Volatile constituents of the boll weevil

When the distillable oil from adult boll weevils, Anthonomus grandis, of both sexes was investigated with an integrated gas chromatographymass spectrometry system, evidence was obtained for a number of mono- and sesquiterpene hydrocarbons and some substituted anilines including o-toluidine; for some C₅ and C₆ alcohols and monoterpene alcohols; and for at least one sesquiterpene alcohol. The major components were a series of alkanes, alkenes, and alkyl alcohols of high molecular weight. This investigation was part of a study made to identify possible additional components of the pheromone produced by the boll weevil.     

Metabolism of sugars to polyols in the boll weevil

When fed to starved adults of Anthonomus grandis, several pentoses and hexoses were metabolized to the corresponding polyols (sugar alcohols). Xylitol, galactitol, arabitol, ribitol, rhamnitol, mannitol, and sorbitol were metabolites of d-xylose, d-galactose and lactose, d-arabinose, d-ribose, l-rhamnose, d-mannose, and d-glucose and d-fructose, respectively. l-Sorbose was not metabolized to a polyol. Large quantities of xylitol and galactitol and intermediate amounts of arabitol, ribitol, and rhamnitol accumulated while only small amounts or traces of mannitol and sorbitol were detected. The limited accumulation of sorbitol in the glucose- and fructose-fed weevils probably was caused by the rapid metabolism of sorbitol to glucose, fructose, trehalose, and glycogen. Each of the ingested sugars, the corresponding polyols, and trehalose were present in the weevil haemolymph. Most of the polyols had never before been detected as metabolites in an insect.     

Regulation of vitellogenin synthesis and uptake in the boll weevil, Anthonomus grandis

Abstract. Hormonal factors influencing reproductive development were examined in adult boll weevils, Anthonomus grandis (Boheman) (Coleoptera: Curculionidae). Long-day, high-temperature rearing conditions promote reproduction whereas short-day, low-temperature conditions do not. Implants of corpora allata (CA), brains, or brains plus retrocerebral complexes taken from long-day donors, or hormone analogue treatments were used to examine onset of vitellogenin synthesis and uptake in decapitated bodies of adult weevils reared in short-day, low-temperature conditions. Weevils decapitated within 2 days after eclosion and reared in short-day, low-temperature conditions never initiated vitellogenin production or ovarian development. Females and males decapitated on day 2 showed haemolymph vitellogenin within 5 days following treatment with Juvenile Hormone (JH) analogue or implantation of CA, but not after implantation of brain alone or implantation of muscle (sham). Uptake of vitellogenin into the oocytes did not occur unless both JH analogue and brain were given as replacement therapy. These experiments indicated that JH is necessary and sufficient to stimulate vitellogenin synthesis in this species but that a brain factor must be present for vitellogenin uptake.     

Proteolytic processing of the vitellogenin precursor in the boll weevil,Anthonomus grandis

The soluble proteins of the eggs of the coleopteran insect Anthonomus grandis Boheman, the cotton boll weevil, consist almost entirely of two vitellin types with M_rs of 160,000 and 47,000. We sequenced their N-terminal ends and one internal cyanogen bromide fragment of the large vitellin and compared these sequences with the deduced amino acid sequence from the vitellogenin gene. The results suggest that both the boll weevil vitellin proteins are products of the proteolytic cleavage of a single precursor protein. The smaller 47,000 M vitellin protein is derived from the N-terminal portion of the precursor adjacent to an 18 amino acid signal peptide. The cleavage site between the large and small vitellins at amino acid 362 is adjacent to a pentapeptide sequence containing two pairs of arginine residues. Comparison of the boll weevil sequences with limited known sequences from the single 180,000 M_r honey bee protein show that the honey bee vitellin N-terminal exhibits sequence homology to the N-terminal of the 47,000 M_r boll weevil vitellin. Treatment of the vitellins with an N-glycosidase results in a decrease in molecular weight of both proteins, from 47,000 to 39,000 and from 160,000 to 145,000, indicating that about 10–15% of the molecular weight of each vitellin consists of N-linked carbohydrate. The molecular weight of the deglycosylated large vitellin is smaller than that predicted from the gene sequence, indicating possible further proteolytic processing at the C-terminal of that protein. © 1993 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Karyotypic analysis of the cotton boll weevil, Anthonomus grandis Boheman

