Challenges of Controlling Vector and Vector-borne Diseases at the Flood Disaster of Khuzestan Province in 2019 According to the Experts of Health Center

Background: Natural disasters, such as floods provide the basis for spreading vector-borne diseases by creating environmental changes. This study aims to investigate the common vector-borne diseases during floods in Khuzestan Province, Iran, in 2019 and the strategies and challenges to control them. Materials and Methods: This research is applied objectively and it is a descriptive survey in terms of collecting data using a qualitative method. The statistical population in the qualitative section included 15 experts from health centers in Khuzestan Province with a history of presence in flooded areas who were purposively selected using the snowball technique. The data collection tool was a semi-structured interview. Results: Qualitative data were categorized into 5 categories of common arthropods, common vector-borne diseases, vector control strategies and challenges, and organs involved in vector control programs during floods. The most common arthropods were lice, mites, mosquitoes, flies, and scorpions. The most prevalent vector-borne diseases during the flood were scabies, pediculosis, mosquito bites, and scorpions. The critical challenge was the lack of national vector control guideline in disaster condition. Conclusion: Considering the history of floods and health problems caused by these natural disasters, it is necessary to recognize the common vector-borne diseases, develop national guidelines, and provide solutions to deal with them.

Pediculicidal Activity of Foeniculum vulgare Essential Oil in Treatment of Pediculus capitis as a Public Health Problem

Background

Pediculosis, caused by Pediculus spp is an important public health problem in urban and rural areas around the world. Natural compounds such as plant essential oils (EOs) have been suggested as a potential alternative for insect pest control recently. The purpose of this study was to investigate the toxicity of Foeniculum vulgare essential oil against the head louse, Pediculus capitis under laboratory conditions.

Methods

Fennel essential oil components were analyzed using GC-mass apparatus. Immersion and contact filter paper bioassays were used to evaluate fennel essential oil toxicity at the two-fold concentrations of 2.5, 5, 10, 20, and 40% against nit and nymph/adult stages of the head louse.

Results

Trans-anethole, α-Thujone, and limonene, which consisted of 76.08%, 10.37%, and 5.34% were the most components of fennel oil respectively. The LC₅₀ values for the adult /nymphs were 11.5, 6.4, 3.9, 3.1 and 2.5% and LC₉₉ values were 29.5, 15.2, 12.8, 10.8, and 7.4% at 10, 20, 30, 45 and 60 minutes after exposure respectively. The lethal times (LT₅₀) for adults/nymphs were 5.2, 8.1, 9.5, 20.5, and 45.8 minutes and LT₉₉ were 138.6, 91.3, 23.8, 21.7, and 13.9 minutes in the concentrations of 2.5, 5, 10, 20 and 40%, respectively. LC₅₀ and LC₉₉ values were 2.32% and 7.36% after 5 days for the eggs.

Conclusion

Fennel essential oil at the concentration of 15% after 20min is suggested to develop as an appropriate formulation to evaluate in clinical trials.

Possible Synergistic Effect of Combined Metarhizium anisopliae and Fenitrothion for Control of German Cockroach (Blattella germanica) as a Novel Approach

Background

Cockroaches are one of the most common pests in many residential areas. In this study, the simultaneous effects of fungi, Metarhizium anisopliae and fenitrothion-coated baits on the mortality rate of the German cockroach nymphs were investigated.

Methods

To determine the lethal level of fenitrothion insecticide, a bioassay test was performed on the last instar nymphs of the German cockroach reared at insectarium conditions. Various toxic concentrations of fenitrothion (0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.5%, and 2%) were used. Different concentrations of M. anisopliae (1×10⁴, 1×10⁵, 1×10⁶, 1×10⁷, 1×10⁸ Conidia/ml) were also applied to nymphs. Eventually, we combined the effective dose of fenitrothion (0.93%) with the effective concentration of M. anisopliae (6.6 ×10⁶ Conidia/ml) to provide the fungus-coated bait to attract insects. Mortality was recorded 24-96 hours after exposure to the toxic bait. The resulting data were subjected to Probit analysis.

