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.     

Structures of Monohydroperoxides Produced from Chlorophyll Sensitized Photooxidation of Methyl Linoleate

The effects on growth and mortality of larvae of pink bollworm (Pectinophora gossypiella, Saunders), bollworm (Heliothis zea, Boddie) and tobacco budworm (Heliothis virescens, F.) of adding selected C₁₀–C₁₂ fatty acid methyl esters to a standard diet were determined. The antibiotic activity of straight chain saturated esters was compared to the activity of esters with an olefinic bond either at C-2 or terminally or with a terminal acetylenic or cyclopropyl group. The ester with the greatest activity was the naturally occurring compound methyl (Z,Z)-deca-2,8-diene-4,6-diynoate (matricaria ester) which was lethal to all pink bollworm larvae at 0.01% in the diet and lethal to all bollworm and tobacco budworm larvae at 0.05%.     

Haemocytes of the pink bollworm, Pectinophora gossypiella, during larval development and diapause

Seven types of haemocytes were observed in the last larval instar of the pink bollworm, Pectinophora gossypiella (Saunders): prohaemocytes, plasmatocytes, granular haemocytes, spherule cells, adipohaemocytes, oenocytoids, and podocytes. Total and differential haemocyte counts made from diapausing and non-diapausing larvae showed that during diapause there was a significant reduction in the numbers of all haemocyte types. Upon termination of diapause, the haemocyte level increased. There were no significant differences in the level of haemocytes in the pharate pupae that developed from diapause or non-diapause type larvae, except in the case of adipohaemocytes, which were three times as prevalent in pharate pupae from diapausing larvae. Functional aspects of various types of haemocytes are discussed, and it is suggested that the lower haemocyte level observed during diapause is the result of lower metabolic activity.     

Predicting spring moth emergence in the pink bollworm (Lepidoptera: Gelechiidae): implications for managing resistance to transgenic cotton.

Cultural control methods have been central in the southwestern United States for reducing pink bollworm, Pectinophora gossypiella (Saunders), damage to cotton. Nevertheless, it is not clear at present how such methods could be integrated within the novel pest management framework allowed by introduction of cotton producing a toxin from Bacillus thuringiensis (Bt) for pink bollworm control. Using statewide pheromone trapping and climatic data in conjunction with deterministic simulation models, we investigated whether manipulation of cotton planting date and use of other cultural control methods could represent valuable tactics for control of the pink bollworm in Arizona. Accumulation of heat units from one January accurately predicted the rate of pink bollworm emergence from diapause in 15 cotton-producing regions. Significant variation in rate of emergence from diapause was present among regions, with earlier emergence at higher altitudes. Most adults emerge from diapause too early to reproduce successfully on cotton, a phenomenon known as suicidal emergence. A method for prediction of the fraction of suicidal emergence resulting from adoption of a given cotton planting date is presented. Results from simulation models suggest that manipulation of planting date and implementation of other control cultural methods reduce the rate of application of insecticides and delay the evolution of resistance to Bt cotton in the pink bollworm.     

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.     

Studies on the neurosecretory system and retrocerebral endocrine glands of Nezara viridula Linn. (Heteroptera: Pentatomidae)

