Glycolytic and chitinolytic activities of Phlebotomus papatasi (Diptera: Psychodidae) from diverse ecological habitats

The sand fly Phlebotomus papatasi Scopoli, 1786, the vector of Leishmania major Yakimoff et Schokhor, 1914, is found in desert areas where sugars are scarce but also in habitats that abound in sugar sources. The sand flies require sugar meals from plant sources for their energy requirements and to hydrolyze these complex sugars, they need a repertoire of glycosidases. We presumed that there are differences in the levels of glycosidase activities in flies from such habitats and also assumed that they may be instrumental in modulating the flies' susceptibility to L. major infections. Phlebotomus papatasi originating from diverse ecological habitats ranging from an oasis to desert sites were colonized. They were analyzed for weight changes and glycosidase activities before and after feeding on 1M sucrose solution. Oasis flies were smaller than desert flies but took larger sugar meals. Homogenates of these flies hydrolyzed 16 synthetic and 2 natural glycoside substrates to varying degrees. The arid-region flies tended to produce more glycosidase activity than those originating in sugar-rich environments, especially sucrase, alpha- and beta-glucosidase, aalpha-fucosidase, alpha-mannosidase, and alpha- and beta-N-acetylgalactosaminidase. However, chitinolytic enzyme activities and particularly the beta-N-acetylhexosaminidase activity of oasis flies were higher than other flies tested. In comparing the desert flies, there were also significant differences in glycolytic enzyme activities between the spring-line (flowering season) of flies and the autumn-line (end of dry season) flies. A range of saccharide inhibitors was tested to demonstrate the specificity of the enzymes.     

Baseline susceptibility of a wild strain of Phlebotomus papatasi (Diptera: Psychodidae) to DDT and pyrethroids in an endemic focus of zoonotic cutaneous leishmaniasis in Iran

BACKGROUND: Phelebotumus papatsi is considered to be the main vector of zoonotic cutaneous leishmaniasis as well as sand fly fever in Iran. There are several measures for vector control, with emphasis on insecticides. The objective of this study was to determine the baseline susceptibility of this vector to the commonly used insecticides in an endemic focus of the disease in central Iran. P. papatasi collected from the field were used for susceptibility status. Its baseline susceptibility to DDT and pyrethroids was assessed on about 6866 specimens collected from Badrood rural district, Esfahan Province, Iran, during the summer of 2010. The LT₅₀ and LT₉₀ values were measured according to the World Health Organisation (WHO) test using probit analysis and regression lines. RESULTS: Results of tests against female P. papatasi revealed LT₅₀ values to DDT 4%, permethrin 0.75%, deltamethrin 0.1%, cyfluthrin 0.15% and lambdacyhalothrin 0.05% of 1104.97, 182.35, 26.79, 15.42 and 1.48 s respectively. The figures for male P. papatasi were 973.51, 59.5, 4.4, 2.65 and 1.5. CONCLUSION: The results of this study provide a guideline for implementation of different vector control measures. Furthermore, guidelines are needed for monitoring and evaluation of insecticide susceptibility tests against sand flies. Copyright © 2012 Society of Chemical Industry     

The role of Tetrastichus giffardianus Silvestri (Eulophidae: Hymenoptera) in natural control of Bactrocera zonata (Saunders) (Tephritidae: Diptera) and its temporal abundance in Sudan

Bactrocera zonata is an alien fruit fly which was introduced into Sudan in 2012 and spread throughout the country, severely hampering the production and export of fruit and vegetable crops. Cataloguing indigenous natural enemies of pests, especially parasitoids, is key to successful biological control programmes, to mitigate damage and decrease reliance on insecticides. This study was conducted to determine the parasitoids of B. zonata in two orchards in Gezira State, Sudan from November 2015 to May 2016 and from February to December, 2016 and to determine their role in natural control of the pest. Three parasitoids emerged from puparia of B. zonata, these were: Tetrastichus giffardianus Silvestri (Eulophidae), an Aganaspis sp. (Figitidae: Eucoilinae) and a Psyttalia sp. (Braconidae Opiinae). Tetrastichus giffardianus was the most numerous parasitoid throughout the study period. The mean percentages of B. zonata from guava fruits that were parasitized by T. giffardianus for the whole study period were 13.7% and 13.2% with 3.1 ± 0.3 and 2.8 ± 2.4 parasitoids per puparium at Fadasi and Gazirat Elfil sites respectively. Data on the temporal abundance of T. giffardianus is presented. Strenuous efforts should be considered to involve the reported natural enemies of B. zonata in integrated management programmes for fruit flies in Sudan.     

