Pre-imaginal exposure to Oberon® disrupts fatty acid composition, cuticular hydrocarbon profile and sexual behavior in Drosophila melanogaster adults.

Oberon® is a commercial formulation of spiromesifen, a pesticide inhibitor of lipid biosynthesis via acetyl CoA carboxylase, widely used in agricultural crop protection. However, its mode of action requires further analysis. We currently examined the effect of this product on Drosophila melanogaster as a non-target and model organism. Different concentrations of spiromesifen were administered by ingestion (and contact) during pre-imaginal development, and we evaluated its delayed action on adults. Our results suggest that spiromesifen induced insecticidal activity on D. melanogaster. Moreover, spiromesifen treatment significantly increased the duration of larval and pupal development at all tested concentrations while it shortened longevity in exposed males as compared to control males. Also, pre-imaginal exposure to spiromesifen quantitatively affected fatty acids supporting its primary mode of action on lipid synthesis. In addition, this product was found to modify cuticular hydrocarbon profiles in exposed female and male flies as well as their sexual behavior and reproductive capacity.

Effects of tebufenozide on ovarian growth and sexual behavior in the German cockroach (Blattella germanica).

Tebufenozide, a dibenzoylhydrazine insect growth regulator, was applied topically (1 microg/insect) on female adults of the German cockroach Blattella germanica and its effects on ovarian measurement and proteins contents were investigated during the first gonadotrophic cycle (0, 2, 4 and 6 days). Dissection of treated females showed a clear reduction in oocyte numbers and volume of the basal oocyte. The ovarian proteins content was also significantly reduced. Behavioral tests demonstrated that treatment of 6-days-old females with tebufenozide caused in 80% of the males an increase in numbers of antennal contacts, but there was no effect on the numbers of wing raisings. In contrast, it was striking that in 20% of the males there was a total loss of antennal contacts and wings raisings in response to a calling treated female. These behavior effects are probably caused by a reduced production of contact sex pheromone in the females and may help in explaining the lower ovary reproductive parameters.

The Cryptocercus punctulatus species complex (Dictyoptera: Cryptocercidae) in the eastern United States: comparison of cuticular hydrocarbons, chromosome number, and DNA sequences.

The goal of the current study was to determine if cuticular hydrocarbons could be used to empirically delimit taxa within the Cryptocercus punctulatus species complex in the eastern United States. Cockroaches were collected from rotting logs in 22 locations across four states. Hydrocarbon phenotypes and two mitochondrial (16S and COII) genes and one nuclear (ITS2) gene were independently analyzed to determine their relationship with chromosome number. Five distinct hydrocarbon phenotypes were found, but these were only partly congruent with chromosome number and thus with purported species descriptions. Molecular and cuticular hydrocarbon data each indicate that Cryptocercus with a male karyotype of 2n=43 belong to at least two distinct, distantly related lineages. One 2n=43 lineage is sister group to the 2n=37 and 2n=39 clade, and has a unique hydrocarbon profile. The other 2n=43 lineage is sister group to the 2n=45 samples, and its cuticular hydrocarbons group with four samples of the 2n=45 lineage. The cuticular hydrocarbons of two additional 2n=45 samples diverge from this assemblage. Results indicate cuticular hydrocarbons and chromosome number have some degree of evolutionary independence; neither is completely reliable in delineating historical lineages. Our data provide support for the parallel model of chromosome evolution in the species complex.

Cuticular hydrocarbon profiles in Blattella germanica: effects of halofenozide, boric acid and benfuracarb.

In order to complete previous studies conducted on Blattella germanica, three insecticides from different groups were evaluated: boric acid, an inorganic compound, benfuracarb, a carbamate, and halofenozide, a non-steroidal ecdysone agonist. Boric acid (8.20%, LD50) and benfuracarb (2%, LD50) were incorporated into the diet and orally administrated to newly emerged adults of both sexes, while halofenozide (0.33%, LD50) was applied topically. Hydrocarbons extracts was made on bidistilled pentane from control and treated series sampled 6 days following treatment. Extracts was analyzed by gas chromatography. Data showed that cuticular profiles of control and treated series were qualitatively similar with thirteen major compounds; however, significant quantitative differences were noted. Boric acid seemed to feminize the cuticular profile in males with a significant reduction of the two first cuticular compounds detected. Halofenozide and benfuracarb reduced cuticular compounds in both sexes.

Reproductive effects in German cockroaches by ecdysteroid agonist RH-0345, juvenile hormone analogue methoprene and carbamate benfuracarb.

