Tiger Beetle Larvae Research Articles

The description of the tiger beetle larvae of Cosmodela aurulenta (Fabricius, 1801)(Coleoptera, Cicindelidae)

All larval instars of the tiger beetle species Cosmodela aurulenta aurulenta (Fabricius, 1801) which is the type species of the genus Cosmodela Rivalier, 1961 are described and illustrated here for the first time, based on material from Bali Island (Indonesia). A brief review of habitat preferences and ecology for adults and larvae of Cosmodela aurulenta are provided. Differences between C. aurulenta and C. batesi (Fleutiaux, 1893) and allied Palaearctic genera of the subtribe Cicindelina are discussed. The preliminary key of known larvae of relevant genera and subgenera of the Oriental Region is given.

Fishing for Tigers: A Method for Collecting Tiger Beetle Larvae Holds Useful Applications for Biology and Conservation

A series of field studies examined the effectiveness of using a grass blade/stem to extract tiger beetle larvae (Coleoptera: Carabidae: Cicindelinae) from their burrows without damaging the larva or the burrow — a procedure often called fishing. We found that larvae of many species can be efficiently sampled at rates equal to or exceeding other methods. Extracted larvae have a low percentage of injury and can be assessed for parasitism and condition. They can be returned to either their own burrow or an alternative burrow where they can be re-sampled. The results of these studies indicate that fishing for tiger beetle larvae can be an effective tool for monitoring populations where larvae can be returned to existing burrows. In addition, the fishing technique allows for relocation of organisms while eliminating the impacts associated with excavating threatened species or larvae from rare habitats.

Hypoxia Tolerance in Adult and Larval Cicindela Tiger Beetles Varies by Life History but Not Habitat Association

Abstract Flooding exposes terrestrial organisms to severe hypoxia. Among the best- studied insects that are frequently exposed to flooding are tiger beetle (Coleoptera: Cicindelidae) larvae. In previous studies with a limited number of species, a correlation was found between habitat and hypoxia tolerance. In the current study, we examined hypoxia tolerance among third instars of six Cicindela species that vary in habitat association; we also tested adult survival of these species. We found that larvae of the different species survived an average of between 60 and 120 h of submersion in severely hypoxic water at 20°C, with larvae that occur in dry sand having somewhat lower survival times. However, among larvae, there was no correlation between survival times and habitat risk of flooding. We found surprisingly high survival times among adult tiger beetles with a range of 10 h to 46 h. Adult Cicindela formosa formosa Say that are associated with dry sand and are active in the spring and fall survived submersion for >40 h, longer than any previously reported adult terrestrial insect exposed to hypoxia at moderate environmental temperatures. The lengthy survival times of adult tiger beetles are likely a result of adaptations to immersion during periods of inactivity. Our study suggests that additional insect species and life stages should be examined for hypoxia tolerance regardless of perceived threat of immersion.

Spatial density‐dependent survival and development at different larval stages of the tiger beetle Cicindela japonica (Thunberg)

AbstractConspecific competition is an important component of the ecological processes of many species. In the case of sessile consumers, high population densities lead to competition within conspecific populations that, in turn, affect the survival, growth, and reproduction of the individuals involved. This study quantified neighborhood crowding and evaluated the extent of density effects on a tiger beetle (Cicindela japonica Thunberg) population by monitoring individually identified larvae at regular intervals. As an index of conspecific competition, the neighborhood density (the number of other larvae within a given radius for each larva) of each individual was measured. The radius size representing the highest mean coefficient of variation of density was determined as a suitable scale for detecting the density effects. Multiple logistic regression analysis was carried out to evaluate the effects of three factors (neighborhood density, prey abundance, and environmental influences) on larval survival and development. The analysis revealed that the neighborhood density significantly influenced the survival and development of larvae through every larval stage from the first to the third‐instars. Moreover, the neighborhood density had a stronger influence on larvae of the same instar as compared to that on those of different instars. Our results suggest that density‐dependent mortality affects the tiger beetle larvae due to the lifestyle pattern of these sedentary, ambushing predators that exhibit an aggregated spatial distribution.

