Brown marmorated stink bug overwintering aggregations are not regulated through vibrational signals during autumn dispersal

The post-diapause vibrational behavior, motility, and survival of the brown marmorated stink bug Halyomorpha halys (Stål) adults at different temperatures

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.

Microscopic morphology and distribution of the antennal sensilla in the double-spined bark beetle, Ips duplicatus (Coleoptera: Curculionidae)

The double-spined spruce bark beetle, Ips duplicatus, has become an infamous secondary pest of Norway spruce, causing extensive ecological and economic destruction in many Central European countries. Antennae are the primary olfactory organs that play a fundamental role in insect-host chemical communication; therefore, understanding morphology is crucial before conducting electrophysiological investigations. Here, we present our analysis of sensilla types on the antennal surface of I. duplicatus for the first time, using high-resolution-scanning electron microscopy. We studied the external morphological characteristics of antennae and the types, numbers, and distribution of the antennal sensilla in males and females. Our results revealed the presence of five different types of morphologically distinct sensilla: sensilla chaetica, sensilla basiconica, sensilla trichodea, sensilla coeloconica, and Böhm's sensilla. We observed two subtypes of sensilla chaetica (SChI and SChII), four subtypes of sensilla basiconica (SBI, SBII, SBIII, and SBIV), three subtypes of sensilla trichodea (STrII, STrIII, and STrIV) and two subtypes of sensilla coeloconica (SCoI and SCoII), respectively in I. duplicatus males and females. Minor differences in length and numbers between the sexes for some sensilla types were found. Distribution maps for different sensillar types were constructed, and specific areas for the respective sensilla were found. Possible functions of observed sensilla types are discussed. The present study provides a basis for future electrophysiological studies to understand how I. duplicatus detects ecologically important olfactory cues. RESEARCH HIGHLIGHTS: • The first report of morphology and distribution pattern of the antennal sensilla in Ips duplicatus is discussed. • A total of 6 main types and 11 antennal sensilla subtypes were observed in male and female Ips duplicatus. • Minor sex-specific differences were seen in the length and numbers in several sensilla types.

A new model of stink bug traps: heated trap for capturing Halyomorpha halys during the autumn dispersal period

Invasive stink bug species, such as Halyomorpha halys (Stål, 1855) (Hemiptera: Heteroptera: Pentatomidae), are serious agricultural pests worldwide. During autumn dispersal, adults aggregate in large numbers in human-made structures, homes and on walls of buildings. Preferred overwintering sites are sun-warmed, well-protected shelters. Exploiting a new concept, we developed a new collection method for monitoring and controlling them in their pre-overwintering period. Our trap design exploits the heat preference of stink bugs seeking overwintering sites. As a result, significantly greater numbers of H. halys adults moved into our black box traps, equipped with a heating apparatus, than into unheated ones. Experiments were performed in October during the pre-overwintering autumn dispersal period. Traps were placed next to a building that served as an overwintering site, where stink bugs usually aggregate in large numbers. Heated traps were operated on sunny afternoon hours when stink bugs were found to be active by visual observations. Our results represent the first example of an effective collection method based on artificially heated traps placed in natural conditions.

Evidence of Receptivity to Vibroacoustic Stimuli in the Spotted Lanternfly Lycorma delicatula (Hemiptera: Fulgoridae)

The spotted lanternfly Lycorma delicatula White (Hemiptera: Fulgoridae) is a polyphagous insect pest that invaded the United States in 2014, in Berks County, Pennsylvania. It has since spread to several northeastern states and poses a significant threat to northeastern grape production. Most studied species of Hemiptera are known to communicate intraspecifically using some form of substrate-borne vibrational signals, although such behavior has not yet been reported in L. delicatula. This report demonstrates that adult and fourth-instar L. delicatula were attracted towards broadcasts of 60-Hz vibroacoustic stimuli directed to a laboratory arena and test substrate, which suggests that both adults and fourth instar nymphs can perceive and respond to vibrational stimuli.

Design of ideal vibrational signals for stinkbug male attraction through vibrotaxis experiments

BACKGROUND

Many groups of insects utilize substrate-borne vibrations for intraspecific communication. This characteristic makes them a suitable model for exploring the use of vibrations as a tool for pest control as an alternative to the use of chemicals. Detailed knowledge of species communication is a prerequisite to select the best signals to use. This study explored the use of substrate-borne vibrations for pest control of the brown marmorated stink bug (BMSB), Halyomorpha halys Stål (Heteroptera: Pentatomidae). For this purpose, we first identified the spectral and temporal characteristics that best elicit male responsiveness. Bioassays were conducted with artificial signals that mimicked the natural female calling signal. Second, we used the acquired knowledge to synthesize new signals endowed with different degrees of attractiveness in single- and two-choice bioassays using a wooden custom-made T stand.

RESULTS

The results from this study showed that males were attracted to female signals along a high range of amplitudes, especially starting from a threshold of 100 μm s^-1 , a high pulse repetition time (1 s) and frequency peak corresponding to the first harmonic (76 Hz). This resulted in an "optimal" signal for use to attract males, while the choice test in the T arena showed that this signal elicits searching behavior and attracts BMSB males towards a stimulation point.

CONCLUSION

We confirm the use of vibrational signals as a strong tool for behavioral manipulation of male BMSB and suggest its possible use in the development of field traps and further management of this pest. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Intrasexual Vibrational Behavior of Philaenus spumarius in Semi-Field Conditions

Insects that communicate by vibrational signals live in a complex interactive network of communication. Most studies on insect intrasexual behavior, based on plant-borne vibrational signals, have targeted few individuals. Despite their importance, behaviors that occur within groups were often overlooked. The study of multiple individuals, when insects occur in high density could simulate the environment in which they live and provide more reliable information on their behavior. In semi-field conditions, we investigated the intrasexual behavior of the meadow spittlebug, Philaenus spumarius. Vibrational signals exchanged among individuals of the same sex were recorded throughout their adult stage, from late spring to early autumn, and during the day, from the morning to the evening using a laser vibrometer. Males were less active than females throughout the season and their interactions were less frequent compared to females. Intrasexual interactions were characterized by signal overlapping in both unisex groups, in addition to signal alternating only in the case of males. In conclusion, the study of signaling behavior in intrasexual groups contributed to a better understanding of P. spumarius social behavior. We discuss the hypothesis of a possible competitive behavior between males and cooperative behavior between females.