Blatta germanica is the more prevalent cockroach species in Algeria. In the present study, we tested the effect on reproduction in B. germanica of two insect growth regulators, RH-0345, a benzoylhydrazine analogue that mimics the action of 20-hydroxyecdysone, and methoprene, one of the most commercially important juvenile hormone analogues, and a novel carbamate insecticide, benfuracarb. The compounds were applied topically (10 and 20 microg/insect for RH-0345, and 1 and 10 microg/insect for methoprene) or orally administrated (at 2% for benfuracarb) on newly emerged females and evaluated on reproductive events during the adult life (2, 4 and 6 days). Treatment with RH-0345 and benfuracarb reduced significantly the number of oocytes, the size and the volume of the basal oocyte during the experimental period. Methoprene distorted the ovarian development since it caused a significant reduction in the number of oocytes at 2, 4 and 6 days for the two tested doses, and an increase in oocyte size at 2, 4 and 6 days with 1 microg and a decrease with 10 microg. In a second series of experiments, the effects of these compounds were assayed on the ovarian proteins. Data from biochemical analysis revealed that RH-0345 and benfuracarb reduced the ovarian amounts of proteins, while treatment with methoprene increased it during the sexual maturation.

Molecular characterization of Lma-p54, a new epicuticular surface protein in the cockroach Leucophaea maderae (Dictyoptera, oxyhaloinae).

The epicuticular surface protein Lma-p54 is imbedded in the "cuticular waxes" which cover the abdominal surface of the adult Leucophaea maderae. Natural Lma-p54 was purified and the complete cDNA sequence was determined by RT-PCR using primers based on Edman degradation fragments. Northern blot and in situ hybridization analyses showed that Lma-p54 was expressed in the adult abdominal epidermis and in the chemical sense organs of both sexes. Sequence alignment indicates that Lma-p54 is closely related to aspartic proteases (EC 3.4.23). However, there are critical amino acid substitutions at the level of the active site and, since no proteolytic activity was detected in the abdominal secretion, the protein is likely inactive. As an inactive aspartic protease, Lma-p54 is related to pregnancy-associated glycoproteins (PAGs) which still present a peptide-binding ability. According to recent experiments using whole tergal protein secretions, a role in intraspecific contact recognition was proposed for this surface protein.

Molecular characterization of a new adult male putative calycin specific to tergal aphrodisiac secretion in the cockroach Leucophaea maderae.

Lma-p18 is an epicuticular surface protein specific to the tergal gland aphrodisiac secretion of Leucophaea maderae adult males. Native Lma-p18 was purified and the complete cDNA sequence was determined by RT-PCR using primers based on Edman degradation fragments. Northern blot and in situ hybridization analyses showed that Lma-p18 is expressed exclusively in the anterior part of male tergal gland, which is exposed only during sexual behavior. Sequence analysis indicated that Lma-p18 belongs to the calycin superfamily and is very similar to Lma-p22, the first known male-specific tergal protein in L. maderae. Lma-p18 and Lma-p22 were proposed to bind different sexually attractive compounds as other calycins.

Toxicity of boric acid to Blattella germanica (Dictyoptera: Blattellidae) and analysis of residues in several organs.

Pestiferous cockroach species are associated closely with humans and are important from medical and public health points of view. Conventional insecticides have been used widely to control cockroaches which have developed resistance to these compounds. Thus, interest has again centered on lesser-used compounds such as boric acid. Boric acid has been used as an insecticide for many years, especially against cockroach. Its mode of action on insects has not been satisfactorily established. In Algeria, Blattella germanica (Dictyoptera: Blattellidae) is a serious pest in the urban environment and their infestation were controlled for many years by organophosphate, carbamate or pyrethroid insecticides. In order to obtain more information on the mode of action of boric acid, we first evaluated the oral toxicity of boric acid on B. germanica adults. Then, the compound was determined in several organs by an colorimetric method. This insecticide was incorporated into the diet and orally administered at different concentrations ranging from 1 to 40% (w/w) to newly emerged adults. Mortality was recorded at different times during treatment (24, 48, 72 and 144 h). Treatment resulted in a dose-dependent mortality since the LD50 (%) recorded are 85 at 24 h, 67 at 48 h, 39 at 72 h and 8 at 144 h, respectively. Then the quantity of boric acid accumulated in several organs (hemolymph, gut, ovaries, testicles and fat body) was determined as function the duration of treatment (1 to 5 days) for two doses (LD50 and LD90). Results revealed that bioaccumulation of residues in these organs increased as function the duration of treatment. In addition, relatively important amounts of residues, are detected in fat body.

Characterization of two male-specific polypeptides in the tergal glands secretions of the cockroach Leucophaea maderae (Dictyoptera, Blaberidae).

During the sexual behavior of cockroaches, the female mounts the courting male to feed on the proteinaceous secretion of the tergal glands. Polyacrylamide gel electrophoresis of male and female protein extracts after cuticle wiping revealed three major bands. Two of 18 and 22 kDa, named Lma-P18 and Lma-P22, are specific to the male tergal extracts. Moreover, Lma-P22 is only found in the male second tergite extracts. The third one of 54 kDa, named Lma-P54, is common to male and female extracts and could be considered as an ubiquitous surface protein. Several other minor proteins are also present on the body surface of adults of both sexes. Quantitation of the total protein amount of the male tergal gland secretion shows a progressive accumulation from adult ecdysis to sexual maturity. Western blot analysis using antibodies raised against Lma-P22 and Lma-P54 confirms that Lma-P22 is only secreted by the male second tergite glands. Immunohistolocalization demonstrates that these three major proteins are produced by class 3 glandular cells.

