Behavioural and sensory responses to some neem compounds by Pieris brassicae larvae

Abstract. The efficacy of a commercial product (Margosan-O) to inhibit feeding in Pieris brassicae L. (Lepidoptera: Pieridae) larvae was compared to that of three pure triterpenoids of botanical origin: azadirachtin and salannin (occurring in Melia azedurach ), and toosendanin (occurring in M. toosendan ). In dual-choice behaviour tests the order of antifeedant efficacy was: Margosan-O > toosendanin > salannin > azadirachtin. The ranking order of their capacity to stimulate the deterrent receptor located in the medial sensillum styloconicum appears to be: Margosan-O = toosendanin > salannin > azadirachtin. In addition to stimulating the medial deterrent cell, toosendanin inhibits the sugar receptor and the glucosinolate receptor, both located in the lateral sensillum styloconicum. The amino acid receptor in this sensillum, however, is not affected. In contrast, neither azadirachtin nor salannin influences the sensitivity of any of the receptor cells in this sensillum.
The adaptation rate of the deterrent receptor is low in comparison to that of the two sugar receptors.
A significant correlation is found between the antifeedant indices of the four neem compounds tested at three different concentrations, and the responses of the deterrent receptor to these compounds at similar concentrations. It is concluded that when this insect species feeds on its natural foodplant (i.e. cabbage), the deterrent effect of neem compounds is mediated solely via the medial deterrent receptor, whereas inhibitory effects on the sugar and glucosinolate receptors do not play a significant role.     

Chemoreception and feeding behaviour in a caterpillar: towards a model of brain functioning in insects

The quantitative relationship between chemoreceptor activity during food intake and total amount of food ingested per unit of time has been studied in last instar larvae of Pieris brassicae. Data on sensory responses and feeding intensity, derived from a study by Blom (1978), show a strong correlation between receptor activity during 1 sec periods of stimulation and food intake during 24 h. It is concluded that nerve impulses from chemoreceptors, which signal the presence of different phagostimulants, are summated algebraically in the central nervous system. Impulses from feeding deterrent receptors counteract the effects of phagostimulants. One impulse from a deterrent receptor neutralizes 2.5 impulses from phagostimulant receptors. Based on the relationships observed a simple model of a feeding centre in the central nervous system has been constructed (Fig. 8).     

Feeding deterrent response of corn insects to β-exotoxin of Bacillus thuringiensis

Exotoxins produced by three varieties of Bacillus thuringiensis were added at different concentrations to the diets of the black cutworm, the fall armyworm, the European corn borer, and the house fly. By day 7 of treatment, mortality of the three lepidopterans was higher at the lower concentrations of exotoxin than at the higher concentrations tested; by day 14 of treatment, mortality was 90% of greater at all the exotoxin concentrations tested. In the house fly tests, mortality increased with increasing exotoxin concentration. Additional lepidopteran tests were run to study both the anomalous effect of toxin concentration on mortality and the effect of feeding inhibition evident by day 7 but not day 14 in treatments with high concentrations of the toxins. The tests, run with the European corn borer and with β-exotoxin calcium salt, showed that both effects could be attributed to a “feeding deterrent” associated with the toxin, and that the deterrent was not odoriforous and did not degrade over time. Apparently, the insects ate very little of the diets high in exotoxin, stopping quickly upon receiving a high dosage of the deterrent, but, nevertheless, having consumed enough toxin to be killed over time (between 7 and 14 days).     

A morphometric analysis of mandibular teeth in Folsomia (Collembola: Isotomidae)

Morphological variation in the apical mandibular teeth of seven Folsomia species (F. bisetosa, F. brevicauda, F. Candida, F. fimentaria, F. inoculata, F. penicula , and F. quadrioculata) was examined by canonical variates analysis of a systematic 'truss' of measurements. Differences were found between all but two species (F. brevicauda and F. quadrioculata) showing that the morphology of 'biting-type' mouthparts can be used for species recognition. The results also show that the truss system of measurement is sensitive to small-scale differences in the mandible morphology of these insects. It is suggested that variation in mouthpart morphology, and in patterns of tooth wear, reflect differences in the feeding behaviour of Folsomia species.     

