Egg-hatch phenology and intraguild predation between two mantid species

Relative timing of egg hatch between two cooccurring, congeneric mantids, Tenodera angustipennis and T. sinensis, was experimentally manipulated in replicated field enclosures to test the importance of intraguild predation to survivorship and development of T. angustipennis. T. angustipennis is normally smaller than its congener because of later egg-hatch. Delaying introduction of T. sinensis relative to normal egg hatch phenology reduced mortality for T. angustipennis, but did not affect its rate of development. The results indicate that intraguild predation by normally earlierhatching T. sinensis can be an important factor in the early life history of T. angustipennis, but that interspecific competition is not a strong selective factor in developmental asynchrony between these two species.     

Cuticular Extracts of Five Common Mantids (Mantodea: Mantidae) of the Eastern United States

We undertook a preliminary investigation of the cuticular extracts of five common mantid species in the eastern United States: Tenodera sinensis (Saussure), T. angustipennis (Saussure) and Mantis religiosa (Linnaeus) introduced from the Old World and Stagmomantis carolina (Johannson) and Bruneria borealis (Scudder), which are New World species. The major components of these mixtures were normal alkanes, predominately hentriacontane, or in the case of the parthenogenic species B. borealis, tritriacontane. Tricontanal was detected in the extracts of all five species, and smaller amounts of other aldehydes and n-tricontanol were detected in some species. Complex mixtures of methyl and dimethylalkanes also were present in these extracts. The composition of the cuticular hydrocarbons of these mantids may be an adaptation for reduction of evaporative water loss in these insects that inhabit open fields.     

Community effects of praying mantids: a meta-analysis of the influences of species identity and experimental design

Abstract 1. Generalist arthropod predators are ubiquitous in terrestrial ecosystems but experimental studies have yielded little agreement as to their effects on prey assemblages. Drawing on results from a suite of experimental field studies, a meta‐analysis was conducted of the impact of praying mantids (Mantodea: Mantidae) on arthropod assemblages in order to identify predictable and unpredictable effects of these extremely generalised predators. 2. Results across different experiments were synthesised using the log response ratio framework, with a focus on quantifying net mantid impacts on arthropod density across taxonomic orders and trophic levels of arthropods, paying special attention to the contribution of mantid species identity and experimental design variables, such as the use of cages, length of experiment, and manipulated mantid density. 3. Calculated on a per mantid‐day basis, the net impacts of Tenodera sinensis on arthropod density were generally weaker but more predictable than the effects of Mantis religiosa. Mantids in general had weak negative effects on density for most taxa but exhibited strong negative and positive effects on some taxa. Tenodera sinensis tended to have negative effects on Homoptera, Diptera, and Hemiptera and herbivores as a group, however M. religiosa exhibited greater variation in response of different taxa that appeared to be affected more strongly by experimental design. The effects of Stagmomantis carolina tended to be negative or non‐significant. 4. Experimental cages had little influence on either the sign or magnitude of net community impacts for T. sinensis, however cage experiments reversed the sign of the mean effect for two of six taxonomic orders when the experimental predator was M. religiosa. Cages also increased the variability of effect size greatly for M. religiosa but not for T. sinensis. 5. It was concluded that it is possible to use log response ratios to determine general, predictable trends in a well‐studied system. Similar meta‐analyses of generalist predator effects in other systems should produce predictions of how these predators influence food webs, an important step towards defining more clearly the influences of generalist predators on community structure and dynamics.     

Prey capture in mantids: Prothoracic tibial flexion reflex

We describe a prothoracic leg tibial flexion reflex (PTFR) of the praying mantis Tenodera aridifolia sinensis which is initiated by tactile stimulation of the movable spines of the ventro-medial border of the femur. This flexion reflex may be responsible for the continuous grasping of a captured prey by the mantid.     

Chinese mantids gut toxic monarch caterpillars: avoidance of prey defence?

