Ultrastructure of the larval eye of the scorpionfly Panorpa dubia (mecoptera: Panorpidae) with implications for the evolutionary origin of holometabolous larvae

The evolutionary origin of holometabolous larvae is a long‐standing and controversial issue. The Mecoptera are unique in Holometabola for their larvae possessing a pair of compound eyes instead of stemmata. The ultrastructure of the larval eyes of the scorpionfly Panorpa dubia Chou and Wang, 1981 was investigated using transmission electron microscopy. Each ommatidium possesses a cornea, a tetrapartite eucone crystalline cone, eight retinula cells, two primary pigment cells, and an undetermined number of secondary pigment cells. The rhabdomeres of the eight retinula cells form a centrally‐fused, tiered rhabdom of four distal and four proximal retinula cells. The rhabdomeres of the four distal retinula cells extend distally into a funnel shape around the basal surface of the crystalline cone. Based on the similarity of the larval eyes of Panorpidae to the eyes of the hemimetabolous insects and the difference from the stemmata of the holometabolous larvae, the evolutionary origin of the holometabolous larvae is briefly discussed. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

昆虫单眼的结构和功能

大多数昆虫的视觉器官除了复眼外还有一些简单的小眼,称为单眼。昆虫成虫和半变态类若虫的单眼称为背单眼,位于头顶两复眼之间。背单眼在数目和结构上都有较大变化,但基本结构包括角膜晶体、一层角膜生成细胞(覆盖在角膜晶体上)、视网膜(由大约1000个感光细胞构成,视类群而不同)。背单眼对弱光比较敏感,但在图像感知方面的作用并不显著;它是一种“激发器官”,可以增加复眼的感知能力。全变态昆虫的幼虫既没有复眼也没有背单眼,但在其头部两侧有些类似复眼小眼的侧单眼。侧单眼的结构也与小眼相似,包括角膜,晶体和由一些视网膜细胞组成的视杆。侧单眼是完全变态类昆虫幼虫仅有的感光器官,与复眼一样,它们可以感知颜色、形状、距离等等。     

On display behaviour and courtship in the praying mantis Ephestiasula amoena (Bolivar)

Display behaviour in a small species of Indian praying mantis, Ephestiasula amoena , is described and the possible role of this display in courtship is discussed. The display involves exposure of the bright pattern on the inside face of the expanded plate-like profemora. The profemoral patterns found in closely related species are discussed and it is suggested that the display may also play a role in species recognition. The courtship behaviour of E. amoena is contrasted and compared with the courtship of other species of praying mantis.     

Phylogeny of the Myriapoda – Crustacea – Insecta: a new attempt using photoreceptor structure*

According to molecular sequence data Crustacea and not Myriapoda seem to be the sister‐group to Insecta. This makes it necessary to reconsider how the morphology of their eyes fit with these new cladograms. Homology of facetted eye structures in Insecta (Hexapoda in the sense of Ento‐ and Ectognatha) and Crustacea is clearly supported by identical numbers of cells in an ommatidium (two corneageneous or primary pigment cells, four Semper cells which build the crystalline cone and primarily eight retinula cells). These cell numbers are retained even when great functional modification occurs, especially in the region of the dioptric apparatus. There are two different possibilities to explain differences in eye structure in Myriapoda depending on their phylogenetic position in the cladogram of Mandibulata. In the traditional Tracheata cladogram, eyes of Myriapoda must be secondarily modified. This modification can be explained using the different evolutionary pathways of insect facetted eyes to insect larval eyes (stemmata) as an analogous model system. Comparative morphology of larval insect eyes from all holometabolan orders shows that there are several evolutionary pathways which have led to different types of stemmata and that the process always involved the breaking up the compound eye into individual larval ommatidia. Further evolution led on many occasions to so‐called fusion‐stemmata that occur convergently in each holometabolic order and reveals, in part, great structural similarities to the lateral ocelli of myriapods. As myriapodan eyes cannot be regarded as typical mandibulate ommatidia, their structure can be explained as a modified complex eye evolved in a comparable way to the development to the fusion‐stemmata of insect larvae. The facetted eyes of Scutigera (Myriapoda, Chilopoda) must be considered as secondarily reorganized lateral myriapodan stemmata, the so‐called ‘pseudo‐compound eyes’. New is a crystalline cone‐like vitreous body within the dioptric apparatus. In the new cladogram with Crustacea and Insecta as sister‐groups however, the facetted eyes of Scutigera can be interpreted as an old precursor of the Crustacea – Insecta facetted eye with modified ommatidia having a four‐part crystalline cone, etc. as a synapomorphy. Lateral ocelli of all the other Myriapoda are then modified like insect stemmata. The precursor is then the Scutigera‐Ommatidium. In addition further interpretations of evolutionary pathways of myriapodan morphological characters are discussed.     

