RESUMEN

Musca domestica L. (Muscidae: Diptera) is a human and livestock pest especially in tropical and sub-tropical areas. Different insecticides have been used to control this pest that pose serious harmful effects on humans and the environment. The current study was planned to investigate the effects of two concentrations (LC25 and LC50) of pyriproxyfen on biological and population parameters of a field strain of M. domestica. The exposed parents (F0) and their progeny (F1) were studied to examine the transgenerational effects. The results indicated that preadult duration was higher in control (13.68 days) compared to LC50 treated individuals (12.44 days). The male and female longevity was relatively lower in the LC25 treated population i.e. 24.62 and 26.62 days, respectively. The adult pre-oviposition period (APOP) and total pre-oviposition period (TPOP) values were higher in the LC25 treated individuals than those of control. Moreover, oviposition days and fecundity were reduced in the treated individuals as compared to the control treatment. A gradual decrease in the net reproductive rate (R0) was observed (8.46-14.07 per day) while the value of R0 was significantly higher in control. The results suggested that pyriproxyfen can be effectively utilized and incorporated in the management programs of M. domestica.

Asunto(s)

RESUMEN

Musca domestica Linnaeus is a devastating insect pest of medical and veterinary importance with reports of resistance development to commonly used insecticides worldwide. Rearing substrates usually play a crucial role in determining susceptibility to insecticides and control of insect pests. The aim of the present study was to investigate the effect of five rearing substrates of M. domestica on its susceptibility to different insecticides and activities of metabolic enzymes. After 30 generations of rearing, susceptibility of M. domestica to tested insecticides, viz., malathion, pirimiphos-methyl, alpha-cypermethrin, deltamethrin, methomyl, propoxur, spinetoram, and chlorfenapyr had evident differences. Musca domestica reared on hen liver exhibited reduced susceptibility to all insecticides followed by the strain reared on poultry manure. However, M. domestica reared on milk-based diet showed the highest susceptibility to tested insecticides followed by the strain reared on manures of buffalo and horse. In addition, M. domestica reared on different substrates exhibited significant differences (p < 0.01) in the activities of glutathione S-transferase (GST), cytochrome P450-dependent monooxygenase, and carboxylesterase (CarE). Overall, hen liver and poultry manure strains exhibited higher activities of metabolic enzymes than those of the milk-based diet, buffalo, and horse manure strains. In conclusion, the data of the present study exhibited a significant effect of rearing substrates on the susceptibility to insecticides and activities of metabolic enzymes in M. domestica. These results could be helpful for the sustainable management of M. domestica on different hosts by selecting appropriate insecticides.

Asunto(s)

RESUMEN

The use of insecticides in agricultural settings often exerts negative effects on nontarget species. Methomyl, a broad-spectrum carbamate insecticide, is recommended to manage a number of insect pests of the cotton crop. Recently, Musca domestica, which is a nontarget insect species in cotton fields, has shown resistance to methomyl in Pakistan. The present study tried to assess resistance-risk assessment, rapidity of resistance development to methomyl, cross-resistance potential to other insecticides, resistance heritability and to forecast the projected rate of resistance development under field conditions. For this purpose, a field strain of M. domestica with 186 fold resistance to methomyl was re-selected in the laboratory for eight consecutive generations. Consequently, LD50 values increased rapidly (126.64 ng/fly to 3112.79 ng/fly) compared to those before selection experiments. Similarly, RR values increased from 186 to 3113 fold as a result of the selection process. However, resistance to methomyl did not remain stable when the selected strain (Meth-SEL) reared for the next five generations in a pesticide free environment. The Meth-SEL strain also developed cross-resistance to permethrin. The realized heritability (h2) value for the Meth-SEL strain was 0.39 with 27% average mortality of M. domestica. Assuming the standard deviation (σp) value 0.27 and the h2 value 0.39 for eight generations of continuous exposure to methomyl, then five, seven, eight, ten and twelve generations at 90, 80, 70, 60 and 50% selection intensity, respectively, would be required for a tenfold increase in the LD50 value of methomyl. In conclusion, the Meth-SEL strain of M. domestica exhibited a high risk of resistance development to methomyl under continuous selection pressure. Resistance increased rapidly during selection experiments that reflect the probability of resistance development under field conditions if M. domestica receive exposures to methomyl during its applications for the management of target pest species.

