The idea of using species-specific behavior-modifying chemicals for the management of noxious insects in agriculture, horticulture, forestry, stored products, and for insect vectors of diseases has been a driving ambition through five decades of pheromone research. Hundreds of pheromones and other semiochemicals have been discovered that are used to monitor the presence and abundance of insects and to protect plants and animals against insects. The estimated annual production of lures for monitoring and mass trapping is on the order of tens of millions, covering at least 10 million hectares. Insect populations are controlled by air permeation and attract-and-kill techniques on at least 1 million hectares. Here, we review the most important and widespread practical applications. Pheromones are increasingly efficient at low population densities, they do not adversely affect natural enemies, and they can, therefore, bring about a long-term reduction in insect populations that cannot be accomplished with conventional insecticides. A changing climate with higher growing season temperatures and altered rainfall patterns makes control of native and invasive insects an increasingly urgent challenge. Intensified insecticide use will not provide a solution, but pheromones and other semiochemicals instead can be implemented for sustainable area-wide management and will thus improve food security for a growing population. Given the scale of the challenges we face to mitigate the impacts of climate change, the time is right to intensify goal-oriented interdisciplinary research on semiochemicals, involving chemists, entomologists, and plant protection experts, in order to provide the urgently needed, and cost-effective technical solutions for sustainable insect management worldwide.

Sex pheromones and their impact on pest management.

Vibrational communication is widespread in insect social and ecological interactions. Of the insect species that communicate using sound, water surface ripples, or substrate vibrations, we estimate that 92% use substrate vibrations alone or with other forms of mechanical signaling. Vibrational signals differ dramatically from airborne insect sounds, often having low frequencies, pure tones, and combinations of contrasting acoustic elements. Plants are the most widely used substrate for transmitting vibrational signals. Plant species can vary in their signal transmission properties, and thus host plant use may influence signal divergence. Vibrational communication occurs in a complex environment containing noise from wind and rain, the signals of multiple individuals and species, and vibration-sensitive predators and parasitoids. We anticipate that many new examples and functions of vibrational communication will be discovered, and that study of this modality will continue to provide important insights into insect social behavior, ecology, and evolution.

https://www.jstor.org/stable/10.1641/0006-3568(2005)055[0323:TBEOIV]2.0.CO;2

The Behavioral Ecology of Insect Vibrational Communication

Fruit Flies (Tephritidae): Phylogeny and Evolution of Behavior

▪ Abstract Tachinidae are one of the most diverse and ecologically important families in the order Diptera. As parasitoids, they are important natural enemies in most terrestrial ecological communities, particularly as natural enemies of larval Lepidoptera. Despite their diversity and ecological impact, relatively little is known about the evolution and ecology of tachinids, and what is known tends to be widely dispersed in specialized reports, journals, or texts. In this review we synthesize information on the evolutionary history, behavior, and ecology of tachinids and discuss promising directions for future research involving tachinids. We provide an overview of the phylogenetic history and geographic diversity of tachinids, examine the evolution of oviposition strategies and host associations, review known mechanisms of host location, and discuss recent studies dealing with the ecological interactions between tachinids and their hosts. In doing so, we highlight ways in which investigation of these par...

Tachinidae: Evolution, Behavior, and Ecology

Divergent natural selection has been shown to promote speciation in a wide range of taxa. For example, adaptation to different ecological environments, via divergent selection, can result in the evolution of reproductive incompatibility between populations. Phytophagous insects have been at the forefront of these investigations of ‘ecological speciation’ and it is clear that adaptation to different host plants can promote insect speciation. However, much remains unknown. For example, there is abundant variability in the extent to which divergent selection promotes speciation, the sources of divergent selection, the types of reproductive barriers involved, and the genetic basis of divergent adaptation. We review these factors here. Several findings emerge, including the observation that although numerous different sources of divergent selection and reproductive isolation can be involved in insect speciation, their order of evolution and relative importance are poorly understood. Another finding is that the genetic basis of host preference and performance can involve loci of major effect and opposing dominance, factors which might facilitate speciation in the face of gene flow. In addition, we raise a number of other recent issues relating to phytophagous insect speciation, such as alternatives to ecological speciation, the geography of speciation, and the molecular signatures of speciation. Throughout, we aim to both synthesize what is known, as well as highlight areas where future work is especially needed.

http://nosil-lab.group.shef.ac.uk/wp-content/uploads/2012/03/MatsubayashietalinsectspeciationEEA2010.pdf

Ecological speciation in phytophagous insects

Communication through substrate-borne vibrations has for long been recognized but in comparison with air-borne sound it has received very little attention. However, in recent years it has become increasingly clear that vibrational signals play a crucial role in communication in many insect groups and we provide a short overview. Vibrational signals are related to sexual behavior, alarm and defensive behavior and are often used to mediate coordinated group actions and complex social interactions. For small insects they are probably the least costly and most far-reaching signals for intraspecific communication and also not easily perceived by a potential predator or parasitoid. Substrate-borne signals are produced by diversed methods and detected by sensitive receptors in all six legs. The courtship behavior of the southern green stink bug Nezara viridula (L.) (Hemiptera: Pentatomidae) is taken as a representative model in illustrating some principal mechanisms of vibrational communication in insects. Species and sex specific vibrational signals produced during the courtship are well suited for propagation through plants and to transmit the relevant information about the species and sex of the sender as well as provide the directional cue for locating the mate. The role of substrate-borne signals as a part of the specific mate recognition systems which are unique for each species makes studies of vibrational signals a very useful tool for resolving taxonomic problems.