Small or far away? Size and distance perception in the praying mantis

Stereo or ‘3D’ vision is an important but costly process seen in several evolutionarily distinct lineages including primates, birds and insects. Many selective advantages could have led to the evolution of stereo vision, including range finding, camouflage breaking and estimation of object size. In this paper, we investigate the possibility that stereo vision enables praying mantises to estimate the size of prey by using a combination of disparity cues and angular size cues. We used a recently developed insect 3D cinema paradigm to present mantises with virtual prey having differing disparity and angular size cues. We predicted that if they were able to use these cues to gauge the absolute size of objects, we should see evidence for size constancy where they would strike preferentially at prey of a particular physical size, across a range of simulated distances. We found that mantises struck most often when disparity cues implied a prey distance of 2.5 cm; increasing the implied distance caused a significant reduction in the number of strikes. We, however, found no evidence for size constancy. There was a significant interaction effect of the simulated distance and angular size on the number of strikes made by the mantis but this was not in the direction predicted by size constancy. This indicates that mantises do not use their stereo vision to estimate object size. We conclude that other selective advantages, not size constancy, have driven the evolution of stereo vision in the praying mantis.This article is part of the themed issue ‘Vision in our three-dimensional world’.     

Behavioural interactions between the lizard <Emphasis Type="Italic">Takydromus tachydromoides</Emphasis> and the praying mantis <Emphasis Type="Italic">Tenodera aridifolia</Emphasis> suggest reciprocal predation between them

The Japanese lacertid lizard Takydromus tachydromoides and the praying mantis Tenodera aridifolia are sympatric generalist predators feeding on similar prey. To confirm reciprocal predation between them, we observed the behavioural interactions between the lizards and the mantises of different sizes in a laboratory condition. The lizards caught small mantises (from first to fifth instars), but sometimes escaped from large mantises (from sixth instar to adult). Large mantises occasionally showed catch responses to the lizards. The lizards sometimes caught the mantis without a tongue-flick response (sampling of chemical cues), and they sometimes did not catch the small mantises showing immobile or cryptic responses that prevent visual detection. These results suggested the primary role of vision on recognition of the mantis as a prey. The lizards spent a longer time to approach larger mantises. The time from orienting to catch was longer when the lizards showed tongue-flick responses. The lizard also spent a longer time before deciding to escape from the mantis than to catch it. Biological significance of these differences in timing was discussed.     

Photoperiodic response of larvae of the yellow-spotted longicorn beetle Psacothea hilaris after removal of the stemmata

The role of the stemmata in photoperiodism has been examined in holometabolic insects, but the only reliable results in Coleoptera have been obtained in Leptocarabus kumagaii (Carabidae), the larvae of which do not respond to photoperiod without stemmata. In the present study, photoperiodism was examined in another coleopteran, Psacothea hilaris (Pascoe) (Cerambycidae), after surgical removal of the stemmata. Larvae reared under short-day conditions and transferred to long-day conditions on day 2 of the 5th instar pupated without further larval molts, whereas those continuously reared under short-day conditions underwent supernumerary molts and did not pupate. When the stemmata were removed on day 2 of the 5th instar, the larvae pupated under long-day conditions but did not do so under short-day conditions. However, under long-day conditions some underwent supernumerary molts before pupation. Larvae from which the sensilla trichodeum were removed showed a similar response to that of stemmata-deficient larvae, and larvae from which stemmata were removed at a younger stage (day 2 of the 4th instar) responded to photoperiod similarly to intact larvae. Thus, supernumerary molts under long-day conditions after removal of the stemmata were attributed to injury due to surgery, rather than a change in photoperiodic photoreception. Therefore, we conclude that larvae of P. hilaris show a photoperiodic response after removal of stemmata, in contrast to larvae of L. kumagaii.     