Asunto(s)

RESUMEN

Resistance to permethrin has been reported in Pakistani strains of Musca domestica. The present study explored the performance of biological traits and analyzed life tables to determine whether there is any detrimental effect of permethrin resistance on the fitness of permethrin-resistant strains [an isogenic resistant strain (Perm-R) and a field strain (Perm-F)] compared to a susceptible strain (Perm-S). Perm-R and Perm-F exhibited 233.93- and 6.87-fold resistance to permethrin, respectively. Life table analyses revealed that the Perm-R strain had a significantly shorter preadult duration, longer longevity, shorter preoviposition period, higher fecundity, finite rate of increase, intrinsic rate of increase, net reproductive rate and a shorter mean generation time, followed by the Perm-F strain when compared to the Perm-S strain. Data of the performance of biological traits reveled that permethrin resistance strains had a better fit than that of the Perm-S strain. The enhanced fitness of resistant strains of M. domestica may accelerate resistance development to permethrin and other pyrethroids in Pakistan. Some possible measures to manage M. domestica and permethrin resistance in situations of fitness advantage are discussed.

Asunto(s)

RESUMEN

Due to ongoing human activities, heavy metals are heavily accumulated in the soil. This leads to an increase in the discharge and the quick spread of heavy metal pollution in human settlements and natural habitats, having a disastrous effect on agricultural products. The current experiment was planned to evaluate the effect of lead-tolerant-plant-growth-promoting rhizobacteria (LTPGPR) on growth, yield, antioxidant activities, physiology, and lead uptake in the root, shoot, and seed of Indian mustard (Brassica juncea) in lead-amended soil. Three pre-isolated well-characterized lead-tolerant rhizobacterial strains-S10, S5, and S2-were used to inoculate seeds of Indian mustard grown at three different levels of lead (300 mg kg-1, 600 mg kg-1, 900 mg kg-1) contaminated soil. The experiment was designed following a completely randomized design (CRD) under factorial arrangements. Lead nitrate was used as a source of lead contamination. At harvesting, data regarding growth, physiology, yield per plant, antioxidant activities, malondialdehyde and proline content, and lead uptake in the root, shoot, and seed of Indian mustard were recorded. Results demonstrated that lead contamination at all levels significantly reduced the plant growth, yield, and physiological processes. Plants inoculated with lead-tolerant rhizobacteria showed a significant improvement in plant growth, yield, antioxidant activities, and physiological attributes and cause a valuable reduction in the malondialdehyde contents of Indian mustard in lead-contaminated soil. Moreover, plants inoculated with lead-tolerant rhizobacteria also showed an increment in lead uptake in the vegetative parts and a significant reduction of lead contents in the seed of Indian mustard.

RESUMEN

Chitinase-producing fungi have now engrossed attention as one of the potential agents for the control of insect pests. Entomopathogenic fungi are used in different regions of the world to control economically important insects. However, the role of fungal chitinases are not well studied in their infection mechanism to insects. In this study, Chitinase of entomopathogenic fungi Trichoderma longibrachiatum was evaluated to control Aphis gossypii. For this purpose, fungal chitinase (Chit1) gene from the genomic DNA of T. longibrachiatum were isolated, amplified and characterised. Genomic analysis of the amplified Chit1 showed that this gene has homology to family 18 of glycosyl hydrolyses. Further, Chit1 was expressed in the cotton plant for transient expression through the Geminivirus-mediated gene silencing vector derived from Cotton Leaf Crumple Virus (CLCrV). Transformed cotton plants showed greater chitinase activity than control, and they were resistant against nymphs and adults of A. gossypii. About 38.75% and 21.67% mortality of both nymphs and adults, respectively, were observed by using Chit1 of T. longibrachiatum. It is concluded that T. longibrachiatum showed promising results in controlling aphids by producing fungal chitinase in cotton plants and could be used as an effective method in the future.

