Misuse Of Insecticides Research Articles

Trends in poisoning associated with the use of insecticides for bed bug infestations: a 20-year retrospective study in France

Bed bugs are pervasive global pests that have reemerged in the last 20 years as a significant public health concern, especially in densely populated urban areas. Beyond financial losses, expenses, inconvenience, and psychological distress, bed bug infestations often necessitate chemical management, posing poisoning risks to those with an infestation. The French Poison Control Centers recorded 1056 cases of exposure to bed bug insecticide products between 1999 and 2021. This study followed cases over 2007–2021, with a notable surge in reports of adverse reactions from 2016 onwards. Data revealed an increased recurrent misuse of insecticides, including substances banned or not approved for this use. Our findings underscore the growing public reliance on chemical insecticides for home bed bug management. With this is the concern of increased poisoning risks, and potential long-term health consequences from non-professional efforts by the public to manage bed bugs in their homes. This escalating trend emphasizes the need for safer and more sustainable pest management strategies in urban environments.

Isolation, characterization and functional analysis of a bacteriophage targeting Culex pipiens pallens resistance-associated Aeromonas hydrophila

BackgroundCulex pipiens pallens is a well-known mosquito vector for several diseases. Deltamethrin, a commonly used pyrethroid insecticide, has been frequently applied to manage adult Cx. pipiens pallens. However, mosquitoes can develop resistance to these insecticides as a result of insecticide misuse and, therefore, it is crucial to identify novel methods to control insecticide resistance. The relationship between commensal bacteria and vector resistance has been recently recognized. Bacteriophages (= phages) are effective tools by which to control insect commensal bacteria, but there have as yet been no studies using phages on adult mosquitoes. In this study, we isolated an Aeromonas phage vB AhM-LH that specifically targets resistance-associated symbiotic bacteria in mosquitoes. We investigated the impact of Aeromonas phage vB AhM-LH in an abundance of Aeromonas hydrophila in the gut of Cx. pipiens pallens and its effect on the status of deltamethrin resistance.MethodsPhages were isolated on double-layer agar plates and their biological properties analyzed. Phage morphology was observed by transmission electron microscopy (TEM) after negative staining. The phage was then introduced into the mosquito intestines via oral feeding. The inhibitory effect of Aeromonas phage vB AhM-LH on Aeromonas hydrophila in mosquito intestines was assessed through quantitative real-time PCR analysis. Deltamethrin resistance of mosquitoes was assessed using WHO bottle bioassays.ResultsAn Aeromonas phage vB AhM-LH was isolated from sewage and identified as belonging to the Myoviridae family in the order Caudovirales using TEM. Based on biological characteristics analysis and in vitro antibacterial experiments, Aeromonas phage vB AhM-LH was observed to exhibit excellent stability and effective bactericidal activity. Sequencing revealed that the Aeromonas phage vB AhM-LH genome comprises 43,663 bp (51.6% CG content) with 81 predicted open reading frames. No integrase-related gene was detected in the vB AH-LH genome, which marked it as a potential biological antibacterial. Finally, we found that Aeromonas phage vB AhM-LH could significantly reduce deltamethrin resistance in Cx. pipiens pallens, in both the laboratory and field settings, by decreasing the abundance of Aeromonas hydrophila in their midgut.ConclusionsOur findings demonstrate that Aeromonas phage vB AhM-LH could effectively modulate commensal bacteria Aeromonas hydrophila in adult mosquitoes, thus representing a promising strategy to mitigate mosquito vector resistance.Graphical

Identification of an Entomopathogenic Fungus, Pseudozyma flocculosa (Traquair, Shaw & Jarvis), and Its Efficacy against Tetranychus urticae Koch

