Insecticidal activity of Bacillus laterosporus

Strains of Bacillus laterosporus demonstrated pathogenic activity for second-instar larvae of the mosquito, Culex quinquefasciatus, but failed to demonstrate detectable pathogenicity against larvae of the cabbage looper, Trichoplusia ni. Of 29 strains of the bacterium screened, 16 displayed pathogenicity for mosquito larvae. One of the most pathogenic strains, NRS 590, also demonstrated pathogenic activity for larvae of the mosquito, Aedes aegypti, and for larvae of the black fly, Simulium vittatum. The pathogenicity for Culex larvae was associated with the cell mass rather than with the culture supernatant. A suspension of ultraviolet irradiation-killed cells demonstrated no loss in pathogenic activity, an indication that the pathogenicity is toxin mediated. The toxic substance produced by NRS 590 was found to be resistant to heating at 96°C for 10 min. The toxin was not associated with the heat-resistant, bacterial endospore or with the associated paraspore since a suspension consisting primarily of spores was not toxic to mosquito larvae. Toxic activity in stationary phase cells of NRS 590 was associated with the cell's particulate fraction rather than with the soluble fraction.     

昆虫激肽的生理功能及机制

昆虫激肽是一类高度保守的小分子神经活性物质,自其从马德拉蟑螂脑中分离得到至今,人们在多种无脊椎动物体内均发现了这一激肽家族成员。它们具有促进昆虫后肠收缩、马氏管扭动、原尿分泌,调节血淋巴量和水盐平衡,使马氏管跨膜电位去极化,抑制昆虫体内消化酶释放、幼虫体重增长等功能。然而,天然的昆虫激肽很容易被蛋白酶所降解,因此须对其进行结构改造及构效关系研究,以开发出更有潜力的假肽和非肽模拟抗酶解昆虫激肽类似物,对今后实现环境友好型害虫防治策略具有重要意义。     

Novel visual-cue-based sticky traps for monitoring of emerald ash borers, Agrilus planipennis (Col., Buprestidae)

We examined various methods of trapping emerald ash borers (EAB), Agrilus planipennis Fairmaire, using solely visual cues based on previous work that has documented the importance of visual cues in EAB mate location. Here, we give the results of two of these methods, coloured sticky cards (yellow or blue), or live ash leaves covered with spray-on adhesive to which dead male EAB visual lures had been pinned. Feral male beetles were captured effectively on the sticky traps made from dead male EAB on ash leaves. These sticky-leaf-traps captured more male EAB when deployed in high-population density areas than low-density areas, but did capture EAB even at lower population densities. More feral males were captured on these traps when they were placed higher in the trees, regardless of the population density of EAB. Very few feral female EAB were captured using the sticky-leaf-traps. This novel method of EAB trapping may allow 'real-time' population detection and monitoring of EAB adults during the active flight period rather than locating larval galleries during the autumn and winter after adult flight and attack. Feral male beetles were also captured using standard yellow- or blue-coloured sticky cards to which male EAB had been affixed with adhesive; however, this type of trap was much less effective overall than using the sticky-leaf-traps. Furthermore, Agrilus cyanescens , a species similar in colour to EAB but smaller in size, showed a strong response to blue-coloured sticky traps to which dead male EAB had been affixed with adhesive, suggesting a general use of visual cues in the mating systems of some of the other Buprestidae as well.     

Impact of urbanization on a gall-inhabiting Lepidoptera assemblage: the importance of reserves in urban areas

This paper examines the structure of a Lepidoptera assemblage in an urban environment in South Africa. The Lepidoptera inhabit fungus-induced galls on Acacia karroo. Habitat patches supporting the moth assemblage were sampled from rural, urban-reserve, suburban and city sites and the habitat quality at each of these sites was quantified. Gall occupancy, larval density and species richness were lowest at the most disturbed, city sites. Non-parametric multivariate techniques showed that the moth-assemblage structure did not differ significantly at rural and urban-reserve sites. Assemblage structure at the suburban sites was variable and appeared to be transitional in structure between the city assemblage and the rural and urban-reserve assemblages. Habitat quality variables however were weakly correlated with moth-assemblage structure. The contribution of urban reserves to the local sustainability of this Lepidoptera assemblage emphasizes the importance of maintaining green areas in and around cities.     

