Abstract The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive insect pest that has caused significant economic losses in a myriad of agricultural crops in ...Europe and the USA. The communication as well as the control of this pest largely rely on semiochemicals (e.g., pheromones) and semiophysicals (e.g., substrate‐borne vibrations). Nevertheless, the nocturnal activity of H. halys is still largely unknown. In the present study, the diel vibrational communication of H. halys was investigated in controlled laboratory and semi‐field conditions. Moreover, the relevance of this ecological trait for integrated pest management (IPM) strategies was assessed by extending playback periods of bimodal (i.e., pheromones + vibrational playbacks) traps to 24 h, and comparing it to the current trap model (solar panel, about 12 h of playback) and a control (no playback, only pheromone). We found that H. halys did not exhibit discernible differences of vibrational activity between photophase and scotophase, with the exception of signal type 2 that in laboratory conditions was predominately emitted within nocturnal and morning hours (i.e., 20:00–12:00). Additionally, the calling activity was negatively affected by warmer (>32 °C) and windier (>7 m s −1 ) conditions in semi‐field settings. Bimodal traps that were power‐supplied for 24 h captured significantly more males than the other groups, and more females than the control group. Results suggest that the nocturnal vibrational activity of H. halys should be accounted for within IPM strategies by activating the bimodal traps also during the scotophase.
Substrate-borne vibrational communication is common in pentatomids. Although several works exist on the vibrational communication of Halyomorpha halys, its vibrational behavior post diapause has not ...been investigated. In this study, we recorded H. halys overwintered adults using laser doppler vibrometers at three temperatures: 10 °C (inactivity), 18 °C (breaking of diapause), and 25 °C (peak of mating activity). The aim was to assess the effect of temperature on the signaling, motility, and survival of H. halys. The insects were sexed into different cages and recorded separately or joined with a cage of the opposite sex. We calculated the total time spent on signaling and walking per replica. The males predominantly emitted male signal 1 (MS1) throughout the four months of recordings. The females exclusively emitted female signal 2 (FS2) when joined with the opposite sex cage the first two months of recordings. Interestingly, they also started FS2 signaling when recorded separately, after two months. No signaling was recorded at 10 °C. At 25 °C, the signaling latency time before vibrational signaling was 24 h compared to 23 days at 18 °C. The short latency time at 25 °C correlated with a higher death rate in early stages of recording. Male walking activity was significantly higher in joined cages at 18 °C and 25 °C, suggesting the increased searching behavior near the opposite sex. Overwintered H. halys could adapt to different conditions whereas low temperatures maintain the diapause which is characterized by no signaling activity. Our results provide a foundation for bioclimatic modeling of climate change effects on H. halys and insights into the use of vibrational playbacks for mass trapping and monitoring as control techniques.
Anthropogenic disturbance has been pointed to as one of the major causes of the world´s biodiversity crisis. Among them, noise pollution is a potential underestimated threat, projected to increase in ...the next decades accompanying urban expansion. Rising levels of noise pollution may result in negative impacts on species highly dependent on acoustic communication. Amphibians have long served as model organisms for investigating animal acoustic communication because their reproduction depends on transmitting and receiving acoustic signals. A few studies have investigated the effects of anthropogenic noise on anurans, but there is still limited knowledge on how it affects them. In this study, we test the effect of two intensities of traffic noise on calling males of two Neotropical treefrogs species. We expect to record more changes in call parameters, to avoid masking effect, at higher intensity noise treatments, and in the species with higher call/noise frequency overlap. We performed a set of field playback experiments exposing male frogs to road noise at two different intensities (65dB and 75dB). Focal species are Boana bischoffi (high call/noise frequency overlap) and B. leptolineata (low call/noise frequency overlap). Both species changed acoustic parameters during or after the exposure to traffic noise. Advertisement call rate of B. bischoffi decreased during road noise, and dominant frequency decreased over time. Call length of B. leptolineata increased or decreased, depending on the order of noise intensity. We also observed spatial displacement in both species, which moved away from the noise source. Our results provide evidence that traffic noise affects anuran calling behavior, and noise intensity is an important factor affecting how species respond.
