A diapause associated protein of the pink bollworm Pectinophora gossypiella Saunders.

A diapause associated protein was electrophoretically isolated from the hemolymph of diapausing last instar larvae of the pink bollworm Pectinophora gossypiella. This protein (M(r) approximately 490,000, glycolipoprotein) was given the name Pectinophora diapause protein (PDP). It is composed of one subunit (M(r) 103,000). The concentration of PDP increased dramatically in the hemolymph of diapausing larvae from 17.4% in prediapause (PD) phase to 29.2% in early diapause (ED) phase reaching a level of 38.6% in larval hemolymph of middiapause (MD) phase. The concentrations of total proteins in the hemolymph of active feeding (A), PD, ED, and MD larvae were 69.8, 106,6, 113.3, and 118 mg/ml, respectively, while those in the fat body of the same larvae were 7.1, 7.4, 8.8, and 4.5 mg/g, respectively. In Pectinophora a drop in the concentration of fat body proteins coincided with a corresponding increase in hemolymph proteins, which suggests an active release of protein from the fat body into the hemolymph during the development of diapause. A partial amino acid sequence of pectinophorin showed the first 15 amino acids starting from the amino terminus of the peptide chain: N-ALA-LYS-THR-ILEU-VAL-GLU-ASN-MET-PRO-PRO-THR-PRO-LEU-ASN-ALA-C.     

A new test for measuring diapause in the pink bollworm Pectinophora gossypiella Sunders.

An ELISA test was developed to assay for the presence of a protein, pectinophorin, that is expressed only in diapausing last instar larvae of the pink bollworm, Pectinophora gossypiella Saunders. Use of the test provides a good estimation of the percent of diapause larvae in populations of pink bollworm in cotton fields in California and Arizona. All plow down dates are chosen before the majority of larvae enter diapause so as to eliminate as many overwintering survivors as possible. These dates may now be determined more precisely for any given field by use of the new ELISA procedure.     

Global variation in the piggyBac-like element of pink bollworm,Pectinophora gossypiella

The piggyBac transposable element, originally discovered in the cabbage looper, Trichoplusia ni, has been used widely in genetic engineering of insects including the pink bollworm, Pectinophora gossypiella, a major lepidopteran pest of cotton. Previously, we identified an intact copy of a piggyBac-like element (PLE) in pink bollworm, designated as PgPLE1.1. Here we report global variation in the occurrence and sequence of PgPLE1.1 and its flanking sequences. Low to high frequency of the PgPLE1.1 insertion was observed in populations from USA, Mexico, China, India, and Israel, while there is no PgPLE1.1 insertion in the populations from Australia. Investigation of the five haplotypes of PgPLE1.1, their frequency, and the flanking sequences of PgPLE1.1 revealed significant differences of the populations from Australia and China compared to other global populations, although recent occurrences of extensive gene flows among global populations were evident.     

Cross-resistance of pink bollworm (Pectinophora gossypiella) to Bacillus thuringiensis toxins

Two strains of pink bollworm (Pectinophora gossypiella) selected in the laboratory for resistance to Bacillus thuringiensis toxin Cry1Ac had substantial cross-resistance to Cry1Aa and Cry1Ab but not to Cry1Bb, Cry1Ca, Cry1Da, Cry1Ea, Cry1Ja, Cry2Aa, Cry9Ca, H04, or H205. The narrow spectrum of resistance and the cross-resistance to activated toxin Cry1Ab suggest that reduced binding of toxin to midgut target sites could be an important mechanism of resistance.     

切断棉红铃虫食物链的探讨

根据棉花早蕾是一代棉红铃虫唯一食料,提出切断红铃虫食物链的构想。经多年实践,摘去7月上旬全部早蕾,能减少大部分蛀铃虫源,收到显著减轻或基本控制二代为害的效果,且能提高优质棉产量,使经济、生态、环境同步获益。     

Sublethal effects of permethrin on the chemical communication system of the pink bollworm moth,Pectinophora gossypiella

Topically applied sublethal doses of permethrin can interrupt chemical communication between the sexes of Pectinophora gossypiella by affecting both the signaler and the responder. The probability of calling by females is reduced when they are treated with doses of permethrin which are much less than the LD₅₀. Similarly, key stages in the behavioral response of males to sex pheromone are effectively blocked at these low doses. Males recover from these effects 4 days after treatment, but calling by females is still significantly reduced at this time. Chemical control of P. gossypiella populations with permethrin may not be limited to mortality, and potentially includes effective control of behavioral aspects of chemical communication.     