Results

The results of applying M. anisopliae spores with fenitrothion composition showed that the mortality rate of German cockroach nymphs was significant. Therefore, the optimal dose of fenitrothion used in combination with M. anisopliae seems essential to reduce the German cockroach nymphs.

Conclusion

The results of this study can be considered a suitable method as a mixture with low cost and minimal damage to the environment and other organisms.

Prevalence and Spatial Distribution of Bed Bug, Cimex lectularius, Infestation in Southwest of Iran: GIS Approach

Background:

The common bed bug, a nocturnal bloodsucking insect, is known as a human parasite and public health problem in the world. The prevalence and geographical dispersion of bed bug in Ahvaz City, southwest of Iran was measured.

Methods:

Spatial distribution of Cimex lectularius was determined by surveying 520 houses in 62 areas of Ahvaz City in 2017. Some information like as infested points, the concern level of the residents and allergic reaction to the insect bite were registered in a form using the secondhand instrument.

Results:

According to the spatial distribution map, of 62 areas, 27 of them are infested with bed bugs. Infestation is scattered throughout the city, but its focus is on the east of the Karun River. The most bed bug infestation was in Asiabad followed by Manbaab areas. Prevalence of bed bug infestation estimated 9.61% in Ahvaz city. It was 5.4% and 11.6% in apartments and single houses, respectively. The lowest and highest infestation rates based on its source were 1.35% and 9.03% in wallpaper and cracks and crevices, respectively. Bedroom and sitting room were the main harborages for bed bug in the houses. The majority of residents who had bitten by a bed bug showed various allergic reactions like redness skin, papules, vesicles, pustules and blisters. Most of the people in the infested houses (62%) were very concern about bed bug infestation.

Conclusion:

Public education and increasing the knowledge of people can lead to successful management, prevention and elimination of this nuisance pest.

Effects of Resident Education and Self-Implementation of Integrated Pest Management Strategy for Eliminating Bed Bug Infestation in Ahvaz City, Southwestern Iran

Background:

Bed bugs as blood-sucking insects have become a public health problem in urban communities throughout the world. The objective of this study was to determine the effects of resident education and self-implementation of Integrated Pest Management (IPM) strategy for eliminating bed bug infestation in infected apartments in Ahvaz City, Iran.

Methods:

This interventional study was conducted in seventy apartments infested with bed bug (Cimex lectularius) in Ahvaz City, southwest Iran, during a 6-month period. The bed bug infestations reported to Health centers were inspected visually and confirmed by medical entomology experts. Then, the heads of the households were received techniques/tools of the IPM program and trained by medical entomology experts before self-implementation of control methods. Finally, the infected apartments were inspected by the experts at 1, 3, and 6 months after intervention and data were recorded in a checklist.

Results:

From the seventy infected apartments, 57%, 28% and 15% were considered as low, moderate, and high level infestation respectively. The bed bug infestation was eliminated from 53 apartments (76%) after one month and it reached to 62 apartments (88%) by the end of third month. Finally, after six months of applying IPM program, bed bugs infestation was eliminated from all infected apartments (100%). Residents expressed their 100% satisfaction with applying the bed bug IPM strategy.

Conclusion:

Training residents to implement the IPM program can reduce pest control costs, the volume of pesticides consumed, and human exposure to chemical pesticides, resulting in increased human and environmental health and safety.

Presence probability of Hemiscorpius lepturus Peters, 1861 using maximum entropy approach in the western areas of Zagros Mountains, Iran

AIM

The purpose of this research was to use environmental variables for predicting the probability of Hemiscorpius lepturus existence in the provinces where situated in the west of the Zagros Mountains.