The neurosecretory system and retrocerebral endocrine glands of Nezara viridula Linn. have been described on the basis of in situ preparations and histological sections employing the paraldehyde fuchsin (PF) and performic acid-victoria blue (PAVB) techniques. In the brain of N. viridula, there are two medial groups–each consisting of five neurosecretory cells which belong to A-type. The lateral neurosecretory cells are absent. The axons of the two groups of medial neurosecretory cells (MNC) compose the two bundles of neurosecretory pathways (NSP) that decussate in the anterodorsal part of the protocerebrum. The two pathways, after the cross-over, run deep into the protocerebrum and deutocerebrum and emerge as NCC-I from the tritocerebrum. The nervi corporis cardiaci-I (NCC-I) of each side which are heavily loaded with NSM terminate in the aorta wall. Thus, the neurosecretory material (NSM), elaborated in the medial neurosecretory cells of the brain, is stored in the aortic wall and nervi corporis cardiaci-I (NCC-I). The NCC-II are very short nerves that originate from the tritocerebrum and terminate in the corpora cardiaca (CC) of their side. Below the aorta, but dorsal to the oesophagus, lie two oval or spherical corpora cardiaca. A corpus allatum (CA) lies posterior to the corpora cardiaca (CC). The corpora cardiaca do not contain NSM; only the intrinsic secretion of their cells has been occasionally observed which stains orange or green with PF staining method. The corpus allatum sometimes exhibits PF positive granules of cerebral origin. A new connection between the corpus allatum and aorta has been recorded. The suboesophageal ganglion contains two neurosecretory cells of A-type which, in structure and staining behaviour, are similar to the medial neurosecretory cells of the brain. The course and termination of axons of suboesophageal ganglion neurosecretory cells, and the storage organ for the secretion of these cells have been reported. It is suggested that the aortic wall and NCC-I axons function as neurohaemal organ for cerebral and suboesophageal secretions.     

Determining the frequency of heteropteran predation on sweetpotato whitefly and pink bollworm using multiple ELISAs

The gut contents of field-collected, predaceous Heteroptera were assayed for the presence of eggs of the sweetpotato whitefly,Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) and the pink bollworm,Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) using multiple enzyme-linked immunosorbent assays (ELISAs). Of seven species examined,Geocoris species andOrius tristicolor (Say) were the most frequent predators of sweetpotato whitefly with 32–39% of the individuals tested over the whole season scoring positive for whitefly antigens. With the exception ofLygus hesperus Knight, a major insect pest as well as a predator, the frequency of predation on pink bollworm eggs was much lower (0.7–14.3% positive over the season). Relatively few predators tested positive for both antigens (0.3–12.5%).     

Climatic limits of pink bollworm in Arizona and California: effects of climate warming

The distribution and abundance of pink bollworm (Pectinophora gossypiella Saunders (PBW)) in cotton in Arizona and California was examined using a validated weather-driven, physiologically based demographic model of cotton and PBW integrated into a geographic information system (GIS). Survival of diapause larvae during winter as affected by low temperatures is a key factor determining the range of PBW. Winter survival was estimated using data from Gutierrez et al. (Can. Entomol. 109 (1977) 1457) and Venette et al. (Environ. Entomol. 29 (5) (2000) 1018). The model was run continuously over the period 1 January 1995 to 31 December 2003 using observed weather data from 121 locations. Three output variables were mapped as measures of PBW persistence: over-winter survival of diapause PBW larvae, cumulative daily PBW larval densities over the season, and the number of diapause larvae produced during the season. The distribution of pink bollworm is predicted to be restricted to the relatively frost-free cotton growing areas of Arizona and Southern California where it currently reaches pest status. The model predicts that extension of PBW's range into the Central Valley of California is unlikely. The analysis questions the efficacy of an ongoing area-wide effort to prevent the establishment of PBW in the Central Valley of California. Four global warming scenarios were examined to estimate the effects on the potential geographic range of PBW. Average observed daily temperatures were increased 1.0, 1.5, 2.0 or 2.5 °C, respectively, in the four scenarios. Scenarios with average increases of 1.5–2.5 °C predicted that the range of PBW would expand into the Central Valley of California and the severity of the pest would greatly increase in areas of current infestation.     

