Number Of Adult Flies Research Articles

The effects of insect repellent on initial Dipteran colonization of decomposing pig remains.

Numerous factors influence insect colonization and development on decomposing remains and can influence postmortem interval (PMI) estimations when insects are used in investigations of suspicious deaths. This study aimed to determine whether insect repellent influences insect colonization of decomposing remains. Pig feet were divided into 4 groups: a control not sprayed with repellent, 40% DEET repellent, 98% DEET repellent, and lemon eucalyptus repellent. The feet were placed in containers, and insect visitation was observed over the course of 3 days, then insects were collected at the end of the third day. This was repeated twice a month from April through November 2022. The analysis focused on the order Diptera. Pairwise comparison determined that there was a significant delay in visitation time for remains with 98% DEET compared to remains with no repellent and 40% DEET. There were significantly fewer adult Diptera collected and more remains with no larvae or eggs present among remains treated with 98% DEET. It was concluded that low concentrations of DEET and lemon eucalyptus repellent did not delay colonization, but that high concentrations of DEET delayed visitation, reduced the number of adult flies collected from the remains, and reduced the likelihood of collecting eggs or larvae from the remains. This contributes to the understanding of factors that can influence insect colonization and development that allow for more accurate PMI estimations by suggesting that insect repellent does not need to be accounted for in PMI estimation, but a high concentration of DEET can deter insects in the short term.

Aggregation pheromones have a non-linear effect on oviposition behavior in Drosophila melanogaster

Female fruit flies (Drosophila melanogaster) oviposit at communal sites where the larvae may cooperate or compete for resources depending on group size. This offers a model system to determine how females assess quantitative social information. We show that the concentration of pheromones found on a substrate increases linearly with the number of adult flies that have visited that site. Females prefer oviposition sites with pheromone concentrations corresponding to an intermediate number of previous visitors, whereas sites with low or high concentrations are unattractive. This dose-dependent decision is based on a blend of 11-cis-Vaccenyl Acetate (cVA) indicating the number of previous visitors and heptanal (a novel pheromone deriving from the oxidation of 7-Tricosene), which acts as a dose-independent co-factor. This response is mediated by detection of cVA by odorant receptor neurons Or67d and Or65a, and at least five different odorant receptor neurons for heptanal. Our results identify a mechanism allowing individuals to transform a linear increase of pheromones into a non-linear behavioral response.

Growth performance of the black soldier fly,Hermetia illucens larvae (Linnaeus, 1758) fed on honeybee propolis-treated wheat bran

Insect-based meals such as the black soldier flyHermetia illucens (Linnaeus, 1758) larvae (BSFL) meal have shown promising results as aqua feed protein supplements. BSFL voraciously consume organic waste converting the nutrients into larval biomass containing 37-63% protein. However, to enable large-scale production of BSFL, the growth performance of BSFL needs to be enhanced. Natural additives such as propolis (a honeybee product) have shown potential to enhance the performance of farmed animals. This study examined the growth performance of BSFL fed on wheat bran treated with ethanol extracted honeybee propolis. A 45-days experiment was carried out in which triplicate groups of 100 BSFL (5 days-old) were each fed on 0.5 kg of wheat bran with a 70% moisture content and treated with either 0, 0.2, 0.4, 0.6 or 0.8 g of ethanol extracted propolis. The mean weight of BSFL at pre-pupae stage, rate of pupation and emergence of adult flies were assessed. The findings indicate that at the end of the first five days, the mean weight of larvae reared on propolis-treated substrate was significantly higher than the weight of larvae on propolis-untreated substrate. The highest mean weight of BSFL was recorded with 0.6 g propolis-treated wheat bran. The highest cumulative mean number of pupae was recorded in wheat bran treated with 0.8 g of propolis. Further, the highest cumulative mean number of adult flies were recorded in wheat bran treated with 0.8 g of propolis. All pupae from propolis treated substrate emerged into adult flies earlier (5 days) compared to other treatments. Therefore, propolis addition to wheat bran enhanced the growth performance of BSFL. However, more studies are necessary to determine the effect of propolis on reproductive performance of BSF and the proximate composition of BSFL.