MATERIALS AND METHODS

In this study, 64 occurrence records of the H. lepturus were extracted from the published documents available in electronic databases. MaxEnt model was used for predicting the ecological niches of this species. Normalized difference vegetation index (NDVI) and 19 climatic variables were used as the environmental variables affecting the distribution of this scorpion. The Jackknife test in the model was used to indicate the importance of variables to predict the probability of the presence of the studied species. The logistic threshold that was evaluated using a logistic regression algorithm showed the converting of the probability model into a binary model. The model was evaluated byarea under the curve (AUC). The probability presence map of this scorpion was then prepared in ArcGIS 10.5 Software.

RESULTS

The results of the analysis showed that the most important environmental factor on the distribution of H. lepturus was the maximum temperature of the warmest month (Bio5) with a contribution rate of 43% and permutation importance of 8%. The Jackknife test revealed that NDVI did not gain any value when it used independently in the model. The logistic threshold was reported 0.255 for the maximum test sensitivity plus specificity. The AUC of the model was 0.7698, shows an acceptable value for model validity. Overall the hot spots for this toxic scorpion seem to be in Khuzestan, Lorestan, and Ilam Provinces of the studied area.

CONCLUSION

Regarding our findings, MaxEnt algorithm, in combination with geographic information system contributed to revealing the effects of environmental variables on the probability of H. lepturus presence in the west of Zagros Mountains. These visualized maps as a warning alarm can be helpful to policymakers for managing, controlling, and monitoring the scorpionism in high-risk areas.

Pediculosis humanus capitis Prevalence as a Health Problem in Girl's Elementary Schools, Southwest of Iran (2017-2018)

BACKGROUND

Head lice as obligated ectoparasite is a public health concern. We aimed to determine the prevalence of Pediculus humanus capitis as public health concern among girl's primary school in southwest of Iran.

STUDY DESIGN

A cross-sectional study.

METHODS

This study was conducted in Karoon County, south-west of Khuzestan Province in Iran in 2017-2018. Totally, 851 students were interviewed randomly, examined by a medical entomologist and completed a questionnaire containing 18 questions based on individual, social, economic, cultural and health information. Results were presented as prevalence and percentages for qualitative variables and also, the data were analyzed by univariate logistic and multivariate regression models.

RESULTS

About 199 (23.38%) girls were infected by head lice. Univariate logistic regression indicated that the prevalence of pediculosis was directly associated with the grade of education, father's job, shared personal hygiene products, number of combing, having permanent head cover at home, infection in other members of the family and previous infection. Multivariate logistic regressions for predicting of head lice infection in girl students were reported permanent head cover at home (OR: 1.399, 95% CI: 0.934, 2.097, P=0.104), grade of education (OR: 1.948, 95% CI: 1.307, 2.905, P=0.001), father's job (OR: 2.385, 95% CI: 1.518, 3.750, P<0.001), shared personal hygiene products (OR: 1.817, 95% CI: 1.224, 2.698, P=0.003) and using hair oil (OR: 1.904, 95% CI: 1.279, 2.836, P=0.002) had significant relation with head lice infestation CONCLUSION: Head lice remind as serious health problem in Karoon County, southwest of Iran. Due to high infestation, periodic screening of the student is recommended for early detection and treatment.

Chemical Composition and Repellency of Origanum vulgare Essential Oil against Cimex lectularius under Laboratory Conditions

