Influence of host plant Brassica species) and temperature on population increase of the cabbage whitefly Aleyrodes brassicae

Laboratory studies on the influence of host plant species on population growth of the cabbage whitefly Aleyrodes brassicae Walk. showed that greatest longevity occurred on mustard and lowest on turnip. Leaf age did not affect survival. At 20 or 25 °C the survival curves from mustard plants were shortened Slobodkin's type I whereas those from purple sprouts and turnip were typical of Slobodkin's type II. At 15 °C the survival curves from young leaves of all host plants were of Slobodkin's type I but those from mature leaves were of Slobodkin's type III except that of mustard which was of type I. Young leaves induced higher fecundities than mature leaves. Fecundity was highest on mustard followed by purple sprouts and turnip. This affected population rate such that, for example, daily r_m values on young leaves of mustard, purple sprouts, and turnip at 25 °C were 0.206, O.172, and 0.147, respectively.     

The control of ovarian development during adult diapause in the cabbage whitefly, Aleyrodes proletella

ABSTRACT. Field collections of overwintering cabbage whitefly, Aleyrodes proletella L. (Homoptera: Aleyrodidae) taken during the autumn and winter of 1982/83 and 1983/84 have shown that ovarian development proceeds at a low, but near uniform rate throughout diapause. Extensive fat body is recorded during the autumn and early winter of both periods, but this gradually diminishes during February and March. There does not appear to be a true refractory phase during the dormancy. A period of chilling primes the females for accelerated ovarian development in favourable conditions. When field collected females were transferred to light: dark 16:8 h (15°C) or L:D 12:12 h (15°C) in the laboratory, the subsequent rates of ovarian development were not significantly different, suggesting that temperature is the major regulator of the activation phase, although there was some evidence to suggest that an increase in photoperiod also has a role.     

Parental care in the whitefly Aleyrodes singularis

1. Patches of Aleyrodes singularis nymphs are characterised by a distinctive phenotype composed of the nymphs' exuviae, which are piled on the nymph, and by a covering layer of wax secreted by the adults; these characteristics have been found to confer defensive properties against natural enemies. 2. In contrast to the behaviour typical for ovipositing females of other aleyrodids, A. singularis females tend to remain near the patch of their progeny throughout their development. These mothers were therefore tested to show whether they exhibited active defensive behaviour towards natural enemies, beyond their contribution to passive defence achieved through the secretion of wax on the immatures. 3. The behaviour of whitefly adults differed significantly when performed in the presence of conspecific adults from their behaviour in the presence of natural enemies (either a parasitoid or a predator). The differences were expressed in the mean time devoted to some behavioural events, the frequency at which events were performed, and the number of transitions between pairs of events. 4. Most of the recorded behavioural differences were associated with departure of the natural enemies, facilitating immature survival. 5. This is the first report of active behavioural changes that convey defence of immature offspring for the family Aleyrodidae. Conditions characterising these findings and their relationship with those in which parental care is expected are discussed.     

The critical field photoperiod inducing ovarian diapause in the cabbage whitefly, Aleyrodes proletella (Homoptera: Aleyrodidae)

ABSTRACT. The ovarian and fat body development of cabbage whitefly, Aleyrodes proletella L., has been determined from field samples taken during the transition from a summer to an overwintering population. Between mid and late September 1983, the state of ovarian development decreases as the proportion of diapausing females increases. This is accompanied by maximum fat body development. Diapausing females emerge from late August onwards, and the critical photoperiod, based upon known larval sensitivity and including civil twilight as part of the photophase, is LD 15.5:8.5h. This is in agreement with laboratory studies. The majority of overwintering females are mated. Very few males survive the autumn.     

Olpidium brassicae in cabbage roots

Morphology and development of the vegetative, asexual and sexual cycle Olpidium brassicae (Woronin) Dangeard parasitic in the roots of cabbage (Brassica oleracea L. var. capitata) seedlings was studied in detail. Release of zoo-spores through an exit tube from zoosporangia, their motility and encystment on the epidermal cells and root hairs, process of infection/host entry and later thallus development were described. Motility and fusion of 2 planogametes resulting in zygote formation were observed in slide cultures and described. The process of infection by zygotes and developmental stages of resting sporangia were also studied and described.     

