Insecticidal bacteria isolated from predatory larvae of the antlion species Myrmeleon bore (Neuroptera: Myrmeleontidae)

Various bacterial species were isolated from the crop (digestive organ) of the antlion species Myrmeleon bore and tested for their insecticidal activity against caterpillars by injection. Sixty-eight isolates from the antlion crop were grouped into twenty-four species based on homologies of 16S rRNA gene sequences and biochemical properties. Isolated Bacillus cereus, Bacillus sphaericus, Morganella morganii, Serratia marcescens and a Klebsiella species killed 80% or more cutworms when injected at a dose of 5x10(5)cells per insect. In addition, cutworms killed by these isolates resembled observations made of caterpillars attacked by antlions. A culture-independent analysis showed that the isolated bacterial species are likely to be frequently present in the antlion crop. These results suggest that insecticidal microorganisms associate with antlions, and may promote the death of prey.     

Effect of density on spatial distribution,pit formation and pit diameter of Myrmeleon acer Walker, (Neuroptera: Myrmeleontidae): patterns and processes

The effect of increasing population density on the formation of pits, their size and spatial distribution, and on levels of mortality was examined in the antlion Myrmeleon acer Walker. Antlions were kept at densities ranging from 0.4 to 12.8 individuals per 100 cm². The distribution of pits was regular or uniform across all densities, but antlions constructed proportionally fewer and smaller pits as density increased. Mortality through cannibalism was very low and only occurred at densities greater than five individuals per 100 cm². Antlions in artificially crowded situations frequently relocated their pits and when more space became available, individuals became more dispersed with time. Redistribution of this species results from active avoidance of other antlions and sand throwing associated with pit construction and maintenance, rather than any attempt to optimise prey capture per se.     

穴蚁蛉的研究

通过多年的观察研究,详细报导粤北穴蚁蛉的生态类型、生物学特性、个体发育与饲食频率的关系;介绍穴蚁蛉幼虫——蚁狮在治疗泌尿系统结石疾病中的重大药用价值和开发、保护蚁狮的方法和途径．     

锈翅蚁蛉(脉翅目:蚁蛉科)的发育生物学研究

锈翅蚁蛉为全变态类昆虫,在贵州省一年发生1代,11月下旬开始越冬,各龄幼虫均可越冬,次年3月苏醒.在室内饲养条件下,卵期13 d±0.56 d,幼虫期63.58 d±1.81d,蛹期26.35 d±1.14 d,成虫期20 d± 1.06 d.结合野外调查和室内饲养,详细描述了锈翅蚁蛉各虫态的形态特征,幼虫的筑穴、捕食、蜕皮、化蛹、羽化以及成虫的捕食、交配等行为习性.     

Substrate particle size affects pit building decision and pit size in the antlion larvae Euroleon nostras (Neuroptera: Myrmeleontidae)

Abstract. The larvae of the antlion Euroleon nostras are pit-builders, constructing pitfall traps in loose sand. The number of pits and the pit diameter are recorded when larvae are kept in substrates with different particle sizes. The most convenient pit-building sand fractions are two fractions with fine sand (≤ 0.23 mm; 0.23–0.54 mm). The largest pits are constructed in sand with a particle size of 0.23–0.54 mm. In this sand fraction, larvae of all three instars most readily build pits. No pits are constructed in sand with a particle size greater than 1.54 mm. First- and second-instar larvae avoid building pits in substrates of particle size 1–1.54 mm, but third-instar larvae construct pits in this sand fraction. It is assumed that the antlion is capable of distinguishing between substrate types and this hypothesis is tested by giving larvae the choice of building a pit in one of four particle-size fractions. Larvae of all three instars prefer to build pits in the fraction with a particle size of 0.23–0.54 mm. Only third-instar larvae build pits in all four fractions, but only occasionally in the coarser fraction.     

Variation in pit size of antlion (Myrmeleon carolinus) larvae: the importance of pit construction

Abstract.Larvae of several antlions build pits that vary in size across and within species. The influence of food limitation and pit building experience on variation in pit size of the larvae of Myrmeleon carolinus was investigated in the laboratory. Unfed larvae that were allowed to build pits had smaller pit diameters than fed larvae. However, fed antlions that had been previously prevented from pit building, initially did not build larger pits than unfed antlion larvae that, too, had been prevented from pit building. Therefore, physiological constraints associated with food limitation alone are not sufficient to explain the reduction in pit size of food limited antlions of this species.     