Background: The common bed bug (Cimex lectularius), a nocturnal blood-feeding ectoparasite, is considered an urban pest with public health importance in human environments. We aimed to determine the repellency effect of oregano essential oil, Origanum vulgare, against this pest under laboratory conditions. Methods: The essential oil was prepared from dried leaves using hydro-distillation method. A gas chromatography-mass spectrometer (GC-MS) was used for analysis and identification of oregano essential oil compounds. Treated surface method in Petri dish was carried out to evaluate repellency potential of the oil using 4th and 5th instar nymphs and adults. The concentration-repellency response of oregano essential oil was calculated and compared with a commercial insect repellent stick containing 33% N, N-diethyl-meta-toluamide (DEET). Results: The oregano essential oil consisted of 158 compounds with terpineol (22.85%) and α–terpinene (20.60%) being the major components by volume. The EC50 and EC99 of oregano oil (effective concentrations causing 50% and 90% repellency of bed bugs) were 1.61 and 6.57mg/cm2 at 9h after application, respectively. The 40% oregano es­sential oil exhibited 100% repellency against bed bug at 3, 5, 9 and 24h after application while the repellency index of DEET 33% was 100% at 3 and 5h and it decreased to 80% and 27% at 9 and 24 hours. Conclusion: Oregano oil 40% exhibited more repellency compared to commercial insect repellent stick containing 33% DEET. Further studies are warranted to confirm the effectiveness of oregano essential oil in personal protecting against bed bug biting.  

Chemical Composition and Repellency of Origanum vulgare Essential Oil against Cimex lectularius under Laboratory Conditions

BACKGROUND

The common bed bug (Cimex lectularius), a nocturnal blood-feeding ectoparasite, is considered an urban pest with public health importance in human environments. We aimed to determine the repellency effect of oregano essential oil, Origanum vulgare, against this pest under laboratory conditions.

METHODS

The essential oil was prepared from dried leaves using hydro-distillation method. A gas chromatography-mass spectrometer (GC-MS) was used for analysis and identification of oregano essential oil compounds. Treated surface method in Petri dish was carried out to evaluate repellency potential of the oil using 4th and 5th instar nymphs and adults. The concentration-repellency response of oregano essential oil was calculated and compared with a commercial insect repellent stick containing 33% N, N-diethyl-meta-toluamide (DEET).

RESULTS

The oregano essential oil consisted of 158 compounds with terpineol (22.85%) and α-terpinene (20.60%) being the major components by volume. The EC₅₀ and EC₉₉ of oregano oil (effective concentrations causing 50% and 90% repellency of bed bugs) were 1.61 and 6.57mg/cm² at 9h after application, respectively. The 40% oregano essential oil exhibited 100% repellency against bed bug at 3, 5, 9 and 24h after application while the repellency index of DEET 33% was 100% at 3 and 5h and it decreased to 80% and 27% at 9 and 24 hours.

CONCLUSION

Oregano oil 40% exhibited more repellency compared to commercial insect repellent stick containing 33% DEET. Further studies are warranted to confirm the effectiveness of oregano essential oil in personal protecting against bed bug biting.

Evaluation of Some Plant Essential Oils against the Brown-Banded Cockroach, Supella longipalpa (Blattaria: Ectobiidae): A Mechanical Vector of Human Pathogens

BACKGROUND

Essential oils, as secondary plant compounds, present a safer alternative to conventional insecticides in insect control programs. So five essential oils including eucalyptus, mint, yarrow, oregano and rosemary oils were evaluated against the brown-banded cockroach Supella longipalpa.

METHODS

Evaluation was done against the 3^rd and 4^th instar nymphs using three bioassay methods; continuous contact toxicity, fumigant toxicity and repellent activity. The study was done in the laboratory of medical entomology, during April 2012 to September 2013.

RESULTS

Mortality rates by the lowest concentration (2.5%) of rosemary, oregano, yarrow, eucalyptus and mint oils were 100%, 62.2%, 45 %, 36.2% and 5.2% at 24 h after exposure respectively. Rosemary oil was determined as the most toxic oil because of 100 % mortality rate at the concentration range of 2.5% to 30%. The lowest fumigation effect using 50 μl/L air was recorded from mint oil with 97.2 % mortality after 24 h, while the other oils caused 100% mortality. The most repel activity was related to oregano oil which showed 96.5-99.1% repellency at the concentration range of 2.5-30% with a residual effect lasting at least a week after treatment.