Tronchuda cabbage flavonoids uptake by Pieris brassicae

The flavonoid pattern of larvae of cabbage white butterfly (Pieris brassicae L.; Lepidoptera: Pieridae) reared on the leaves of tronchuda cabbage was analysed by HPLC-DAD-MS/MS-ESI. Twenty flavonoids were identified or characterised, namely 16 kaempferol and four quercetin derivatives. Kaempferol 3-O-sophoroside, a minor component of tronchuda cabbage, was found to be the main component in P. brassicae (15.8%). Apart from this, only two other flavonoids present in significant amounts in tronchuda cabbage (kaempferol 3-O-sophoroside-7-O-glucoside and kaempferol 3-O-sophoroside-7-O-sophoroside) were found in the larvae. The larvae have high amounts of quercetin derivatives (18.5%), which were present only in trace amounts in tronchuda cabbage extracts, suggesting that P. brassicae is able to selectively sequester these flavonoids. The occurrence of a high content of flavonoids not detectable in tronchuda cabbage extracts indicates that P. brassicae larvae are able to metabolize dietary flavonoids.     

Mortality of eggs, larvae and pupae and larval dispersal of the cabbage moth, Mamestra brassicae, in white cabbage in south-eastern Norway

The mortality of eggs, larvae and pupae and larval dispersal of the cabbage moth, Mamestra brassicae (L.) (Lepidoptera: Noctuidae) was investigated in a series of small-scale field experiments in white cabbage, Brassicae oleracea var. capitata (L.), and in the laboratory during 1990–1992 in south–eastern Norway. The highest mortality was found in young larvae and in hibernating pupae. In 1990, larval mortality in the first instar was 80% (range 9–97% for the individual cohorts). Most larvae died within the first 1–3 days after hatching. The dispersal activity during these days was high, and failure to establish feeding sites and predation were probably the main mortality causes. Pupal mortality during winter was 90% on average for 1990–1993 (range 81–100%). The main mortality factor was probably unfavourable weather conditions, and indications of cold stress were found. The impact from parasitoids and diseases was generally low. Trichogramma semblidis (Aurivillius) (Trichogrammatidae) was reared from M. brassicae eggs in very low numbers in 1991. Larval parasitism increased from < 1% in 1990 to almost 24% in 1992, and was almost totally caused by the braconids Microplitis mediator (Haliday) and Aleiodes (Aleiodes) sp. Predation of frozen larvae on the soil surface was 75% on average (range 63–96%) during 1990–1992 in first instar larvae and decreased gradually with larval age. The consumption rates of Philonthus atratus (Gravenhorst) (Staphylinidae) and the carabids Bembidion tetracolum (Say), Pterostichus melanarius (Illiger) and Harpalus rufipes (Degeer) on M. brassicae eggs and larvae were investigated in non-choice experiments in the laboratory. A preliminary survival model based on estimates of the mortality factors identified in this study is presented.     

Paenibacillus brassicae sp. nov., isolated from cabbage rhizosphere in Beijing, China

A novel Gram-positive, rod-shaped, motile, spore-forming, nitrogen-fixing bacterium, designated strain 112^T, was isolated from cabbage rhizosphere in Beijing, China. The strain was found to grow at 10–40 °C and pH 4–11, with an optimum of 30 °C and pH 7.0, respectively. Phylogenetic analysis based on a fragment of the full-length 16S rRNA gene sequence revealed that strain 112^T is a member of the genus Paenibacillus. High levels of 16S rRNA gene similarities were found between strain 112^T, Paenibacillus sabinae DSM 17841^T (97.82 %) and Paenibacillus forsythiae DSM 17842^T (97.22 %). However, the DNA–DNA hybridization values between strain 112^T and the type strains of these two species were 10.36 and 6.28 %, respectively. The predominant menaquinone was found to be menaquinone 7 (MK-7). The major fatty acids were determined to be anteiso-C_15:0 and C_16:0. The major polar lipids were found to be diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and unknown aminophospholipids. The cell wall peptidoglycan was found to contain meso-diaminopimelic acid. The DNA G+C content was determined to be 55.4 mol%. On the basis of its phenotypic characteristics, 16S rRNA gene sequence analysis and the value of DNA–DNA hybridization, strain 112^T is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus brassicae sp. nov. is proposed. The type strain is 112^T (= ACCC 01125^T = DSM 24983^T).     