Eye and optic lobe metamorphosis in the sunburst diving beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae)

Nearly nothing is known about the transition that visual brain regions undergo during metamorphosis, except for Drosophila in which larval eyes and the underlying neural structure are strongly reduced. We have studied the larvae of the sunburst diving beetle, Thermonectus marmoratus (Coleoptera: Dytiscidae), which are sophisticated visually oriented predators characterized by six elaborate stemmata on each side of the head and an associated large optic lobe. We used general neurohistological staining and 3D reconstruction to determine how the eyes and optic lobe of T. marmoratus change morphologically during metamorphosis. We find that in third (last) instar larvae, the adult neuropils are already forming de novo dorsally and slightly anteriorly to the larval neuropils, while the latter rapidly degenerate. Larval eyes are eventually reduced to distinct areas with dark pigmentation. This complete reorganization, which may be an evolutionarily conserved trait in holometabolous insects, occurs despite the considerable costs that must apply to such a visually complex animal. Our findings are consistent with the concept that stemmata are homologous to the most posterior ommatidia of hemimetabolous insects, an idea also recently supported by molecular data.     

Similar yet different: differential response of a praying mantis to ant‐mimicking spiders

Batesian mimics typically dupe visual predators by resembling noxious or deadly model species. Ants are unpalatable and dangerous to many arthropod taxa, and are popular invertebrate models in mimicry studies. Ant mimicry by spiders, especially jumping spiders, has been studied and researchers have examined whether visual predators can distinguish between the ant model, spider mimic and spider non‐mimics. Tropical habitats harbour a diverse community of ants, their mimics and predators. In one such tripartite mimicry system, we investigated the response of an invertebrate visual predator, the ant‐mimicking praying mantis (Euantissa pulchra), to two related ant‐mimicking spider prey of the genus Myrmarachne, each closely mimicking its model ant species. We found that weaver ants (Oecophylla smaragdina) were much more aggressive than carpenter ants (Camponotus sericeus) towards the mantis. Additionally, mantids exhibited the same aversive response towards ants and their mimics. More importantly, mantids approached carpenter ant‐mimicking spiders significantly more than often that they approached weaver ant‐mimicking spiders. Thus, in this study, we show that an invertebrate predator, the praying mantis, can indeed discriminate between two closely related mimetic prey. The exact mechanism of the discrimination remains to be tested, but it is likely to depend on the level of mimetic accuracy by the spiders and on the aggressiveness of the ant model organism.     

Visual deprivation and distance estimation in the praying mantis larva

Abstract. Young larvae of the praying mantis, Tenodera sinensis Saussure, were placed on an off-centre island surrounded by a round arena with six black bars painted on a white inner wall. In this situation, it was shown that the horizontal peering movements of the head often seen in mantids are in fact used to measure distances; motion parallax may be involved in this process. Aimed jumps that followed peering were taken to be the distinct result of an absolute distance measurement. Specific visual deprivation such as painting over of certain parts of the eye with opaque black varnish or degeneration of the fovea with sulforhodamine showed that: absolute evaluation of distance is only possible with two fully intact eyes; the peering mechanism is under visual control; and visual experience has a long-term effect on distance measurement involving peering movements.     

Seasonal aspects of sexual cannibalism in the praying mantis (<Emphasis Type="Italic">Mantis religiosa</Emphasis>)

According to the adaptive foraging hypothesis of sexual cannibalism, females face a trade-off between mating and consuming a courting male. Because male and prey availability can change seasonally, sexual cannibalism may change with season. However, we are not aware of any work examining how sexual cannibalism in insects relates to the time of season. Here, we examined the seasonal pattern of sexual cannibalism and reproductive behaviour in the sexually cannibalistic praying mantis (Mantis religiosa). We repeatedly collected the last instars of praying mantises from the field and brought them up under natural weather and photoperiod, but standardised feeding and socioecological conditions. After the females reached sexual maturity, we allowed all of the females to mate during two mating trials. In comparison to female praying mantises maturing later in the season, early-maturing females were larger but of poorer body condition on the day of a mating trial (20 days after the adult moult). During the first round of mating trials, early-maturing virgin females cannibalised males more frequently than their late-maturing counterparts. In contrast, late-maturing females that mated in the first round of mating trials were more likely than early-maturing, nonvirgin females to be cannibalistic in the second round of mating trials. The latency time until copulation was correlated with a risk of sexual cannibalism and was longer in early-maturing females. Our study suggests that the date of the last (adult) moult plays an important role in the occurrence of sexual cannibalism.     