葫芦素B对美洲斑潜蝇成虫产卵和取食的抑制作用研究

美洲斑潜蝇是严重危害瓜、豆类蔬菜的世界性害虫之一,主要以幼虫潜伏在叶表皮下的叶肉组织中为害,给防治带来很大困难。本研究测定了葫芦素B对美洲斑潜蝇成虫产卵和取食的抑制作用。在非选择性试验中,当葫芦素B使用浓度为500~2000 mg/L时,对美洲斑潜蝇成虫的产卵抑制率达31.2~69.9%,对美洲斑潜蝇成虫的取食抑制率达61.7~64.9%;在选择性试验中,葫芦素B使用浓度达1000~2000 mg/L时,对美洲斑潜蝇成虫的产卵抑制率和取食抑制率分别为54.8~71.1%和57.2~65.2%;研究结果表明:利用葫芦素B可有效地抑制美洲斑潜蝇成虫的产卵和取食,减轻其幼虫的为害,为安全、有效地控制美洲斑潜蝇提供了一条新途径。     

昆虫分子生物学的一些研究进展：生物钟的基因

昆虫分子生物学的一些研究进展：生物钟的基因翟启慧（中国科学院动物研究所北京１０００８０）生物的许多行为和生理现象有周期性波动,称为生物节律或生物钟。长期以来,这是一个十分吸引人却又难以理解的问题。虽然有大量文献描述生物钟的现象,但对其机理却一无所知。...     

印楝素乳油对小菜蛾种群的控制作用

通过室内外系统试验探讨了印楝素乳油对小菜蛾Plutella xylostella种群的控制作用。结果表明,其控制作用主要表现在对成虫产卵的显忌避作用。对幼虫的拒食作用以及对生长发育的影响和减少幼虫危害为等方面,印楝素乳油0.005mL/59.0%,使小菜蛾种群趋势指数（I值）降为2.4干扰作用控制指数（IIPC）为0.1079,采用状态空间分析法就印楝素乳油施用后小菜蛾种群数量动态的模拟分析亦表明,其显的控制作用表现在种群发展初期对成虫的忌避作用。     

INSECTICIDAL AND OXIDATIVE EFFECTS OF AZADIRACHTIN ON THE MODEL ORGANISM Galleria mellonella L. (LEPIDOPTERA: PYRALIDAE)

The insecticidal effects, specifically, changes in hemolymph total protein and malondialdehyde (MDA) levels, and antioxidant enzyme activities of azadirachtin (AZA) given to the wax moth, Galleria mellonella L. (Lepidoptera: Pyralidae) larvae via force feeding were investigated. Bioassays showed that the LD₅₀ and LD₉₉ (lethal dose) values of AZA were 2.1 and 4.6 μg/larva, respectively. Experimental analyses were performed with five doses of AZA (0.5, 1, 1.5, 2, and 3 μg/larva). Total protein level in larval hemolymph increased at all AZA doses at 24 h whereas a considerable decrease was observed at 2 and 3 μg/larva doses, and only an increase displayed at 1.5 μg/larva at 72 h. The level of MDA increased at 2 and 3 μg/larva doses at 24 h compared with controls. This trend was also observed at 1.5, 2, and 3 μg/larva doses at 72 h and MDA levels were lower when compared with those of 24 h at all doses except for 1.5 μg/larva dose. Catalase activity decreased at 1, 1.5, and 2 μg/larva doses at 24 h whereas increased at all doses except for 0.5 μg/larva at 72 h compared with controls. AZA led to a decline in superoxide dismutase activity at all experimental doses at 24 and 72 h except for 3 μg/larva doses at 72 h. An increase in glutathione‐S‐transferase (GST) activity was evident at all AZA doses at 24 h. AZA displayed 68% decline in GST activity at 72 h post treatments when compared to 24 h. Consequently, We infer that the toxicity of AZA extends beyond its known actions in molting processes to redox homeostasis.     

