Electrical properties of the oriental hornet (Vespa orientalis) cuticle

Consistent electrical and physical phenomena in the cuticle of the Oriental hornet have been recorded and measured. Active or narcotized, live hornets as well as dead ones produce, at optimal temperature for vespine biological activity, voltages of several hundred mV, currents of up to several tenths of nA, and the appropriate power. The electric resistance of the hornet cuticle and hornet silk cocoon point to their being organic semiconductors. Both of these have a large electric capacitance relative to their volume. A theoretical model is proposed to explain the capacitance phenomenon. Other phenomena observed are the production of electric energy under the influence of light and heat and also change in the various other electric properties of hornet cuticle under the influence of solar irradiation. The distribution of daily hornet activities seems to be correlated with the hours of maximal irradiation. All the afore mentioned phenomena point to the fact that there is recourse to electric energy in the daily routine of hornets and that this electric energy seems to be derived from solar energy. The conversion of the latter into the former takes place in the body of the hornet which thereby functions in the manner of a solar cell. The presence of a cuticular exoskeleton containing chitin, characterizes very many species of Invertebrates (Arthropoda). We assume that the phenomena similar to those described in this paper take place also in many other species. We hope that part of our findings will be utilizable in future developments in the fields of semiconductors and the use of solar energy.     

Temperature-dependent electrical resistivity of the hornet cuticle: Changes induced by colchicine and purine in the diet

Various cuticular areas of the Oriental hornet (Vespa orientalis) were measured for their electrical resistivity within the range of 3–40°C. It was found that: (1) the electrical resistivity is temperature dependent; (2) there are no significant differences in this respect between hornets collected in different regions; (3) there are no differences in the electrical resisitivity between the yellow and brown areas of the cuticle in control hornets; (4) there are however, significant changes in resistance between the yellow and brown strips of hornets fed on purine; (5) hornets fed on colchicine reach a minimum resistance at a higher temperature than do the control hornets; and (6) hornets fed on purine reach a minimum resistance at a lower temperature. It is suggested that the cuticular changes in resistivity at different temperatures reflect the hornets' mechanism of detecting and adjusting to changes in the ambient temperature.     

Thermal properties of hornet colonies: thermography of individual hornets and their nests and the role of the pupal silk in thermoregulation.

The present study focused on temperature assessments within a hornet nest. The measurements encompassed adult hornets, brood combs and the various stages of brood, and involved a thermographic method. Body parts of adult hornets were found to vary in their temperature, with the thorax eliciting the highest temperature and the abdomen the lowest. Similarly, there were thermal variances between larvae at instars 4-5, light-colored pupae and dark pupae. The measurements were made at day and night (when the entire population was present in the nest) on nests containing thousands of individuals at various ages. Most of the pupae measured during October were hornet drones. The usual air temperature between the (subterranean) combs was 28.7 degrees C, while the outside (ground level) temperature was 23.5 degrees C. The paper discusses the creation of heat by hornets, the thermoregulation throughout night and day, both by the hornets proper as well as by their products (comb and silk). Also discussed is the intra-nest conversion of one form of energy to another, as heat to electric current or vice versa.     

Communication by electrical means in social insects

Social insects, belonging to the order Hymenoptera, maintain a fixed, optimal temperature in their nest. Thus, in social wasps and hornets, the optimal nest temperature is 29 degrees C, despite the fact that they are distributed in regions of varying climates both in the northern and southern hemispheres of the globe. Since hornets and bees are relatively small insects, determination of their own body temperature as well as that of their nest and the brood was made via thermometers or by the use of infrared (IR) rays. It has been suggested that thermoregulation in social insect colonies is effected primarily by the adult insects via muscle activation, that is, fluttering of their wings, which can raise both their own and the ambient temperature by many degrees centigrade. However, the larval brood can also contribute to the thermoregulation by acting as heat resources and thereby raising the ambient temperature by 1-2 degrees C. To this end, the adult hornets are endowed with a well-developed musculature and their larvae, too, have muscles that enable them to move about. Not so the hornet pupae which are enclosed in a silk envelope (the cocoon), with a rather thick silk cap spun by the pupating larvae, and have rather undeveloped muscles. In the latter instance, it stands to reason that the pupae benefit from the nest warming achieved primarily by the adult hornets, but how is the information regarding their thermal needs relayed from them to the adults? Previously we showed that the adult hornets are attracted to the pupae by pheromones released by the latter, but such chemical compounds can only convey information of a general nature and we are still left with the question as to how the adult hornet can gauge or ascertain the temperature of a single insulated pupa. The present study provides evidence that the hornet pupa can indeed transmit information regarding its body temperature via electrical means.     