1. Monarch caterpillars, Danaus plexippus (Linnaeus), feed on milkweed plants in the genus Asclepias and sequester cardenolides as an anti–predator defence. However, some predators are able to consume this otherwise unpalatable prey. 2. Chinese mantids, Tenodera sinensis (Saussure), were observed consuming monarch caterpillars by ‘gutting’ them (i.e. removing the gut and associated internal organs). They then feed on the body of this herbivore without any apparent ill effects. 3. How adult T. sinensis handle and consume toxic (D. plexippus) and non–toxic [Ostrinia nubilalis (Hübner) and Galleria mellonella (Linnaeus)] caterpillars was explored. The differences in the carbon/nitrogen (C:N) ratio and cardenolide content of monarch tissue consumed or discarded by mantids were analysed. 4. Mantids gutted monarchs while wholly consuming non–toxic species. Monarch gut tissue had a higher C:N ratio than non–gut tissue, confirming the presence of plant material. Although there were more cardenolide peaks in the monarch body compared with gut tissue, the total cardenolide concentration and polarity index did not differ. 5. Although T. sinensis treated toxic prey differently than non–toxic prey, gutting did not decrease the mantid's total cardenolide intake. As other predators consume monarch caterpillars whole, this behaviour may be rooted in species–specific vulnerability to particular cardenolides or simply reflect a preference for high–N tissues.     

Foraging strategy of a mantid,Paratenodera angustipennis S.: Mechanisms of switching tactics between ambush and active search

Summary Foraging strategies of a mantid, Paratenodera angustipennis de Saussure were investigated both in the laboratory and in the field to determine how mantids assess the profitability of their location, and based on it, how they switch their tactics. Although mantids are often considered to be ambush predators, nymphs and adult females changed their tactics from ambushing to active searching when they did not capture any prey for more than about 2 days (nymphs) and 3 days (adult females). Switching between the two tactics was such that the females and nymphs spent more searching effort in sites with higher prey density. As opposed to the females and nymphs, male mantids did not change their tactics according to their hunger level (in our definition, and the prey density in the hunting site. The males moved around more than twice as much as did the females. In the field, female mantids moved less frequently at higher female densities.     

Behavioral response of mantid Tenodera aridifolia (Mantodea: Mantidae) to windy conditions as a cryptic approach strategy for approaching prey

Crypsis can be either defensive or aggressive in function, and the first evidence that crypsis reduces the probability of being detected by a predator was collected almost a century ago. Crypsis in mantids may reduce the probability that a mantid will be detected by its prey, but no experiments have been carried out to test this idea. We tested the hypothesis that the approach strategy of the mantid Tenodera aridifolia (Stoll) toward prey when the wind is blowing is adaptive. Significantly less time elapsed between the discovery of the prey by the predator and capture action under windy conditions than under windless conditions. Approach behaviors (walking and body swaying) were observed more frequently under windy than under windless conditions. When the wind stopped, mantids became still, and they changed their behavior in response to alternately changing wind conditions. Moreover, the discovery rate of the predator mantids by conspecific prey mantids was significantly lower on swaying leaves than on fixed leaves. The capturing rate of the prey by the mantid was significantly higher under windy conditions than under windless conditions. We suggest that the strategy of approaching prey quickly when the wind blowing is adaptive for reducing the risk of discovery and escape by the prey.     

Male mate choice in a sexually cannibalistic species: male escapes from hungry females in the praying mantid <Emphasis Type="Italic">Tenodera angustipennis</Emphasis>

While competing males and choosy females may be common in animal mating systems, male choice can evolve under certain conditions. Sexual cannibalism is such a condition because of the high mortality risk for males. In mantids, female body condition is associated with male mate preference, with fat females preferred, due to at least two reasons: females in poor nutritional condition are likely to attack and predate males, and fat females can potentially increase the number of offspring. Thus, the risk of cannibalism and female fecundity can influence male mating behavior. In this study, we attempted to separate these factors by using the praying mantid Tenodera angustipennis to examine whether male preference for fat female mantids was based on avoiding sexual cannibalism (cannibalism avoidance hypothesis) or preference for female fecundity (fecundity preference hypothesis). The feeding regimes were experimentally manipulated to discriminate between the effects of female fecundity and female hunger status on male and female mating behaviors. We found that recently starved females more frequently locomoted toward the male, and that male abdominal bending was less intensive and escape was sooner from recently starved females. These female and male behavioral responses to female hunger condition may reveal male avoidance of dangerous females in this mantid.     