Field evaluation of food baits against female melon fruit fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae)

The attraction of the female melon fly, Zeugodacus cucurbitae (Coq.) (Diptera: Tephritidae) to three food baits were evaluated in snake gourd (Trichosanthes anguina L.) and ridge gourd (Luffa acutangula (L.)) ecosystems at both Coimbatore and Tiruppur districts during January to march 2020. Food bait admixtures were prepared by combining base baits (guava-B1, muskmelon-B2 and guava+ muskmelon-B3) and bait additives (yeast, food grade alcohol, cane sugar and ProtineX®). The result indicated that both ridge gourd and snake gourd at Coimbatore (23 fruit flies/trap/day) attracted more adult flies than at Tiruppur. Greater number of Z. cucurbitae were attracted to food bait traps in snake gourd field (24 fruit flies/trap/day) at both Coimabtore and Tiruppur. In common, the performance of guava bait admixture (21 fruit flies/trap/day) was relatively greater than other two baits by trapping more adult flies. At individual sites, the three food baits attracted equivalently higher number of females than males (about 70% females). The number of adult flies trapped at first week (42 fruit flies/trap/day) was high and gradually decreased in successive weeks and found low at 11th (2 fruit fly/trap/day) and 12th (1 fruit fly/trap/day) weeks. This management practice for Z. cucurbitae effectively reduced the pest population by attracting most females.

Differential side-effects of Bacillus thuringiensis bioinsecticide on non-target Drosophila flies

Bioinsecticides based on Bacillus thuringiensis (Bt) spores and toxins are increasingly popular alternative solutions to control insect pests, with potential impact of their accumulation in the environment on non-target organisms. Here, we tested the effects of chronic exposure to commercial Bt formulations (Bt var. kurstaki and israelensis) on eight non-target Drosophila species present in Bt-treated areas, including D. melanogaster (four strains). Doses up to those recommended for field application (~ 106 Colony Forming Unit (CFU)/g fly medium) did not impact fly development, while no fly emerged at ≥ 1000-fold this dose. Doses between 10- to 100-fold the recommended one increased developmental time and decreased adult emergence rates in a dose-dependent manner, with species-and strain-specific effect amplitudes. Focusing on D. melanogaster, development alterations were due to instar-dependent larval mortality, and the longevity and offspring number of adult flies exposed to bioinsecticide throughout their development were moderately influenced. Our data also suggest a synergy between the formulation compounds (spores, cleaved toxins, additives) might induce the bioinsecticide effects on larval development. Although recommended doses had no impact on non-target Drosophila species, misuse or local environmental accumulation of Bt bioinsecticides could have side-effects on fly populations with potential implications for their associated communities.

Pest potential of Neotephritis finalis (Loew) on Silphium integrifolium Michx., Silphium perfoliatum L., and interspecific hybrids

AbstractNeotephritis finalis (Loew), a fly known as a minor pest of cultivated sunflowers (Helianthus annuus L.), has been observed to attack Silphium spp., which are being evaluated as new crops to produce biomass or edible oil. Infestations of Silphium integrifolium Michx., Silphium perfoliatum L. and their interspecific hybrids were assessed by securing bags over heads late in bloom and counting emerged adult flies ∼30 d later. Effects on seed production were assessed by examining the percent of achenes containing fully developed seeds (i.e., seed set). In 2017, more flies emerged from S. integrifolium and hybrids than from S. perfoliatum, but even high numbers of adult flies emerged per head appeared unrelated to seed set in S. integrifolium. In 2018, far fewer flies were found across Silphium spp., but seed set was similar to 2017. Combined, results indicate that N. finalis is unlikely to limit seed production of Silphium spp.

Population dynamics of an invasive bird parasite, Philornis downsi (Diptera: Muscidae), in the Galapagos Islands.

The invasive parasitic fly, Philornis downsi (Muscidae), is one of the greatest threats to the avifauna of the Galapagos Islands. The larvae of this fly feed on the blood and tissues of developing nestlings of at least 18 endemic and native birds. The aim of the current study was to investigate biotic and abiotic factors that may influence the population dynamics of this invasive parasite. To study the influence of vegetation zone and related climatic factors on fly numbers, a bi-weekly monitoring program using papaya-baited traps was carried out at a dry, lowland site and at a humid, highland site on Santa Cruz Island between 2012–2014. Female flies, a large proportion of which were inseminated and gravid, were collected throughout the year at both sites, indicating females were active during and between the bird breeding seasons. This is the first evidence that female flies are able to persist even when hosts are scarce. On the other hand, catch rates of male flies declined between bird breeding seasons. Overall, catch rates of P. downsi were higher in the drier, lowland habitat, which may be a consequence of host or resource availability. Time was a stronger predictor of adult fly numbers than climate, further suggesting that P. downsi does not appear to be limited by its environment, but rather by host availability. Seasonal catch rates suggested that populations in both habitats were continuous and multivoltine. Numbers of adult female flies appeared to be regulated chiefly by simple direct density dependence, and may be governed by availability of bird nests with nestlings. Nevertheless, confounding factors such as the existence of reservoir hosts that perpetuate fly populations and changes in behavior of P. downsi may increase the vulnerability of bird hosts that are already IUCN red-listed or in decline.