Navigation and thermophotovoltaic activity by hornets at different light conditions: the influence of UVB blockers

The aim of the present investigation was two-fold: a) to observe the homing of the Oriental hornet, Vespa orientalis (Hymenoptera, Vespinae) from different distances; and b) to study the photothermoelectric activity of hornet cuticle obtained from the subjects of goal (a) and kept frozen for a number of days prior to its testing. In both the above mentioned phases of the investigation, an attempt was made to assess how the covering of the hornets' cuticle with Ultra Violet B (UVB) blockers affects their activity as compared to the control. Flying hornets were observed to return to the nest from distances of up to 7 km, once they had learned the way back. However, covering of the cuticle with UVB blockers increases the percentage of 'non-returners' to nearly 100%. Covering the cuticle completely or partly with a number of UVB blockers (except for Sisley) proves lethal for the hornets within 24 hours. A statistical model on homing is proposed of the effect of range, of covering with UVB blockers and covering ocelli with Tippex. In the wing of the hornet there is increase in the electric current with rise in the temperature and decrease in the current upon drop of the temperature, but light has no effect on this alar (wing) current. Contrariwise, the body cuticle of the hornet responds to both temperature and illumination in terms of its electric current. Coating of the cuticle with UVB blockers causes in the wing (under all conditions of illumination) and in the cuticle (only in the dark) a moderation in the amplitude of the photothermoelectric current.     

Photo-induced arousal response by hornets

When an Oriental hornet Vespa orientalis is subjected to ether anesthesia and then exposed to ultraviolet A light (UVAL) (at a wavelength of 366 nm), it commences showing signs of awakening by starting to move its limbs. While in the process of waking the voltage on its body surface surges sharply from 17-180 mV (median = 71.0) to a level of 93-570 mV (median = 327.5). This elevated level is maintained for several minutes but subsequently drops sharply to starting level. The increase in voltage is throughout accompanied by fluttering of the wings and movements of the legs, as well as attempts to extricate itself from the bindings to the electrodes. These movements by the awakening hornet persist for several minutes even after the irradiation source is turned off but shortly after the switch-off the hornet lapses into sleep again. The described scenario is generally similar in worker, queen and drone hornets, and may even occur in decapitated specimens. The same type of awakening can be repeated in the same fashion after a while, but then the increase in voltage will be smaller than the first time. Continuous UV irradiation of an anesthetized hornet results in a generalized and protracted awakening which, however, is significantly shorter than in a hornet left anesthetized in the dark.     

Temperature dependence of the electric resistivity of the hornet cuticle

Resistance to electricity of the oriental hornet cuticle is temperature dependent. Evidence is provided to suggest that this electric resistance and its organic semiconductor-like behaviour are possibly interconnected with temperature detection by hornets.     

Electrical properties of the cuticle,silk caps and comb of Oriental hornet Vespa orientalis (Hymenoptera : Vespidae)

Electrical and physical phenomena have been recorded and measured in the cuticle, silk caps and comb of the Oriental hornet Vespa orientalis (Hymenoptera : Vespdnae). Cuticle of active or narcotized live hornets as well as dead ones, produce, at optimal temperature for Vespinae biological activity, voltages of several hundred mV, currents of up to several hundred nA and the appropriate electric power. The cuticle has a large electrical capacitance, relative to its volume and contains non-linear and active electrical elements. A theoretical model was proposed to explain the capacitance phenomenon. An additional phenomenon observed is the production of electric energy under the influence of light and heat. Some electrical phenomena, especially the photoconductivity were measured also in 3 ant species.Measurements of the electrical capacitance of silk caps revealed that it is dependent on: (a) age of the pupa; immediately on pupation, the values are highest and diminish with maturation; (b) caste; capacitance for the queen pupae is 20–50 mF; and which is higher than for worker pupae, where it ranges between about 5–7 mF; and (c) location of the measuring electrodes; in the case of external-internal measurements, the values obtained were greater by 2 orders of magnitude than those obtained with both electrodes placed on the same side of the silk cap. In all cases, it was found that the capacitant values are high when compared with the size of the caps and the available commercial capacitors of the same size.The hornet comb may be regarded as comprised of an array of 3-dimensional capacitors linked in parallel, thereby forming a large dry battery having one negative pole — the pedicel — which grounds the comb, and one positive pole — the silk domes of the comb cells. The possibility that the electric energy stored in the comb cell walls may have a thermoregulatory function, serving both the brood and the adult nest population was discussed. We assumed that this mechanism is common for the combs of all social as well as many solitary wasps.     