Identification of the molecular origin and development of a panzootic caused by Beauveria bassiana in praying mantis populations in eastern China

A panzootic in praying mantid species Tenodera sinensis and Statilia maculate, caused by Beauveria bassiana, occurred in north, southwest and southeast regions of Anhui Province, eastern China in Autumn, 2009. A 3-d principal component analysis (PCA) of 123 isolates from three sites revealed that the B. bassiana populations were heterogeneous with obvious dominance. Furthermore, the causal source of the panzootic in Anhui was shown to be polyphyletic. The populations were homogenized into homogenous subunits for investigation of genetic structure by inter-simple sequence repeat (ISSR) markers. Variance was greater than 70%, largely due to genetic differences within populations and subpopulations. Genetic distances and genetic differentiation were negatively associated with geographic distances and it was speculated that this was due to the effects of monsoons and topography. Mantid isolates were divided into five pathotypes based on a two-way cluster analysis of genetic distance. Pathotype I consisted of the predominant subpopulations of Huangcangyu and Chashui populations, with a genetic distance of 0.120 and gene flow up to 1.833. This pathotype caused a widespread epizootic in north and southwest Anhui, and Pathotype III caused enzootic at Site A in September and then epizootic in October, while the other three pathotypes caused enzootics at all three investigation sites. The widespread epizootics and isolated enzootics composed the polyphyletic panzootic in Anhui. A strong gene flow between isolates from the two mantid species was identified, resulting in negligible gene differentiation. This indicated a lack of host specificity in mantid isolates of B. bassiana.     

Estimation of prey consumption of a mantid,Paratenodera angustipennis (S.) in a natural habitat

Using a relationship between prey consumption and growth rate, field prey consumption of adults of Paratenodera angustipennis (S.) in a paddy field was estimated. Since a great number of grasshoppers (Oxya japonica) lived in the research area and the mantids had frequently eaten O. japonica, we presumed that they consumed only O. japonica. As a result, it was estimated that average prey consumptions for 6 days were 406 mg for the females and 23 mg for the males. From the result of this estimation and the feeding rhythm of the mantids, it is concluded that each female captured one grasshopper on average every a few days. By comparing this actual feeding level of P. angustipennis with those of other predacious arthropods, characteristics of P. angustipennis as a predator were discussed.     

Enzymic activities involved in the oothecal sclerotization of the praying mantid,Tenodera aridifolia sinensis saussure

The enzyme(s) responsible for the sclerotization of mantid ootheca is secreted by the left colleterial gland. From an extract of the glands of Tenodera aridifolia sinensis, two soluble enzyme fractions of different activities were obtained. One fraction acted on N-acetyldopamine (NADA), a precursor of a representative sclerotizing agent, and produced NADA-quinone. The other did not act on NADA itself but converted the quinone to a highly reactive intermediate, such as quinone methide, which was able to react nonenzymically with nucleophilic compounds. Other insoluble enzyme preparations obtained from the silk and pupal cuticle of the Japanese giant silk moth, Dictyoploca japonica, also had these two activities.     

Predatory behavior of the praying mantis,Tenodera aridifolia II. Combined effect of prey size and predator size on the prey recognition

Predatory behavior of the praying mantis,Tenodera aridifolia, as a function of the combined effect of its size and the size of the prey was investigated by using prey models. Behavioral responses were almost identical through the nymphal development in the predator. As the mantis grew, it attacked larger prey models, suggesting that it recognizes the prey's size in accordance with its own body size. Regression analyses demonstrate that the ratio of the prey's volume to the cube and the square of the predator's length is a more important parameter for prey recognition than are the one-dimensional parameters of the prey's and the predator's sizes.     