Life cycle and epizootiology of Amblyospora ferocis (Microspora: Amblyosporidae) in the mosquito Psorophora ferox (Diptera: Culicidae)

A natural population of Psorophora ferox (Humbold, 1820) infected with the microsporidium Amblyospora ferocis Garcia et Becnel, 1994 was sampled weekly during a seven-month survey in Punta Lara, Buenos Aires Province, Argentina. The sequence of development of A. ferocis in larvae of P. ferox leading to the formation of meiospores followed the developmental pathway previously reported for various species of Amblyospora. The natural prevalence of A. ferocis in the larval population of P. ferox ranged from 0.4% to 13.8%. Spores were detected in the ovaries of field-collected females of P. ferox and were shown to be responsible for transovarial transmission of A. ferocis to the next generation of mosquito larvae in laboratory tests. These spores were binucleate and slightly pyriform in shape. The prevalence of A. ferocis in the adult population ranged from 2.7% to 13.9%. Data on effects of the infection on female fecundity showed that infected field-collected adults of P. ferox laid an average of 47.6 +/- 6.5 eggs of which 35.8% +/- 4.1% hatched. Uninfected field-collected adults of P. ferox laid 82.8 +/- 6.8 eggs of which 64.1% +/- 5.5% hatched. Six species of copepods living together with P. ferox were fed meiospores from field-infected larvae but none became infected. Horizontal transmission of A. ferocis to P. ferox larvae remains unknown.     

Characterisation of spinosad resistance in the housefly Musca domestica (Diptera: Muscidae)

BACKGROUND: Spinosad, a relatively new, effective and safe pesticide, has been widely used in pest control over the last 10 years. However, different levels of resistance to this insecticide have developed in some insects worldwide. RESULTS: After continuous selection for 27 generations, a strain (SpRR) of the housefly developed 247‐fold resistance to spinosad compared with the laboratory susceptible strain (CSS). The estimated realised heritability (h²) of spinosad resistance was 0.14. There was no significant difference in the LD₅₀ values and slopes between reciprocal progenies F₁ and F₁′, and values of 0.33 (F₁) and 0.30 (F₁′) were obtained for the degree of dominance. Chi‐square analysis from responses of self‐bred (F₂) and backcrosses (BC₁ and BC₂) were highly significant, suggesting that the resistance was probably controlled by more than one gene. Synergists piperonyl butoxide (PBO), diethyl maleate (DEM) and S,S,S‐tributyl phosphorotrithioate (DEF) affected the toxicity of spinosad at a low level, and demonstrated that metabolic‐mediated detoxification was not an important factor in conferring resistance to spinosad in the SpRR strain. CONCLUSION: It was concluded that spinosad resistance in the housefly was autosomal and incompletely dominant, and the resistance was probably controlled by more than one gene. These results provide the basic information for designing successful management programmes for the control of houseflies. Copyright © 2011 Society of Chemical Industry     

Inheritance of beta-cypermethrin resistance in the housefly Musca domestica (Diptera: Muscidae)

BACKGROUND: Beta-cypermethrin, a synthetic pyrethroid insecticide, was applied frequently in the control of health pests including houseflies, Musca domestica L., in China. However, different levels of resistance to beta-cypermethrin were monitored in field strains of houseflies. A strain of M. domestica, 4420-fold resistant to beta-cypermethrin after continuous 25 generations of selection, was used in this paper to determine the mode of inheritance of pyrethroid resistance. RESULTS: The estimated realized heritability (h(2)) of beta-cypermethrin resistance was 0.30 in this resistant strain. Results of bioassays showed no significant difference in values of LD(50) and slope of log dose-probit lines between reciprocal progenies F(1) and F'(1), and yielded values of - 0.10 (F(1)) and - 0.11 (F'(1)) for the degree of dominance (D). Chi-square analysis from responses of self-bred and backcross progenies (F(2), BC(1) and BC(2) respectively) indicated that the null hypothesis, a single gene responsible for resistance, was accepted. The minimum number of independent segregation genes was 0.93 for F(1) by Lande's method. CONCLUSION: It was concluded that beta-cypermethrin resistance in the housefly was inherited as a single, major, autosomal and incompletely recessive factor. These results would provide the basic information for pest management programmes.     