Evolutionswege zum Larvalauge der Insekten -Die Stemmata der höheren Dipteren und ihre Abwandlung zum Bolwig-Organ

Evolutionary pathways to the larval eyes of insects. Higher Dipteran stemmata and the evolutionary development of Bolwig's organ 1. A cornrehensive morphological study of the photoreceptors in the so-called hemi — Institut für Biologie I (Zoologie) der Albert-Ludwigs-Universität, Albertstr. 21a, D-7800 Freiburg i. Brsg., FRGand acephalic lrvae of Brachycera was undertaken. In Brachyceran larvae the head casule originally is more or less retracted into the thorax. The larval hotoreceptor in Musca and Drosophila, here called Bolwig's organ, is situated on the outer side of the cephalopharyngeal apparatus, well below the surface. The aim of this study is to elucidate the homology of Bolwig's organ, i. e. whether Bolwig's organ originated from typical stemmata during the evolution of Cyclor-rhaphan larval organlsation or whether it represents a unique type of hotoreceptor. Larval photoreceptors and the anatomy of the head capsules of representative Erachycerans were examined by means of light and electron microscopy. In particular, the site and the structure of the photofecetors of Stratiomys (Stratiomyidae, Solva (Solvidae), Atherix ibis (Athericidae), Rhagio (Rhagionidae), Thereva (derevidae), Lonchoptera (Lonchoteridae), Epistrohe balteata, Volu-cella bombylans, Eristalis tenax (Syrphidae), Drosophila (f;rosophilidae), jannia and Musca domestica (Muscidae) were investigated. 2. Brachyceran stemmata are either situated on the ocular plates of the free remnant of the head (Stratiomyidae, Therevidae), or on the inner wall of an epidermal invaination, which includes epithelia of the head as well as of the thorax (Tabaniformia). In adfition, they can be found on the outer side of the tentorial phragmata (Cyclorrhapha). In all taxa studied, stemmata keep contact directly with the epithelium or through short processes of eithelial cells. 3. Ancestral Brachycera have fused stemmata that correspond with typical larval eyes of other holometabolan insects. 4. A cornea is found solely in Stratiomyidae and Xylophagidae, in contrast to all other taxa, where no dioptric apparatus is found. 5. In “Orthorrapha” and in “Aschiza”, rhabdomeric photoreceptors occur, forming a fused, star-shaped or Ktticed rhabdom. In Schizophoran larvae, retinular cells are distinguished by a different type of surface enlargement of the photoreceptor cell membrane. Here, the membrane forms flat ramella. The latter originate from transformed and/or rudimentary rhabdomeric microvilli. 6. In the primitive “Orthorrhapha”, pigment cups can be found, that are composed of retinular pirnent, whereas in derived Brachycera, pigment grains are absent. In Cyclorrhapha, tentorial piramata and their optic deressions operate as external and functional piment cups 7. In Therevidae and in Syrphidae, a tracheal tapetum lucidum can be founfi which la, been evolved independently in both families. The tapetum is always found together with inversely orientated retinular cells. 8. The homology of Brachceran stemmata is shown by a transformation series of stem-mata's site and fine structure. The homology is corroborated by the identical innervation in primitive and derived taxa, the identical site within Cyclorrhaha, and structural similarities of “Orthorrhaphan” and primitive Cylorrhaphan stemmata. Although transformations of the fine structure appear as a sequence or reductions, particular adaptations such as multilication of retinular celfs (Epistrophe), or deepening of the pigment cup (Musca) have evolved separately. Despite the fact that in Brachyceran larvae the head has been reorganized, the eyes still keep contact with the epithelium of the frontal sacks and/or tentorial phragmata. 9. The transformation series given shows that Bolwig's organ represents a highly modified stemma.     

The number of stripes on the compound eyes reflects each instar in <Emphasis Type="Italic">Acromantis satsumensis</Emphasis> (Mantodea: Hymenopodidae)

The praying mantis genus Acromantis is characterized by its compound eyes with stripe patterns in the Japanese Mantodea. In the laboratory, we observed that the 1st instar nymphs of Acromantis satsumensis Matsumura had a single stripe on their compound eyes, and one more stripe appeared on both of their compound eyes when they became 2nd instar nymphs. Likewise, the 3rd instars had 3 stripes, the 4th instars had 4 stripes, and so on. These results suggest that the stripe patterns on the compound eyes increase one by one with each molt in A. satsumensis.     