Asunto(s)

RESUMEN

Insecticides are an integral part of most of the cropping systems worldwide; however, these usually exert negative impact on the environment and non-target insects as well. Non-target insects are prone to develop resistance to insecticides due to prolonged and repeated lethal and sublethal exposures. Musca domestica is a common non-target, pollinator and nectar feeder species in cotton ecosystem, besides its status as a public health pest in human habitations. In the present work, resistance to methomyl, one of the major insecticides used for cotton pest management, was assessed in 20 M. domestica strains from the major cotton producing areas of the Punjab and Sindh provinces of Pakistan. The results revealed that toxicity values of methomyl for Punjabi and Sindhi strains ranged from 28.07 to 136.16 µg fly-1 and 29.32 to 136.87 µg fly-1, respectively. Among Punjabi strains, D.G. Khan, Lodhran, Bahawalpur, Toba Tek Singh, Bahawalnagar, Rajanpur and Jhang strains exhibited very high levels of resistance (RR > 100) to methomyl; Bhakkar, Kasur, Vehari, Layyah, Muzaffargarh and R.Y. Khan showed high resistance (RR = 51-100 fold), while the Mianwali strain showed a moderate level of resistance to methomyl (RR = 36.45 fold). In case of Sindhi strains, very high levels of resistance (> 100 fold) were reported for Sukkar and Sanghar strains, high levels of resistance (RR 51-100 fold) for Khairpur, Jamshoro and Ghotki, and moderate resistance to methomyl (38.08 fold) in the Dadu strain. There was a significant synergism of methomyl toxicity in all field strains when methomyl bioassayed along with piperonyl butoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) providing clues of metabolic-based mechanisms of resistance to methomyl. In conclusion, insecticides used in crop farming can cause resistance development in non-target M. domestica. It is necessary to adopt the pest management activities that are safe for the environment and non-target insect species.

Asunto(s)

RESUMEN

Indiscriminate use of insecticides in food storage facilities for controlling insect pests has deleterious effects on the environment and non-targeted organisms in the premises. Continuous use of insecticides may result in resistance development in insect pests, which compel the stakeholders to increase the dosage of insecticides to manage resistant insect pests. The increased dosage of insecticides ultimately may result in contamination of stored food stuff that affects human health. The present study was planned to generate data that will be helpful to delay resistance development and to reduce environmental pollution. A field strain of Sitophilus oryzae, one of the most common insect pests of stored foodstuff, was selected separately with pirimiphos-methyl, permethrin, or spinosad for five consecutive generations. The selected strains were studied for resistance risk assessment, time taken to develop resistance to insecticides after continuous exposure in the selection process, preliminary mechanism of resistance, and whether the development of resistance due to the selection with a particular insecticide could develop cross-resistance to other insecticide or not. In comparison to a laboratory susceptible reference strain, the insecticide-selected strains revealed rapid development of resistance against insecticides as a result of selection process: 31.05-fold resistance to pirimiphos-methyl, 156.49-fold resistance to permethrin, and 65.6-fold resistance to spinosad. The selected strains did not show cross-resistance to insecticides to with these strains were not exposed during selection experiments, i.e., strain selected with pirimiphos-methyl did not show cross-resistance to spinosad and permethrin. In the synergism bioassays, the synergists (S,S,S-tributyl phosphorotrithioate and piperonyl butoxide) significantly reduced resistance of the selected strain against insecticides to with these were selected, revealing the probability of metabolic mechanism of resistance. The present study revealed high risks of resistance development to pirimiphos-methyl, spinosad, and permethrin under consistent selection pressure. Lack of cross-resistance among insecticides provides an opportunity to use insecticides in rotation instead of increasing dosages to manage resistant insects that will ultimately pollute the environment.

Asunto(s)

RESUMEN

Cyromazine is a triazine insect growth regulator insecticide that is recommended for control of Musca domestica worldwide. Cyromazine is highly effective in causing mortality of M. domestica; however, some aspects of its lethal and sublethal effects on the biology of M. domestica are still unknown. The present study explored lethal and sublethal effects on several biological traits and population parameters of M. domestica. Concentration-response bioassays of cyromazine against third-instar larvae of M. domestica exhibited sublethal and lethal effects from concentrations of 0.03 (LC10), 0.06 (LC25), and 0.14 (LC50) µg/g of a larval medium. Exposure of M. domestica larvae to these concentrations resulted in reduced fecundity, survival, longevity and oviposition period, and delayed development of immature stages (i.e., egg hatch time and larval and pupal durations) in the upcoming generation of M. domestica. The values of population parameters such as intrinsic rate of increase, finite rate of increase, net reproductive rate, age-specific survival rate and fecundity, and age-stage life expectancy and reproductive value, analyzed using the age-stage and two-sex life table theory, were significantly reduced in a concentration-dependent manner in comparison with the control group. In conclusion, the study highlights the significant effects of cyromazine on the biology of M. domestica that could help suppress its population in cases of severe infestations.