Selection for altered pheromone-component ratios in the pink bollworm moth,Pectinophora gossypiella (Lepidoptera: Gelechiidae)

Female pink bollworm moths, Pectinophora gossypiella(Saunders), were selected for altered component ratios of the long-distance sex pheromone, (Z, E)-and (Z, Z)-7,11- hexadecadienyl acetate. Selection for 12 generations increased the mean (± SD) percentage of the (Z, E)isomer from 42.9 ± 1.0 in the parental generation to 48.2 ± 1.2. Although statistically significant, a change of this magnitude may be transparent to males because of their relatively broad response spectrum. Selection for a lower percentage of the (Z, E)isomer yielded no change in the mean pheromone ratio. The total amount of pheromone produced declined in both selected lines. In the line selected for females producing a high percentage of the (Z, E)isomer, the duration of wing fanning by males to high (Z, E)blends was elevated.     

Binding of Bacillus thuringiensis toxins in resistant and susceptible strains of pink bollworm (Pectinophora gossypiella)

Evolution of resistance by pests could cut short the success of transgenic plants producing toxins from Bacillus thuringiensis, such as Bt cotton. The most common mechanism of insect resistance to B. thuringiensis is reduced binding of toxins to target sites in the brush border membrane of the larval midgut. We compared toxin binding in resistant and susceptible strains of Pectinophora gossypiella, a major pest of cotton worldwide. Using Cry1Ab and Cry1Ac labeled with (125)I and brush border membrane vesicles (BBMV), competition experiments were performed with unlabeled Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry1Ca, Cry1Ja, Cry2Aa, and Cry9Ca. In the susceptible strain, Cry1Aa, Cry1Ab, Cry1Ac, and Cry1Ja bound to a common binding site that was not shared by the other toxins tested. Reciprocal competition experiments with Cry1Ab, Cry1Ac, and Cry1Ja showed that these toxins do not bind to any additional binding sites. In the resistant strain, binding of (125)I-Cry1Ac was not significantly affected; however, (125)I-Cry1Ab did not bind to the BBMV. This result, along with previous data from this strain, shows that the resistance fits the "mode 1" pattern of resistance described previously in Plutella xylostella, Plodia interpunctella, and Heliothis virescens.     

棉红铃虫田间产卵规律的进一步研究

在棉株结铃前,红铃虫一代卵主要分布于棉株新展开叶上。在棉花单株结铃达2．5个左右时,红铃虫卵均集中分布于棉青铃上。红铃虫二、三代卵分别以由外到内第二、三和第三、四大铃圆锥体位上的青铃卵量分布最多,分别占全株卵量的58．56％和67．19％红铃虫在10天以上日龄的青铃上均可产卵,其中在20～34天日龄的青龄上产卵量最大,占青铃上总卵量的55．02％。一代和二、三代红铃虫卵常分别1～8粒和1～13粒聚产成堆,单个青铃上可同期产卵1～16粒。     

Field longevity of a fluorescent protein marker in an engineered strain of the pink bollworm, Pectinophora gossypiella (Saunders)