Effects of luminance, size, and angular velocity on the recognition of nonlocomotive prey models by the praying mantis

Adult females of the mantis Tenodera angustipennis were presented with the "nonlocomotive" prey model, a static rectangle with two lines oscillating regularly at its sides, generated on a computer display. The models were varied in rectangle luminance (black, gray, and light gray), rectangle height (0.72, 3.6, and 18 mm), rectangle width (0.72, 3.6, and 18 mm), and angular velocity of oscillating lines (65°, 260°, and 1040°/s) to examine their effects on prey recognition. Before striking the model, the mantis sometimes showed peering movements that involved swaying its body from side to side. The black model of medium size (both height and width) elicited higher rates of fixation, peering, and strike responses than the large, small, or gray model. The model of medium angular velocity elicited a higher strike rate than that of large or small angular velocity, but angular velocity had little effect on fixation and peering. We conclude that mantises respond to a rectangle in deciding whether to fixate, and to both rectangle and lines in deciding whether to strike after fixation. Received: September 2, 1999 / Accepted: March 21, 2000     

Responses to non-locomotive prey models by the praying mantis,Tenodera angustipennis Saussure

Adult females of the praying mantisTenodera angustipennis were presented with computer-generated images, and the attractiveness of “non-locomotive” prey models was examined. Mantises fixated and struck the “body and leg” model (consisting of an immobile black square on a white background with 2 black lines oscillating randomly at its sides) more frequently than the “leg” model (only oscillating lines) or the “body” model (static square only). This indicates that the model consisting of a static object and moving lines effectively elicits mantis strike behavior, although it is “non-locomotive.”     

Short-term responses to elevated predator densities: noncompetitive intraguild interactions and behavior

We investigated the short-term response of an arthropod assemblage to elevated generalist predator densities by introducing Chinese mantids (Tenodera sinensis) to field plots in a replicated, controlled experiment. Abundances of carnivorous arthropods were reduced by mantids to a greater extent than herbivores, and cursorial spiders emigrated from treatment plots in greater numbers than from controls. Initially, this emigration consisted only of small spiders that were demonstrated in the laboratory to be prey for mantids. Thus, the initial response of an arthropod assemblage to increased predators, densities was increased interactions among predators, which caused decline in predator population densities in a shorter time than competition for prey would require. Predator avoidance behavior must be considered together with intraguild predation and competition when interpreting the outcome of predator manipulations. Shortterm experiments may be more valuable than longer term studies in detecting this effect.     

A trophic cascade in a diverse arthropod community caused by a generalist arthropod predator

We tested the hypothesis that a generalist arthropod predator, Tenodera sinensis Saussure, could trigger a trophic cascade in an old-field ecosystem. These mantids had relatively weak effects on abundance and biomass of other carnivorous arthropods as a group. The effect of mantids on herbivores was stronger than on carnivores, mainly concentrated in Homoptera and Diptera. Herbivore load was reduced by mantids with the consequence that overall plant biomass (mainly grasses) was increased. Percapita interaction strengths between mantids and other arthropod taxa were, for the most part, weakly negative. Our study demonstrates that a significant trophic cascade can be triggered by a generalist predator even within the framework of a diverse community with relatively diffuse interactions. Received: 13 January 1997 / Accepted: 28 July 1997     

Predatory impacts of alien decapod Crustacea are predicted by functional responses and explained by differences in metabolic rate