Morphological and optical properties of the corneal lens and retinal structure in the posterior large stemma of the tiger beetle larva

The morphological and optical features of the corneal lens and retina have been examined in the posterior large stemma of the larva of the tiger beetle ( Cicindela chinensis). A cup-shaped retina was positioned 55 ± 6 μm beneath the posterior margin of the corneal lens, which was 479 ± 20 μm in diameter and 391 ± 18 μm in thickness ( n = 41). A light path through an isolated corneal lens showed that the object at infinite distance was focused on the distal margin of the retina. Geometrical optics gave a value of 334 ± 15 μm ( n = 55) for the posterior focal length of the corneal lens. The refractive index of the corneal lens was estimated to be around 1.8, if the lens was considered to be homogenous in structure. The internal structure of the lens, including concentric lamellae, was presumed to contribute to such a high refractive index, because this was higher than that of insect cuticle. The retinal structure and how images were blurred at different focus levels were also examined. Data obtained for optics of the corneal lens and retinal structures are discussed with reference to the distinct visual behavior of the larva.

Morphological and physiological identification of medulla interneurons in the visual system of the tiger beetle larva.

The morphology of visual interneurons in the tiger beetle larva was identified after recording their responses. Stained neurons were designated as either medulla or protocerebral neurons according to the location of their cell bodies. Medulla neurons were further subdivided into three groups. Afferent medulla neurons extended processes distally in the medulla neuropil and a single axon to the brain through the optic nerve. They received their main input from stemmata on the ipsilateral side. Two distance-sensitive neurons, near-by sensitive and far-sensitive neurons, were also identified. Atypical medulla neurons extended their neurites distally in the medulla and proximally to the brain, as afferent medulla neurons, but their input patterns and the shapes of their spikes differed from afferent neurons. Protocerebral neurons sent a single axon to the medulla neuropil. They spread collateral branches in the posterior region of the protocerebrum on its way to the medulla neuropil. They received main input from stemmata on the contralateral side. Medulla intrinsic neurons did not extend an axon to the brain, and received either bilateral or contralateral stemmata input only. The input patterns and discharge patterns of medulla neurons are discussed with reference to their morphology.

Responses of medulla neurons to illumination and movement stimuli in the tiger beetle larvae.

Intracellular responses of medulla neurons (second-order visual interneurons) have been examined in the tiger beetle larva. The larva possesses six stemmata on either side of the head, two of which are much larger than the remaining four. Beneath the cuticle housing the stemmata an optic neuropil complex occurs consisting of lamina and medulla neuropils. Response patterns of medulla neurons to illumination and moving objects varied from neurons to neurons. For movement stimuli black discs and a black bar were moved in the rostro-caudal direction above the larva. Comparison of responses to the discs and the bar suggested a spatial summation of responses in some neurons, and tuning to small objects in some neurons. The majority of neurons responded to objects moving at heights of 10 mm and 50 mm with the same discharge pattern. A few neurons, however, showed distance sensitivities responding with an increase of spike discharges to moving objects only at either of the two heights. Such distance sensitivities still remained in one-stemma larvae, three of the four stemmata being occluded. These data are discussed in relation to distinct visual behavior of the larva and with special reference to perception of the hunting range.

Behavioural responses of the tiger beetle larva to moving objects: role of binocular and monocular vision.

The larva of the tiger beetle Cicindela chinensis is an ambushing hunter with a body length of 15-22 mm that lives in a tunnel in the ground. It ambushes prey, keeping its head horizontal at the opening of the tunnel. When prey approaches the tunnel, the larva jumps to snap at it. When an object moves beyond its jumping range (approximately 15 mm), however, the larva quickly withdraws deep into the tunnel. These responses are mediated by two of six pairs of stemmata. How does the larva judge the hunting range using such a simple visual system? A previous study suggested that both binocular and monocular vision are used for distance estimation. Range estimation by binocular vision was further confirmed in the present behavioural observations: larvae jumped towards objects beyond the normal hunting range when virtual images of such distant objects were formed close to the larva using prisms or a narrow window. A possible mechanism involved in range estimation by monocular vision was also examined in behavioural experiments. The depth of the image in the retina appears to play a role in distance estimation because a larva with one functional stemma, the other stemmata being occluded, changed its response to a very distant object from an escape to a predatory jump when a concave lens was placed above its head. Two alternative ideas, based on optical and morphological data, are proposed to explain this behavioural change by the one-stemma larvae. First, as for myopic people, the larva might see clearly only objects that are close. Second, an infinitely distant object might produce a focused image only on the central part of the retina, whereas an object within hunting range (<15 mm) might do so on surrounding regions of the retina. The latter idea implies that the region of the retina at which the larva perceives a clear image is concerned with which type of behaviour is released, a predatory jump or an escape. We conclude that visual information about hunting range in the tiger beetle larva is extracted both peripherally by the spatial pattern of image clarity and centrally by binocular vision.

