ABSTRACT
Female cowpea weevils,Callosobruchus maculatus, produce a sex pheromone that elicits orientation and sexual behavior in males. Bioassay-directed isolation of the sex pheromone was conducted and compounds in the active fraction were identified and synthesized. Volatiles were collected from individual virgin females by adsorption on filter paper dises and hexane extraction. A bioassay was used in which the locomotory response of single males in glass vials was recorded upon exposure to treatments or controls. Crude extracts were subjected to silica gel column chromatography with solvents of increasing polarity; all activity eluted with methanol. Activity in the highly polar methanol fraction suggested a carboxylic acid or a compound with multiple polar functionality. Acid-base partitioning of the crude extract isolated all activity in the acid fraction, confirming that the pheromone was a carboxylic acid. The acid fraction was further fractionated by preparative GC with a Carbowax column. The most active GC fraction contained the following five 8-carbon acids identified by GC-MS and comparison with synthetic candidates: 3-methyleneheptanoic acid, (Z)-3-methyl-3-heptenoic acid, (E)-3-methyl-3-heptenoic acid, (Z)-3-methyl-2-heptenoic acid, and (E)-3-methyl-2-heptenoic acid. Each of the synthetic acids was active individually for males, and combinations of two or more of the acid pheromones had an additive effect. Upwind flight responses to natural and synthetic pheromones were observed in a flight tunnel. (Z)-3-Methyl-2-heptenoic acid was previously identified as the sex pheromone for the relatedC. analis, but this and the other four acid pheromones fromC. maculatus were inactive for maleC. analis. There was no cross-attraction betweenC. maculatus andC. analis in reciprocal studies using extracted volatiles from females of both species, GC-MS analysis ofC. analis female volatiles failed to detect any of theC. maculatus compounds but did find an unidentified C-8 acid with a GC retention time different from any of theC. maculatus pheromones.
ABSTRACT
Laboratory experiments were conducted to study the behavioral activity of grain-derived volatiles as attractants and pheromone synergists forSitophilus oryzae, an internal-feeding pest of sound grain, andTribolium castaneum, an external-feeding pest of damaged grains and flour. Behavioral studies with two-choice pitfall bioassays determined that the fresh grain volatiles valeraldehyde, maltol, and vanillin were attractive toS. oryzae at various doses, butT. castaneum were not attracted to any dose of any of these three compounds. When oils from pressed grains were bioassayed, sesame oil was significantly repellent and oat and wheat germ oils were attractive toS. oryzae. However, rice, soybean, oat, wheat germ, and corn oils were all attractive toT. castaneum. A commercial food product composed primarily of soybean oil and wheat germ was highly attractive toT. castaneum, but elicited no response fromS. oryzae. A combination of the three grain volatiles valeraldehyde, maltol, and vanillin with the synthetic pheromone sitophinone was more attractive toS. oryzae than either the pheromone alone or the tripartite grain volatile mix. Similarly, a combination of the commercial food product with the pheromone 4,8-dimethyldecanal was more attractive toT. castaneum than either food alone or pheromone alone. Behavioral responses to grain volatiles may reflect the ecological niche of the granivore:S. oryzae colonizes sound grain and is attracted to volatiles characteristic of fresh grain, whileT. castaneum utilizes damaged or deteriorated grains and responds best to oils characteristic of damaged or fungus-infested grain. Synergism of food odors and pheromones suggests that more effective traps can be devised for management of these pest insects.
ABSTRACT
The chirality of the pheromone of the rice weevil,Sitophilus oryzae (L.), and the maize weevil,S. zeamais (Motschulsky), 5-hydroxy-4-methyl-3-heptanone, was determined using an acetyl lactate derivatization procedure. Maize weevils were shown to produce >98% 4S,5R. Determination was more difficult with rice weevils due to a smaller quantity of insect extract, but they were shown to produce at least 92% 4S, 5R.The attractancy of the four synthetic stereoisomers of 5-hydroxy-4-methyl-3-heptanone was tested using rice and maize weevils. As expected, both species were most strongly attracted to the 4S, 5R enantiomer. Maize weevils also showed low but significant responses (P < 0.05) to both 4R, 5R and 4S,5S. Rice weevils showed a highly significant (P < 0.01) response to 4R, 5S, although it was only about one third the response to 4S, 5R. Thus, (4S,5R)-5-hydroxy-4-methyl-3-heptanone is clearly the major component of the pheromone of bothS. zeamais andS. oryzae.
ABSTRACT
A male-produced aggregation pheromone, common to the rice weevil,Sitophilus oryzae, and the maize weevil,S. zeamais, was isolated and identified from hexane extracts of highly absorbent paper disks exposed individually to young virgin male weevils. A combination of preparative column and gas-liquid chromatography of disk extracts yielded purified natural pheromone. When analyzed by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry, the structure of the natural pheromone, "sitophilure," proved to be (R (*),S (*))-5-hydroxy-4-methyl-3-heptanone, of unknown enantiomeric composition. Synthetic racemic pheromone was highly attractive to males and females of both rice and maize weevils. In addition, both sexes of the granary weevil,S. granarius (L.) were attracted to the racemic preparation.