RESUMEN

Insecticidal control of insect pests of rice crop may influence the environment and nontarget species in rice fields. Aedes albopictus, one of the most common nontarget species present in rice fields, received lethal and sublethal exposures to insecticides used in rice cultivated fields. The present work explores the effects of insecticides in six non-targeted Ae. albopictus strains collected from rice fields with a history of insecticidal usage in comparison with a laboratory susceptible reference strain (REF) and a strain (LHR) collected from a rice field with no, or minimal, history of insecticidal usage. Two types of effects, the resistance development and performance of biological traits, were studied by selecting seven commonly used insecticides in rice fields in Punjab, Pakistan. The results revealed that the strains collected from the rice fields with histories of insecticidal usage exhibited significant levels of resistance to flonicamid, chlorantraniliprole, gamma-cyhalothrin, fipronil, monomehypo, triazophos, and carbofuran, when compared with REF and LHR strains. In addition, Ae. albopictus strains revealed a significantly weaker performance of biological traits (rate of pupae formation, survival of male and female adults (except females of OKR and MTN strains), and ovipositing females) than those of the REF and LHR strains. However, the fecundity of all field strains was only significantly different with that of the REF strain. In conclusion, the results highlight the problem of the negative effects of insecticidal usage in rice fields on nontarget species present in the same environment, and emphasize the need to adopt pest management activities that are safe for the environment.

Asunto(s)

RESUMEN

The widespread use of insecticides for the management of insect pests in storage facilities and food industries have caused insecticide resistance a frequent issue worldwide. Nonetheless, this issue has been little explored in Pakistan that resulted in control failures and increased dosage of insecticides. In the present study, insecticide resistance to chlorpyrifos-methyl, pirimiphos-methyl, permethrin and spinosad was surveyed in five field strains of Sitophilus oryzae: FSD-SO, GJR-SO, DGK-SO, MTN-SO and BWP-SO, collected from five different localities of Punjab, Pakistan, and contrasted with an insecticide susceptible reference strain (Lab-SO). Dose-mortality bioassays were performed in glass vials containing insecticide-treated rice grains, and lethal doses (LD50 and LD95) were calculated and compared using the ratio tests. In comparison to the Lab-SO strain at LD50 and LD95 levels, field strains exhibited: 24.51 to 52.80 and 36.55 to 69.31 resistance ratios (RRs), respectively, for chlorpyrifos-methyl; 15.89 to 45.97 and 55.12 to 194.93 RRs, respectively, for pirimiphos-methyl; 39.76 to 108.61 and 61.33 to 130.12 RRs, respectively, for permethrin; 4.23 to 27.50 and 6.28 to 41.00 RRs, respectively, for spinosad. In the synergism experiments using the Lab-SO and the most resistant strains against each insecticide, the enzyme inhibitors (PBO and DEF) failed to synergize toxicity of insecticides in the Lab-SO strain; however, toxicity of chlorpyrifos-methyl, pirimiphos-methyl and permethrin significantly enhanced in the resistant strains of S. oryzae, suggesting possibility of metabolic mechanism of resistance. In addition, activities of detoxification enzymes (CarE, MFO and GST) were significantly higher in resistant strains compared to the Lab-SO strain. The results revealed presence of insecticide resistance in field strains of S. oryzae that necessitate the need to develop a resistance management strategy.

Asunto(s)