Anoxia tolerance of con-familial tiger beetle larvae is associated with differences in energy flow and anaerobiosis.

In this study, we compared survivorship, heat dissipation and biochemical features of anaerobiosis of two tiger beetle species (Coleoptera: Cicindelidae) exposed to anoxia. One species commonly experiences environmental immersion from rainfall and snowmelt (Cicindela togata), and the habitat of the other (Amblycheila cylindriformis) is not prone to flooding. The ancestral genus, A. cylindriformis, survives anoxia for only 2 days at 25 degrees C. In response to anoxia, these larvae immediately lose locomotory abilities, tissue concentrations of ATP fall precipitously within 12 h, and significant amounts of lactate are quickly produced. In contrast, C. togata larvae tolerate anoxia for 5 days. Heat dissipation is downregulated to a greater degree than that seen in A. cylindriformis (3.4% versus 14% of standard normoxic rate, respectively), the ability for locomotion is maintained and normoxic levels of ATP are defended for at least 24 h. Lactate is not accumulated until well into anoxic bout, and significant amounts of alanine are also produced. This study provides evidence that tiger beetles differ in physiological responses to anoxia, and that these differences are correlated with flooding risk and with species distribution.

Survival of Immersion and Anoxia by Larval Tiger Beetles, Cicindela togata

Abstract The sedentary terrestrial larvae of the tiger beetle, Cicindela togata, inhabit areas that are often flooded for days or weeks. We tested the ability of these larvae to survive immersion and anoxia. Maximum survival time of immersed, anoxic C. togata was 6 days at 25 C. Time to 50% mortality (LT50) in these conditions was 85.9 ± 23.5 h. Survival times were more than eight times longer than those of similarly treated larvae of Tenebrio molitor (LT50 10.1 ± 3.2 h). Similar or somewhat longer survival times were observed in larvae of C. togata exposed to an anoxic nitrogen atmosphere (LT50 102 ± 31 h) and of T. molitor (LT5014.4 ± 6.5 h). At 10 C, LT50 of C. togata in anoxic atmospheres exceeded 10 days. Tiger beetle larvae are physiologically capable of surviving several days of inundation during floods without mechanisms to prevent burrow flooding. By entering a quiescent state, C. togata larvae survive much longer periods of anoxia than has been previously reported for terrestrial insect larvae.

Behavioral analysis of two distinct visual responses in the larva of the tiger beetle ( Cicindela chinensis )

The tiger beetle larva shows two distinct visual responses, a predatory jump and an evasive withdrawal into the burrow (escape). In the present study the visual stimuli controlling these two responses have been behaviorally analyzed in the larva of Cicindela chinensis. The threshold size needed for a target to elicit both responses is a visual angle of 5–7°. The velocities of moving targets needed to elicit the responses are 0.4–33° s−1 for the jump and 0.76–90° s−1 for the escape. Choice between the two responses appears to be controlled by the actual target size rather than by the angular size. It also appears to be controlled by the target height. As the height of the target increases, the probability for the jump decreases, whereas the probability for the escape increases. Response properties of the larva with only a single functional stemma, the other stemmata being occluded, are different from those of the intact larva, which suggests cooperation of at least two stemmata for the release of different visual responses. Visual responses of the one-stemma larva still vary, however, with target size and target height, which suggests the visual responses are partially controlled even by a single stemma. Although our data do not resolve these conflicting results, more than one stemma is necessary for a firm choice between the two responses.

Water relations of tiger beetle larvae (Cicindela marutha): correlations with habitat microclimate and burrowing activity

Rates of water loss/gain for third instar larvae of the tiger beetle Cicindela marutha Dow were measured at various temperatures and humidities. The larvae occupy burrows in exposed hot, dry sand ridges. They are active at the surface at midday during spring and fall, but plug their burrows during the summer day and become active only at night. Water loss rates increase moderately with increasing temperatures (25 to 40°C) and show a consistent decline with increasing relative humidity (0 to 97·5%). The larvae do not absorb sufficient atmospheric moisture at any of the high humidities to offset water lost via transpiration; however, they ingest moist sand while burrowed and absorb the water from their digestive tract. This uptake mechanism supplements water obtained from prey, whose availability is limited, and also enables them to remain in positive water balance during times that microclimatic conditions prevent them from feeding on the surface.

