Selection of high-level abamectin resistance from field-collected house flies, Musca domestica

Abamectin is a novel, highly promising insecticide with activity against many pests. To determine if resistance to abamectin could occur, we collected house flies from several New York dairies and selected them in the laboratory. Resistance developed rapidly and to a high level (36 or greater than 60,000-fold, depending upon test technique and/or adjuvant) that could not be overcome by the synergists piperonyl butoxide or S,S,S-tributylphosphorotrithioate. There was no increase in (cross)resistance to crotoxyphos, dichlorvos, dimethoate, tetrachlorvinphos, permethrin, dieldrin or lindane following abamectin selection. Our results suggest the potential for abamectin resistance is high, at least in house flies, and that the judicious use of abamectin will be needed to prolong its usefulness as an insecticide.     

A wide spectrum of resistance to pyrethroid insecticides inMusca domestica

Summary Selection of a strain of house flies with the pyrethroid bioresmethrin has resulted in a wide range of cross resistance to 15 other pyrethroid insecticides.     

Fecundity and longevity of houseflies after space flight

Summary After 7 days of space flight house flies,Musca domestica, exhibited similar longevity, but a reduction in reproductive output as compared to earthbound controls. This reduction was not observed in later generations. These data suggest that space flight directly alters the rate of ovarian development, but that this effect is not genetically transmitted.Acknowledgment. We thank Todd E. Nelson, student participant in the Space Shuttle Student Involvement Project, John T. Jackson, NASA/Johnson Space Center, and James R. Peterson, Honeywell, Inc. for providing us with the flies and information related to the in-flight experiments.     

Ethanol as a ‘food’ forDrosophila melanogaster: Influence of theEbony gene

Summary The survival time of adultDrosophila melanogaster flies without food is greater in the presence of ethanol, especially for flies of strains or lines with a higher alcohol dehydrogenase activity. It seems that theebony gene can act in some populations as a selective factor favoring the ADH^F allele, as well as the minor genes enhancing the alcohol dehydrogenase activity level.Chargé de Recherches au F. N. R. S.     

Insulin-producing cells in the brain of adult Drosophila are regulated by the serotonin 5-HT1A receptor

Insulin signaling regulates lifespan, reproduction, metabolic homeostasis, and resistance to stress in the adult organism. In Drosophila, there are seven insulin-like peptides (DILP1–7). Three of these (DILP2, 3 and 5) are produced in median neurosecretory cells of the brain, designated IPCs. Previous work has suggested that production or release of DILPs in IPCs can be regulated by a factor secreted from the fat body as well as by neuronal GABA or short neuropeptide F. There is also evidence that serotonergic neurons may regulate IPCs. Here, we investigated mechanisms by which serotonin may regulate the IPCs. We show that the IPCs in adult flies express the 5-HT_1A, but not the 5-HT_1B or 5-HT₇ receptors, and that processes of serotonergic neurons impinge on the IPC branches. Knockdown of 5-HT_1A in IPCs by targeted RNA interference (RNAi) leads to increased sensitivity to heat, prolonged recovery after cold knockdown and decreased resistance to starvation. Lipid metabolism is also affected, but no effect on growth was seen. Furthermore, we show that DILP2-immunolevels in IPCs increase after 5-HT_1A knockdown; this is accentuated by starvation. Heterozygous 5-HT_1A mutant flies display the same phenotype in all assays, as seen after targeted 5-HT_1A RNAi, and flies fed the 5-HT_1A antagonist WAY100635 display reduced lifespan at starvation. Our findings suggest that serotonin acts on brain IPCs via the 5-HT_1A receptor, thereby affecting their activity and probably insulin signaling. Thus, we have identified a second inhibitory pathway regulating IPC activity in the Drosophila brain.     

Selection for resistance to azadirachtin in the green peach aphid,Myzus persicae

Two lines ofMyzus persicae of the same origin were treated repeatedlywith pure azadirachtin (aza), or a refined neem seed extract (NSE), at the equivalent concentration of aza. After 40 generations, the aza-selected line had developed 9-fold resistance to aza compared to a non-selected control line, whereas the NSE-selected line did not. These results suggest that a blend of active constitutents in a botanical insecticide such as neem might diffuse the selection process, mitigating the development of resistance compared to that expected with a single active ingredient.     