Identification of a new hobo element in the cabbage moth, Mamestra brassicae (Lepidoptera)

A complete hobo-like element, called Mbhobo, was identified in the cabbage moth, Mamestra brassicae. This element has a high sequence similarity to the HFL1 hobo element of Drosophila melanogaster. Amplification of Mbhobo termini indicated that transposition occurred into a 5'-GTGGGTAC-3' target sequence that was duplicated upon insertion. This target site conforms to the consensus sequence established for the insertion sites of insect hAT elements. Mbhobo has a single 1935 bp long ORF with significant homology to the D. melanogaster HFL1 hobo transposase. FISH experiments evidenced Mbhobo clusters located in heterochromatic regions of Z and W sex chromosomes and in heterochromatic areas of chromosome pair 10.     

Molecular cloning and functional expression of chitinase-encoding cDNA from the cabbage moth, Mamestra brassicae

Chitinase is a rate-limiting and endo-splitting enzyme involved in the bio-degradation of chitin, an important component of the cuticular exoskeleton and peritrophic matrix in insects. We isolated a cDNA-encoding chitinase from the last larval integument of the cabbage moth, Mamestra brassicae (Lepidoptera; Noctuidae), cloned the ORF cDNA into E. coli to confirm its functionality, and analyzed the deduced amino acid sequence in comparison with previously described lepidopteran chitinases. M. brassicae chitinase expressed in the transformed E. coli cells with the chitinase-encoding cDNA enhanced cell proliferation to about 1.6 times of the untransformed wild type strain in a colloidal chitin-including medium with only a very limited amount of other nutrients. Compared with the wild type strain, the intracellular levels of chitin degradation derivatives, glucosamine and N-acetylglucosamine were about 7.2 and 2.3 times higher, respectively, while the extracellular chitinase activity was about 2.2 times higher in the transformed strain. The ORF of M. brassicae chitinaseencoding cDNA consisted of 1686 nucleotides (562 amino acid residues) except for the stop codon, and its deduced amino acid composition revealed a calculated molecular weight of 62.7 and theoretical pI of 5.3. The ORF was composed of N-terminal leading signal peptide (AA 1-20), catalytic domain (AA 21-392), linker region (AA 393-498), and C-terminal chitin-binding domain (AA 499-562) showing its characteristic structure as a molting fluid chitinase. In phylogenetic analysis, the enzymes from 6 noctuid species were grouped together, separately from a group of 3 bombycid and 1 tortricid enzymes, corresponding to their taxonomic relationships at both the family and genus levels.     

The hormonal control of diuresis in the cabbage white butterfly Pieris brassicae.

The diuresis which follows the pupal-adult ecdysis of Pieris brassicae is hormonally controlled. Use of the isolated Malpighian tubules as a bioassay shows the presence of substantial diuretic activity in homogenates of the brain and corpus cardiacum-corpus allatum complex. The hormone is probably produced in the brain and released from a storage site in the corpora cardiaca. The tubules of the butterfly are maximally responsive to the diuretic hormone at the time of eclosion.     

Sex pheromone components of the cabbage armyworm, Mamestra brassicae: Isolation, identification and field experiments

Glass capillary gaschromatography coupled to a mass spectrometer has shown that in addition to Z-11-hexadecenyl acetate, hexadecyl acetate and Z-11-heptadecenyl acetate are present in pheromone glands of calling virgin females of Mamestra brassicae L. (Lepidoptera: Noctuidae, Hadeninae). Electroantennography revealed positive responses for Z 11–17: Ac and 16: Ac, while behavioural tests were only positive for Z 11–17: Ac.