Control of corpus allatum activity during the imaginai diapause in females of Locusta migratoria L

In the Savio strain of Locusta migratoria an imaginai diapause is induced by long daylength. In diapausing females, the haemolymph level of juvenile hormone (JH) was undetectable during the first 3-wk of imaginai life and later rose only slightly to about 20 ng/JH₃IR per ml. Only peripheral cells of the corpora aliata (CA) were active. In nondiapausing animals, or after the termination of diapause, the JH level was high (140–200 ng/ml) and the ultrastructure of the gland exhibited signs of activity. CA severance in 3-wk-old diapausing females terminated diapause as a result of activation of the CA. CA disconnection in the fifth larval instar or at the imaginai moult in long daylength animals did not break diapause and the CA stayed inactive. The lateral cells of the protocerebrum exert a jdual effect: at the end of larval life they bring about CA maturation and render them active, whereas during the imaginai diapause they inhibit CA activity. The median neurosecretory cells of the pars intercerebralis support CA activity during vitellogenesis.     

Neurosecretory system of the earwig Labedura riparia, and the rôle of the aorta as a neurohaemal organ

The neurosecretory system of Labedura riparia has been described from sections and whole mounts using a variety of techniques. The pars intercerebralis contains two clusters of medial neurosecretory cells (MNC), each cluster consisting of 8 to 10 A-cells and occasional B-cells. The lateral sides of the brain have a few B-cells. The axons of the median neurosecretory cells terminate in the cephalic aorta (AO), whereas the axons of the lateral neurosecretory cells (LNC) terminate in the corpora cardiaca (CC). It appears that the neurosecretory material (NSM) elaborated in the MNC is stored in the cephalic aorta and that elaborated in the LNC is stored in the corpora cardiaca, which are two oval or elongate bodies composed of large chromophobe and small chromophil cells. Posteriorly there is the oval or elongate corpus allatum (CA) attached to the CC by thick nerves. The CA consists of one cell type only. Both CC and CA contain no A-cell neurosecretory material. It has been suggested that the neurosecretory system of L. riparia is composed of two complexes. One is formed by the medial neurosecretory cells for which the aorta functions as a neurohaemal organ, and the other is formed by lateral neurosecretory cells-lateral neurosecretory pathways-nervi corporis cardiaci-II in which the corpora cardiaca function as a neurohaemal organ.     

Climatic limits of pink bollworm in Arizona and California: effects of climate warming

The distribution and abundance of pink bollworm (Pectinophora gossypiella Saunders (PBW)) in cotton in Arizona and California was examined using a validated weather-driven, physiologically based demographic model of cotton and PBW integrated into a geographic information system (GIS). Survival of diapause larvae during winter as affected by low temperatures is a key factor determining the range of PBW. Winter survival was estimated using data from Gutierrez et al. (Can. Entomol. 109 (1977) 1457) and Venette et al. (Environ. Entomol. 29 (5) (2000) 1018). The model was run continuously over the period 1 January 1995 to 31 December 2003 using observed weather data from 121 locations. Three output variables were mapped as measures of PBW persistence: over-winter survival of diapause PBW larvae, cumulative daily PBW larval densities over the season, and the number of diapause larvae produced during the season. The distribution of pink bollworm is predicted to be restricted to the relatively frost-free cotton growing areas of Arizona and Southern California where it currently reaches pest status. The model predicts that extension of PBW's range into the Central Valley of California is unlikely. The analysis questions the efficacy of an ongoing area-wide effort to prevent the establishment of PBW in the Central Valley of California. Four global warming scenarios were examined to estimate the effects on the potential geographic range of PBW. Average observed daily temperatures were increased 1.0, 1.5, 2.0 or 2.5 °C, respectively, in the four scenarios. Scenarios with average increases of 1.5–2.5 °C predicted that the range of PBW would expand into the Central Valley of California and the severity of the pest would greatly increase in areas of current infestation.     