蜜柑大实蝇在中国的适生性研究

蜜柑大实蝇Bactrocera(Tetradacus)tsuneonis(Miyake)是重要的检疫性有害生物,危害柑橘类作物.本研究在中国748气象站点的气象数据和蜜柑大实蝇生物学数据的基础上综合运用CLIMEX软件与ArcGIS软件对蜜柑大实蝇在我国的适生性进行研究.结果显示:蜜柑大实蝇在我国具有较高的适生性,适生范围涉及33个省、市(区),其中广西、广东、贵州、重庆、湖北、江苏的广大地区,四川、云南的东南部,陕西、河南的南部,安徽、台湾的北部和海南的中部地区等为高度适生区.本研究明确了蜜柑大实蝇在我国的适生性,提出了针对不同适生程度区域内的防控措施建议,对科学制定我国蜜柑大实蝇检疫政策和措施、防止该实蝇入侵和进一步扩散等具有重要的意义.     

Distribution and tephritid hosts (Diptera) of braconid parasitoids (hymenoptera) in Brazil

Tephritid parasitoids reared from 26 different host fruit species showed remarkably little diversity across 21 Brazilian counties. The majority of the parasitoids (81.4%) belonged to the braconid subfamily Opiinae, with Doryctobracon areolatus (Szépligeti) the most commonly encountered species. Four other opiines, namely D. brasiliensis (Szépligeti), Opius bellus Gahan, Optus sp. and Utetes (Bracanastrepha) anastrephae (Viereck) were also reared, but in much smaller numbers. Asobara anastrephae (Muesebeck), an alysiine braconid parasitoid of tephritids, accounted for an additional 18–6% of the individuals reared from tephritids. The hosts and distribution patterns of the braconid parasitoids of Brazilian fruit‐infesting Tephritidae are summarized.     

Genetics of Pyrethroid Resistance in a Strain (ALHF) of House Flies (Diptera: Muscidae)

Five house fly lines were derived from crosses of the pyrethroid-resistant ALHF (wildtype) and the susceptible aabys (bearing recessive morphological markers on each of five autosomes) strains. Each line was homozygous for one mutant-type marker from aabys. The level of resistance to permethrin was measured for each line to determine the genetic linkage of pyrethroid resistance in ALHF. Permethrin resistance in ALHF was 6600-fold compared with that in aabys. Resistance in flies bearing a mutant-type marker on autosome 4 was similar to that in ALHF. Flies with mutant-type markers on autosomes 1 and 2 had relatively lower resistance than ALHF; flies with mutant-type markers on autosomes 3 and 5 had much lower levels of resistance. These results demonstrated that factors on autosomes 3 and 5 play very important roles in pyrethroid resistance, whereas factors on autosomes 1 and 2 may have relatively small roles in resistance. Piperonyl butoxide (PBO) increased toxicity of permethrin in strains with mutant-type markers on autosomes 3 and 4 similar to that in ALHF. Slightly decreased synergism ratios in strains with autosomes 1 and 2 mutant-type markers compared with ALHF indicated that factors on autosomes 1 and 2 might make a small contribution in P450 monooxygenase-mediated resistance. However, when the autosome 5 mutant-type marker was present, PBO did not substantially decrease resistance, suggesting that the factor(s) on autosome 5 plays the most important role in P450 monooxygenase-mediated resistance. The resistance ratios of permethrin + PBO in strains with mutant-type markers on autosomes 1, 2, and 5 were significantly lower than those in ALHF, suggesting that factors on autosomes 1, 2, and 5 might be involved in pyrethroid resistance mechanisms other than P450-mediated detoxication. Injection did not change levels of resistance in the house flies tested, revealing that decreased rate of cuticular penetration (pen) probably does not play an important role in pyrethroid resistance in ALHF. The interaction and regulation of different mechanisms and/or factors involved in pyrethroid resistance in house flies are discussed.     