RESUMEN

BACKGROUND: Indiscriminate use of broad-spectrum insecticides can have deleterious effects on insects and the environment. The use of nanoparticles synthesized from microbes has recently gained importance as a safe alternative to conventional insecticides. Recently, zinc oxide (ZnO) nanoparticles synthesized using Bacillus thuringiensis have shown insecticidal potential; however, in addition to its acute toxicity, it is necessary to determine possible sublethal effects at the organismal level to understand the toxicity of a new insecticide. Bt-derived enzymes such as nitrate reductase and other biomolecules play a vital role in the reduction of metal ions to metal nanoparticles. Here, we assessed the acute toxicity and sublethal effects of ZnO nanoparticles produced in the culture supernatant of B. thuringiensis ser. israelensis (Bti) as a reducing agent on the biological traits of Musca domestica. RESULTS: Concentration-response larval bioassays using different concentrations of ZnO-Bti-supernatant nanoparticles revealed LC10 , LC20 , LC50 and LC90 values of 4.17, 6.11, 12.73 and 38.90 µg g-1 of larval diet, respectively. Exposure of M. domestica larvae to two concentrations (LC10 and LC20 ) resulted in a lengthened developmental time (egg to adult) and preoviposition period, and reduced fecundity, survival, longevity and oviposition period. Furthermore, population parameters including net reproductive rate, mean generation time, age-specific survival rate, fecundity, life expectancy and reproductive values, analyzed following age-stage and two-sex life table theory, were significantly decreased after exposure to these concentrations of ZnO-Bti-supernatant nanoparticles compared with the control. CONCLUSION: ZnO-Bti-supernatant nanoparticles were shown to be toxic to M. domestica. Exposure of M. domestica to low concentrations of ZnO-Bti-supernatant nanoparticles resulted in negative transgenerational effects on progeny production in this fly. © 2022 Society of Chemical Industry.

Asunto(s)

RESUMEN

Musca domestica is a global insect-pest of human beings and animal agriculture. Pyriproxyfen, a juvenile hormone analog, has shown its potential for effective management of M. domestica. However, lethal and sublethal effects of pyriproxyfen on biological traits and demographic growth parameters of M. domestica are still unknown. The present study investigated the effects of lethal and sublethal concentrations on different biological traits of M. domestica for two generations i.e., exposed parents (F0) and their offspring (F1). Concentration-response bioassays revealed that concentrations of pyriproxyfen that caused 50% (LC50), 25% (LC25), 10% (LC10) and 2% (LC2) mortality of M. domestica were estimated as 0.12, 0.06, 0.03 and 0.01 µg/g, respectively. In the F0 generation, exposure of 3rd instar larvae to these concentrations resulted in a reduced pupation rate, lengthened pupal stage duration, light weight pupae and reduction in adult emergence in a concentration-dependent manner. In the case of F1 generation, similar trend was observed for pupation rate, pupal stage duration, and total developmental period (i.e., egg to adult); however, pupal weight was affected at LC10, LC25, LC50 levels, and adult emergence at only LC25 and LC50 levels. The values of demographic growth parameters, analyzed through age-stage, two-sex life table theory, were significantly decreased at all the levels of pyriproxyfen compared with control. This study highlights that pyriproxyfen has the potential to suppress the population of M. domestica through its lethal and sublethal effects and presents an empirical basis from which to consider management decisions for chemical control in the field.

Asunto(s)

RESUMEN

Musca domestica is one of the major cosmopolitan pests in livestock facilities because it can be both a nuisance and a vector of pathogens to animals. Currently, treatment of animal manure with insect growth regulator (IGR) insecticides is among major practices to control M. domestica throughout the year over wide-ranging environmental temperatures. Fluctuation in daily or seasonal temperature is one of the most established factors impacting toxicity of insecticides against insect pests. In this study, the effect of posttreatment temperature (range, 20-36 °C) on the toxicity of eight IGRs: five chitin synthesis inhibitors (cyromazine, diflubenzuron, lufenuron, novaluron, triflumuron), two juvenile hormone analogs (methoprene, pyriproxyfen), and one ecdysone agonist (methoxyfenozide), was investigated against M. domestica. The toxicity of lufenuron and novaluron increased by 1.78 times over the range of 20-28 °C, and 2.25 and 1.83 times, respectively, over the range of 28-36 °C, with an overall increase by 4.00 and 3.26 times, respectively (i.e., positive temperature coefficient). In contrast, the toxicity of diflubenzuron, pyriproxyfen, and triflumuron decreased by 1.43, 1.89, and 2.10 times, respectively, over the range of 20-28 °C, and 1.70, 2.00, and 1.95 times, respectively, over the range of 28-36 °C, with an overall decrease by 2.43, 3.78, and 4.10 times, respectively. The toxicity of cyromazine, methoprene, and methoxyfenozide did not change significantly. Overall, these data will help stakeholders to choose appropriate insecticides for M. domestica control depending on the prevailing environmental temperature and to avoid misuse of insecticides that ultimately lead to environmental safety.