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most important agricultural pests worldwide, with chemical application being the primary control method. However, frequent heavy use or misuse of insecticides has accelerated the development of varying degrees of resistance in T. urticae. This makes the chemical control of this mite more challenging. Biocontrol methods have attracted much attention due to their safety and environment-friendly impact. Based on previous observations that the population of T. urticae was infected by unknown pathogenic fungi, we isolated, identified, and evaluated the pathogenicity of the fungi from infected mites. Through available morphological and molecular identification, the fungus was identified as Pseudozyma flocculosa. The virulence activity of the strain was evaluated at different concentrations of spore suspension (106–109 conidia/mL) using a spraying method. The strain showed pathogenic activity against the T. urticae in adult females that varied with different concentrations and temperatures. Meanwhile, the P. flocculosa also had a significant toxic effect on the developmental stages of T. urticae. In the laboratory bioassay, the mortality rate of the tested mites reached 100% at 9 d after P. flocculosa treatment. Additionally, a wettable powder processed with P. flocculosa conidia was applied on the T. urticae in the greenhouse and the control efficacy reached up to 90% at 7 d after treatment. The results showed a high insecticidal activity of P. flocculosa against T. urticae, indicating that this fungus possesses great potential for use as a bio-insecticidal agent.

Advances in CRISPR/Cas9-Based Gene Editing Technology in Mosquitoes

As global warming increases, mosquito activity areas are expanding, alongside changes in the natural environment and the misuse of insecticides, thus further increasing mosquito resistance and exposing the world to an elevated risk of mosquito-borne diseases. With advancements in gene editing technology, researchers are continually attempting to modify various mosquito genes and validate their functional roles with CRISPR-Cas9 technology. Here, we review recent applications of CRISPR-Cas9-based gene editing technology in mosquito-borne disease prevention and control, as well as mosquito population suppression, phenotyping, and resistance. We further discuss the development of new techniques, such as ReMOT Control and DIPA-CRISPR, which differ from conventional embryo microinjection and should be expanded in future insect gene editing research.

An overview of insecticide usage and resistance of insect vector to insecticide: An implication to public health

Insecticides are highly effective when optimally implemented and crop damage from insect pest infestations and diseases transmitted by insect vectors often result in serious consequences, warranting the need to use insecticides. The main strategy for the elimination of insect vectors is the use of chemical insecticides. Since its discovery, chemical insecticides have represented the most widely method used to control insect vectors and insect pests. The use of insecticides has helped to reduce insect-borne diseases. However, despite their benefits, insecticides pose potential danger to public health when inappropriately handled. Almost all public health insecticide classes and nearly 90% of all insecticides worldwide are used for agricultural purposes. The insecticide resistance development in disease vectors are as a result of selection pressure due to agrochemicals and this occur in places where pesticides are more frequently applied, indiscriminately used and misused. Despite increasing concern about overuse and misuse of insecticides in developing countries, insecticide is still intensively used and the massive use of these chemicals have caused detrimental effects on the agroecosystem, such as the acquisition of resistance, pest resurgence/replacement, and environmental pollution. Insecticide resistance may increase insect’s vectorial capacity, which may lead to a dramatic increase in the transmission of the disease and even to a higher prevalence than in the absence of insecticides. Disease control failure, however follow from vector control failure. Increase in diseases transmission, mortality, injury to the crop and potential losses in crop production, disruption of biological control programmes and increase in management costs for additional chemical controls to prevent further injury are the consequences of insect resurgence, replacement and or resistance.

Transmission Effectivity of Rice Yellow Stunt Disease by Imidacloprid-Resistant and Susceptible Brown Plant Hopper