中国柑橘大实蝇遗传多样性分析

利用4对微卫星引物对采自中国7省市的18个柑橘大实蝇地理种群进行标记,并进行遗传多样性分析。结果表明,从供试柑橘大实蝇地理种群检测到的等位基因数为19~30个,平均为23.06个,且4个微卫星位点(Bp125、BcuF 1.6、Bcac 5.10、Bcac 6.10)的等位基因数分别为7、14、9、8个。对18个柑橘大实蝇种群的哈迪—温伯格平衡测试结果显示,其卡方值的变化范围为5.582~∞,各种群间差异显著(变化范围为0.000~0.694)。表明中国柑橘大实蝇种群的遗传多样性较高,且不同种群间存在较大的遗传分化。     

Additional diet of the parasitoids (Hymenoptera: Braconidae) and the parasitizing of the Elm Bark Beetle (Coleoptera: Scolytidae)

Supplementing the diet of Coeloides scolyticida, Dendrosoter protuberans and Ecphylus silesiacus (Hymenoptera: Braconidae) with Parker's diet and the nectars of melliferous plants: Daucus carota L., Sinapis alba L. and Stachys recta L. had a significant effect on longevity, reproduction, developmental rate, and parasitizing of Scolytus scolytus (Fab.), Scolytus multistriatus (Marsh.) and Scolytus pygmaeus (Fab.) (Coleoptera: Scolytidae). These values were considerably lower for wasps fed with the nectar of Sinapis arvensis L. and Trifolium repens L. and the lowest for those without dietary additives. Parker's diet had the most significant effect on the parasitoids and parasitizing of the bark beetles. Nectar of S. recta and S. alba proved most suitable for C. scolyticida and D. protuberans, while E. silesiacus using the nectar from D. carota flower significantly increased parasitizing of S. pygmaeus. T. repens flowers were not a suitable additive for the diet of parasitoids. The parasitoids without additives in their diet had shorter lives, shorter development, and were less effective in reducing host numbers. E. silesiacus wasps had the longest development, and C. scolyticida the shortest. Generally, the parasitoids of the second generation had a slightly prolonged development (1–2 days).     

Soybean stem fly,Melanagromyza sojae (Diptera: Agromyzidae), on Sumatra: Seasonal incidence and the role of parasitism

Abstract

The density of M. sojae and percentage parasitism was studied in unsprayed soybean at 18 farmers’ field sites in Aceh, North Sumatra and West Sumatra provinces, Indonesia, during 1992 and 1993. M. sojae generally infested soybean throughout the season; infestation was initially low, reached its peak from the fifth till the eighth week after planting and declined towards the end of the season. A complex of seven hymenopterous parasiloids had a high impact on the pest. Parasitism levels built up alongside with host density and remained high until just before harvest. The eucoilid Gronotoma sp. was the most prevalent species during the early and mid‐season; a complex of pteromalids became dominant towards the end of the season. In soybean planted successively at 2‐week intervals, the parasitism level in the first‐planted crop built up slowly, whereas the parasitism level in the third‐planted crop was high from the early crop stage onwards, which suggests that the third‐planted crop benefited from parasitism build‐up in the earlier‐planted crops. The role of parasitoids in controlling beanflies in unsprayed soybean is discussed.     

Biochemical and molecular characterisation of acetylcholinesterase in four field populations of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

BACKGROUND: The oriental fruit fly, Bactrocera dorsalis, is a major pest that infects fruits and agricultural products worldwide. The latest resistance monitoring of B. dorsalis from mainland China has identified high levels of resistance to insecticides. In this study, the biochemical and molecular characteristics of acetylcholinesterase (AChE) in four field populations of B. dorsalis are investigated. RESULTS: Among the four populations, the DG population and its purified AChE were found to be the least susceptible to malathion and five inhibitors, whereas the KM population and its purified AChE were the most susceptible. The highest catalytic activity of purified AChE was found for the KM population, and the catalytic activity of the DG population was the lowest. Among developmental stages, the AChE purified from larvae was found to be the most insusceptible to inhibitors, but its catalytic activity was the highest. Sequence analysis of the cDNA encoding AChE showed that some residue differences existed. However, no significant differences in expression levels of the AChE gene among populations and developmental stages were detected. CONCLUSION: The results suggest that the decrease in susceptibility of B. dorsalis was mainly caused by decrease in AChE activity, and they provide a broad view on the relation between AChE and resistance. Copyright © 2012 Society of Chemical Industry