Allele-specific PCR reveals thatCYP6D1 is on chromosome 1 in the house fly,Musca domestica

A cytochrome P450, termed P450lpr, is the major P450 responsible for pyrethroid resistance in the Learn-PyR (LPR) strain of house fly. Recently, the putative gene (CYP6D1) coding for P450_lpr has been sequenced from the LPR and aabys strains of house fly. Allele-specific polymerase chain reaction (ASPCR) was used for linkage group analysis with backcross progeny from the wild type LPR strain and a multiple marker strain (aabys). We found thatCYP6D1 is linked to chromosome 1. The possible role of regulatory or modifying genes responsible for elevated P450_lpr expression is discussed in relation to the chromosomal linkage ofCYP6D1.     

Sterility in tsetse flies (Glossina morsitans Westwood) caused by loss of symbionts

Summary Tsetse flies fed on blood containing oxytetracycline, sulphaquinoxaline or lysozyme do not reproduce. It could be proved that primarily the symbionts in flies are damaged, which secondarily leads to sterility.I thank Dr.A. M. Jordan, Tsetse Research Laboratory at Bristol, for providing me with pupae ofG. morsitans, Dr.H. Wetzel, International Atomic Energy Authority, Vienna, for providing antibiotictreated flies and the Gesellschaft für Strahlen und Umweltforschung, München, for financial support.     

Toxic effects of boric acid on the German cockroach

Boric acid is a slow-acting, inorganic insecticide whose mode of action has not been satisfactorily elucidated. Reported here is evidence which shows that ingested boric acid destroys the cellular lining of the foregut of German cockroaches,Blattella germanica (L.). This effect appears to be sufficient to bring about the death of the insects, perhaps ultimately by starvation. This finding is important because resistance to conventional insectivides may re-establish boric acid as a prominent cockroach control chemical.     

Ontogenetische Änderungen im Gehalt an Isoxanthopterin bei verschiedenen Genotypen vonDrosophila melanogaster

Summary The content of isoxanthopterine in different developmental stages and different genotypes ofDrosophila melanogaster has been investigated. In male pupae of the red eyed wild type the isoxanthopterine reaches a high concentration which is maintained during the whole period of imaginal life. It could be shown that the mutantsw (white) andbw (brown) though they are unable to synthesize the red eye pigment do nonetheless accumulate considerable quantities of isoxanthopterine during metamorphosis. This isoxanthopterine, however, disappears gradually from the body ofw andbw during the first 3 days of imaginal life till nothing of it is left in adult flies. The transitory appearance of isoxanthopterine in the two mutants, sets new problems with regard to the pleiotropic effect of thew- andbw-loci in pigment synthesis.     

Chlorpyrifos (Dursban®) resistance inCulex pipiens pipiens L. from Southern France: Inheritance and linkage

Summary InCulex pipiens mosquitos from Southern France, resistance to the organophosphorus insecticide chlorpyrifos is due to the dominant allele (Chl ^R) of an autosomal gene. TheChl gene is localized between thea-Gpd andEst-2 loci at 26.8 and 5.8 units of crossing-over respectively.     

β-Lactam resistance in Staphylococcus aureus: the adaptive resistance of a plastic genome

Staphylococci have two mechanisms for resistance to β-lactam antibiotics. One is the production of β-lactamases, enzymes that hydrolytically destroy β-lactams. The other is the expression of penicillin-binding protein 2a (PBP 2a), which is not susceptible to inhibition by β-lactam antibiotics. Strains of S. aureus exhibiting either β-lactamase or PBP 2a-directed resistance (or both) have established a considerable ecological niche among human pathogens. The emergence and subsequent spread of bacterial strains designated as methicillin-resistant S. aureus (MRSA), from the 1960s to the present, has created clinical difficulties for nosocomial treatment on a global scale. The recent variants of MRSA that are resistant to glycopeptide antibiotics (such as vancomycin) have ushered in a new and disconcerting chapter in the evolution of this organism. Received 2 April 2005; received after revision 15 July 2005; accepted 25 July 2005     