The diploid chromosome number of the cotton boll weevil, Anthonomus grandis Boheman, is 44. Both C‐ and N‐banding techniques of mitotic cells demonstrated constitutive heterochromatin in the p arm of the eight largest chromosomes, the p arm of the X chromosome, and the centromeric region of autosomal groups A–D. Neither the y nor the group E autosomes appeared to contain constitutive heterochromatin. Supernumerary chromosomes were not found in the boll weevil. Restriction endonuclease banding of primary spermatocytes revealed a rod‐shaped Xy tetrad in which the X and y were terminally associated. The p arm of the large, submetacentric X was C‐band positive. While two of the autosomal tetrads were typically ring‐shaped in primary spermatocytes, the remaining 19 autosomal tetrads were rod‐shaped. This revised version was published online in July 2006 with corrections to the Cover Date.     

Functions of the spermathecal muscle of the boll weevil,Anthonomus grandis

In female boll weevils, Anthonomus grandis, spermathecal filling was not affected by severing the spermathecal muscles. Females whose spermathecal muscles were severed 2 to 4 weeks after mating laid infertile eggs and resumed virginal ovipositional behaviour indicating the importance of this muscle in supplying sperm for egg fertilization. The presence of normal active sperm within the spermatheca in no way influenced ovipositional behaviour. In females whose spermathecal muscles had been severed, 22 per cent sperm displacement occurred after a second mating compared with 66 per cent for normal females. The physical displacement of sperm was thus largely dependent on a functional spermathecal muscle.     

Endocrine regulation of reproduction and diapause in the boll weevil,Anthonomus grandis Boheman

A review of the literature for the hormonal control of reproduction and diapause in Coleoptera is presented. The role of juvenile hormone and juvenile hormone esterase (JHE) in the control of the different life history strategies of the boll weevil are examined. Elevated levels of hemolymph JHE were found to be positively correlated with survival throughout the winter in South Texas population of weevils. Winter weevils were examined for hemolymph vitellogenin (Vg) and their subsequent survival was monitored. The majority of weevils surviving beyond ten weeks had no hemolymph Vg. We conclude that elevated hemolymph JHE and the absence of Vg are good predictors of survivors in the South Texas population. The hormonal basis of diapause termination was examined using hormone treatment and implant therapy. We were unsuccessful in our attempt to induce post-diapause reproductive development with all of our treatments. Only weevils given access to a food source were capable of reproductive development. Our recent experimental findings in the control of Vg synthesis and uptake in the boll weevil are reviewed. Arch. Insect Biochem. Physiol. 35:455–477, 1997. © 1997 Wiley-Liss, Inc.     

Cuticle proteins of the boll weevil,Anthonomus grandis,abdomen: Structural similarities and glycosylation

Cuticle proteins are thought to be important in defining the structural and functional differences occurring in insect cuticle. In order to explain and better understand the structural similarities among the cuticle proteins of the cotton boll weevil, Anthonomus grandis Boheman, described in a previous study (Stiles and Leopold, 1990, Insect Biochem.20, 113–125) three series of monoclonal antibody producing hybridoma cell lines were produced. Larval, pupal or adult cuticle proteins were used as antigens. While some of the monoclonal antibodies were specific for one or two cuticle proteins from a single developmental stage, the majority showed multiple cuticle protein binding patterns on Western blots. To determine whether this cross-reaction was due to common oligosaccharide chains bound to the proteins, lectins were used to probe Western blots. Many of the cuticle proteins were found to be glycosylated. The majority of the Con A reactive carbohydrate could be removed from the protein by N-glycosidase F digestion (specific for N-asparagine linked carbohydrate). N-glycosidase F digestion did not reduce the multiple cross-reactions of the monoclonal antibodies, nor did periodate oxidation of the CP. The carbohydrate remaining after enzyme digestion is presumably O-linked to serine/threonine.     