Alien predators can have large impacts on prey. It is important that we understand, and ideally predict, these impacts. Here, we compare predatory impacts of size-matched decapod crustaceans—invasive alien Eriocheir sinensis and Pacifastacus leniusculus, and native European Austropotamobius pallipes—and use this case study to inform methods for impact prediction. We quantify functional responses (FRs) on three macroinvertebrate prey species, examine switching behaviour, and measure metabolic rates as a possible mechanistic explanation for differences in predation. FRs show a consistent pattern: attack coefficients and maximum feeding rates are ordered E. sinensis?≥?P. leniusculus?≥?A. pallipes for all prey species. Attack coefficients of E. sinensis are up to 6.7 times greater than those of size-matched crayfish and maximum feeding rates up to 3.0 times greater. FR parameters also differ between the invasive and native crayfish, but only up to 2.6 times. We find no evidence of switching behaviour in crayfish but suggestions of negative switching in E. sinensis. Differences in FR parameters are mirrored by differences in routine, but not standard, metabolic rate. Overall, our data predict strong predatory impacts of E. sinensis, even relative to alien P. leniusculus. Strong impacts of P. leniusculus relative to A. pallipes may be driven more by body size or abundance than per capita effect. FRs vary between prey types in line with existing knowledge of impacts, supporting the use of FRs in quantitative, prey-specific impact predictions. MRs could offer a general mechanistic explanation for differences in predatory behaviour and impacts.     

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.     

Size-selective predation by roach (Rutilus rutilus) on zebra mussel (Dreissena polymorpha): field stuides

Summary Studies of predation by roach (Rutilus rutilus) on zebra mussel (Dreissena polymorpha) in a large, eutrophic lake showed that there was a clearly marked size threshold ( 160 mm SL) above which roach began to feed on mussels. Roach preying on various sizes of mussels selected them in proportions different from their abundance and accessibility in the habitat. The mean size of mussels ingested by roach of 220 mm and larger, which fed predominantly on Dreissena, closely followed the pattern expected for a constant ratio of mean prey size to mean predator mouth size = 0.59. To explain the size selection we applied an optimal foraging approach, based on the ability of different-sized fish to crush (cost) mussels of different sizes, and hence crushing resistance, and energy contents (benefit). We found that fish smaller than 160 mm, which showed no inclination to eat Dreissena, would only be able to take small mussels with a very high cost/benefit ratio. The real switch to Dreissena would be expected in fish of 230–240 mm that could take most of their prey from highly profitable, numerous, and easily accessible size classes while keeping the mean prey size at the optimal level relative to mean predator mouth size.     

Episodes of unpalatable prey reduce consumption and growth of juvenile praying mantids

Third-instar praying mantids (Tenodera sinensisSaussure: Mantidae) were fed either a sequence of unpalatable milkweed bugs (Oncopeltus fasciatusDallas: Lygaeidae) and palatable fruit flies (Drosophila melanogasterMeigen: Drosophilidae) or a control diet of palatable flies only. Mantids fed a sequence of 3 days of unpalatable bugs and 4 days of palatable flies took, on average, 5 days longer to develop to the fourth instar than the controls, and consequently, their growth rate was less than that of the controls. They ate 10–15 unpalatable bugs in that time, but also, because the stadium was prolonged, they ended up eating as many flies as the faster-growing controls and therefore attained similar biomass. Mantids subjected to episodes of 2 days with unpalatable bugs followed by 4 days of flies had reduced growth rates that were a function of both more time spent in the stadium and less weight gained than the controls. Mantids subjected to episodes of 1 day with unpalatable bugs followed by 4 days of flies did not gain as much weight as the controls but had similar growth rates. Mantids fed unpalatable bugs on Days 1 and 6 and palatable flies on the other days and mantids fed flies for 4 days and then 1 day without food grew at the same rate. In this case, eating unpalatable prey for 2 days of 7 (with 7 days = average stadium duration) slowed weight gain as much as missing food for a day. We conclude that, depending on the sequence, episodes (in this case, 1 or more days) of eating unpalatable prey can reduce the daily rate of consumption sufficiently to have a negative impact on biomass gained, stadium duration, and growth rate.