Aposematic signals as well as body behaviours may be important anti-predator defences. Species of the genus Melanophryniscus are characterised by having toxic lipophilic alkaloids in the skin and for ...presenting a red ventral colouration, which can be observed when they perform the behaviour called the unken reflex. Both the reflex behaviour and the colouration pattern are described as defence mechanisms. However, there are currently no studies testing their effectiveness against predators. This study aimed to test experimentally if both ventral conspicuous colouration and the unken reflex in Melanophryniscus cambaraensis function as aposematic signals against visually oriented predators (birds). We simulated the species studied using three different clay toad models as follows: (a) in a normal position with green coloured bodies, (b) in the unken reflex position with green coloured body and extremities and (c) in the unken reflex position with a green body and red extremities. Models were distributed on a known M. cambaraensis breeding site and in the adjacent forest. More than half of the attacks on the models were from birds; however, there was no preference for any model type. Thus, just the presence of the red colour associated with the motionless unken reflex position does not seem to prevent attacks from potential predators. It is possible that the effective aposematic signal in Melanophryniscus is achieved through the unken reflex movement together with the subsequent exhibition of the warning colouration and the secretion of toxins.
The directional orientation of pre- and post-reproductive migration was studied in the Brazilian red-bellied toad Melanophryniscus cambaraensis, a species that forms explosive-breeding aggregations ...at irregular intervals throughout the entire year. Migrating toads were captured by enclosing the breeding site in dual drift fences with inward- and outward-facing funnel traps. Data were collected over 5 mo and totalled 333 captures. The observed directional orientation was significantly different from expected under a uniform distribution for both pre- and post-reproductive migration, regardless of gender. Males and females did not differ significantly from each other in the orientation of entry or exit, and the directional orientation of pre-reproductive migration was not significantly different from post-reproductive migration. It is suggested that the observed directional bias may be due to a dirt road next to the breeding site that could restrict juvenile dispersal to the adjacent forest.
Halyomorpha halys
(Stål, 1855), the brown marmorated stink bug (BMSB), is an invasive species that has become a key agricultural pest in its invaded range. Commercial traps available for BMSB ...monitoring rely on male produced aggregation pheromones as lure, with two possible shortcomings: trap spillover and low detection precision. In this study, we assessed if vibrational signals can increase the attractiveness of pheromone traps by testing the optimized vibration-based lure (Female Song 2, FS2) associated with a specifically designed trap (i.e., the vibrotrap). We evaluated the efficacy of this bimodal trap (i.e., pheromones + vibrations) on females, males and nymphs in controlled conditions (greenhouse) and in the field, in two sites at the margin of two commercial vineyards. In the field, bimodal vibrotraps were compared to three unimodal (i.e., only pheromone) trap types. Both experiments showed that the vibrotrap is highly attractive for BMSB, and the optimized FS2 signal significantly improved its effectiveness. Even though FS2 was selected to target males, the number of trapped females increased as well. Overall, the presented findings show a feasible improvement to future commercial BMSB traps through the synergic use of semiophysicals and semiochemicals. Further research is needed to evaluate the effectiveness of vibrotraps for both early detection and mass trapping.
Anurans are known to detect vibrations, but few studies explore relationships between vibrations and resultant behaviors. We studied the reaction of calling captive-bred male midwife toads (
Alytes ...obstetricans
) to the randomized playback of a vibrational crescendo stimulus train. We considered two sources of natural abiotic vibrational stimuli: rainfall and wind. Rainfall was expected to induce calling and wind was expected to inhibit it. Playback experiments with two synthetic tones (200 Hz and 300 Hz) tested the sensitivity to pure tones and could possibly reveal a hearing sensitivity trend between these frequencies. The toads did not increase call rate in response to rainfall vibrations and only one of the five wind stimulus levels caused a significant decrease in call rate. This limited response could be explained, because the tested toads came from a captive population, where emergence may not be mediated by rainfall vibrations. We found that
A. obstetricans
is highly sensitive to very low frequencies, which could explain the sensitivity observed to vibrational stimuli. Playback of a random crescendo stimulus train proves to be a valid approach for addressing behavioral questions. However, the use of a captive population may have been a limitation in the clarity of the results.
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