Isolation and characterization of farnesyl diphosphate synthase from the cotton boll weevil,Anthonomus grandis

Farnesyl diphosphate synthase (FPPS) catalyzes the consecutive condensation of two molecules of isopentenyl diphosphate with dimethylallyl diphosphate to form farnesyl diphosphate (FPP). In insects, FPP is used for the synthesis of ubiquinones, dolicols, protein prenyl groups, and juvenile hormone. A full‐length cDNA of FPPS was cloned from the cotton boll weevil, Anthonomus grandis (AgFPPS). AgFPPS cDNA consists of 1,835 nucleotides and encodes a protein of 438 amino acids. The deduced amino acid sequence has high similarity to previously isolated insect FPPSs and other known FPPSs. Recombinant AgFPPS expressed in E. coli converted labeled isopentenyl diphosphate in the presence of dimethylallyl diphosphate to FPP. Southern blot analysis indicated the presence of a single copy gene. Using molecular modeling, the three‐dimensional structure of coleopteran FPPS was determined and compared to the X‐ray crystal structure of avian FPPS. The α‐helical fold is conserved in AgFPPS and the size of the active site cavity is consistent with the enzyme being a FPPS. © 2009 Wiley Periodicals, Inc.     

Selection for mating propensity in irradiated populations of the cotton boll weevil

Summary Twelve generations of family selection for 10-day post-irradiation male mating propensity resulted in significant divergence between the selected and unselected control populations. Much of this divergence was the result of a decline in the control population which was believed to have been a function of both inbreeding and environmental effects. Significant correlated responses as measured by differences in the two populations for linear time trends of performance on generations of selection were observed for 10-day post-irradiation survival, percent survivors mating at 10 days, and 7-day egg production of unirradiated females.     

Susceptibility of the boll weevil to Steinernema riobrave and other entomopathogenic nematodes

The susceptibility of the boll weevil (BW), Anthonomus grandis Boheman, to Steinernema riobrave and other nematode species in petri dishes, soil (Hidalgo sandy clay loam), and cotton bolls and squares was investigated. Third instar weevils were susceptible to entomopathogenic nematode (EN) species and strains in petri dish bioassays at 30 degrees C. Lower LC(50)'s occurred with S. riobrave TX- 355 (2 nematodes per weevil), S. glaseri NC (3), Heterorhabditis indicus HOM-1 (5), and H. bacteriophora HbL (7) than H. bacteriophora IN (13), S. riobrave TX (14), and H. bacteriophora HP88 (21). When infective juveniles (IJs) of S. riobrave were applied to weevils on filter paper at 25 degrees C, the LC(50) of S. riobrave TX for first, second, and third instars, pupae, and 1-day-old and 10-days-old adult weevils were 4, 5, 4, 12, 13, and 11IJs per weevil, respectively. The mean time to death, from lowest to highest concentration, for the first instar (2.07 and 1.27days) and second instar (2.55 and 1.39days) weevils were faster than older weevil stages. But, at concentrations of 50 and 100IJs/weevil, the mean time to death for the third instar, pupa and adult weevils were similar (1.84 and 2.67days). One hundred percent weevil mortality (all weevil stages) occurred 3days after exposure to 100IJs per weevil. Invasion efficiency rankings for nematode concentration were inconsistent and changed with weevil stage from 15 to 100% when weevils were exposed to 100 and 1IJs/weevil, respectively. However, there was a consistent relationship between male:female nematode sex ratio (1:1.6) and nematode concentration in all infected weevil stages. Nematode production per weevil cadaver increased with increased nematode concentrations. The overall mean yield of nematodes per weevil was 7680IJs. In potted soil experiments (30 degrees C), nematode concentration and soil moisture greatly influenced the nematode efficacy. At the most effective concentrations of 200,000 and 400,000IJs/m(2) in buried bolls or squares, higher insect mortalities resulted in pots with 20% soil moisture either in bolls (94 and 97% parasitism) or squares (92 and 100% parasitism) than those of 10% soil moisture in bolls (44 and 58% parasitism) or squares (0 and 13% parasitism). Similar results were obtained when nematodes were sprayed on the bolls and squares on the soil surface. This paper presents the first data on the efficacy of S. riobrave against the boll weevil, establishes the potential of EN to control the BW inside abscised squares and bolls that lay on the ground or buried in the soil.     

Uric acid in nucleic and amino acid synthesis in the boll weevil, Anthonomus grandis

When uric acid-2-¹⁴C was injected into the boll weevil, Anthonomus grandis, it was metabolized to RNA, DNA, amino acid, and ¹⁴CO₂ at the end of 2 hr. The free amino acids, lipoamino acids, and protein amino acids were all labelled with the free amino acids showing the highest specific activity. Incorporation in DNA was slight, but it was extensive in RNA; cytidylic acid showed the greatest amount of incorporation.