Vitamin C content in plants is modified by insects and influences susceptibility to herbivory

Analysis of a diverse cross‐sample of plant‐insect interactions suggests that the abundance of vitamin C (L ‐ascorbic acid, ascorbate or AsA) in plants influences their susceptibility to insect feeding. These effects may be mediated by AsAs roles as an essential dietary nutrient, as an antioxidant in the insect midgut, or as a substrate for plant‐derived ascorbate oxidase, which can lead to generation of toxic reactive oxygen species. Ascorbate can also influence the efficacy of plant defenses such as myrosinases and tannins, and alter insects' susceptibility to natural enemies. Conversely, herbivores appear to influence both de novo synthesis and redox cycling of AsA in their host plants, thereby potentially altering the nutritional value of crops and their susceptibility to pests. The recent development of genetically modified crops with enhanced AsA content provides both an impetus and a tool set for further studies on the role of AsA in plant‐insect interactions.     

Insect cells as hosts for the expression of recombinant glycoproteins

Baculovirus-mediated expression in insect cells has become well-established for the production of recombinant glycoproteins. Its frequent use arises from the relative ease and speed with which a heterologous protein can be expressed on the laboratory scale and the high chance of obtaining a biologically active protein. In addition to Spodoptera frugiperda Sf9 cells, which are probably the most widely used insect cell line, other mainly lepidopteran cell lines are exploited for protein expression. Recombinant baculovirus is the usual vector for the expression of foreign genes but stable transfection of - especially dipteran - insect cells presents an interesting alternative. Insect cells can be grown on serum free media which is an advantage in terms of costs as well as of biosafety. For large scale culture, conditions have been developed which meet the special requirements of insect cells.With regard to protein folding and post-translational processing, insect cells are second only to mammalian cell lines. Evidence is presented that many processing events known in mammalian systems do also occur in insects. In this review, emphasis is laid, however, on protein glycosylation, particularly N-glycosylation, which in insects differs in many respects from that in mammals. For instance, truncated oligosaccharides containing just three or even only two mannose residues and sometimes fucose have been found on expressed proteins.These small structures can be explained by post-synthetic trimming reactions. Indeed, cell lines having a low level of N-acetyl--glucosaminidase, e.g. Estigmene acrea cells, produce N-glycans with non-reducing terminal N-acetylglucosamine residues. The Trichoplusia ni cell line TN-5B1-4 was even found to produce small amounts of galactose terminated N-glycans. However, there appears to be no significant sialylation of N-glycans in insect cells. Insect cells expressed glycoproteins may, though, be 1,3-fucosylated on the reducing-terminal GlcNAc residue. This type of fucosylation renders the N-glycans on one hand resistant to hydrolysis with PNGase F and on the other immunogenic. Even in the absence of 1,3-fucosylation, the truncated N-glycans of glycoproteins produced in insect cells constitute a barrier to their use as therapeutics. Attempts and strategies to mammalianise the N-glycosylation capacity of insect cells are discussed.     