The cotton pest, pink bollworm (Pectinophora gossypiella (Saunders)), is a significant pest in most cotton-growing areas around the world. In southwestern USA and northern Mexico, pink bollworm is the target of the sterile insect technique (SIT), which relies on the mass-release of sterile pink bollworm adults to over-flood the wild population and thereby reduce it over time. Sterile moths reared for release are currently marked with a dye provided in their larval diet. There are concerns, however, that this marker fails from time to time, leading to sterile moths being misidentified in monitoring traps as wild moths. This can lead to expensive reactionary releases of sterile moths. We have developed a genetically marked strain that is engineered to express a fluorescent protein, DsRed2, which is easily screened under a specialised microscope. In order to test this marker under field conditions, we placed wild-type and genetically marked moths on traps and placed them in field cages. The moths were then screened, in a double-blind fashion, for DsRed2 fluorescence at regular intervals to determine marker reliability over time. The marker was shown to be robust in very high temperatures and generally proved reliable for a week or longer. More importantly, genotyping of moths on traps by PCR screening of the moths was 100% correct. Our findings indicate that this strain--and fluorescent protein markers in general--could make a valuable contribution to SIT.     

Some structural and functional properties of nerves and muscles in the oviduct of the pink bollworm moth,Pectinophora gossypiella (Saund.)

The oviduct of the pink bollworm is innervated by an intrinsic neural network arising from 4 nerves from the terminal ganglion. The nerve tracts in this network often contained elliptical swellings, each with a central nucleus.

A distinct surface topography was evident in the muscular sheath of the common and lateral oviduct. A very thin muscular envelope consisting of an inner band of circular fibers and an outer layer of longitudinal fibers was also found in the ovarioles. Although conventional A and I bands were recognized, the z-disk was composed of an irregular and loose meshwork, suggesting that the visceral muscles of the reproductive tract possess super-contracting properties. Even when the oviduct and the ovarioles were isolated from the central nervous system, an endogenous rhythmic activity was evident.

Two types of spontaneous excitatory postsynaptic potentials were detected in the oviduct. The type most frequently observed had a complex of multiple spikes with a duration of 18–32 msec. The other type had a saw-tooth shape and a duration of 80–160 msec. Spontaneous action potentials with a plateau-type configuration and a duration of 280–320 msec were also observed. After the removal of the terminal ganglion, endogenous electrical activity distinct from the events just described was found in the midand upper common oviduct. Such discharges seem to originate from the intrinsic neural network and had durations similar to those found for neurosecretory cells.     

Regulation of pheromone production by female pink bollworm moths Pectinophora gossypiella (Sanders) (Lepidoptera: Gelechiidae)

Abstract. We present in this study data which indicate that there is a diel periodicity in the pheromone production of the pink bollworm moth Pectinophora gossypiella (Sanders) (Lepidoptera: Gelechiidae) but that it is not well defined. Moreover the control mechanism of pheromone production differs somewhat from that reported for other moths. No pheromonotropic response was obtained when photophase females were injected with synthetic Helicoverpa zea pheromone biosynthesis activating neuropeptide (Hez-PBAN). After decapitation for 24 h, Hez-PBAN did not induce pheromonotropic activity above control levels, which themselves remained relatively high. No effect on pheromone production was observed after treatment with the non-steroidal ecdysone agonist (RH5999). Decapitation for 72 h resulted in a significant drop in the control levels of pheromone titres. After decapitation for 72 h, stimulation by injections of Hez-PBAN and pink bollworm head extracts was observed. In addition, an enhancement of the PBAN stimulation was observed when combined with severance of the ventral nerve cord before injection. On the other hand, pink bollworm head extracts did not cross-react with Hez-PBAN antiserum in a radioimmunoassay, indicating that the pheromonotropic factor present is sufficiently different from Hez-PBAN and does not recognize the antigenic binding sites. In studies using isolated abdomen and pheromone gland cultures in vitro , no stimulation of de novo pheromone biosynthesis was observed but a 3-fold increase in the de novo fatty acid biosynthesis was detected in pheromone gland cultures.     

Isolation and characterization of polymorphic microsatellite loci from the pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae)

Thirteen polymorphic microsatellite markers were developed from an enriched partial genomic library for the pink bollworm, Pectinophora gossypiella (Saunders), one of the most important cotton pests in the world. The total number of alleles ranged from two to 12 for a sample of 50 individuals and the expected heterozygosity at these loci ranged from 0.042 to 0.830. Although the presence of null alleles in some loci is suspected, these polymorphic markers are likely to provide useful tools for the population genetic studies of this species.     