/pdf/vibrational-communication-in-insects-1ts8aewpq0.pdf

Vibrational communication in insects

Vibratory signals of plant-dwelling insects, such as land bugs of the families Cydnidae and Pentatomidae, are produced mainly by stridulation and/or vibration of some body part. Signals emitted by the vibratory mechanisms have low-frequency characteristics with a relatively narrow frequency peak dominant around 100 Hz and differently expressed frequency modulation and higher harmonics. Such spectral characteristics are well tuned to the transmission properties of plants, and the low attenuation enables long-range communication on the same plant under standing wave conditions. Frequencies of stridulatory signals extend up to 10 kHz. In some groups, vibratory and stridulatory mechanisms may be used simultaneously to produce broadband signals. The subgenual organ, joint chordotonal organs, campaniform sensilla and mechanoreceptors, such as the Johnston's organ in antennae, are used to detect these vibratory signals. Species-specific songs facilitate mate location and recognition, and less species-specific signals provide information about enemies or rival mates.

Communication with substrate-borne signals in small plant-dwelling insects.

Vibrational directionality in the southern green stink bug, Nezara viridula (L.), is mediated by female song

Scaphoideus titanus Ball (Hemiptera: Cicadellidae: Deltocephalinae) is the vector of the grapevine disease Flavescence doree. In S. titanus the male–female duet (MFD), based on species-specific vibrational signals, is essential for successful copulation. The female reply within a duet is a single pulse that is coupled with the male pulse with constant latency. It has been shown that a rival male can interrupt an existing duet by emitting disruptive noise signals. We tested whether the reproductive behaviour of S. titanus can be disrupted by the playback of intra-specific and synthesized vibrational signals. Tested males responded to the playback of an MFD with typical rivalry behaviour. Such behaviour includes silent search for a duetting female (satellite behaviour) and/or emission of disruptive signals. These signals were emitted either after exchange of male–female pulses or after two male pulses coupled by latency corresponding to the female response window. The onset of male disruptive signals overlapped with a female pulse. We suggest that the intruder’s disruptive signals can mask the female reply and confuse courting males. Playback of disruptive vibrational signals reduced the level of male calling and interrupted an established MFD that consequently resulted in a significantly reduced number of copulations. These results indicate that the vibrational communication channel is open to interference either from abiotic environmental noise or from signals produced by sexual competitors or heterospecifics. The present study also suggests that a detailed understanding of leafhopper behaviour is essential for trying new approaches in the development of more environmentally friendly control practices.

Disruption of the reproductive behaviour of Scaphoideus titanus by playback of vibrational signals

Songs of the southern green stink bug Nezara viridula L, recorded on a non-resonant loudspeaker membrane, reflect frequency characteristics of body vibrations. The song dominant frequency directly depends on the repetition rate of potentials recorded from synchronously contracting muscles that vibrate the abdomen during singing. Spectra of naturally emitted signals recorded on the pronotum of a singing bug or on a plant contain peaks characteristic of plant resonant spectra. The dominant resonant frequency of sound-induced vibrations in bean and other stink bug host plants ranges between 160 and 215 Hz and subdominant peaks do not exceed 600 Hz. There is no correlation between spectral peak positions and recording points on a plant. The dominant resonance peak corresponds to the best frequency sensitivity of N. viridula middle frequency subgenual receptor cell. Subdominant peaks around and below 100 Hz lie close to the dominant frequency of body vibrations during singing and to the range of best frequency sensitivity of low frequency receptor cells. Tuning of plant resonant frequencies with spectral properties of songs and frequency sensitivity of sensory organs is discussed in the context of stink bug substrate-borne communication.

/pdf/tuning-of-host-plants-with-vibratory-songs-of-nezara-1uwljbtem2.pdf

Andrej Čokl

Papers

Vibrational communication in insects

Communication with substrate-borne signals in small plant-dwelling insects.

Vibrational directionality in the southern green stink bug, Nezara viridula (L.), is mediated by female song

Disruption of the reproductive behaviour of Scaphoideus titanus by playback of vibrational signals

Tuning of host plants with vibratory songs of Nezara viridula L (Heteroptera: Pentatomidae).