Two Gut-Associated Yeasts in a Tephritid Fruit Fly have Contrasting Effects on Adult Attraction and Larval Survival.

Yeast-insect interactions have been well characterized in drosophilid flies, but not in tephritid fruit flies, which include many highly polyphagous pest species that attack ripening fruits. Using the Queensland fruit fly (Bactrocera tryoni) as our model tephritid species, we identified yeast species present in the gut of wild-collected larvae and found two genera, Hanseniaspora and Pichia, were the dominant isolates. In behavioural trials using adult female B. tryoni, a fruit-agar substrate inoculated with Pichia kluyveri resulted in odour emissions that increased the attraction of flies, whereas inoculation with Hanseniaspora uvarum, produced odours that strongly deterred flies, and both yeasts led to decreased oviposition. Larval development trials showed that the fruit-agar substrate inoculated with the 'deterrent odour' yeast species, H. uvarum, resulted in significantly faster larval development and a greater number of adult flies, compared to a substrate inoculated with the 'attractive odour' yeast species, P. kluyveri, and a yeast free control substrate. GC-MS analysis of volatiles emitted by H. uvarum and P. kluyveri inoculated substrates revealed significant quantitative differences in ethyl-, isoamyl-, isobutyl-, and phenethyl- acetates, which may be responsible for the yeast-specific olfactory responses of adult flies. We discuss how our seemingly counterintuitive finding that female B. tryoni flies avoid a beneficial yeast fits well with our understanding of female choice of oviposition sites, and how the contrasting behavioural effects of H. uvarum and P. kluyveri raises interesting questions regarding the role of yeast-specific volatiles as cues to insect vectors. A better understanding of yeast-tephritid interactions could assist in the future management of tephritid fruit fly pests through the formulation of new "attract and kill" lures, and the development of probiotics for mass rearing of insects in sterile insect control programs.

Feeding by Leucopis argenticollis and Leucopis piniperda (Diptera: Chamaemyiidae) from the western USA on Adelges tsugae (Hemiptera: Adelgidae) in the eastern USA.

Leucopis argenticollis (Zetterstedt) and Leucopis piniperda (Malloch) are known to feed on the lineage of Adelges tsugae Annand that is native to western North America, but it is not known if they will survive on the lineage that was introduced from Japan to the eastern USA. In 2014, western Leucopis spp. larvae were brought to the laboratory and placed on A. tsugae collected in either Washington (North American A. tsugae lineage) or Connecticut (Japanese lineage). There were no significant differences in survival or developmental times between flies reared on the two different adelgid lineages. In 2015 and 2016, western Leucopis spp. adults were released at two different densities onto enclosed branches of A. tsugae infested eastern hemlock (Tsuga canadensis (L.) Carr.) in Tennessee and New York. Cages were recovered and their contents examined 4 weeks after release at each location. Leucopis spp. larvae and puparia of the F1 generation were recovered at both release locations and adults of the F1 generation were collected at the Tennessee location. The number of Leucopis spp. offspring collected increased with increasing adelgid density, but did not differ by the number of adult flies released. Flies recovered from cages and flies collected from the source colony were identified as L.argenticollis and L. piniperda using DNA barcoding. These results demonstrate that Leucopis spp. from the Pacific Northwest are capable of feeding and developing to the adult stage on A. tsugae in the eastern USA and they are able to tolerate environmental conditions during late spring and early summer at the southern and northern extent of the area invaded by A. tsugae in the eastern USA.

Laboratory Bioassays with Three Different Substrates to Test the Efficacy of Insecticides against Various Stages of Drosophila suzukii (Diptera: Drosophilidae).