Overwintering cost associated with resistance to transgenic cotton in the pink bollworm (Lepidoptera: Gelechiidae)

Fitness costs associated with resistance to transgenic crops producing toxins from Bacillus thuringiensis (Bt) may have important effects on the evolution of resistance. We investigated overwintering costs in pink bollworm, Pectinophora gosypiella (Saunders), strains with different degrees of resistance to Bt cotton. Frequency of resistant individuals in a strain was not associated with induction of diapause or emergence from diapause in early winter. Emergence from diapause in the spring was 71% lower in three highly resistant strains than in two heterogeneous strains from which the resistant strains were derived. This underestimates the overwintering cost because the frequency of the resistance allele was relatively high in the heterogeneous strains. Emergence in the spring in hybrid progeny from crosses between the resistant and heterogeneous strains was greater than in resistant strains but did not differ from susceptible strains, showing that the overwintering cost was recessive to some extent.     

Remodeling of the corpora cardiaca and the corpora allata during adult metamorphosis in <Emphasis Type="Italic">Bombyx mori</Emphasis>: identification of invisible corpora cardiaca by the expression of adipokinetic hormone

It is problematic to identify the corpora cardiaca (CC) of pupal and adult stages of Bombyx mori because of the presence of tissues similar in appearance near the associated corpora allata (CA). To find the CC, we performed in situ hybridization experiments using the adipokinetic hormone II (AKH-II) gene as a probe, as AKH-II expression occurs only in the CC. Shortly after pupation, the CC and CA began to move toward the esophagus and had attached there tightly by 4 days; during this period, the distance between the CC and CA increased from 65 to 507 μm. The CC became flattened during the remodeling period, although the CA stayed globular until adult ecdysis. In situ hybridization analyses, after the CC had been correctly identified during adult development, showed that the mRNA expression of all the mevalonate enzymes and juvenile hormone acid O-methyltransferase involved in JH synthesis occurred only in CA cells, indicating that the fluctuations of enzyme mRNA amounts in CC-CA complexes (Kinjoh et al. in Insect Biochem Mol Biol 37:808–818, 2007) were derived solely from those in the CA.     

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.     

Molecular characterisation of Bacillus thuringiensis isolates from the Egyptian soils

Molecular characterisation of nine different Bacillus thuringiensis isolates from the soil of different Egyptian governorates and with varying activities against some lepidopterous insects was carried out using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), polymerase chain reaction (PCR) and randomly amplified polymorphic DNA (RAPD)-PCR analysis. Molecular weights of the major components of the crystal proteins of the tested strains revealed that those strains with bands 39 and 141 KDa would be possibly potent against the cotton leafworm Spodoptera littoralis (Biosduval) (Lepidoptera: Noctuidae), those with bands 39–73 and 104–178 KDa showed toxicity against the American bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) and those with bands 25–3 and 135 KDa may be toxic to the pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae). PCR analysis indicates that the frequency of the cry 1 genes predominated 72.41% of isolates amplifying cry 1 gene. DNA fingerprinting-based randomly amplified polymorphic DNA (RAPD) techniques proved to be a reliable method for identification of different B. thuringiensis strains at the DNA level.     

Earliness index deters <Emphasis Type="Italic">Pectinophora gossypiella</Emphasis> incidence on advanced cultivars of <Emphasis Type="Italic">Bt</Emphasis> cotton

Pink bollworm (Pectinophora gossypiella) is recognized as an important pest of cotton and can damage flowers and bolls of both Bt and non-Bt cultivars. Cry-1Ac in Bt cultivars is considered very effective in controlling lepidopterous larvae; therefore, the present study was carried out to investigate the impact of Cry1-Ac and the earliness index on the natural incidence of P. gossypiella at the Cotton Research Institute, Faisalabad. During 2015–2016, ten cultivars were used to determine the incidence of pink bollworm infestation. The experiment was repeated for 2 years. During the next year, Cry1-Ac and earliness traits of selected cultivars were also observed to determine their impact on pink bollworm. Correlation coefficient results regarding days to first flower (r value = 0.66) as well as the earliness index (r value = ? 0.62) exhibited a strong association with pink bollworm, but Cry1-Ac had a weak association (r value = ? 0.058) with pink bollworm. The coefficient of determination (R ²) explained that variability of pink bollworm due to Cry1-Ac, the earliness index, and days to first flower was 18.0, 38.5, and 43.5%, respectively. Principal component analysis results showed that the first two PCs expressed 87% of the total variability. Clusters made on the basis of the studied parameters revealed that clusters 2 and 3 comprised the cotton cultivars possessing earliness traits compared with cluster 1. Therefore, it can be concluded that the earliness index in cotton is an important component for the sustainable management of pink bollworm infestation, the need for which is endless to evade the pink bollworm problem in the era of climate change.     