CONCLUSION

Oregano oil could be used as a potential repellent against S. longipalpa. Also, all five essential oils could be used as the safe compounds for surface treating or fumigation in cockroach control programs while rosmary and oregano oils exhibited the most toxicity.

Epidemiological Survey of Crimean-Congo Hemorrhagic Fever (CCHF), a Fatal Infectious Disease in Khuzestan Province, Southwest Iran, During 1999 - 2015

Background

Crimean-Congo hemorrhagic fever (CCHF) is an arboviral zoonotic disease transmitted to humans mainly through the bite of blood-sucking Ixodidae ticks and also via contact with the blood and tissues of infected livestock.

Objectives

This study is a retrospective descriptive survey based on data collected from the health center of Khuzestan province, Iran, during 1999 - 2015.

Patients and Methods

Patients with symptoms of severe headache, high fever, and bleeding were evaluated. Laboratory tests and serological or molecular assays were used to detect probable and confirmed cases, respectively. The epidemiological parameters of this study were analyzed on the basis of probable cases.

Results

A total of 42 patients were diagnosed as probable cases, and 17 of these (42.5%) were confirmed serologically. Two peaks of the disease occurred in Khuzestan province, in 2003 and 2010, with seven cases each of those years, leading to the deaths of five and two patients, respectively. Men and women comprised 57.1% and 42.9% of the patients, respectively. Of all probable cases, 64.3% were from urban areas and 35.7% were from rural areas. The age groups of 10 - 19 and 20 - 29 years, with a frequency of 26.2% in each group, were exposed to the most infections. Farmers and housewives were the highest at-risk occupational groups with a frequency of 28.6% and 26%, respectively. Fever, bleeding, and thrombocytopenia were reported in 95% of the patients, and the case-fatality ratio was calculated to be 28.6% (12 of 42 cases).

Conclusions

Continuous training is necessary to improve the knowledge and awareness of the highest-risk groups with regard to the transmission modes, prevention, symptoms, and treatment of this disease.

Biocontrol of the Brown-Banded Cockroach, Supella longipalpa F. (Blattaria: Blattellidae), with Entomopathogenic Fungus, Metharhizium anisopliae

BACKGROUND

Considering to the high distribution of cockroaches as urban pests, the efficacy of different formulations of Metarhizium anisopliae strain Iran 437C were assessed against the brown-banded cockroach, Supella longipalpa F. under laboratory and field conditions.

METHODS

Metarhizium anisopliae isolates were screened with immersing adults of the brown-banded cockroachs in aqueous suspension of 10(8) conidia ml(-1) followed by surface or bait treated with different doses of the most virulent isolate against the nymphs. Then formulations of conidia oil-in-water were examined versus cockroach nymphs using different plant oils and paraffin. Then they were evaluated and compared with aqueous suspension and control group. On a large-scale, the sunflower oil-in-water formulation of conidia was sprayed at houses using a hand sprayer.

RESULTS

Metarhizium anisopliae IRAN 437C was the most virulent isolate against the brown-banded cockroach, causing 100% mortality in adults at seven days post-exposure. Inoculated bait with this isolate was not enough pathogenic against the cockroach even at two weeks after treatment. Treated surface with conidia as aqueous suspension or oil-in-water formulation was more effective than the bait formulation against the cockroach caused 39.4-97.2% mortality compared with 2.5% mortality in control group after two days. Spraying the conidia formulated with sunflower oil was an effective formulation causing 76.1% reduction in the cockroach density on the third day post treatment in the houses.

CONCLUSION

The oil-in-water formulation of M. anisopliae IRAN 437C could be recommended as a promising alternative for cockroach control.

Evaluation of Conidia-Dust Formulation of the Entomopathogenic Fungus, Metarhizium anisopliae to Biocontrol the Brown-Banded Cockroach, Supella longipalpa F

Background:

The brown-banded cockroach Supella longipalpa (F.) as a mechanical vector of pathogens and source of allergens has recently become widespread in the city of Ahvaz, southwestern Iran.

