Reconstruction of sound driven, actively amplified and spontaneous motions within the tree cricket auditory organ

Hearing consists of a delicate chain of events. Sound is first captured by an eardrum or similar organ which is set into vibrations, these vibrations must then be transmitted to sensory cells in a manner that opens mechanosensory channels generating an electrical signal. Studying this process is challenging. Auditory vibrations are in the nano- to picometer-scale and occur at fast temporal scales of milli to microseconds. Finally, most of this process occurs within the body of the animal where it is inaccessible to conventional measurement techniques. For instance, even in crickets, a century-old auditory model system, it is unclear how sound evoked vibrations are transmitted to sensory neurons. Here, we use optical coherence tomography (OCT) to measure how vibrations travel within the auditory organ of the western tree cricket (Oecanthus californicus). We also measure the reversal of this process as mechanosensory cells generate spontaneous oscillations and amplify sound-evoked vibrations. Most importantly, we found that while the mechanosensory neurons were not attached to the peripheral sound collecting structures, they were mechanically well-coupled through acoustic trachea. Thus, the acoustic trachea are not merely conduits for sound but also perform a mechanical function. Our results generate several insights into the similarities between insect and vertebrate hearing, and into the evolutionary history of auditory amplification.

Neoxabea mexicana sp. nov. (Gryllidae: Oecanthinae): A new species from Mexico and a key for Neoxabea in North and Central America

A new species of tree cricket, Neoxabea mexicanasp. nov., is described from northeast Mexico. Although it has morphological similarities to two other species found in Mexico, there are distinguishing characters, such as a well-developed tubercle on the pedicel, black markings on the maxillary palpi, one of the two pairs of spots on the female wings positioned at the base of the wings, stridulatory teeth count, and the pulse rate of the male calling song. The calling song description and pre-singing stuttering frequencies are provided. Character comparisons that rule out other species in the genus are presented. The common name given to this new species is Mexican tree cricket. Sound recordings and video are available online. We also make some clarification of the status of Neoxabea formosa (Walker, 1869), described as Oecanthus formosus, and present a key of Neoxabea in North and Central America.

Oecanthus rohiniae sp. nov. (Gryllidae: Oecanthinae): A new chirping tree cricket of the rileyi species group from Mexico

A new species of Oecanthus is described from Mexico. Oecanthus rohiniaesp. nov. occurs in central Mexico in the understory of tropical deciduous forest and is currently known only from Mexico. This new species has the coloring, antennal markings, slightly widened tegmina, and calling song that are found in the rileyi species group. Although morphologically very similar to Oecanthus fultoni, the shapes of the distal hooks on the male copulatory blades differ between the two species. There are also differences in the song pulse patterns and chirp rate response to temperature. This new species has been given the common name Cri-Cri tree cricket. Video and song recordings are available online.

The dynamics of the development of harmful insects on the mother planting of basic grape plants in the Rostov region

The study results on prevalence of the main harmful insects on the mother planting of the basic grape plants of the Rostov region: rose leafhopper, buffalo treehopper, tree cricket, tobacco and grape thrips, which are polyphagous phytophages, are presented. As a result of the negative impact of harmful organisms the plant normal development is disrupted. The spread and increase in the insect harmfulness in the Rostov region is facilitated by an increase in the average annual temperature to 9.5-11.6 °C in the last 10-15 years, which is the lower limit for their survival. A close direct relationship was revealed between the average annual temperature and the leafhopper and thrip harmfulness: r=0.72-0.89 and an unobvious dependence of the tree cricket harmfulness on thermal conditions (r=0.59). The phytosanitary control system in the mother planting made it possible to restrain the harmful organism development, with a harmfulness not exceeding 1.3 points for thrips and 2 points for other insects for further reproduction of practically healthy grape planting material while maintaining the status basic plants.