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Résumé Il a été procédé à l'identification des phéromones par chromatographie en phase gazeuse et par spectrographie de masse. Outre l'acétoxy-1 hexadécène-11Z, on identifié l'acétoxy-heptadécène-11Z et l'acétoxy-1-hexadécane dans les glandes des femelles vierges de M. brassicae. L'antennographie a montré des réactions positives à l'acétoxy-hepta-décène-11Z et à l'acétoxy-1-hexadécane, tandis que seul l'acétoxyhepta-décène-11Z provoque un comportement sexuel des mâles.

     

The fecundity of the cabbage root fly Erioschia brassicae under field conditions

Flies enclosed in large (1.8 m high × 3.0 m wide × 15.2 m long) field cages containing a section of hedgerow and a plot of brassicas laid an average of 63 eggs/female during May 1968. This represented the first batch of eggs and was equivalent to that of the flies fed on sucrose alone. The principal natural source of carbohydrate in hedgerows at Wellesbourne in May was the nectar of A. sylvestris and two Anthriscus flowers per female per day were sufficient to sustain the development and oviposition of the first batch of eggs. The average fecundity of second generation flies in field cages was very low because many of the females were killed by the fungus Empusa muscae.A thin-layer chromatographic method was used to assess the free amino acids in extracts from the abdomens of female cabbage root flies. Quantities of valine and leucine in excess of 5 g/l of sample and an extinction of the extract in excess of 0.2 at 505 nm indicated that such samples included females that had fed from proteinaceous materials.Using these criteria, 3% of the flies captured from the second generation during July and August were assessed as having fed from proteinaceous sources and dissections showed that 6% of these flies had imbibed sufficient proteinaceous material to mature the second or subsequent batches of eggs. These results suggest that 94–97% of the females of the first and second generations of cabbage root flies at Wellesbourne feed only from carbohydrates. Under field conditions, therefore, the fecundity of the cabbage root flies was only 20–30% of their potential fecundity.

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Zusammenfassung Kohlfliegen, die in einem großen Feldkäfig (15,2 m lang, 3 m breit und 1,8 m hoch) gehalten wurden, der einen Teil einer Feldhecke sowie eine mit Brassica oleracea botrytis L. bebaute Fläche enthielt, legten während des Mai 1968 im Durchschnitt 63 Eier pro Weibchen. Das entspricht dem ersten Satz Eier (Gelege) und gleicht der Eiproduktion von Fliegen, die nur mit Rohrzucker ernährt wurden. Die Hauptquelle der im Mai in Hecken von Wellesbourne natürlich vorkommenden Kohlenhydrate ist der Nektar von Anthriscus sylvestris. Zwei Anthriscus-Blüten pro Weibchen und Tag genügen, um die Entwicklung und Ablage des ersten Eigeleges zu gewährleisten. Die durchschnittliche Fruchtbarkeit der Fliegen der zweiten Generation war in den Feldkäfigen sehr niedrig, da viele Weibchen durch Empusa muscae getötet wurden.Zur Ermittlung der freien Aminosäuren in Hinterleibsextrakten weiblicher Fliegen wurde eine dünnschichtchromatographische Methode benutzt. Mehr als 5 g/l Valin und Leucin je Probe und Extinktion bei 505 m in einem Extrakt von über 0,2 deutet darauf hin, daß solche Proben Weibchen enthielten, die sich von eiweißhaltigen Stoffen ernährt hatten. Benutzt man diese Kriterien, so zeigen 3% der während Juli und August gefangenen Fliegen der zweiten Generation, daß sie ihre Nahrung von eiweißhaltigen Quellen bezogen. Sektionen ergaben, daß diese Fliegen genügend eiweißhaltige Stoffe aufgenommen hatten, um einen zweiten oder weiteren Satz Eier produzieren zu können. Diese Ergebnisse lassen vermuten, daß sich 94–97% der Weibchen der ersten und zweiten Generation der Kohlfliege in Wellesbourne ausschließlich von Kohlenhydraten ernähren. Deshalb beträgt ihre Fruchtbarkeit unter Feldbedingungen nur 20–30% des Möglichen.