三倍体白鲫的生物学特性

由人工诱导的异源四倍体白鲫雄鱼与正常的二倍体白鲫雌鱼交配获得的异源三倍体白鲫,其主要生物学特性同二倍体白鲫进行比较研究表明,三倍体白鲫具有体形较大、相对体高和相对尾柄高较高、侧线上下鳞数目较多的形态特征,仍保留着二倍体白鲫以浮游植物为主的植食性营养方式,雌雄均不育,比二倍体生长快,网箱养殖１１２天后,体重比二倍体平均增加３２．３８％。试验证实三倍体白鲫是一个具有养殖生产前景的新对象。     

Desensitization of fifth instar Spodoptera litura to azadirachtin and neem

The deterrence of azadirachtin, in its pure form and as a constituent of neem seed extract, to fifth instar Spodoptera litura (Fab.) larvae, was measured using cabbage, Brassica oleraceae (L.) var. capitata, leaf disc assays. Paired-choice assays, in which larvae could choose between feeding on a treated (1.3 ng azadirachtin per square cm leaf area) or an untreated leaf disc for 2 h, were conducted at 24 h intervals throughout the fifth instar. In addition, no-choice assays, in which larvae could feed on only one leaf disc (10 ng azadirachtin per square cm leaf area) for 1.5 h, were conducted consecutively over a six hour period at the beginning of the fifth instar. The effects of hunger and habituation on desensitization in our no-choice tests were partitioned. After repeated exposures, larvae became desensitized to pure azadirachtinal in both choice and no-choice tests, but did not desensitize to neem containing the same absolute amount of azadirachtin in choice tests. Hunger was responsible for approximately one third of the desensitization response in the no-choice tests. Sensitivity to azadirachtin was independent of age within the fifth instar.     

Exploring the dichotomy between animals building using self‐secreted materials and using materials collected from the environment

The collection and the secretion of building materials are two radically different processes: one behavioural; the other physiological. This article examines whether selection pressures operating upon these have led to quite different outcomes or whether priorities common to both have led to parallel solutions. The article also examines selection pressures peculiar to secreted materials. It explores the influence of diet on the biochemistry of the secreted material and the evolutionary consequences for social species of the allocation of the costs of secreting the building material. Conclusions in some of these areas are hindered by a lack of evidence, but this also indicates opportunities for future research. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

Recent speciation and secondary contact in endemic ants

Gene flow is the main force opposing divergent selection, and its effects are greater in populations in close proximity. Thus, complete reproductive isolation between parapatric populations is not expected, particularly in the absence of ecological adaptation and sharp environmental differences. Here, we explore the biogeographical patterns of an endemic ant species, Cataglyphis floricola, for which two colour morphs (black and bicolour) coexist in parapatry throughout continuous sandy habitat in southern Spain. Discriminant analyses of six biometric measurements of male genitalia and 27 cuticular hydrocarbons reveal high differentiation between morphs. Furthermore, the low number of shared alleles derived from nuclear markers (microsatellites) between the morphs at their contact zone suggests the absence of recent gene flow. Mitochondrial DNA (COI) phylogenetic analysis and median‐joining networks show that the black morph is basal to the bicolour morph, with unique haplotypes recovered for each morph. Mismatch distribution analysis and Bayesian skyline plots suggest that they are undergoing different demographic changes, with the bicolour and black morphs at demographic equilibrium and expansion, respectively. Thus, our results show complete reproductive isolation between the two colour morphs as evidenced from genetic, chemical and morphological data. We suggest that these divergence events could be explained by historical vicariance during the Pleistocene, in which reproductive traits experienced strong divergent selection between the morphs initiating or culminating speciation.     

生物进化研究的回顾与展望

生物进化是自然科学的永恒之迷。随着历史的发展和科学的进步,生物进化思想从早期的萌芽,到自然选择学说、新达尔文主义,从现代综合理论,到分子进化的中性学说。再到新灾变论和点断平衡论等。当前,由于生物学各分支学科的飞速发展．它们就各自的研究对象在宏观和微观上不断地拓展和深入,并在不同的层次上形成了广泛的交叉、渗透和融合,现代的进化生物学研究从宏观的表型到微观的分子,从群体遗传改变的微进化到成种事件以及地史上生物类群谱系演化的宏进化,从直接的化石证据到基于形态性状、分子证据和环境变迁的综合推理,从基于遗传基础的比较基因组学到演化机理的进化发育生物学等。可以预见,在新的世纪里,在哲学和具体方法论(如系统论、控制论和信息论)的指导下,在生命科学、其他自然科学乃至社会科学工作者的通力合作下,综合遗传、发育和进化等研究领域的各种理论成果,生物进化理论即将出现也一定会出现的一个新的大综合和新的大统一。     

The movement of water into submerged prey during feeding by the aquatic bug Ranatra dispar (Heteroptera: Nepidae), the water stick insect

By the use of a fluorescent dye it was shown that, during feeding by an aquatic bug, water from the external environment passes into the prey's body though puncture holes from previous feeding sites. Such a phenomenon, resulting in the diluting of the prey's body contents, may be used as a physiological stimulus to detect the quality of the prey, leading to movement to another part of the prey's body or discarding the prey.     