An appetite for pests: Synanthropic insectivorous bats exploit cotton pest irruptions and consume various deleterious arthropods

Conservation biological control (CBC) seeks to minimize the deleterious effects of agricultural pests by enhancing the efficiency of natural enemies. Despite the documented potential of insectivorous bats to consume pests, many synanthropic bat species are still underappreciated as beneficial species. We investigated the diet of Kuhl's pipistrelle (Pipistrellus kuhlii), a common synanthropic insectivorous bat that forages in urban and agricultural areas, to determine whether it may function as a natural enemy in CBC. Faecal samples of P. kuhlii were collected throughout the cotton‐growing season from five roost sites near cotton fields located in a Mediterranean agroecosystem, Israel, and analyzed using DNA metabarcoding. Additionally, data on estimated abundance of major cotton pests were collected. We found that the diet of P. kuhlii significantly varied according to sites and dates and comprised 27 species of agricultural pests that were found in 77.2% of the samples, including pests of key economic concern. The dominant prey was the widespread cotton pest, the pink bollworm, Pectinophora gossypiella, found in 31% of the samples and in all the roosts. Pink bollworm abundance was positively correlated with its occurrence in the bat diet. Furthermore, the bats’ dietary breadth narrowed, while temporal dietary overlap increased, in relation to increasing frequencies of pink bollworms in the diet. This suggests that P. kuhlii exploits pink bollworm irruptions by opportunistic feeding. We suggest that synanthropic bats provide important pest suppression services, may function as CBC agents of cotton pests and potentially contribute to suppress additional deleterious arthropods found in their diet in high frequencies.     

Intervention des cellules neurosecretrices medianes dans la castration parasitaire d'Anacridium aegyptium (Orthoptère)

The median neurosecretory cells (M-NSC) of Anacridium aegyptium were studied by light and electron microscopy during the ovarian diapause (autumn and winter) and the ovarian activity (spring) in normal females and in females infected by a tachinid fly Metacemyia calloti. In spring, the M-NSC contain comparatively much stainable material in normal females than in parasitized ones. This difference results from the ovarian maturity of normal females and the ovarian immaturity of parasitized females.The activity of the M-NSC was assessed in spring using the evolution of the radioactivity of the pars intercerebralis (PI) and corpora cardiaca (CC) after injection of ³⁵S-cysteine. The activity of the M-NSC is impaired in the parasitized females without ovarian development.The ovarian diapause was broken by massive implantations of corpora allata (CA) or electrical stimulations of the PI. Implantations of CA induce in parasitized females the same state of ovarian development than during natural activity in spring. Electrical stimulations of the PI. which increase the activity of the M-NSC. enhance the ovarian development of the parasitized females. A hypoactivity of the M-NSC is involved in the ‘castration’ of the Egyptian grasshopper.     

Cyt1A from Bacillus thuringiensis Lacks Toxicity to Susceptible and Resistant Larvae of Diamondback Moth (Plutella xylostella) and Pink Bollworm (Pectinophora gossypiella)

We tested Cyt1Aa, a cytolytic endotoxin of Bacillus thuringiensis, against susceptible and Cry1A-resistant larvae of two lepidopteran pests, diamondback moth (Plutella xylostella) and pink bollworm (Pectinophora gossypiella). Unlike previous results obtained with mosquito and beetle larvae, Cyt1Aa alone or in combination with Cry toxins was not highly toxic to the lepidopteran larvae that we examined.