The brown plant hopper (BPH) is a major pest of rice and as a vector of Rice ragged stunt virus (RRSV) and Rice grassy stunt virus (RGSV). Curently, numerous rice yellow stunt disease symptoms are found in the field that caused by the single and simultaneous infection of these two viruses. Brown plant hopper population correlate with the incidence and severity of the disease. Misuse of insecticides, would cause of BPH resistances to imidacloprid. This study aimed to investigate the ability of BPH imidacloprid-resistant and susceptible to transmit of rice yellow stunt disease on rice plants. The variables tested were the acquisition period, inoculation period, number of infesting BPH, and lifespans of the viruliferous BPH that used in this research. Experiments were set as separated Completely Randomized Design with 10 replications for each treatment within an experiment. The results showed that both resistant and susceptible BPH to imidacloprid was able to transmit the virus to healthy plants. The acquisition and inoculation period test showed the BPH could transmit the virus with the shortest acquisition time for 30 minutes followed 24 hours of inoculation, as well as the acquisition time of 10 days with the shortest inoculation time for 30 minutes. Based on the incubation time, symptoms variation, and disease severity, susceptible BPH were more effective in transmitting rice yellow stunt disease than imidacloprid-resistant BPH. Single imidacloprid-resistant or susceptible BPH was proven able to transmit rice yellow stunt disease to healthy plants during its lifespan. Lifespans BPH viruliferous of imidacloprid-resistant were shorter than susceptible, which was 16 days for resistant BPH and 21 days for susceptible BPH.

Variation in susceptibility to insecticides and synergistic effect of enzyme inhibitors in Pakistani strains of Trogoderma granarium

Trogoderma granarium is an important quarantine insect pest of economic importance worldwide. Insecticides are heavily used against this pest that can reduce its susceptibility levels, and if left unchecked, this could lead to misuse of insecticides. Here, the susceptibility of five field strains of T. granarium in comparison to a reference strain (Lab-TG) was determined against pirimiphos-methyl, permethrin and spinosad using dose-mortality bioassays. Based on lethal dose (LD50 and LD99) values, the Lab-TG strain was the most susceptible to all the insecticides in comparison to the field strains. In the case of field strains, LD50 values varied from: 17.68–31.97 mg/kg for pirimiphos-methyl, 20.50–42.47 mg/kg for permethrin, and 1.34–5.00 mg/kg for spinosad. Whereas LD99 values for pirimiphos-methyl, permethrin and spinosad of field strains varied from 409.07 to 730.24 mg/kg, 374.24–949.48 mg/kg, and 11.41–72.25 mg/kg, respectively. The resistance ratios (RR) at LD50 and LD99 levels were in the range of 13.71–24.78 and 39.33–70.21 fold for pirimiphos-methyl; 13.49–27.94 and 37.31–94.66 fold for permethrin; 2.35–8.77 and 3.37–21.31 fold for spinosad, respectively. Considering the overall results, spinosad proved to be the most toxic insecticide to the laboratory and field strains of T. granarium when compared with toxicity of pirimiphos-methyl or permethrin. Insecticidal bioassays implementing enzyme inhibitors revealed no effect on synergizing the toxicity of all the insecticides in the Lab-TG strain; however, enzyme inhibitors significantly synergized toxicity of pirimiphos-methyl in all the field strain suggesting the major involvement of metabolic mechanism associated with pirimiphos-methyl resistance. The study demonstrates variation in susceptibility to insecticides in T. granarium strains. The results might be helpful for monitoring future variation in susceptibility to insecticides in T. granarium and for setting field rates.

Posttreatment temperature influences toxicity of insect growth regulators in Musca domestica.

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.

Dengue Vector Control: A Review for Wolbachia-Based Strategies

Mosquito-borne diseases continue to pose a major health problem globally and have had a significant impact on human life and economy. Consequently, many countries have implemented national vector control programs in an effort to suppress/eradicate mosquitos contributing to spread of diseases including Malaria, Dengue, Yellow fever, Rift valley fever, West Nile fever, Zika, Chikungunya etc. Of these endemic diseases, Dengue fever is an arbovirus and transmitted primarily by Aedes aegypti mosquito that has become a rapidly emerging infection, especially in the tropical countries. Insecticides spraying remains the main method to control the transmition of dengue virus. However, the overuse and misuse of insecticides can result in negative consequences such as the development of insecticides resistance. This, in part, has led to the development of a more eco-friendly measures to suppress mosquitoes e.g. gene-drive based controls and Wolbachia-based approaches. The latter approach has the ability to block the dengue virus transmission by inhibiting virus intracellular replication in mosquito. In addition, Wolbachia decreases adult mosquito lifespan and can be naturally passed from one generation to the next. In recent years, Aedes aegypti mosquitos infected with Wolbachia released and tested in the field in several countries and have achieved very promising results. In this review, we focus and discuss the emerging Wolbachia-based biocontrol approaches that are already being deployed, evaluated and tested in the field.