Objectives:

This research was done to evaluate the efficacy of a dust-formulation of Metarhizium anisopliae isolate IRAN 437C, as a common entomopathogenous fungus, against S. longipalpa.

Materials and Methods:

Conidia dust-formulations of M. anisopliae were prepared in proportions of 1%, 5%, 10%, 25%, 50% and 100% with bad wheat flour as the carrier. Cockroaches were exposed to surfaces treated with 1.5 mg/cm² of the formulations under laboratory and semi-field conditions.

Results:

Cockroach mortality rates increased and survival times (ST₅₀) decreased with an increased proportion of conidia from 1% to 100% but records taken for mortality and survival time from proportions of 25%, 50% and 100% were not significantly different. The mortality rates reached 100% and 90-100% in adults and nymphs, respectively on the seventh day. The lowest ST₅₀ was related to the proportion of 100% (3 days). Probit analysis indicated LD₅₀ and LD₉₀ values of 1.7 × 10⁶ and 1.7 × 10⁷ conidia/cm² for adults and these values changed to 4.5 × 10⁶ and 2.9 × 10⁷ for third and fourth instar nymphs at three days post exposure. Proportion of 25% caused mortality rates of 87%, 81% and 73% in adult, adult & nymph and nymph populations, respectively at four days after exposure under room conditions.

Conclusions:

Conidia dust-formulation of M. anospliae isolate IRAN 437C could present a promising alternative to control the brown-banded cockroach.

The First Report of Drug Resistant Bacteria Isolated from the Brown-Banded Cockroach, Supella longipalpa, in Ahvaz, South-western Iran

BACKGROUND

The brown-banded cockroach, Supella longipalpa is known as a carrier of pathogenic bacteria in urban environments, but its role is not well documented regarding the carriage of antibiotic-resistant pathogenic bacteria in Iran. The aim of this study was to determine the resistance bacteria isolated from the brown-banded cockroach in Ahvaz, south west of Iran.

METHODS

Totally 39 cockroaches were collected from kitchen area of houses and identified. All specimens were cultured to isolate the bacterial agents on blood agar and MacConky agar media. The microorganisms were identified using necessary differential and biochemical tests. Antimicrobial susceptibility tests were performed for isolated organisms by Kirby-Bauer's disk diffusion according to NCLI guideline, using 18 antibiotics.

RESULTS

From the 39 collected S. langipalpa, 179 bacterial agents were isolated, 92 of alimentary ducts and 87 of external body surfaces. Isolated bacteria from cockroaches were identified as Enterobacter spp., Klebsiella spp., Citrobacter spp., Escherichia coli, Salmonella spp., Proteus spp., coagulase negative staphylococci, Serratia marcescens, Staphylococcus aureus, and Bacillus species. The pattern resistance rates were determined for gram negative bacilli and gram positive cocci regarding 18 antibiotics.

CONCLUSION

The brown-banded cockroach can be involved in the spread of drug resistant bacteria and increases the possibility of contacting human environment to drug resistant bacteria. Therefore, the potential of removing this insect should be improved. This is the first original report of drug resistant bacteria isolated from the brown-banded cockroach of Iran.

Monthly activity of Phlebotominae sand flies in Sistan-Baluchistan Province, Southeast Iran