Rapid worldwide spread and polyphagous nature of the spotted wing Drosophila Drosophila suzukii Matsumura (Diptera: Drosophilidae) calls for efficient and selective control strategies to prevent severe economic losses in various fruit crops. The use of insecticides is one option for management of this invasive pest insect. Efficacy of insecticides is usually assessed first in laboratory bioassays, which are compounded by the cryptic nature of D. suzukii larvae and the fact that fruits used in bioassays often start to rot and dissolve before larvae have reached the adult stage. Here, we report on laboratory bioassays using three different types of substrates allowing a thorough screening of insecticides for their potential effects against D. suzukii eggs, larvae and adults. Suitability of our bioassays was validated in an assessment of the efficacy of four bioinsecticides and one synthetic insecticide against various developmental stages of D. suzukii. Water-apple juice agar used as a bioassay substrate allowed egg counting and observation of larval development due to its transparency, while apple-nutrition medium allowed complete metamorphosis. Use of grape berries in bioassays made it possible to assess effects of an insecticide present on a fruit’s surface on oviposition and larval hatch from eggs. Insecticides tested in these three different bioassays with acetamiprid, spinosad or natural pyrethrins as active ingredients achieved a significant D. suzukii control if they were applied before egg deposition. Number of adult flies was significantly reduced if the bioassay medium was treated with an azadirachtin A containing insecticide both before or after egg deposition.

Measurement of Carbon Dioxide Production from Radiolabeled Substrates in Drosophila melanogaster.

The power of Drosophila genetics is increasingly being applied to questions of hormone signaling and metabolism and to the development of models of human disease in this organism. Sensitive methods for measurements of parameters such as metabolic rates are needed to drive the understanding of physiology and disease in small animals such as the fruit fly. The method described here assesses fuel oxidation in small numbers of adult flies fed food containing trace amounts of 14C-labeled substrates such as glucose or fatty acid. After the feeding period and any additional experimental manipulations, flies are transferred to short tubes capped with mesh, which are then placed in glass vials containing KOH-saturated filter paper that traps exhaled, radiolabeled CO2 generated from oxidation of radiolabeled substrates as potassium bicarbonate, KHCO3. This radiolabeled bicarbonate is measured by scintillation counting. This is a quantitative, reproducible, and simple approach for the study of fuel oxidation. The use of radiolabeled glucose, fatty acids, or amino acids allows determination of the contribution of these different fuel sources to energy metabolism under different conditions such as feeding and fasting and in different genetic backgrounds. This complements other approaches used to measure in vivo energy metabolism and should further the understanding of metabolic regulation.

Measurement of Carbon Dioxide Production from Radiolabeled Substrates in <em>Drosophila melanogaster</em>

The power of Drosophila genetics is increasingly being applied to questions of hormone signaling and metabolism and to the development of models of human disease in this organism. Sensitive methods for measurements of parameters such as metabolic rates are needed to drive the understanding of physiology and disease in small animals such as the fruit fly. The method described here assesses fuel oxidation in small numbers of adult flies fed food containing trace amounts of 14C-labeled substrates such as glucose or fatty acid. After the feeding period and any additional experimental manipulations, flies are transferred to short tubes capped with mesh, which are then placed in glass vials containing KOH-saturated filter paper that traps exhaled, radiolabeled CO2 generated from oxidation of radiolabeled substrates as potassium bicarbonate, KHCO3. This radiolabeled bicarbonate is measured by scintillation counting. This is a quantitative, reproducible, and simple approach for the study of fuel oxidation. The use of radiolabeled glucose, fatty acids, or amino acids allows determination of the contribution of these different fuel sources to energy metabolism under different conditions such as feeding and fasting and in different genetic backgrounds. This complements other approaches used to measure in vivo energy metabolism and should further the understanding of metabolic regulation.