Mobile genetic elements of Staphylococcus aureus

Bacteria such as Staphylococcus aureus are successful as commensal organisms or pathogens in part because they adapt rapidly to selective pressures imparted by the human host. Mobile genetic elements (MGEs) play a central role in this adaptation process and are a means to transfer genetic information (DNA) among and within bacterial species. Importantly, MGEs encode putative virulence factors and molecules that confer resistance to antibiotics, including the gene that confers resistance to beta-lactam antibiotics in methicillin-resistant S. aureus (MRSA). Inasmuch as MRSA infections are a significant problem worldwide and continue to emerge in epidemic waves, there has been significant effort to improve diagnostic assays and to develop new antimicrobial agents for treatment of disease. Our understanding of S. aureus MGEs and the molecules they encode has played an important role toward these ends and has provided detailed insight into the evolution of antimicrobial resistance mechanisms and virulence.     

C-banding pattern on the chromosomes of the Japanese house shrew,Suncus murinus riukiuanus,and its implication

Summary The C-band on the chromosomes of the Japanese house shrew,Suncus murinus riukiuanus (Insectivora), was studied. Various types of C-banding pattern were found in the genome of this subspecies. Such banding patterns could be useful for an understanding of autosome and sex-chromosome polymorphisms withinS. murinus.Acknowledgment. The authors are very grateful to Prof. T. Wasano of Fukuoka University for his encouragement, Dr K. Ogawa of Fukuoka University, the Nohara family for help in collecting specimens, and Prof. E.W. Jameson, Jr, University of California, Dr J.W. Bickham and his students of Texas A & M University for comments.     

Hemolymph proteins in an ascitic condition,induced by lethal1(3)gl tumorous tissue inDrosophila hydei

Summary Drosophila hydei larvae homozygous for the gene1(3)gl may survive to the age of 3 weeks, become bloated and be incapable of metamorphosis. Wild-type flies after the injection of a fragment of the1(3)gl disc, which has been previously culture in vivo for 40–500 days, also become bloated (ascitic reaction). In the hemolymph of both the advanced1(3)gl larvae and ascitic adult hosts the accumulation of a specific protein is observed.Acknowledgments. This work was supported by the Swiss National Science Foundation under Grant No.3.792-0.76 and the Georges und Antoine Claraz-Schenkung. We thank Prof. H. Gloor, University of Geneva, and Prof. P.S. Chen, University of Zürich, for advice and criticism.     

Identification and biological significance of 4-methyl-3Z,5-hexadienoic acid produced by males of the gall-forming tephritidsUrophora cardui (L.) andUrophora stylata (Fab.) (Diptera: Tephritidae)

Summary A new natural substance has been identified in the rectal ampullae of gall-forming fruit flies. The substance was found to be the only volatile compound in the rectal ampulla of maleUrophora cardui andUrophora stylata. GC-MS methods were used to characterize its structure as 4-methyl-3Z,5-hexadienoic acid. Physiological parameters such as the amount of the acid at different ages and under different conditions were investigated. The biological significance of the new volatile as an arresting pheromone was tested in several bioassays. The arrestant function could not be established, but the results gave hints of a territorial function between conspecific males. The results are discussed with respect to gland morphology and predictions of communication models among fruit flies.     

Cyanidin-3-β-glucoside,a newly recognized basis for resistance in cotton to the tobacco budwormheliothis virescens (Fab.) (lepidoptera: Noctuidae)

Summary Cyanidin-3--glucoside was shown to be an important factor of resistance in cottonGossypium hirsutum L. leaves to the tobacco budwormHeliothis virescens (Fab.). This provides a potential basis for achieving insect resistance in non-glanded cotton and other crops infested byHeliothis.In cooperation with the Mississippi Agriculture and Forestry Experiment Station, Mississippi State. Mention of a trademark, proprietary product or vendor does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

Mating competitiveness and fertility of thiotepa-sterilized flies

Summary In the present investigation, an attempt has been made to study the mating competitiveness and fertility of males as well as females ofDacus dorsalis Hendel (Diptera: Tephritidae) treated topically with thiotepa. In the mixed population, treated flies of either sex were found to be sexually more vigorous than untreated flies. However when the mating competitiveness of either sex was determined separately using various methods, treated males were found not to differ significantly in sexual competitiveness from untreated flies. Receptivity of treated and untreated females to males was also studied by the single choice method. Thiotepa-treated and untreated females were found to be equally receptive to males.