Internal state effects on behavioral shifts in freely behaving praying mantises (Tenodera sinensis)

How we interact with our environment largely depends on both the external cues presented by our surroundings and the internal state from within. Internal states are the ever-changing physiological conditions that communicate the immediate survival needs and motivate the animal to behaviorally fulfill them. Satiety level constitutes such a state, and therefore has a dynamic influence on the output behaviors of an animal. In predatory insects like the praying mantis, hunting tactics, grooming, and mating have been shown to change hierarchical organization of behaviors depending on satiety. Here, we analyze behavior sequences of freely hunting praying mantises (Tenodera sinensis) to explore potential differences in sequential patterning of behavior as a correlate of satiety. First, our data supports previous work that showed starved praying mantises were not just more often attentive to prey, but also more often attentive to further prey. This was indicated by the increased time fraction spent in attentive bouts such as prey monitoring, head turns (to track prey), translations (closing the distance to the prey), and more strike attempts. With increasing satiety, praying mantises showed reduced time in these behaviors and exhibited them primarily towards close-proximity prey. Furthermore, our data demonstrates that during states of starvation, the praying mantis exhibits a stereotyped pattern of behavior that is highly motivated by prey capture. As satiety increased, the sequenced behaviors became more variable, indicating a shift away from the necessity of prey capture to more fluid presentations of behavior assembly.     

Sexual dimorphism of auditory function and structure in praying mantises (Mantodea; Dictyoptera)

Sexual dimorphism of tympanate auditory systems in insects has bees described in only a few taxonomically isolated cases. However, widespread sexual dimorphism occurs in the ultrasound-sensitive, midline ear of the praying mantis.
In dimorphic species, it is always the female mantis that shows a reduction in ultrasonic hearing. The dimorphism may be mild—a difference in tuning and small reduction in sensitivity—or extreme with no evidence of audition in the female. In all but the mildest cases, the reduction in hearing is accompanied by significant anatomical divergence from the male ear structure. Two distinct metathoracic groove ('ear') types are linked to hearing reduction in the females.
Anatomical evidence of auditory sexual dimorphism appears in 34% of the 183 mantis genera examined. The dimorphic genera are widely but non-uniformly distributed within three of the four largest mantis families.
Auditory sexual dimorphism is closely correlated with dimorphism in wing length. In general, mantises with functional wings have sensitive ultrasonic hearing while those with short wings do not. These findings support the hypothesis that ultrasonic hearing in mantises is part of a defensive system against attack by echolocating bats.     

Optic lobes of the larval and imaginal scorpionfly Panorpa vulgaris (Mecoptera,Panorpidae): A neuroanatomical study of neuropil organization,retinula axons,and lamina monopolar cells

Panorpa larvae possess stemmata (lateral ocelli), which have the structure of compound eyes, and stemma lamina and stemma medulla neuropils. A distinct lobula neuropil is lacking. The stemma neuropils have a columnar organization. They contain lamina monopolar cells, and both short and long visual fibers. All the identified larval monopolar neurons have radially arranged dendrites along the entire depth of the lamina neuropil and a single terminal arborization within the medulla (L1/L2-type). The terminals of visual fibers have short spiny lateral projections. Long fibers possess en passant synapses within the lamina. The same principles of organization of first and second order visual neuropils are found in Panorpa imagines. In contrast to the larvae, a lobula neuropil is present. Adults have monopolar cells of the L1-type that are similar to the L1-neurons found in Diptera. The columnar organization, the presence of short and long visual fibers, and lamina monopolar neurons are thus features common to both visual systems, viz., the larval (stemmata) and the imaginal (compound eyes).     

Wing morphology of a new Cretaceous praying mantis solves the phylogenetic jigsaw of early‐diverging extant lineages

The extremely derived morphology and behaviour of extant praying mantises combined with a scarce record of fossil relatives introduce significant challenges to tracing their evolution from Palaeozoic stem‐dictyopterans. Extant members of Chaeteessidae, Mantoididae and Metallyticidae could be invaluable to resolving the mantodean tree, yet their inclusion in phylogenetic analyses led to conflicting hypotheses due to their highly disparate respective morphologies. In this contribution, we present Labradormantis guilbaulti gen. et sp.n. , a new fossil species described from both fore‐ and hind‐wing imprints discovered in the Redmond Mine locality (Late Cretaceous, Cenomanian, Redmond Formation; Labrador, Canada). The examination of its hind‐wing AA2* supports the hypothesis that this structure, unique to Chaeteessidae among extant mantises, is a true vein and that its occurrence represents a plesiomorphy for Mantodea. A parsimony analysis including newly coded wing‐related characters further established that L. guilbaulti gen. et sp.n. displays a unique combination of plesiomorphic and apomorphic character states that situates it within the extinct family Baissomantidae. This dataset resolved the phylogenetic relationships of early‐diverging extant lineages as (Chaeteessidae (Mantoididae (Metallyticidae, Artimantodea))), and suggested that the Eocene Lithophotina floccosa Cockerell might be a close relative of extant metallyticids. It also indicated a trend towards increased modularity within mantis fore‐wings, in contrast with a trend towards increased morphological integration in their hind‐wings, both of which are potentially associated with improved flight performance for modern mantises. This study emphasizes the importance of fossils for resolving phylogenetic relationships and for introducing transitional phenotypes to infer ancient evolutionary trends of extant derived clades.     