Control of resistant pink bollworm (Pectinophora gossypiella) by transgenic cotton that produces Bacillus thuringiensis toxin Cry2Ab

Crops genetically engineered to produce Bacillus thuringiensis toxins for insect control can reduce use of conventional insecticides, but insect resistance could limit the success of this technology. The first generation of transgenic cotton with B. thuringiensis produces a single toxin, Cry1Ac, that is highly effective against susceptible larvae of pink bollworm (Pectinophora gossypiella), a major cotton pest. To counter potential problems with resistance, second-generation transgenic cotton that produces B. thuringiensis toxin Cry2Ab alone or in combination with Cry1Ac has been developed. In greenhouse bioassays, a pink bollworm strain selected in the laboratory for resistance to Cry1Ac survived equally well on transgenic cotton with Cry1Ac and on cotton without Cry1Ac. In contrast, Cry1Ac-resistant pink bollworm had little or no survival on second-generation transgenic cotton with Cry2Ab alone or with Cry1Ac plus Cry2Ab. Artificial diet bioassays showed that resistance to Cry1Ac did not confer strong cross-resistance to Cry2Aa. Strains with >90% larval survival on diet with 10 microg of Cry1Ac per ml showed 0% survival on diet with 3.2 or 10 microg of Cry2Aa per ml. However, the average survival of larvae fed a diet with 1 microg of Cry2Aa per ml was higher for Cry1Ac-resistant strains (2 to 10%) than for susceptible strains (0%). If plants with Cry1Ac plus Cry2Ab are deployed while genes that confer resistance to each of these toxins are rare, and if the inheritance of resistance to both toxins is recessive, the efficacy of transgenic cotton might be greatly extended.     

The effects of the infestation ratio of spiny bollworm (Earias insulana) and pink bollworm (Pectinophora gossypiella) on cotton yield grown in semi-arid region of Turkey

Abstract:  Field studies were conducted in Harran Plain, Turkey, to investigate the infestation of spiny bollworm (SBW) and pink bollworm (PBW) in cotton blind bolls during the period 1999–2001. Blind bolls left on the cotton plants after the harvest were collected, and the PBW and SBW larvae, which are the causes of infection were counted in the laboratory by splitting the bolls. The statistical methods reveal that the infestation ratio variable plays an important role in reducing cotton yield. The infestation ratio variable was found to be statistically significant in all models used. Different soil types may have little effects on yield. We also estimate elasticity of yield with respect to infestation ratio variable. A 1% increase in infestation ratio would reduce about 2.5–6% of cotton yield. Although the infestation ratio of cotton yield is inelastic, which means that the yield is less responsive to the infestation ratio, the elasticity is however an economically important indication because additional cost spent on pests will increase total cost thereby increasing the level where marginal revenue equals the marginal cost.     

Population structure and introduction history of the pink bollworm, Pectinophora gossypiella, in China

The pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), a cotton pest probably native to Indo-Pakistan, invaded China at the beginning of the 20th century. Chinese P. gossypiella have been assumed to be the result of indiscriminate introductions from Pakistan and America by transport of cotton seed. We tested this long-held hypothesis and genotyped a total of 527 individuals from 14 sites at 13 microsatellite loci. We analyzed these data with traditional statistics as well as with Bayesian methods. The loci were, for the most part, highly polymorphic. The allelic richness of Chinese populations at six loci was greater than those of the Pakistani and American populations. Significant deficits of heterozygotes were recorded for all 14 populations, and null alleles were the most probable factor contributing to these deficits. Pairwise F_ST estimates showed that there was significant differentiation among the pooled Chinese, Pakistani, and American populations, and there was structure within most of the Chinese populations. The Bayesian analysis revealed that the combined Chinese, American, and Pakistani populations formed separate clusters, and the nine Chinese populations were divided into two clusters. Allelic frequency distributions showed that private and shared alleles within Chinese P. gossypiella were derived only partly from the Pakistani and American populations. The microsatellite-based genetic analyses suggested that the Chinese P. gossypiella populations originated from multiple sources.