Effect of sublethal doses of some insecticides and their role on detoxication enzymes and protein-content of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

BackgroundThe indiscriminating and intensive use of insecticides to control the cotton leafworm (CLW), Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), usually induces high levels of resistance. The insecticides are the principal method for controlling this pest because of its critical role in reducing insects when the economic threshold (ETL); therefore, the effectiveness of these insecticides should be maintained. So, the target of the present work was directed to focus on studying the change in the activities of some important enzymes as a result of sublethal treatment concentrations (viz. LC25 values) of tested new insecticides (profenofos, cyfluthrin, emamectin benzoate, lufenuron, and spinetoram). The expected results could offer better understanding and more specific information about the resistance development in field populations of CLW because resistance is a significant challenge to pest control workers and these results may contribute to making the right decision at the right time.Materials and methodsBioassays were performed on fourth instar larvae of S. littoralis field populations compared with the laboratory strain to assess the activity of the emamectin benzoate, lufenuron, and spinetoram by LC25 and study the biochemical activities of some detoxification enzymes, like acetylcholinesterase (AChE), glutathione S-transferases (GST), alkaline phosphatase (ALP), and acid phosphatase (ACP) in fourth larval instar which was treated with LC25; protein content is also determined.ResultsThe emamectin benzoate was the most toxic compound followed by lufenuron, cyfluthrin, spinetoram, and profenofos with the corresponding LC50 values of 0.05, 49.18, 70.99, 130.26, and 156.78 ppm respectively. The results showed that all the tested insecticides at LC25 value gave a slight inhibition of the acetylcholinesterase (AChE) activity, except profenofos was the most potent one. The activity of glutathione S-transferase (GST) of larvae treated with spinetoram has significantly increased, whereas the enzyme activity was significantly inhibited following cyfluthrin and non-significantly inhibited following profenofos, lufenuron, and emamectin benzoate application. There were no significant differences between treated and untreated larvae in ACP activity. In contrast, the alkaline phosphatase (ALP) activity of larvae treated with tested insecticides significantly increased, while the activity was inhibited following cyfluthrin application. On the other hand, spinetoram, emamectin benzoate, and lufenuron exhibited significant increment in the protein content, whereas there was no significant effect following either cyfluthrin or profenofos treatments.ConclusionsIn summary, the present results suggest that not only the lethal effects but also the sublethal effects of newly tested insecticides could have a negative influence on the dynamics of CLW; thus, these sublethal effects can be integrated into pest control to reduce the overuse and misuse of insecticides. This effect appears reduction in the activity of detoxification enzymes, resulting in response to the tested insecticide by the lowest concentration of (sublethal doses). Also, the inhibition of detoxification enzymes, which represents defensive reactions in insects, is playing important role in reducing resistance in S. littoralis, which is one of the most dangerous pests of all agricultural crops in the world. Therefore, these results were valuable for the practical use of these insecticides in IPM programs.

Farmers’ knowledge, perceptions and management practices for termite pests of maize in Southern Benin