Statilia maculata (Thunberg, 1784) – the first invasive praying mantis (Mantodea,Mantidae) in the fauna of Russia

Summary

Recent years have seen an increasing number of alien praying mantis species being introduced and establishing populations across Europe. Here we add to this count, reporting a stable and spreading population of an Asian species, Statilia maculata (Thunberg, 1784), in Krasnodar Krai of Southern Russia. This is the first introduced praying mantis species in the Russian fauna and the first representative of the genus Statilia Stål, 1877 in Europe. We review what is known about biology of this species and provide diagnostic characters to distinguish nymphs, adults and oothecae from native and introduced European species of praying mantis. Our attempts at captive breeding identify humidity as one of the most important factors limiting possible spread of S. maculata. Invasion to neighbouring territories and other countries with a humid subtropical climate remains a very real possibility with an unknown outcome for local ecosystems.     

Structure and development of the larval visual system in embryos of Lytta viridana leconte (coleoptera,meloidae)

At hatching (252–264 hr. at 25 ± 0.5°C), the visual system in larvae of Lytta viridana consists of paired stemmata, stemmatal nerves, optic neuropiles, and inner and outer imaginal optic lobe anlagen. It originates between 64 and 72 hr. with invagination of an optic lobe primordium in the side of each protocephalic lobe. These primordia later differentiate into protocerebral ganglion cells and the imaginal optic lobe anlagen. Each stemma arises at 72 hr. from epidermis below and behind the optic lobe invagination and subsequently becomes cupshaped, closes over, and differentiates. At hatching, it consists of a planoconvex corneal lens, a corneagenous layer, and an everse retina of numerous, pigmented retinular cells, each with a terminal rhabdomere. Between 96 and 104 hr, proximal ends of the retinular cells grow posteromedially into a transverse, horizontal fold in the posterior wall of each optic lobe invagination and along its length to the protocerebral neuropile, which they contact by 112 hr. As the brain withdraws posteriorly within the head, these axons elongate correspondingly. Sheath cells of stemmata and stemmatal nerves descend either from protocerebral perineurium or the optic lobe primordia. Structure and development of the larval visual system in L. viridana are compared with those of other insects and its various components are shown to be homologous throughout the Insecta. However, the stemmata of this insect more closely resemble the atypical imaginal eyes of male scale insects than the photoreceptors of other holometabolous larvae–a similarity arising through convergence.     

Non‐invasive techniques for investigating and modelling root‐feeding insects in managed and natural systems

1 Root‐feeding insects are now considered to play a greater role in ecosystem processes than previously thought, yet little is known about their specific interactions with host plants compared with above‐ground insect herbivores. Methodological difficulties associated with studying these insects in the soil, together with the lack of empirical and theoretical frameworks, have conventionally hindered progress in this area. 2 This paper reviews recent empirical and theoretical developments that have been adopted for studying root‐feeding insects, focusing on the non‐invasive techniques of X‐ray tomography and acoustic field detection and how these can be integrated with new mathematical modelling approaches. 3 X‐ray tomography has been used for studying the movements of several insects within the soil and has helped to characterize the host plant location behaviour of the clover root weevil, Sitona lepidus. Acoustic detection of soil insects has been used in various managed systems, ranging from nursery containers to citrus groves. 4 Mathematical modelling plays a complementary role for investigating root‐feeding insects, illustrated by a number of published models. A model is presented for the movement of S. lepidus in the soil, which suggests that these insects undergo Lévy movements, similar to those recently demonstrated for above‐ground organisms. 5 The future directions and challenges for investigating root‐feeding insects are discussed in the context of the wider ecosystem, incorporating both above and below‐ground organisms.