Effects of different animal manures on attraction and reproductive behaviors of common house fly, Musca domestica L

Insects rely mainly on their well-developed and highly sophisticated olfactory system to discriminate volatile cues released from host and nonhost substances, mates, oviposition substrates, and food sources. Onset of first mating, mating duration, and onset of first oviposition, oviposition period, fecundity (number of eggs laid by a female), and longevity of freshly emerged Musca domestica L. (Diptera: Muscidae) adults were observed in the presence of different animal manures: cow, horse, donkey, poultry, and an artificial diet. The M. domestica adults exposed to horse manure showed a delay in onset of first mating and first oviposition, prolonged mating duration, and reduced fecundity compared to the artificial diet (control). Likewise, the fecundity was reduced in the presence of donkey manure as compared to artificial diet. The onset of first mating was delayed and duration of first mating was shortened in the presence of cow manure as compared to artificial diet and no oviposition was observed throughout the duration of the experiment. However, the reproductive behaviors and all fitness measures in adults exposed to poultry manure were similar or even better, compared to the artificial diet. Surprisingly, in a free-choice attraction assay, the highest numbers of adult flies were attracted toward the cow manure as compared to all other manures as well as the artificial diet. However, the numbers of flies captured in all other types of manures were not different than the artificial diet (control). Furthermore, chemical analysis of headspace samples of manures revealed qualitative differences in odor (volatile) profiles of all manures and artificial diet, indicating that behavioral differences could be due to the differences in the volatile chemistry of the adult ovipositional substrates and larval growth mediums. This study may contribute toward both understanding the linkage between ecological adaptations and host selection mechanisms and the development of pest management strategies against this serious pest of medical and veterinary importance.

Численность имаго мух и их личинок в условиях свинокомплекса в осенний период

Objective of research: To study the abundance of adult of flies and their larvae in a pig farm in the fall two weeks before the end of the production cycle. Materials and methods: The abundance of adult flies and their larvae was investigated in September - October 2015 at the pig farm “Kuznetsovsky” of Moscow region in two sow houses and one pigsty for weaned piglets two weeks before the end of the production cycle. To calculate the number of adult flies, we have placed in each selected pigsty the flytraps (sticky tapes) “Mukholov-Proshka” produced in St. Petersburg. The trap has an adhesive base containing rosin, rubber and mineral oil. Traps were placed at 1 and 2 m from the floor, six traps in each room. The number of adhered insects was calculated at the laboratory of the All-Russian Research Institute of Fundamental and Applied Parasitology of animals and plants named after K.I. Skryabin, 24 hours after placement of traps. To calculate the number of fly larvae and pupae, in cooperation with the pig farm veterinary service the scrapings were taken from the floor with dimensions of 10 × 10 cm (six scrapings from each pigsty). Scrapings with the mass of 3-5 g were placed into individual plastic minicontainers with a particular number and delivered to the laboratory of the Institute for examination. Results and discussion: The study on initial number of adult flies and their larvae conducted two weeks before the end of the previous technological cycle showed a significant insect number at different heights from the floor. In the first pigsty, the number of flies in a flytrap (at a height of 1 and 2 m from the floor) ranged from 199 to 286 ind. Calculated 24 hours after the placement of flytraps; the average number was 257 individuals. In the second pigsty, the number of flies ranged from 108 to 198 individuals; the average number was 147individuals. In the pigsty for weaning piglets, one day after the placement of traps, the number of adult flies in one flytrap ranged from 162 to 286 individuals, and the average number was 249 individuals. The average number of fly larvae in one tested sample taken from the floor of a pigsty was 267 and 118 individuals, and in a pigsty for weaning piglets - 29 individuals.

Comparative Effectiveness of Insecticides for Use Against the House Fly (Diptera: Muscidae): Determination of Resistance Levels on a Malaysian Poultry Farm.

In this study, the toxicology of two commercial larvicides--cyromazine (Neporex 50SP) and ChCy (combination of chlorpyrifos and cypermethrin, Naga 505)--and five commercial adulticides--thiamethoxam (Agita 10WG), cyfluthrin (Responsar WP), lambda-cyhalothrin (Icon 2.8EC), fipronil (Regent 50SC), and imidacloprid (Toxilat 10WP)--was examined against the WHO/VCRU (World Health Organization/ Vector Control Research Unit) susceptible strain and the AYTW (Ayer Tawar) field strain of house fly, Musca domestica L. These pesticides were administered topically, in the diet, or as a dry residue treatment on plywood. Probit analysis using at least five concentrations and the concentration that was lethal to 50% (LC(50)) of the organisms was applied to compare the toxicology and resistance levels of the AYTW population to different insecticides. In the larvicide laboratory study, ChCy was more effective than cyromazine, with a significantly lower LC(50) value when administered topically or in the diet, although the AYTW population was susceptible to both larvicides with a resistance ratio (RR) <10. For the adulticide laboratory study, cyfluthrin and fipronil exhibited the lowest LC50 values of the adulticides, indicating that they are both effective at controlling adult flies, although lambda-cyhalothrin showed moderate resistance (RR = 11.60 by topical application; 12.41 by plywood treatment). Further investigation of ChCy, cyromazine, cyfluthrin, and fipronil under field conditions confirmed that ChCy and cyromazine strikingly reduced larval density, and surprisingly, ChCy also exhibited adulticidal activity, which significantly reduced adult fly numbers compared with the control group. Cyfluthrin and fipronil were also confirmed to be effective, with a significant reduction in adult fly numbers compared with the control group.