Abstract Termite (Isoptera: Termitidae) infestation is an important constraint of maize production in Benin. A survey of 300 households was conducted in 2018 throughout 30 villages in Southern Benin to evaluate farmers’ knowledge, perceptions and management practices of maize termite pests using focus group discussions and individual interviews with a semi-structured questionnaire. The results showed that for most of the farmers, maize is the most susceptible crop to termite attacks and the maturation developmental stage having the highest termite abundance and damage. A total of 43 different names of maize termite pests corresponding to 8 species were recorded in the study area. Size and colour were the main criteria used by farmers to classify and identify maize termite pests. Amitermes evuncifer was perceived as the most damaging to maize during vegetative and maturation stages, while Macrotermes bellicosus was perceived by famers (32.5%) as most damaging during seedling and flowering maize development stages. Erratic rainfall was perceived by maize producers as the most important factor favouring termite infestation in maize fields. The majority of the local maize is considered by farmers as susceptible to termites. The use of synthetic insecticides was the main method to control termites. Four of the 20 pesticides used by farmers have active ingredients that have been listed as highly hazardous (class Ib) by the World Health Organization (WHO). Farmers training on the danger and impact of misuse of insecticides on the development of termite insecticide resistance was recommended. The development of an integrated termite management strategy is discussed and the future research for its implementation identified.

Hubungan Perilaku Penggunaan Insektisida dengan Status Kerentanan Nyamuk Aedes aegypti di Daerah Endemis Kabupaten Purbalingga

Purpose: This study aimed to identify the correlation between behavior towards insecticide use and susceptibility status of Aedes aegypti mosquito and to identify the level of mosquito susceptibility from an endemic area in Purbalingga.Methods: This research used a cross-sectional design and was conducted from January 2017 until April 2017 in four endemic villages of Purbalingga. 40 respondents were involved in the research. Samples from each village were taken using purposive sampling. Ovitraps were installed and interviews were conducted using questionnaires for selected households. Mosquito susceptibility status was described based on the results of WHO’s standardized bioassay test.Results: The results of susceptibility test indicated that Aedes aegypti from three endemic villages (Purbalingga Lor, Penaruban, Sempor Lor) were resistant, while mosquitoes from Kembaran Kulon Village were tolerant to cypermethrin 0.05%. Variables correlated with susceptibility status of Aedes aegypti mosquito were respondent's negative attitude (PR = 0.55; 0.37 - 0.80) and behavior towards insecticide use (PR = 1.24; 1.05 - 1.47).Conclusions: Misuse of insecticides increased susceptibility status of Aedes aegypti mosquito and becomes the main risk factor for resistance. It is necessary to rotate the insecticide use for programs and households through different modes of action and to provide public health education about insecticide use, selection of active ingredients, dosage, mode of application and periodic replacement of insecticides.

Natural History, Ecology, and Management of Diamondback Moth (Lepidoptera: Plutellidae), With Emphasis on the United States

Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), has become the most destructive insect pest of cruciferous vegetables ( Brassica oleracea L.) worldwide, and is a continuing problem especially in the southern United States. Because of inconsistencies in individual control methods, inefficiencies and time demands of scouting, and the lack of clear thresholds, current management practices emphasize the prophylactic use of insecticides. Numerous other methods are available for the management of P. xylostella including host plant resistance, biological controls, cultural controls, behavioral management, and judicious use of insecticides. Past experience has shown that alone, none of these strategies will work sufficiently and insecticide misuse and resistance issues will likely continue. However, when used together, these tactics can complement each other and lead to a more sustainable system. Recent research focused on the molecular genetics and genomics of P. xylostella has dramatically increased our understanding of specific mechanisms controlling P. xylostella physiology and its interactions with plants. This has the potential to revolutionize the way we manage this pest. Here we summarize the natural history and ecology of diamondback moth and present options for its sampling and management. Additionally, we highlight recent research that may lead to a more integrated approach to managing this pest and the suite of other insect pests of Brassica crops.

Decrease of insecticide resistance over generations without exposure to insecticides in Nilaparvata lugens (Hemipteran: Delphacidae).

