…43 Moreover, PAA had a strong effect on the behavior activity and field trapping of Meligethes aeneus and Pachnoda interrupta. 44,45 El-Sayed et al found that the total catch and the number of species of insects increased with increases in the PAA concentration. 46 Although LoryOR20/LoryOrco responded to these four compounds, the results of the EAG experiment showed that the RWW antennae only responded significantly to c3HB and CJ at the highest concentration (100 μg/μL) and that RWW did not respond to t2HA at all.…”

Aldehyde-specific responses of olfactory sensory neurons in the praying mantis

“…The perception of aldehydes emitted from their prey is likely important for entomophagous insects. Aldehydes are contained in 'green leaf volatiles' 21 and the pheromones in many insect species [22][23][24][25][26][27] . In the locust Schistocerca www.nature.com/scientificreports/ gregaria, for example, hexanal, octanal, nonanal, and decanal have been documented in the aggregation pheromone emitted from nymphs 22 .…”

“…In the locust Schistocerca www.nature.com/scientificreports/ gregaria, for example, hexanal, octanal, nonanal, and decanal have been documented in the aggregation pheromone emitted from nymphs 22 . In the beetle Pachnoda interrupta, phenylacetaldehyde was recorded in female volatile emissions and attracts both male and female conspecifics 25 . Moreover, phenylacetaldehyde is present in www.nature.com/scientificreports/ the honeydew excreted by the aphids A. gossypii and attracts the aphid predator A. aphidimyza 3 .…”

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

“…4 ) and field trapping (Table S1 - S2 ), collectively confirming that 4-methylanisole was significantly attractive to both sexes of WSFCs. Combined with food, aggregation pheromones also show higher attractiveness in other chafers 16 . It makes sense that the beetles release chemical signals to summon conspecifics during eating, which could provide conspecific individuals with more opportunities to find food sources and mate partners.…”

“…A previous study on the chemical communication of Scarabaeoidea beetles identified aggregation and sex pheromones of more than 50 species in four subfamilies (Dynastinae, Rutelinae, Melolonthinae and Cetoniinae) 12 , 13 . Unfortunately, pheromones of only a few species of Cetoniinae, have been reported, including a contact pheromone ( Z )-9-pentacosene in the large hive beetle Oplostomus haroldi Witte 14 , ( R )-γ-decalactone (a male-produced sex pheromone) in an endangered saproxylic beetle Osmoderma eremita Scopoli 15 , and phenylacetaldehyde (a female-produced sex pheromone) in the sorghum chafer Pachnoda interrupta Olivier 16 .…”