Evaluation of maternal and embryotoxic effects following the treatment of chloral hydrate in Drosophila melanogaster.

Chloral hydrate (CH) is commonly used as a sedative and a hypnotic in pediatric medicine. In this study, the effects of CH on various developmental stages of Drosophila melanogaster were investigated. Different concentrations of CH (0.1; 0.3; 0.5 and 1mg/mL) were used during development of the flies. Maternal toxicity due to increasing the concentration of CH was observed as a large number of adult flies died. When the F1 progeny of the control and application groups were compared, CH was found to extend the process of metamorphosis and to decrease the total number of offspring. The embryotoxic effects on the offspring and an increase in the number of malformed offspring was identified as depending on feeding. It was found that the difference between the groups was significantly important (p<0.05).

Larval breeding sites of Lutzomyia longipalpis (Diptera: Psychodidae) in visceral leishmaniasis endemic urban areas in Southeastern Brazil.

BackgroundThe scarcity of information on the immature stages of sand flies and their preferred breeding sites has resulted in the focus of vectorial control on the adult stage using residual insecticide house-spraying. This strategy, along with the treatment of human cases and the euthanasia of infected dogs, has proven inefficient and visceral leishmaniasis continues to expand in Brazil. Identifying the breeding sites of sand flies is essential to the understanding of the vector's population dynamic and could be used to develop novel control strategies.Methodology/Principal findingIn the present study, an intensive search for the breeding sites of Lutzomyia longipalpis was conducted in urban and peri-urban areas of two municipalities, Promissão and Dracena, which are endemic for visceral leishmaniasis in São Paulo State, Brazil. During an exploratory period, a total of 962 soil emergence traps were used to investigate possible peridomiciliary breeding site microhabitats such as: leaf litter under tree, chicken sheds, other animal sheds and uncovered debris. A total of 160 sand flies were collected and 148 (92.5%) were L. longipalpis. In Promissão the proportion of chicken sheds positive was significantly higher than in leaf litter under trees. Chicken shed microhabitats presented the highest density of L. longipalpis in both municipalities: 17.29 and 5.71 individuals per square meter sampled in Promissão and Dracena respectively. A contagious spatial distribution pattern of L. longipalpis was identified in the emergence traps located in the chicken sheds.ConclusionThe results indicate that chicken sheds are the preferential breeding site for L. longipalpis in the present study areas. Thus, control measures targeting the immature stages in chicken sheds could have a great effect on reducing the number of adult flies and consequently the transmission rate of Leishmania (Leishmania) infantum chagasi.

Host Susceptibility of Citrus Cultivars to Queensland Fruit Fly (Diptera: Tephritidae)

Citrus crops are considered to be relatively poor hosts for Queensland fruit fly, Bactrocera tryoni (Froggatt), as for other tephritid species. Australian citrus growers and crop consultants have reported observable differences in susceptibility of different citrus cultivars under commercial growing conditions. In this study we conducted laboratory tests and field surveys to determine susceptibility to B. tryoni of six citrus cultivars [(Eureka lemon (Citrus limon (L.) Osbeck); Navel and Valencia oranges (C. sinensis (L.) Osbeck); and Imperial, Ellendale, and Murcott mandarins (C. reticulata Blanco). The host susceptibility of these citrus cultivars was quantified by a Host Susceptibility Index, which is defined as the number of adult flies produced per gram of fruit infested at a calculated rate of one egg per gram of fruit. The HSI was ranked as Murcott (0.083) > Imperial (0.052) > Navel (0.026) - Ellendale (0.020) > Valencia (0.008) > Eureka (yellow) (0.002) > Eureka (green) (0). Results of the laboratory study were in agreement with the level of field infestation in the four citrus cultivars (Eureka lemon, Imperial, Ellendale, and Murcott mandarins) that were surveyed from commercial orchards under baiting treatments against fruit flies in the Central Burnett district of Queensland. Field surveys of citrus hosts from the habitats not subject to fruit fly management showed that the numbers of fruit flies produced per gram of fruit were much lower, compared with the more susceptible noncitrus hosts, such as guava (Psidium guajava L.), cherry guava (P. littorale Raddi), mulberry (Morus nigra L.), loquat (Eriobotrya japonica (Thunb.) Lindl.), and pear (Pyrus communis L.). Therefore, the major citrus crops commercially cultivated in Australia have a relatively low susceptibility to B. tryoni, with Eureka lemons being a particularly poor host for this tephritid fruit fly.