Asunto(s)

RESUMEN

BACKGROUND: Permethrin has been used frequently in the control of Musca domestica worldwide including Pakistan, with reports of resistance development in different field strains. A near-isogenic line of M. domestica with permethrin resistance (Perm-R) was constructed to elucidate mode of inheritance and cross-resistance analyses. RESULTS: Toxicity responses of reciprocal progenies F1 and F1' showed no significant difference in median lethal dose (LD50 ) values, suggesting that permethrin resistance was inherited in an autosomal fashion with neither sex linkage nor maternal effects in the Perm-R strain of M. domestica. Degree of dominance was 0.6 and 0.7 for F1 and F1' progenies, respectively, which suggests that permethrin resistance was expressed as an incompletely dominant trait. Chi-square analyses for self-bred (F2), and backcross progenies (BC1, BC2, BC3 and BC4) revealed significant differences between the observed and expected mortality, indicating the possibility of multiple genes responsible for permethrin resistance. Moreover, the Perm-R strain did not show cross-resistance to propoxur, chlorpyrifos, profenofos or spinetoram. CONCLUSION: Permethrin resistance in the Perm-R strain of M. domestica was inherited as autosomal, incompletely dominant and governed by more than one gene. Lack of cross-resistance between permethrin and propoxur, chlorpyrifos, profenofos or spinetoram provides an opportunity for rotational use of these insecticides in the control of M. domestica. These data could help to manage M. domestica and the problem of permethrin resistance.

Asunto(s)

RESUMEN

The widespread use of insecticides has ecological consequences such as emergence of insecticide resistance and environmental pollution. Aedes albopictus is a major vector of dengue virus in the Punjab province, Pakistan. Control of Ae. albopictus with insecticides along with source eradication is critical in the prevention and control of dengue fever but is threatened by the development of insecticide resistance. Here, field strains of Ae. albopictus from eight cities of Punjab were evaluated for resistance against temephos, deltamethrin and permethrin. For temephos, high resistance (RRLC50 > tenfold) was found in larvae of the Rawalpindi strain, moderate resistance (RRLC50 = five- to tenfold) in Multan, Faisalabad, Sialkot, Lahore and Sheikhupura strains, and low resistance (RRLC50 < fivefold) in Kasur and Sahiwal strains. In the case of deltamethrin, high resistance was seen in adults of the strain from Faisalabad, moderate resistance in the strains from Sialkot, Sheikhupura, Lahore and Kasur, and low resistance in Sahiwal, Multan and Rawalpindi strains. For permethrin, adults of all the field strains exhibited high levels of resistance. In synergism bioassays, toxicity of all the insecticides in the field strains significantly enhanced when tested in combination with piperonyl butoxide or S,S,S-tributylphosphorotrithioate, suggesting the probability of metabolic-based mechanisms of resistance. In conclusion, field strains of Ae. albopictus from Punjab exhibit resistance to temephos, deltamethrin and permethrin, which might be associated with metabolic mechanisms of resistance.

Asunto(s)

RESUMEN

Resistance to commonly used grain protectants and fumigants in stored product insect pests necessitates the need to explore alternative substances. Indoxacarb is a reduced-risk oxadiazine insecticide that is generally used in field crops, but there are limited reports of its susceptibility in stored insect pests. The objective of this study was to determine susceptibility to indoxacarb in laboratory and field strains of five major stored product insects: Rhyzopertha dominica (Fabricius), Sitophilus zeamais (Motschulsky), S. oryzae (Linnaeus), Tribolium castaneum (Herbst), and Oryzaephilus surinamensis (L.), using dose-mortality bioassays on wheat grains. In most of the cases, the susceptibility of laboratory strains of all the studied pests were significantly higher than the corresponding field strains. The LD50 and LD99 values (mg a.i./kg of grains) of field strains ranged from 0.13 to 0.38, and 3.44 to 24.76, respectively (for R. dominica), 0.26 to 0.55, and 5.26 to 19.37, respectively (for S. oryzae), 0.41 to 1.01, and 13.11 to 22.46, respectively (for S. zeamais), 0.67 to 1.37, and 15.43 to 43.44, respectively (for T. castaneum), and 0.52 to 0.92, and 18.06 to 61.63, respectively (for O. surinamensis). Synergism bioassays implementing piperonyl butoxide or S,S,S-tributyl phosphorotrithioate along with indoxacarb on selected field strains revealed enhanced susceptibility to indoxacarb. The study demonstrates relative susceptibility to indoxacarb in major stored product insects. Synergism results support the probability of metabolic-based mechanisms responsible for mitigating indoxacarb toxicity. The results might be helpful for monitoring future variation in susceptibility to indoxacarb in the selected insect species and for setting field rates.