A look into the invisible: ultraviolet-B sensitivity in an insect (Caliothrips phaseoli) revealed through a behavioural action spectrum

Caliothrips phaseoli, a phytophagous insect, detects and responds to solar ultraviolet-B radiation (UV-B; λ ≤ 315 nm) under field conditions. A highly specific mechanism must be present in the thrips visual system in order to detect this narrow band of solar radiation, which is at least 30 times less abundant than the UV-A (315–400 nm), to which many insects are sensitive. We constructed an action spectrum of thrips responses to light by studying their behavioural reactions to monochromatic irradiation under confinement conditions. Thrips were maximally sensitive to wavelengths between 290 and 330 nm; human-visible wavelengths (λ ≥ 400 nm) failed to elicit any response. All but six ommatidia of the thrips compound eye were highly fluorescent when exposed to UV-A of wavelengths longer than 330 nm. We hypothesized that the fluorescent compound acts as an internal filter, preventing radiation with λ > 330 nm from reaching the photoreceptor cells. Calculations based on the putative filter transmittance and a visual pigment template of λ_max = 360 nm produced a sensitivity spectrum that was strikingly similar to the action spectrum of UV-induced behavioural response. These results suggest that specific UV-B vision in thrips is achieved by a standard UV-A photoreceptor and a sharp cut-off internal filter that blocks longer UV wavelengths in the majority of the ommatidia.     

Insect diversity over 36 years at a protected Sierra Nevada (California) site: towards an evaluation of the insect apocalypse hypothesis

1. Recent authors have suggested that declines of insect abundance or diversity, documented first for particular insect taxa of high interest (e.g., butterflies, bees), may apply to insect diversity more generally. This has led to an urgent call for analysis of additional longitudinal datasets to examine trends in general insect diversity.
2. Here we present a dataset gathered from 1982 to 2018 by advanced undergraduate students and graduate students enrolled in a taxonomy course that involved collecting as many insect families as possible over a 5-week period at a high-elevation protected forested site in the Sierra Nevada, California, USA.
3. The data do not support any consistent gain or loss of family-level richness between 1982 and 2018 (no linear trend); a non-linear model suggested a possible small decrease in family-level richness collected between 1986 and 1990, followed by a gradual increase from 1990 to 2018. Neither weather variables nor collector experience or skill appeared to explain among-year variation in collected insect diversity.
4. We urge caution in attempting to draw conclusions from single-site, longitudinal datasets like this one; a definitive answer to the hypothesis of a broad, global decline of insect diversity will require the joint analysis of many datasets like the one we share here.

     

昆虫标本馆建设与昆虫系统学的未来

昆虫标本馆是昆虫标本的保藏、研究和科学教育的实体,代表国家或者区域水平,致力于研究昆虫多样性、揭示昆虫进化规律,为国民经济建设持续发展服务。昆虫系统学研究是昆虫标本馆研究人员的主要任务,它的发展与昆虫标本馆的建设唇齿相依。本文阐述了昆虫标本馆的功能与作用,建设昆虫标本馆的重要性和迫切性;展望了昆虫系统学的未来以及昆虫系统学发展的机遇。     

Establishment and characterization of a cell line from embryos of the Indianmeal moth,Plodia interpunctella

A cell line, UMN-PIE-1181, initiated in November, 1981, from embryos of a malathion-resistant strain of Indianmeal moth, Plodia interpunctella, was in the 83rd passage on January 28, 1985. The line consists of single, small, fibroblastlike cells that are polyploid with chromosome numbers ranging from 56 to 180. Growth rate is dependent on seeding density, there being no growth at or below seeding densities of $\text{2 ×}\text{10}{}^5\text{5}\text{,}\text{ml}$; optimum growth requires a fetal bovine serum concentration of at least 5%. Twenty-nine isozymes were examined. Five enzymes from the cell lines resolved well and subsequently were compared to enzymes extracted from 4-day-old embryos and other life stages of the insects. Phosphomannose isomerase, malic enzyme, malate dehydrogenase, phosphoglucose isomerase, and glucose-6-phosphate dehydrogenase in extracts from the cultured cells and from the insects had identical patterns. Two bands for glutamate-oxalacetate transaminase, present in the cell line, were not observed in the tissue extracts. Furthermore, lactate dehydrogenase from the cultured cells appeared as four bands but was not detectable in any of the samples run from the various life stages of the insects.