The brown planthopper, Nilaparvata lugens (Stål), is one of the most important insect pests on paddy rice in tropical and temperate Asia. Overuse and misuse of insecticides have resulted in the development of high resistance to many different insecticides in this pest. Studies were conducted to evaluate the change of resistance level to four insecticides over 15 generations without any exposure to insecticides in brown planthopper. After 15 generations' rearing without exposure to insecticide, brown planthopper could reverse the resistance to imidacloprid, chlorpyrifos, fipronil, and fenobucarb. The range and style of resistance reversal of brown planthopper differed when treated with four different insecticides. To monitor potential changes in insect physiological responses, we measured the activity of each of the three selected enzymes, including acetylcholinesterases (AChE), general esterases (EST), and glutathione S-transferases. After multiple generations' rearing without exposure to insecticide, AChE and EST activities of brown planthopper declined with the increased generations, suggesting that the brown planthopper population adjusted activities of EST and AChE to adapt to the non-insecticide environment. These findings suggest that the reducing, temporary stop, or rotation of insecticide application could be incorporated into the brown planthopper management.

Reducing insecticide use in Southeast Asian irrigated rice fields: From experimental ecology to large scale change in practices

The green revolution in irrigated rice has tripled its production in Asia, but also created serious environmental problems, especially a common overconsumption of insecticides. It has led to disorganized ecological regulations, shortened food webs, infestations by secondary pests, crop losses, farmer health problems and lower economic results. Based on the understanding of ecological regulations enhanced by the enrichment of the biodiversity of all functional groups of useful organisms, since 1993 the implementation of integrated pest management (IPM) on the International Rice Research Institute (IRRI) experimental farm has led to a 97 % reduction in insecticide use while retaining the same production level. Following demonstration trials, to reach millions of small Vietnamese rice growers and encourage them to change their practices, a series of mass media campaigns and the entertainment-education approach were introduced. To entertain and educate by making learning fun, the radio soap opera method was successfully used in combination with other on-the-ground activities and media. The series consisted of episodes broadcast twice a week telling stories about village living with simple messages on IPM knowledge and principles built into them. First, simple decision rules were promoted which led to a very significant reduction in insecticide use. This was followed by an incremental approach under the "three reductions and three gains" program, with more reductions in seed and nitrogen rates, and insecticide sprays to boost economic returns. Significant differences in beliefs and practices between listeners and non-listeners were found. The analysis of this successful case study underlines the importance of taking into account social factors influencing the misuse of insecticides, and the need for rigorously enforced legal rules to regulate the marketing of this kind of input.

Insecticide Resistance in Insect Vectors of Disease with Special Reference to Mosquitoes: A Potential Threat to Global Public Health

Context: Arthropod-borne diseases are remaining as a major public health issue in the resource-constrained settings. Mosquitoes are closely associated with mankind since time immemorial and play an important role in the transmission of many dreadful diseases like malaria, filariasis, Japanese encephalitis, dengue and yellow fever. Over the decades, vector control is an important element to minimize the vector-borne disease burden worldwide and in fact, it heavily relies upon synthetic insecticides as a mainstay. However the overuse and misuse of insecticides have led to the emergence of resistance, which undermines the potentiality of vector control. Evidence Acquisition: In order to pursue effective research pertained to this issue, a detailed search on Scopus, Medline, Google Scholar and academic premier databases has been conducted between the time periods of 1955 and 2012. Results: Over the past six decades, insecticides are serving as one of the important arsenals in the fight against vector-borne diseases to save hundreds of millions of lives. Consequently, in the last decade we have attained a remarkable success to combat with many diseases particularly malaria due to the combined effect of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs). Currently, malaria mortality rates have drastically fallen by more than 25% globally, 33% in sub-Saharan Africa and over a million lives have been saved attributable to massive scale-up of LLINs and IRS. Since, both LLINs and IRS are cost-effective and robust form of interventions; they are serving as a central pillar in the National Malaria Control Programmes (NMCPs) of malaria endemic countries. Nevertheless, LLINs are easy-to-deliver, most economical and practical even in the resource-poor settings, where implementation of IRS is not feasible. The heavy reliance, recurrent and inappropriate insecticide applications are key sources for resistance which is a potential threat to the global public health. Therefore, it has to be addressed immediately to sustain the recent success of vector control, unless otherwise it would become uncertain. Conclusions: Though, development of resistance is an evolutionary phenomenon, it can be tackled judiciously by implementing appropriate and comprehensive resistance monitoring and management strategies within the framework of integrated vector management. This scrutiny recommends the following measures; (i) identification of effective novel tools for monitoring and evaluation, (ii) searching for alternative interventions to minimize the further resistance evolution as well as to preserve the efficiency of existing insecticides, (iii) exploration of next generation vector control tools in terms of nets and new classes of non-pyrethroid insecticide formulation with new mode of action, (iv) building partnership by bringing together the people actively engaged in the vector control, like public health experts, policy-makers, researchers, medical entomologists and insecticide manufacturers, could ideally pave the way to collectively address the current debacle in the near future.