Learning in a sedentary insect predator: Antlions (Neuroptera: Myrmeleontidae) anticipate a long wait

Pit-building antlions, the larvae of a winged adult insect, capture food by digging funnel-shaped pits in sand and then lying in wait, buried at the vertex, for prey to fall inside. The sedentary nature of this sit-and-wait predatory behaviour and, especially, antlions’ innate ability to detect prey arrival, do not fit the typical profile of insects that possess learning capabilities. However, we show, for the first time, that learning can play an important role in this unique form of predation. In three separate experiments, individual antlions received, once per training day, either a vibrational cue presented immediately before the arrival of food or that same cue presented independently of food arrival. Signalling of food not only produced a learned anticipatory behavioural response (Experiment 1), but also conferred a fitness advantage: Associative learning enabled antlions to dig better pits (Experiments 2 and 3), extract food more efficiently (Experiments 2 and 3), and, in turn, moult sooner (Experiment 3) than antlions not receiving the associative learning treatment.     

Thermal dependence of trap building in predatory antlion larvae (Neuroptera: Myrmeleontidae)

Trap-building predators remain under strong selection from thermal microenvironments. To address how soil temperature and body size affect trap building, we conducted a laboratory experiment using larvae of the antlion Myrmeleon bore at six ecologically relevant temperatures. Larger larvae built larger traps, and warmer soil led to more and larger traps. Body mass did not alter the dependence of trap building on temperature. Our results suggest that the physiological capacity of antlion larvae, which is affected by larval size and body temperature, is the major determinant of trap building. This effect should be considered when assessing interactions between antlions and prey.     

Factors Influencing Site Abandonment and Site Selection in a Sit-and-Wait Predator: A Review of Pit-Building Antlion Larvae

There is a large body of evidence indicating that predator behavior may strongly influence patterns and processes at the population and community level. Site selection is a major component of fitness in sit-and-wait predators, especially when relocation is rare. Although several review articles dealt with these issues in web-building spiders, this is the first attempt to summarize the effects of biotic and abiotic factors on site selection and relocation in another group of sit-and-wait predators, the pit-building antlions (Neuroptera: Myrmeleontidae). Our synthesis shows that prey abundance may have relatively little effect on pit relocation and that physical properties of the habitat or competition often override its effect. We suggest that owing to a variety of constraints such as physiological constraints or difficulties in assessing site quality, site selection and relocation are not necessarily optimal and thus food intake rate is not maximized. We call for a multi-factorial study on a single species in order to pinpoint the dominant factors and to assess to what extent they influence site selection and relocation. We conclude by proposing new research directions, such as studying whether pit relocation is an adaptive response, when controlling for possible phylogenetic effects.     

Bergmann's rule in the ant lion Myrmeleon immaculatus DeGeer (Neuroptera: Myrmeleontidae): geographic variation in body size and heterozygosity

Aim Geographic variation in body size and heterozygosity were surveyed for discrete populations of the ant lion, Myrmeleon immaculatus DeGeer, collected from the central and northeastern United States. Location Collection sites were located in the central and eastern United States ranging from western Oklahoma to northern New York. Methods We collected 872 M. immaculatus larvae from thirty-four collecting sites. At each site, we randomly sampled ant lion pits and collected between fifteen and fifty-two larvae in total. Larvae were preserved in 95% ETOH for morphological analysis and frozen in a ?80°C freezer for protein electrophoresis. We measured the body size of eighty-five preserved adult M. immaculatus obtained from museum collections using head width as an indicator of body size. Five enzymes [GPI (glucose phosphate isomerase), MDH (malate dehydrogenase), PEP (peptidase), DIA (diaphorase) and SOD (superoxide dismutase)] were used in the heterozygosity analyses. Results Larval and adult body size increased with latitude, but decreased with elevation. Average heterozygosity, measured at five polymorphic loci, also increased significantly with latitude. Minimum temperature variance was the best predictor of body size, whereas precipitation and maximum temperature were the best predictors of heterozygosity. Populations were genetically differentiated from one another and showed a pattern of isolation by distance, as measured by Wright's F_st values and Nei's genetic distances. Main conclusions Sampling artifacts, heat conservation, character displacement, cell-size variation, density-dependent mortality, and differential dispersal probably cannot account for latitudinal variation in ant lion body size. Our results implicate the importance of diurnal photoperiod, which varies with latitude, but not with elevation. Because photoperiod often controls growth, diapause, and metamorphosis, it may be an important determinant of latitudinal clines in body size and life history of insects.     