The monthly activity of sand flies, which are vectors of leishmaniasis, was studied from May to October 1997 in three regions (plains, mountainous, coastal) of the Sistan-Bluchistan Province using sticky paper traps. In each village, three houses were selected. 30 sticky traps were installed indoors (bedroom, guestroom, toilet, bathroom) and 30 were installed outdoors (rodent burrows, wall cracks). In total, 8,558 and 1,596 sand fly specimens were collected and identified from outdoors and indoors, respectively. Ten species of Phlebotomus and eight species of Sergentomyia were collected outdoors, and nine species of Phlebotomus and 10 species of Sergentomyia were collected indoors. Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) was the predominant species found indoors in the plains region (58.4% of insects caught in the region) and was active during the whole study period. The P. papatasi peaks of activity were in early May and early October. Sergentomyia clydei (Sinton) was found to be the most abundant species outdoors in the plains region and comprised 64.7% of the total insects caught in the region. Sergentomyia clydei and S. tiberiadis (Alder, Theodor, and Lourie) were the predominant indoor and outdoor, respectively, species from the mountainous region, making up 19.8% and 35%, respectively, of all the insects caught in the region. Phlebotomus sergenti Parrot is a proven vector of urban cutaneous leishmaniasis, and P. alexandri (Sinton) is a probable vector of Kala-Azar, and both were collected during this study. Phlebotomus papatasi was the most predominant species collected indoors in the coastal region (50.8%), its peak activity was in May. Sergentomyia sintoni Pringle was the most predominant species collected outdoors in the coastal region (36.4%), and its peak activity was in October. Awareness of the peak activity times of sand flies can be useful in developing strategies to control the flies.

Horizontal Transmission of the Entomopathogen Fungus Metarhizium anisopliae in Microcerotermes diversus Groups

An experiment was carried out in order to investigate fungal conidia transmission of Metarhizium anisopliae (Metschnikoff) Sorokin from vector (donor) to healthy Microcerotermes diversus Silvestri (Iso.: Termitidae) and determine the best donor/concentration ratio for transmission. After preliminary trials, concentrations of 3.1 × 10⁴, 3.9 × 10⁵, 3.2 × 10⁶ and 3.5 × 10⁸ conidia mL⁻¹ were selected for testing. The experiment was performed at three donor : Recipient ratios of 10, 30 and 50%. The highest mortality of recipient workers was observed after 14 days at the concentration of 3.5 × 10⁸ conidia mL⁻¹ and donor ratio of 50%. The mortality of recipient workers was less than 20% at all concentrations at a donor ratio of 10%. Our observations indicate social behavior of M. diversus, such as grooming, can be effective in promoting epizootic outbreaks in a colony. While the current results suggest good potential for efficacy, the use of M. anisopliae as a component of integrated pest management of M. diversus still needs to be proven under field conditions.

Interactions between Entomopathogenic Fungus, Metarhizium anisopliae and Sublethal Doses of Spinosad for Control of House Fly, Musca domestica

BACKGROUND

Metarhizium anisopliae strain IRAN 437C is one of the most virulent fungal isolates against house fly, Musca domestica. The objective of this study was to determine the interaction of this isolate with sublethal doses of spinosad against housefly.

METHODS

In adult bioassay, conidia of entomopathogenic fungus were applied as inoculated bait at 10(5) and 10(7) spore per gram and spinosad at 0.5, 1 and 1.5 μg (A.I.) per gram bait. In larval bioassay, conidia were applied as combination of spore with larval bedding at 10(6) and 10(8) spore per gram and spinosad at sublethals of 0.002, 0.004 and 0.006 μg (AI) per gram medium.

RESULTS

Adult mortality was 48% and 72% for fungus alone but ranged from 66-87% and 89-95% in combination treatments of 10(5) and 10(7) spore/g with sublethal doses of spinosad respectively. The interaction between 10(5) spore/g with sublethals exhibited synergistic effect, but in combination of 10(7) spore in spite of higher mortality, the interaction was additive. There was significant difference in LT(50) among various treatments. LT(50) values in all combination treatments were smaller than LT(50) values in alone ones. Larval mortality was 36% and 69% for fungus alone but ranged from 58%-78% and 81%-100% in combination treatments of 10(6) and 10(8) spore/g medium with sublethals of spinosad respectively. The interaction was synergistic in all combination treatments of larvae.

CONCLUSION

The interaction between M. anispliae and spinosad indicated a synergetic effect that increased the house fly mortality as well as reduced the lethal time.