Asunto(s)

RESUMEN

Insecticidal usage in the rice farming system may affect non-target insect species present in the same fields. Musca domestica, a well-known pest of medical and veterinary importance worldwide, is one of the important non-target insect species present in the rice farming system. In this study, five strains of M. domestica were exclusively collected from rice fields in major rice cultivated areas of Punjab, Pakistan, and evaluated for the presence of insecticide resistance against nine commonly used insecticides in the rice farming system. Moreover, the performance of life-history traits was also studied. Compared with a Lab-susceptible reference strain of M. domestica, all the field strains exhibited moderate levels of resistance to carbofuran (RRs = 27.96-46.00 fold) and cartap hydrochloride (RRs = 31.48-48.21 fold), low to moderate levels of resistance to gamma-cyhalothrin (RRs = 19.00-43.00 fold), chlorantraniliprole (RRs = 11.90-27.10 fold), monomehypo (RRs = 14.38-25.84 fold), and fipronil (RRs = 13.23-40.15 fold), low levels of resistance to triazophos (RRs = 11.13-19.83 fold), and very low to low levels of resistance (RRs = 7.83-13.28 fold) to flonicamid. The performance of life-history traits (developmental time, adult eclosion rate, fecundity, egg hatch rate, and longevity of adults) of field strains was weaker as compared with that of the Lab-susceptible strain. These results contribute to the growing knowledge on the effects of insecticidal usage in agriculture on non-target invertebrates, and necessitate the need to explore alternate insecticides that can effectively control insect pests but safe for non-target organisms.

Asunto(s)

RESUMEN

A Musca domestica L. strain collected from Pakistan has recently been shown to be resistant to spinosad; however, there is scarce information about the mechanism of resistance. For this reason, we explored whether a metabolic-based mechanism was responsible by analyzing the activities of the metabolic detoxifying enzymes, carboxylesterases, glutathione S-transferases, and mixed-function oxidases, in both a spinosad-selected (Spin-SEL) strain of M. domestica and a susceptible counterpart (Lab-susceptible). The results revealed that both strains were statistically at par in terms of enzyme activities. The activity of carboxylesterases in the Lab-susceptible strain was 78.17 ± 3.06 in comparison to 79.16 ± 3.31 nmol min-1 mg-1 in the Spin-SEL strain. The activity of mixed-function oxidases was 51.58 ± 4.20 in the Lab-susceptible strain, whereas 54.33 ± 4.08 pmol min-1 mg-1 was recorded in the Spin-SEL strain. The activity of glutathione S-transferases was 86.50 ± 4.59 (Lab-susceptible) and 90.33 ± 2.81 nmol min-1 mg-1 (Spin-SEL). These results revealed that the studied enzymes might not be responsible for spinosad resistance in the studied strain of M. domestica. Therefore, studies should be extended to find out other possible mechanisms of spinosad resistance.

Asunto(s)

RESUMEN

Musca domestica Linnaeus is an important public health pest with the ability to adapt to diverse climates. Assessment of variations in biology and life-history traits of insects along geographical gradients is important for a successful management plan in different regions. We investigated life-history traits and life table parameters of M. domestica from six different geographical regions of Punjab, Pakistan: Rahim Yar Khan (RYK), Bahawalpur (BWP), Multan (MTN), Lahore (LHR), Gujrat (GJT), and Murree (MRE). Overall, M. domestica from localities of lower latitude and elevations with higher mean temperatures completed their development faster than those from localities of higher latitude and elevations with lower mean temperatures. The immature developmental time was the longest for the MRE population that was collected from higher latitude and elevation with cooler climate, whereas the shortest for the RYK population from lower latitude with warmer climate. Pupal weights were heavier for the RYK, BWP, and MTN populations, all were from the lowest latitude and elevations with warmer climate, compared with rest of the field populations. Similarly, rate of adult eclosion, fecundity, egg hatching, longevity, and life table parameters such as intrinsic rate of population increase, mean relative growth rate, net reproductive rate, and biotic potential were significantly higher for the RYK, BWP, and MTN populations compared with the GJT, LHR, and MRE populations of M. domestica. The current results will probably be of importance when planning management of M. domestica in different geographical regions of Pakistan.

Asunto(s)