Substrate selection for pit making and oviposition in an antlion, Myrmeleon bore Tjeder, in terms of sand particle size

The larvae of the pit‐making antlion Myrmeleon bore Tjeder live in open sand in riverbeds with a substratum consisting of various particle sizes. We analyzed the spatial distribution of their pits in a sandy floodplain to determine their larval and adult responses to the heterogeneous substrate. The spatial distribution pattern of their pits had an aggregated distribution, and there was a significant positive correlation between pit density and the ratio of medium‐size sand particles to total weight of sand. We examined the size of sand particles selected in the larval pit‐building behavior and the oviposition behavior of the adult. Both larvae and adults selected medium‐size sand particles. The larvae of M. bore are relatively sedentary predators and rarely move great distances. Thus, the present results suggest that habitat selection by adult females is a major factor causing the aggregative distribution of the pits.     

Utilisation of prey by antlion larvae (Neuroptera: Myrmeleontidae) in terms of energy and nutrients

Prey utilisation at low prey densities was determined for third instar Cueta sp., Furgella intermedia (Markl) and Palpares annulatus (Stitz) larvae in terms of wet weight, dry weight, energy and nutrients. Prey utilisation was similar to other insects on a wet weight (42-47%), dry weight (46-49%), energetic (40-58%) and nutritive basis (62-79%). Lipids (33-36%) provided energetically the highest contribution of the nutrients ingested. The quantities of water, proteins, nucleic acids, lipids and carbohydrates extracted by the antlion larvae were in proportion to their availability in their prey, the Hodotermes mossambicus larvae. The quantities of nutrients extracted by the antlion larvae at low prey densities were not significantly influenced by the differences in mandible size, antlion body weight or the trapping method (building a pit or not) of the antlion species. It is proposed that a low metabolic rate and the accumulation of fat reserves, and not the extent of prey utilisation, enable P. annulatus larvae to tolerate a 123-d starvation period in which 22.3% of their body weight is lost.     

Comparative study of sensilla and other tegumentary structures of Myrmeleontidae larvae (Insecta,Neuroptera)

Antlion larvae have a complex tegumentary sensorial equipment. The sensilla and other kinds of larval tegumentary structures have been studied in 29 species of 18 genera within family Myrmeleontidae, all of them with certain degree of psammophilous lifestyle. The adaptations for such lifestyle are probably related to the evolutionary success of this lineage within Neuroptera. We identified eight types of sensory structures, six types of sensilla (excluding typical long bristles) and two other specialized tegumentary structures. Both sensilla and other types of structures that have been observed using scanning electron microscopy show similar patterns in terms of occurrence and density in all the studied species (with few exceptions). The sensilla identified are: coeloconica, placoidea, basiconica, trichodea type I, trichodea type II, and campaniformia. All these sensilla have mechano- or chemosensorial functions. Some regions of the larval body have been studied using SEM for the first time, such as the surface of the food canal, which bears sensilla coeloconica, and the abdominal segment X, that bears three types of sensilla: coeloconica, basiconica, and campaniformia. Sensilla placodea are newly reported on antlion larvae, being present on the mandibular base, pronotum, mentum, and cardum. Also, new locations of sensilla coeloconica (e.g., on rastra) and sensilla campaniformia (e.g., on odontoid processes) are noted. A novel porous texture with chemoreceptor function has been identified in the base of mandibles. A mechanism of dentate-notched surfaces that anchor maxillae and mandible, reinforcing the food canal, is detailed. All these sensorial structures, in addition to ocular tubercles for light caption and their great muscular system, confer to these larvae an extraordinary predation capacity to success hunting and living in such harsh environments.     

Comparative study on the behavioral response to starvation in three species of antlion larvae (Neuroptera: Myrmeleontidae)

To clarify how pit-building antlion larvae behave during prolonged periods of low resource abundance, pit relocation rate, giving-up time, and respiration rate under starvation conditions were examined, using three species of antlion larvae. Most larvae ofMyrmeleon bore never relocated their pits before they starved to death, while larvae ofHagenomyia micans relocated more often thanMyrmeleon formicarius (average number of pit relocations 0.04 forM. bore, 0.19 forM. formicarius, and 0.62/individual/10 days forH. micans). The relative respiration rate, a ratio of respiration rate at starvation to that at satiation, was lower inM. bore andM. formicarius than in H. micans. Thus, there was an inversely proportional relationship between the pit relocation rate and the decrease in respiration rate under starvation conditions in the three species of antlion larvae.     