Diversification in the use of resources by Idarnes species: bypassing functional constraints in the fig–fig wasp interaction

Mutualisms such as the fig–fig wasp mutualism are generally exploited by parasites. We demonstrate that amongst nonpollinating fig wasps (NPFWs) parasitic on Ficus citrifolia, a species of Idarnes galls flowers and another species feeds on galls induced by other wasps killing their larvae. The galling wasp inserts its ovipositor through the fig wall into the fig cavity. The ovipositor then follows a sinuous path and is introduced through the stigma and style of the flower. The egg is deposited between the integument and nucellus, in the exact location where the pollinating mutualistic wasp would have laid its egg. Gall induction is a complex process. In contrast, the path followed by the ovipositor of the other species is straightforward: attacking a larva within a developed gall poses different constraints. Shifts in feeding regime have occurred repeatedly in NPFWs. Monitoring traits associated with such repeated evolutionary shifts may help understand underlying functional constraints. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 114–122.     

FUNCTIONAL AND EVOLUTIONARY ASPECTS OF THE POSTCRANIAL ANATOMY OF DICYNODONTS (SYNAPSIDA, THERAPSIDA)

Abstract:  Restoration of the major skeletal muscles and functional morphological analysis of the postcranium were carried out on two Triassic dicynodont genera, Wadiasaurus and Lystrosaurus . A phylogenetic analysis of 12 selected Permian and Triassic dicynodont taxa was conducted and the postcranial character states were then mapped onto the most parsimonious tree. The analysis revealed changes in pectoral girdle and forelimb morphology, which included reduction of the coracoid plate, increasing robustness of the deltopectoral crest, change in humeral orientation from lateral to caudolateral, increasing prominence of the humeral head, and increasing robustness of the radius. Such changes can be associated with a functional tendency to reduce the lateral component of the propulsive force while still in an abducted mode. On the other hand, changes associated with the pelvic girdle included expansion of the preacetabular iliac process, reduction of the postacetabular iliac process, craniocaudal expansion of the iliac blade, change in the shape of the pubis from flat and plate-like to small and rod-like with a cranial process, and change in acetabular orientation from lateral to caudolateral. The femoral head, starting from a cranioproximal position, progressively became dorsally pronounced and offset from the body. Other features/changes associated with the femur included increasing robustness of the trochanter major, and increasing flattening of the femoral midshaft. Changes in the axial skeleton included increasing stiffening of the trunk to reduce lateral undulations, increasing dorsoventral flexion, and increasing sacral vertebral count, which can be correlated with the preacetabular iliac expansion. These findings suggest that the dicynodont postcranial skeleton evolved towards more upright hindlimb morphology with the body held well off the ground.     

Habituation by a tortoise beetle to the deterrents of spinach

Abstract:  Feeding responses of Cassida nebulosa to spinach vary depending on prior dietary experience. Adults reared on spinach, eat much spinach whereas those reared on Chenopodium album var. centrorubrum rarely eat it. However, there are a few reports that address the mechanisms of this phenomenon, which is termed 'induction of preference'. It has been presumed that this phenomenon arises in response to a reduction of sensitivity to the feeding deterrents contained in spinach as a result of early experience feeding on it. Therefore, we attempted to verify the effects of the feeding deterrent that was isolated from spinach. The feeding-deterrent response was reduced in adults reared on spinach compared with adults reared on C. album var. centrorubrum . Additionally, consumption of spinach by adults reared on deterrent-treated leaves of C. album var. centrorubrum was significantly higher than that by adults reared on control leaves of C. album var. centrorubrum . These results indicate that C. nebulosa acquires the ability to tolerate spinach because sensitivity to the feeding deterrent contained in spinach is reduced by early experience with the deterrent.