ABSTRACT
The sawtoothed grain beetle,Oryzaephilus surinamensis (L.) (Coleoptera: Cucujidae), is attracted to certain volatile components that occur in whole and rolled oats as determined by a laboratory pitfall chamber bioassay. More than 100 components were detected in the attractive carbonyl-containing fractions; 14 of these, making up 60% of the total, were identified and bioassayed. Although hexanal, heptanal, octanal, (E)-2-heptenal, and 2-furaldehyde, at doses ranging variously from 1 to 100 µg, were all significantly attractive, only 1 /10 to 1 /100 as much (E)-2-nonenal or (E,E)-2,4-nonadienal was necessary to produce comparable insect response. In addition, propanal and formaldehyde (previously reported in oats but not detected by us) were bioassayed and found to be attractive.
ABSTRACT
A dual-choice pitfall bioassay was used to demonstrate the existence of a male-produced aggregation pheromone in the maize weevil. Both males and females showed a highly significant preference for extracts of disks exposed to wheat-feeding males over extracts of disks exposed to wheat kernels only. Neither sex responded significantly to extracts from females. Mating did not reduce pheromone release by males. Response by virgin females to pheromone was significantly higher than response by mated females, but males of either mating status responded equally well. There was no apparent daily periodicity in the responsiveness to pheromone. Rice and maize weevils showed a strong interspecific cross-attraction. Granary weevils of both sexes responded well to maize weevil extracts, but only females showed a significant response to rice weevil extracts. Neither maize nor rice weevils responded significantly to granary weevil extracts.
ABSTRACT
Female cowpea weevils,Callosobruchus maculatus (F.), emitted a pheromone which excited males. Pheromone release began soon after emergence and continued for one week. Synchronization of pheromone release with calling behavior was demonstrated. Mating reduced pheromone release but not male response. Pheromone obtained by aeration collection was utilized for determining a quantitative dose-response relationship.
ABSTRACT
Evidence for a male-produced aggregation pheromone inSitophilus granarius is reported. Hexane extracts of Tenax®-trapped volatiles from males held on wheat were attractive to both sexes in a multiple-choice olfactometer and pitfall bioassay chamber. A quantitative relationship existed between days of insect exposure on disks and degree of responsiveness. The maximum response was to 35 insect-day-equivalents. Diel-related activity showed both sexes responsive during photophase and nonresponsive during scotophase.
ABSTRACT
Adult males of the lesser grain borer,Rhyzopertha dominica (F.), produce a pheromone that attracts both sexes. The volatiles from males collected on filter paper or Porapak-Q were attractive in two laboratory bioassays. The mating behavior is described and the function of the phen infested with the borer.
ABSTRACT
Evidence for the existence of a male-produced aggregation pheromone secreted from the prothoracic femoral setiferous sex patch ofTribolium castaneum is reported. Both sexes were attracted toca. 60 ng of crude secretion. Males and females perceive the pheromone on the day of emergence while perception differs between the sexes: male response reaches a maximum on day 1 posteclosion, when tested at <1, 1, and 30 days; females show a maximum response at 30 days posteclosion. Behavioral responses to pheromone odors and a complex Chromatographic profile are reported.
ABSTRACT
Volatiles from lesser grain borers,Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), were collected on Porapak Q, and those from the male beetles were shown to contain two compounds, that were attractive individually and in combination to both sexes. These compounds were identified as (S)-(+)-1-methylbutyl (E)-2-methyl-2-pentenoate and (S)-(+)-1-methylbutyl (E)-2,4-dimethyl-2-pentenoate by spectrometry and comparison with synthesized compounds. The two compounds have been assigned the trivial names dominicalure 1 and dominicalure 2, respectively. Synthesized samples of these compounds, individually and in combination, were effective in trapping both sexes in field studies.
ABSTRACT
Two components of the sex attractant of a female dermestid beetle Trogoderma inclusum Le Conte were identified. They are (-)-14-methyl-cis-8-hexadecen-1-ol and (-)-methyl-14-methyl-cis-8-hexadecenoate. Other Trogoderma species also respond to the compounds.
ABSTRACT
A method of mounting insects was devised. The procedure is simple to perform and facilitates quantitative bacteriological studies of feces with a minimal possibility of cross contamination. By this method, it was observed that approximately 10(7) cells of Salmonella were required for passage through the intestinal tract. Multiple doses of this magnitude were necessary to initiate intestinal infection. The numerical considerations cast doubt that Dermestes is involved significantly in the dissemination of Salmonella in the environment of food and feed plants.
Subject(s)
Coleoptera , Insect Vectors , Salmonella , Animals , Feces/microbiology , Salmonella Infections/etiologyABSTRACT
The principal component of the sex attractant of the black carpet beetle Attagenus megatoma (Fabricius) is trans-3, cis-5-tetradecadienoic acid.