Temperature distribution and electrical properties along the Oriental hornet body

The hornet is an endothermic insect. Daily variations in hornet surface temperature were measured. Three peaks were found between 9:30 and 10: 30 a.m., 11 and 12 a.m. and between 2 and 3 p.m. Electrical current and voltage values were highest along the head. Electrical current along the gaster and the head flowed towards the thorax, i.e., from body parts with minimal temperature towards the body part with maximal temperature. Current and voltage values measured across the cuticle of the gaster were about 5nA and 100 mV, respectively, and these were of the same order of magnitude as the current and voltage values along the cuticle. It was found that: 1) temperature regulation most probably originates in the thorax and 2) there is a correlation between the temperature distribution along the hornet body surface and levels of the cuticular electrical signals.     

European honeybee defense against Japanese yellow hornet using heat generation by bee‐balling behavior

The Japanese honeybee, Apis cerana japonica Radoszkowski, uses unique generation of heat by bee‐balling to defend against, overheat and kill predacious Japanese hornets. We have now observed the European honeybee, Apis mellifera Linnaeus, using similar bee‐balling behavior and heat generation against the Japanese yellow hornet, Vespa simillima xanthoptera Cameron. We monitored temperatures in the center of the bee‐ball and inside thoracic muscles of the captured hornet and found that the thoracic internal temperature (45.8 ± 2.32°C) was higher than that of the bee‐ball (44.0 ± 0.96°C). Although the thoracic temperature of captured hornets rose to the upper lethal level, defending European bees also showed some stinging attempts against the hornet, unlike the sympatric Japanese honeybee, which never stings during bee‐balling. The European honeybee bee‐balling behavior consists of three phases: (i) heating; (ii) heat‐retaining; and (iii) break up. Our results suggest that European honeybees kill hornets by raising the body temperature of hornets rapidly without stinging. The tactics of bee‐balling against hornets are complex and may be performed by extended division of labor.     

The effects of micro-gravity on hornet's nest building and activity

Principal scientific objectives: 1.) Comb building by hornet workers in micro-G: randomness of orientation, structural integrity, delay or rapidity of construction, all as a function of developmental state of the hornet. 2.) Dark-light effects on building hornets--will light provide building cues? 3.) Effect of domicile geometry on building practices--will the hornets build in spherical, domed or cube-shaped containers? 4.) Semiconductive properties of hornet cuticle and comb--will these be different than in the controls? Will the yellow granules developed in space be physico-chemically different from control granules? 5.) Post flight experiments--Will the hornets returned from space--build and oviposit as usual? Will the laid eggs embryonate? Will the comb be orientated as usual? How about other parameters of orientation (geotaxis) and social behavior (thigmotaxis)? Will there be any changes in the dominant gut microflora of returned hornets?     

Differences in heat sensitivity between Japanese honeybees and hornets under high carbon dioxide and humidity conditions inside bee balls

Upon capture in a bee ball (i.e., a dense cluster of Japanese honeybees forms in response to a predatory attack), an Asian giant hornet causes a rapid increase in temperature, carbon dioxide (CO?), and humidity. Within five min after capture, the temperature reaches 46°C, and the CO? concentration reaches 4%. Relative humidity gradually rises to 90% or above in 3 to 4 min. The hornet dies within 10 min of its capture in the bee ball. To investigate the effect of temperature, CO?, and humidity on hornet mortality, we determined the lethal temperature of hornets exposed for 10 min to different humidity and CO?/O? (oxygen) levels. In expiratory air (3.7% CO?), the lethal temperature was ≥ 2° lower than that in normal air. The four hornet species used in this experiment died at 44-46°C under these conditions. Hornet death at low temperatures results from an increase in CO? level in bee balls. Japanese honeybees generate heat by intense respiration, as an overwintering strategy, which produces a high CO? and humidity environment and maintains a tighter bee ball. European honeybees are usually killed in the habitat of hornets. In contrast, Japanese honeybees kill hornets without sacrificing themselves by using heat and respiration by-products and forming tight bee balls.     

Frequencies of the sounds produced by the oriental hornet, Vespa orientalis

Three distinct categories of sounds have been detected in the Oriental hornet colony: (a) hunger signals produced by the larvae, (b) tapping sounds produced by workers facing the queen, and (c) awakening taps produced by workers at a different rhythm than (b) (Ishayet al., 1974). These sounds have been analysed by means of a real time analyser. The possible correlation between the main frequencies of the various noises produced by the hornets and the absorption values of the hornet comb is discussed.     

Temperature dependence of the electrical resistivity of social wasp cuticle: A comparative study

Resistance to electricity by social wasp cuticle is temperature dependent within the range of 1–40°C. This was measured on the species Vespa orientalis (the Oriental hornet), Vespa crabro (the European hornet) and the wasp Dolichovespula saxonica. The resistance at first decreases with increased temperature, reaching a nadir which differs according to species, and then rises again up to 40°C, the highest temperature tested. It is suggested that the cuticular changes in resistivity at different temperatures reflect the wasp's mechanism for detecting and regulating the temperature in their normal environment.     