     

Hourglass and oscillator expressions of photoperiodic diapause response in the cabbage moth Mamestra brassicae

Abstract. Both oscillator and hourglass features are found in the photoperiodic response that controls the pupal winter diapause of Mamestra brassicae. The expression of oscillatory response to extended long-night cycles is temperature dependent, i.e. circadian resonance appears at 23 and 25^oC but not at 20 and 28^oC. At 20^oC, scanning of extended scotophases by a short light pulse does not reveal any clear circadian rhythmicity. However, a circadian feature of the photoperiodic response is indicated even at 20^oC by a bistability phenomenon, i.e. either one of the two dark periods in symmetrical skeleton photoperiods determines the diapause response depending on the phase angle with the preceding (entraining) light-dark cycles. At 20 and 25^oC, the incidence of diapause increases as a function of the number of light–dark cycles regardless of the cycle length (T) , if T is 24 h or 2 X 24h (with a 12 h light period). A non-diel cycle (r=36h) is less effective, suggesting that disturbance of the circadian organization partly impairs the diapause-inducing function. The inductive effect of a long night is largely affected by temperature, and becomes saturated with eight cycles at 20^oC and 14 cycles at 25^oC. Presumably, an hourglass mechanism measures the dark time, and a circadian component involved in some later sequence of the photoperiodic response may or may not be expressed depending on the mode of interaction between them.     

Purification and cloning of pierisin-2, an apoptosis-inducing protein from the cabbage butterfly, Pieris brassicae.

The cabbage butterfly Pieris rapae contains a strong apoptosis-inducing substance, pierisin, against human cancer cell lines, which is thought to act via ADP-ribosylation. Here we report the purification and cloning of an apoptosis-inducing substance, designated as pierisin-2, from another cabbage butterfly, Pieris brassicae. Pierisin-2 was purified from pupae by sequential chromatography and its cytotoxic and apoptosis-inducing activities to various cancer cells were similar to those of pierisin, designated as pierisin-1, from P. rapae. cDNA cloning of pierisin-2 was performed on the basis of the partial amino-acid sequence. The nucleotide sequence indicated that the cDNA encodes an 850-amino-acid protein with a calculated molecular mass of 97 986. The deduced amino-acid sequence of pierisin-2 was 91% identical with that of pierisin-1. In vitro expressed protein in the reticulocyte lysate exhibited apoptosis-inducing activities against human gastric carcinoma TMK-1 and cervical carcinoma HeLa cells, similar to the purified native pierisin-2 from the pupae. Pierisin-2 shows regional sequence similarities with certain ADP-ribosylating toxins such as the A-subunit of cholera toxin. The results from site-directed mutagenesis at Glu165, a conserved residue among ADP-ribosylating enzymes necessary for NAD binding, and from experiments with ADP-ribosylating enzyme inhibitors suggested that pierisin-2 could be considered as an ADP-ribosylating toxin like pierisin-1.     

Control of ommochrome synthesis by both juvenile hormone and melanization hormone in the cabbage armyworm,Mamestra brassicae

Summary Pigmentation of last instar larvae of the cabbage armyworm,Mamestra brassicae is of two types: melanin in the cuticle and ommochrome in the epidermis. The latter was found to be primarily xanthommatin. When allatectomy was performed 8 h before head capsule slippage (HCS) in the last larval molt, later ommochrome synthesis was inhibited. Application of juvenile hormone (JH) up to 12 h after HCS (9 h before ecdysis) (activity: methopreneJH I>JH II>JH III) restored ommochrome synthesis. After that time it has less and less effect.Removal of the suboesophageal ganglion from the larvae 8 h before HCS prevented both later ommochrome synthesis and melanization. Melanization of isolated abdomens was restored by implantation of 3 suboesophageal ganglia or injection of melanization and reddish coloration hormone (MRCH) 18 h after HCS. Restoration of ommochrome synthesis required exogenous JH in addition to melanization hormone from suboesophageal ganglion or MRCH. Therefore, melanization appears to be critical for the later onset of ommochrome synthesis even in a larva which has been exposed to JH during the critical period.Abbreviations CC·CA corpora cardiaca-corpora allata complex - JH juvenile hormone - MRCH melanization and reddish coloration hormone - HCS head capsule slippage