Male sex pheromone of cockroachEurycotis floridana (walker) (Blattidae, Polyzosteriinae): Role and composition of tergites 2 and 8 secretions.

InEurycotis floridana, the male calling behavior is associated with the exposition of epidermal glands located under tergites 2, 7, and 8. 4-Hydroxy-5-methyl-3(2H)-furanone and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were recently identified as the specific components of tergite 7 secretion. Methylene chloride extracts of tergite 7 and its major compound 4-hydroxy-5-methyl-3(2H)-furanone attract the conspecific females at a distance. Methylene chloride extracts of tergite 8 are also attractive at a distance to the females, whereas extracts of tergite 2 had no effect on males and females. Our GC investigations showed the absence of specific compounds in tergite 2 secretions. The GC-MS analyses revealed that the male secretion of the gland under tergite 8 is mainly a mixture of (2R*, 3R*)-butanediol, 1-dodecanol and benzyl 2-hydroxybenzoate. These compounds were tested at different concentrations on their own, or as a mixture. Only (2R*, 3R*)-butanediol and 1-dodecanol were attractive for the females. Their functions, as components of the male sex pheromone, in addition with the two derivatives of the furanone are discussed.

Evidence for sex pheromones produced by males and females inBlatta orientalis (Dictyoptera, Blattidae).

Males and females ofBlatta orientalis produce a volatile sex pheromone attractive at a distance. The male initiates courtship behavior by adopting a calling posture while emitting his sex pheromone. He exposes the anterior region of his tergites by stretching his abdomen horizontally. Morphological observations show the existence of male tergal glands on the anterior region of tergites 1 to 8. Behavioral assays of females utilizing methylene chloride extracts of various male body parts reveal that extracts of the anterior region of tergites are highly attractive and induce more positive responses that any other body part. Once near the male, the attracted female opens widely her genital atrium thus exposing her atrial glands. Behavioral assays reveal that these atrial glands are certainly the site of production of the female sex pheromone.

Chemistry of pheromonal and defensive secretions in the nymphs and the adults ofDysdercus cingulatus Fabr. (Heteroptera, Pyrrhocoridae).

The exocrine secretions from the nymphs and the adults of both sexes inD. cingulatus were chemically investigated. Seven compounds were identified in the anterior glands, and eleven in the median dorsoabdominal glands of nymphs and adults of both sexes. Fifty-five compounds were identified in the defensive glands (34 in posterior dorsoabdominal glands ofnymphs and 21 in metathoracic glands of adults), and six in the sternal glandular epithelium of the males. The biological function of the glandular secretions and of their identified compounds were investigated and are discussed.

Chemistry of defensive secretions in nymphs and adults of fire bug,Pyrrhocoris apterus L. (Heteroptera, Pyrrhocoridae).

The defensive secretions from the nymphs and the adults of both sexes inP. apterus were chemically investigated. Forty components were identified from the nymphal posterior dorsoabdominal glands and 35 from the adult metathoracic glands of both sexes. Within the 43 identified chemicals, we found 23 aldehydes, five saturated hydrocarbons, five alcohols, three ketones, three lactones, two terpenes, one phenol and one ester. Thirteen of these compounds had never been reported within the Heteroptera. Whereas eight components are specific to the nymphs, methyl pentenal, (E)-2-hexenol, and heptadecanal are the only adult-specific components. The biological role of all the identified chemicals is almost unknown inP. apterus and is discussed comparatively with regard to other Heteroptera.

2-Methylthiazolidine and 4-ethylguaiacol, male sex pheromone components of the cockroachNauphoeta cinerea (dictyoptera, blaberidae): A reinvestigation.

InNauphoeta cinerea, male calling behavior is associated with sex pheromone release by the sternal glands. The male pheromone that attracts females from a distance is a mixture of 2-methylthiazolidine and 4-ethylguaiacol. It is active at very low concentrations, 0.05 and 0.01 ng, respectively. Two other compounds, 3-hydroxy-2-butanone and 2-methyl-2thiazoline, act at close range, keeping the female in the vicinity of the male. The function of the volatile pheromone and those of previously described contact pheromones are discussed in regard to their possible involvement in the establishment of male dominant-subordinate relationships.

Tergal glands of male and femaleCryptocercus punctulatus scudder (Dictyoptera: Cryptocercidae): Composition, sexual dimorphism, and geographic variation of secretion.

Males and females ofCryptocercus punctulatus possess tergal glands, but they differ in position, size, morphology, and secretion chemistry. Compound A (linalyl acetate) is the most abundant of the 21 compounds found only in the secretion of these glands. Compound B, 4,6,8-trimethyl-7,9-undecadien-5-ol, is specific to the tergal secretion of females.C. punctulatus lives only in the United States; its distribution is disjunct. Compound A is found in samples from the eastern population but is absent in samples from the western population. The amount of compound B per gland in samples from the western population is at least twice as high as in the samples from the eastern populations.