Hornet peak flight activity is correlated with solar UV radiation: a multi-annual survey

This study deals with the effect which solar irradiation of short wavelength, particularly ultraviolet (UV), exerts on the activities of hornets. The findings are based on multi-annual observations carried out during the years 1985, 1989 and 1998 on hornet nests in the field. At the peak of UV radiation, which occurs at noon, hornet activity is greater by 1-2 orders of magnitude than that during the morning or evening hours. The main visible hornet activity appears to be the removal of soil particles from the nest so as to enlarge its volume, enable the building of additional combs and also increase the size of existing combs. Hornet flight during peak insolation hours is characterized by its briefness (5-20 seconds only) and brevity (to distances of 5-10 meters only) as compared to flights at other hours of the day. These prolonged, multi-annual observations lead to the conclusion that hornets are capable of converting the energy of UV radiation into a form amenable to metabolic usage. In this respect the hornet cuticle behaves as a thermophotovoltaic device, i.e., a semiconductor diode that converts photons radiating from the sunlight into electrical energy.     

Temperature dependence of the electrical resistance of hornet cuticle: A statistical model

The electric resistance to d.c. of the yellow strips in the cuticle of worker hornets was measured in the dark under temperature changes within the optimal range of activity outside the nest (10–32°C). A distinct inverse correlation was observed between the resistance and the temperature, the former decreasing with rise of the latter. In all, each individual hornet measured was subjected to four successive cycles of measurement during which the specimens underwent warming followed by cooling. A slight unidirectional rise in the resistance both during warming and cooling was observed between two successive cycles. A typical thermal hysteresis loop formed between the warming and cooling lines, thus suggesting a memory effect.     

Thermoelectric (seebeck) effect of the cuticle of social wasps

The thermoelectric (Seebeck) coefficient ($\text{S =}\text{ΔV}\text{ΔT}$) in various cuticular areas of the Oriental hornet (Vespa orientalis) fluctuates from 0·3 to 2·4 mV deg^?1 within a temperature range of 27–36°C and when the temperature difference between the two measuring electrodes (ΔT) is 0·6–8·0°C. The values measured on the brown-colored cuticle suggest an n-type conduction, while those measured on the yellow-colored cuticle point to a p-type conduction. It is suggested hornets use this phenomenon for temperature detection.     

Der Einfluß der Umgebungstemperatur auf Motilität,Körpertemperatur und Sauerstoffverbrauch von normalen und Pervitin-behandelten Mäusen

Single mice were kept in various ambient temperatures (15° to 35° C) and motility, oxygen consumption, and body temperature were recorded. Untreated animals: Motility was least at 25° C room temperature. Relations between motility and body temperature were linear at all ambient temperatures. The body temperatures of very agile mice did not vary at ambient temperatures from 15° to 30° C whereas that of quiet mice was strongly influenced by the milieu. The relations between oxygen consumption and body weight were also linear at all ambient temperatures; the corresponding regression coefficients decreased progressively with rising ambient temperatures. Oxygen consumption increased at a constant rate with motility, independent of ambient temperatures. Animals treated with methamphetamine: The LD₅₀ of methamphetamine decreased considerably with rising ambient temperature. The influence on body temperature of methamphetamine was very variable and depended on both dose and ambient temperature. Toxic doses of methamphetamine induced hyperthermia in warm surroundings and hypothermia in a cool milieu. Under the influence of methamphetamine, oxygen consumption increased or decreased considerably with the body temperature. Ambient temperatures exerted an essential influence on the cause of death after toxic doses of methamphetamine.     

The effects of ligation of the oesophagus on body and brain temperature in pigeons

1. We measured brain and colonic temperatures in adult pigeons (Columba livia) with or without oesophageal ligation, and with or without simultaneous eye covering at ambient temperatures between 24 degrees C and 45 degrees C. 2. Colonic and brain temperatures rose at the higher ambient temperatures; the temperature elevations were no different in pigeons with oesophageal ligation, compared to sham-operated controls. The presence of simultaneous eye covering also had no effect on colonic or brain temperatures. 3. Oesophageal inflation decreased from a rate of 2.8 +/- 1.4 per minute (mean +/- SEM) to zero, in anaesthetized pigeons when warmed from a colonic temperature of 40.5 degrees C to 43.8 degrees C. 4. In pigeons oesophageal inflation plays no significant part in body temperature regulation or in the maintenance of a lower brain than body temperature even in hot ambient conditions.