Baffling: a condition-dependent alternative mate attraction strategy using self-made tools in tree crickets

Intense sexual selection in the form of mate choice can facilitate the evolution of different alternative reproductive strategies, which can be condition-dependent. Tree cricket males produce long-distance acoustic signals which are used by conspecific females for mate localization and mate choice. Our study shows that baffling, an acoustic call amplification strategy employed by male tree crickets using self-made tools, is a classic example of a condition-dependent alternative strategy. We show that though most males can baffle, less preferred males, such as smaller and lower-amplitude callers, predominantly use this alternative strategy. Baffling allows these males to increase their call amplitude and advertisement range, which attracts a higher number of females. Baffling also gives these males a mating benefit because females mate for longer durations with them. Our results suggest that the advantage of baffling in terms of gain in the number of sperm cells transferred while mating is primarily limited to less preferred males, thus maintaining the polymorphism of calling strategies in the population. We summarize that baffling is a condition-dependent strategy used by less preferred tree cricket males to obtain mating benefits.

First report of the genus Kohliella Brauns, 1910 (Hymenoptera: Crabronidae: Crabroninae) from India with the species K. anula Pulawski, 1991 from Kerala

The digger wasp genus Kohliella Brauns, 1910, a member of the tribe Larrini, subfamily Crabroninae of the family Crabronidae, is a rarely occurring genus comprising only three known species worldwide (Pulawski 1991; 2020). The genus has been recorded from the Ethiopian (South Africa and Zimbabwe; two species) and Oriental (Sri Lanka; one species) regions. Brauns (1910) erected the genus based on the type species Kohliella alaris from South Africa. The genus is characterized by a V-shaped swelling on the frons, an oblong tubercle on the mandible and a petiolate third submarginal cell of the forewing (Bohart & Menke 1976; Pulawski 1991). The nesting habits are known only for Kohliella alaris. Gess and Gess (1980) studied the life history of this species. It preys on nymphal tree cricket Oecanthus filiger Walker, and nests in the ground in flat, sandy areas with sparse vegetation; nests are constructed prior to hunting. In this paper, Kohliella anula Pulawski, 1991, previously known from Sri Lanka only, is recorded for the first time from India.

Oecanthus salvii sp. nov. (Orthoptera: Gryllidae: Oecanthinae): A new tree cricket species from Modoc County in northeast California

A new species of Oecanthus is described from extreme northeast California. Oecanthus salviisp. nov. is currently known only from Lake Annie in Modoc County, California, and occurs on sagebrush (Artemisia) and rabbitbrush (Ericameria). It has the narrow tegmina, antennal markings, metanotal gland configuration, and trilling song found in the Oecanthus nigricornis species group. Song details and morphology, including the shape of the subgenital plate and copulatory blades, are provided in this paper. This new species has been given the common name of sage tree cricket.

Baffling: A cheater strategy using self-made tools in tree crickets

Intense sexual selection in the form of mate choice can facilitate the evolution of different alternative reproductive strategies. These strategies can be condition-dependent, wherein genetically similar individuals express the strategy based on their condition. Our study shows that baffling, a mate attraction strategy using self-made acoustic amplifiers, employed by male tree crickets, is a classic example of a condition-dependent alternative strategy. We show that less preferred males, who are smaller or produce less loud calls, predominantly use this alternative strategy. Baffling allows these males to increase their call loudness and advertisement range, and attract a higher number of mates. Baffling also allows these males to deceive females into mating for longer durations with them. Our results suggest that the advantage of baffling in terms of sperm transfer is primarily limited to less preferred males, thus maintaining the polymorphism of calling strategies in the population.Impact statementThis study shows that less preferred tree cricket males use an alternative signaling strategy to call louder, thus attracting and mating with otherwise choosy females using deception.

The Audible Silence

Specific American crickets (snowy tree cricket) synchronize their chirps with the others in the swarm, with great precision. The chirp frequency is moreover a measure of the temperature of the environment, allowing a temperature measurement through chirp counting. Again the synchronization becomes possible only through intrinsic timing devices for each animal.