Visual determinants of escape in tiger beetle larvae (Cicindelidae)

Larvae of tiger beetles (Coleoptera: Cicindelidae) are burrow-dwelling, visual ambush predators which withdraw into their burrows with the passing of large objects. Laboratory experiments confirmed that stimulation of each of the four principal stemmata can elicit escape and that the necessary visual stimulus is contracting, expanding, or transverse movement of a high-contrast image. Response frequency increases as a power function of contrast. Whole-field dimming is ineffective. Movement of large images composed of multiple texture elements, e.g., checkerboards, does not elicit escape, even if each element is much larger than the system's minimum visible angle (4–8° depending upon image contrast). In pilot experiments with a single figure before a textured background, coherent movement of the two inhibits escape, whereas motion in opposite directions does not. Thus, the processing mechanism functions as a feature detector and directs a response to large, single, moving objects.

Respiratory gas concentrations in the microhabitats of some florida arthropods

1. 1. The concentrations (dry gas %) of oxygen and carbon dioxide were measured in a variety of microhabitats of arthropods in Florida: at the ends of the burrows of three spider species ( Sphodros abboti, Geolycosa micanopy, Cyclocosmia torreya) and a tiger beetle ( Megacephala carolina) larva, within ant ( Solenopsis invicta) mounds, within stumps inhabited by termites ( Reticulitermes flavipes), and within and under decaying hardwood logs. 2. 2. Hypoxia and hypercarbia occurred in all microhabitats, with the ratio of oxygen decrement to carbon dioxide increment close to one. Changes for both gases were minor in the spider burrows, under decaying logs, and within ant mounds (<2.3% for O 2 and 1.1% for CO 2) and are probably physiologically unimportant to their inhabitants. 3. 3. In contrast, %O 2 fell to as low as 12–14%, and CO 2 rose to as high as 6–8%, in the burrows of tiger beetle larvae, within decaying logs, and inside decaying stumps inhabited by termites. 4. 4. Such changes, particularly for CO 2 may present a challenge to organisms living in these microenvironments. 5. 5. Approximately 20–25% of the changes in the concentrations of respiratory gases in the burrows of tiger beetle larvae are attributable to the metabolism of the larva, the remainder being due to diffusional exchanges with the soil.

Miocene invertebrate trace fossils from a braided river environment, western Nebraska, U.S.A

Lower Miocene cross-stratified sands of the Gering and Monroe Creek Formations exposed on Scotts Bluff National Monument in western Nebraska, U.S.A., were deposited by migrating sand bars in a braided river system similar to the modern Platte River in eastern Nebraska and, like the Platte, contain local lenses of parallel stratified sediment that accumulated in ponded areas of abandoned channels. During times of low discharge, broad areas of river bar sands and abandoned channel sediments were subaerially exposed on the Miocene river plain. These sediments, like those exposed in the Platte River today, were subjected to burrowing by insects and other animals. Trace fossils in Lower Miocene braided river deposits are: vertical shelter burrows, horizontal deposit-feeding burrows, bioturbated layers, and vertical passageways between bioturbated layers. The burrows are cylindrical to sub-cylindrical in cross-section, internally meniscate or massive, generally non-branching, and smooth walled. Shelter burrows are similar in shape and size to recent burrows dug by beetles in river sediment for protection from day-time temperatures, to pass the night, and to hibernate. The shelter burrows, deposit-feeding burrows, and vertical passageways in the Lower Miocene sediments occur in four distinct “populations” with modal diameters of 1–2, 3–4, 7–8, and 10–12 mm. The occurrence of both vertical and horizontal burrows in all four “populations” suggests that they could have been made by the same insect. “Populations” with modal diameters of 1–2, 3–4, and 7–8 mm also occur in modern Platte River sediment and are made by tiger-beetle larvae (3–4 mm) and heterocerid (1–2 mm) beetles. Miocene shelter burrows, deposit-feeding burrows, bioturbated layers, and vertical passageways, therefore, could have been formed by different types of beetles, and/or larval instars and adults of the same beetle species.

Observations on the “ Furau ” (Cicindelidae) of Northern Nigeria

In the “ Furau,” or Tiger-beetle larva of Nigeria, the digestion of the prey is mainly extra-intestinal. A dark brown slightly acid fluid, which is actively proteolytic and causes blackening of the tissues, is ejected from the intestine of the larva and dissolves the tissues of the prey. The resulting fluid is swept towards the mouth by the labium and re-ingested.The bites of the larvae had no effect upon the skin of a monkey or of man, and there is little doubt that the larvae have no relation to the inflammatory lesion of the foot of man, which also is called “ Furau ” in Northern Nigeria.