Developing an Integrated Management Approach for the Fruit Fly Dacus punctatifrons on Tomatoes

Aims: To document the various insecticides employed and also test alternative and/or complementary less-toxic and eco-friendly management methods against the notorious fruit fly Dacus punctatifrons on tomatoes as potential components of a multi-pronged ecofriendly integrated approach for this pest. Study Design: Random interviewing of tomato farmers and field testing of different pest management methods in a randomized block design. Place and Duration of Study: Interviewed farmers in Buea and its environs. Field experiments at the Research Farm of the University of Buea, South Western Cameroon. October 2010 to September 2011. Methodology: Structured questionnaires administered to 110 farmers to document how they managed Dacus punctatifrons on their tomatoes and testing the efficacy of Piper Research Article American Journal of Experimental Agriculture, 3(3): 470-481, 2013 471 guineense aqueous extract, cultural practices like staking, pruning and farm sanitation against this pest in field studies. Results: Most of the farmers, 58(52.73%) cited Dacus punctatifrons as their main insect pest on tomatoes. All the farmers used conventional insecticides injudiciously to control the insect pests. The synthetic pyrethroid, Cypercal 50EC was the most popular insecticide used. The numbers of fruits with fruit fly damage signs, and number of adult flies that emerged from plots treated with Piper guineense seed extract were not significantly different from those of plots treated with the neonicotinoid Parastar 40EC insecticide. These two treatments were significantly superior to the untreated control plots and those where the plants were staked, regularly weeded and judiciously pruned. Fallen fruits and those harvested from farms even up to five weeks after farmers had harvested all marketable fruits still contained Dacus punctatifrons larvae that eventually developed into adults which emerged after laboratory incubation. Conclusion: Integrating the judicious use of appropriately formulated insecticides, Piper guineense aqueous seed extract, early detection, collection and destruction of fruit flyinfested tomato fruits and destruction of crop residue after harvest can be a sustainable and reduced-risk multi-trigger management system for Dacus punctatifrons on tomatoes.

Identification of Genes Underlying Hypoxia Tolerance inDrosophilaby a P-element Screen

Hypoxia occurs in physiologic conditions (e.g. high altitude) or during pathologic states (e.g. ischemia). Our research is focused on understanding the molecular mechanisms that lead to adaptation and survival or injury to hypoxic stress using Drosophila as a model system. To identify genes involved in hypoxia tolerance, we screened the P-SUP P-element insertion lines available for all the chromosomes of Drosophila. We screened for the eclosion rates of embryos developing under 5% O2 condition and the number of adult flies surviving one week after eclosion in the same hypoxic environment. Out of 2187 lines (covering ∼1870 genes) screened, 44 P-element lines representing 44 individual genes had significantly higher eclosion rates (i.e. >70%) than those of the controls (i.e. ∼7–8%) under hypoxia. The molecular function of these candidate genes ranged from cell cycle regulation, DNA or protein binding, GTP binding activity, and transcriptional regulators. In addition, based on pathway analysis, we found these genes are involved in multiple pathways, such as Notch, Wnt, Jnk, and Hedgehog. Particularly, we found that 20 out of the 44 candidate genes are linked to Notch signaling pathway, strongly suggesting that this pathway is essential for hypoxia tolerance in flies. By employing the UAS/RNAi-Gal4 system, we discovered that genes such as osa (linked to Wnt and Notch pathways) and lqf (Notch regulator) play an important role in survival and development under hypoxia in Drosophila. Based on these results and our previous studies, we conclude that hypoxia tolerance is a polygenic trait including the Notch pathway.