The mitochondrial genome of Gatzara jezoensis (Neuroptera: Myrmeleontidae) and phylogenetic analysis of Neuroptera

Phylogenetic relationship within Neuroptera is controversial, particularly for the various hypotheses based on both morphological and molecular evidence. In the present study, we determined the complete mitochondrial genome (mitogenome) of Gatzara jezoensis, which is the second representative of the tribe Dendroleontini. The G. jezoensis mitogenome contained the conserved set of 37 mitochondrial genes and a putative control region, with a conserved gene arrangement which was similar to that of most sequenced neuropteran mitogenomes. All transfer RNAs exhibited the canonical cloverleaf secondary structure, except for trnS^(AGN). The control region contained two conserved elements (ploy-T stretch and ATGGTTCAAYAAAATAAYYCYCTC motif) and abundant microsatellite-like elements. The phylogenetic analysis of sequenced neuropteran mitogenomes using the concatenated protein-coding genes (PCGs) and ribosomal genes recovered the monophyly of Myrmeleontidae, which revealed this dataset could generate the more robust phylogeny of Neuroptera than that of 13 PCGs dataset.     

长鞘卷叶甲种群空间分布格局的生物地理统计学分析

应用生物地理统计学方法分析了长鞘卷叶甲成虫种群的空间分布格局,在3 m×3 m样方下建立东南→西北方向的半方差函数理论模型,并应用克立格插值方法对其种群密度和空间结构进行估计和模拟。结果表明:球状模型对长鞘卷叶甲成虫种群在该方向上的理论半方差函数有较好拟合效果,其空间分布格局为弱聚集型;成虫在山坡竹林与河岸竹林的变程分别为21.2157和38.8266 m,空间聚集分布的连续性强度分别只有0.3633和0.1758,说明种群在研究区内由空间自相关而产生的结构性变异在总变异中所占比例较小,即变异主要由种群结构的随机性成分引起。     

黑角直缘跳甲幼虫空间分布型及抽样技术的研究

通过运用二种回归方法和六种聚集度指标对黑角直缘跳甲幼虫的空间格局和抽样技术进行了研究。所有的指标表明黑角直缘跳甲幼虫在林间呈聚集分布,分布的基本成分是个体群,且个体间相互吸引。在空间分布型研究的基础上提出了理论抽样数和序贯抽样方案。通过不同抽样方式的精确度比较,表明对角线抽样方式最佳。     

Geometric constraints and spatial pattern of species richness: critique of range-based null models

Abstract. Does the shape of a biogeographical region influence its spatial patterns of species richness? A complete answer must include careful distinction between the distribution of a species, which is a complex geometric object, and the range of a species, which is relatively simple, especially when reduced to one dimension. We consider range‐based models of species richness, in particular range overlap counts in one dimension, for which we give a unified mathematical treatment via the joint probability P(m,l) of midpoints and lengths of ranges. We discuss a number of difficulties, in practice and in principle, using range‐based models, and show that the so‐called mid‐domain effect, a proposed null model for the effect of geometric constraint, is qualitatively a property of all biologically realistic models based on range overlap counts. As such, range‐based models provide little insight into understanding or explaining biogeographical patterns in species richness. We characterize the quantitative null model for range overlap counts in one dimension, for which we give a simple and direct field test based on P(m,l). We apply this test to a large clade in a complete bioregion (the Proteaceae of the Cape Floristic Region): geometric constraint does not explain the spatial pattern in this case. We show that any geometric constraint on species richness, including range overlap counts, must act via edge effects. Thus, to understand biogeographical patterns, an understanding of the effects and consequences of edges is fundamental.     

思茅松毛虫幼虫空间格局与抽样技术的初步研究

采用聚集度指标法和回归分析法,对思茅松毛虫幼虫在林间的空间格局进行测定,并用刀切法对聚集度指标进行估计和检验,结果表明,思茅松毛虫幼虫在林间呈聚集分布,分布的基本成份为个体群．并计算了林间调查的理论抽样数,列出序贯抽样分析表。     

不同生境条件下中国柽柳空间分布点格局分析

通过聚类分析方法将黄河三角洲中国柽柳的生境划分为三种类型,即高盐干旱型生境,低盐干旱型生境和低盐湿润型生境;同时运用点格局分析方法,分析了不同生境中中国柽柳在不同尺度下空间分布规律,结果表明,高盐干旱和低盐干旱生境中龄级2的中国柽柳以及低盐湿润生境中龄级3的中国柽柳在所有尺度范围内都呈随机分布,而其它龄级在不同生境的空间分布规律具有较显著差异,说明黄河三角洲低龄级和高龄级中国柽柳能够通过调整空间分布模式来适应适应水盐平衡变化等生态过程;不同生境中的中国柽柳各龄级之间关系在不同尺度内呈正相关概率要大于呈负相关概率,个别尺度上某些龄级之间没有相关性.