Study on Some Trace Element Contents in Serum and Nail Samples Obtained from Sudanese Subjects

This study was performed to investigate trace elements and arsenic contents among Sudanese inhabitants living in the north, east, and west of Sudan. Inductively coupled plasma atomic emission spectrometry was used to determine the contents of Zn and Cu. Graphite furnace atomic absorption spectrometry was used to determine Se in serum samples. It was found that Se and Cu are in the normal range. Zinc showed discrepancies among all studied groups. Acute Zn deficiency was detected in the northern and eastern regions of Sudan. Inductively coupled plasma mass spectroscopy was operated in the dynamic reaction cell mode to determine the arsenic content in the nail samples of the northern inhabitants of Sudan. High values of arsenic were found in the northern people compared with the control group. This elevation could be linked to the misuse of insecticides and herbicides which might be associated with the high rate of cancer incidence in this region.

Current control methods for diamondback moth and other brassica insect pests and the prospects for improved management with lepidopteran-resistant Bt vegetable brassicas in Asia and Africa

The diamondback moth (DBM), Plutella xylostella (L.), remains a major pest of brassica crops worldwide. DBM has been estimated globally to cost US$ 1 billion in direct losses and control costs. Chemical control of this pest remains difficult due to the rapid development of resistance to insecticides and to their effect on natural enemies. These problems are especially severe in South Asia and Africa where lack of knowledge, limited access to newer and safer insecticides, and a favourable climate result in DBM remaining a serious year-round pest which substantially increases the cost and uncertainty of crop production. Despite these problems, application of synthetic insecticides remains overwhelmingly the most common control strategy. Biologically-based efforts to control DBM in Africa and Asia have focused strongly on parasitoid introductions. However, despite the identification and deployment of promising parasitoids in many regions, these efforts have had limited impact, often because farmers continue early-season spraying of broad-spectrum insecticides that are lethal to parasitoids and thus exacerbate DBM outbreaks. A significant driver for this pattern of insecticide use is the presence of aphids and other pests whose appearance initiates inappropriate spraying. Despite often extensive training of producers in farmer field schools, many growers seem loath to discard calendar or prophylactic spraying of insecticides. The introduction of an IPM technology that could replace the use of broad-spectrum insecticides for DBM and other key Lepidoptera is crucial if the benefits of parasitoid introduction are to be fully realised. The deployment of DBM-resistant brassicas expressing proteins from Bacillus thuringiensis could help to break this cycle of insecticide misuse and crop loss, but their deployment should be part of an integrated pest management (IPM) package, which recognises the constraints of farmers while addressing the requirement to control other Lepidoptera, aphids and other secondary pests.

Developing an Evidence-Based Decision Support System for Rational Insecticide Choice in the Control of African Malaria Vectors

The emergence of Anopheles species resistant to insecticides widely used in vector control has the potential to impact directly on the control of malaria. This may have a particularly dramatic effect in Africa, where pyrethroids impregnated onto bed-nets are the dominant insecticides used for vector control. Because the same insecticides are used for crop pests, the extensive use and misuse of insecticides for agriculture has contributed to the resistance problem in some vectors. The potential for resistance to develop in African vectors has been apparent since the 1950s, but the scale of the problem has been poorly documented. A geographical information system-based decision support system for malaria control has recently been established in Africa and used operationally in Mozambique. The system incorporates climate data and disease transmission rates, but to date it has not incorporated spatial or temporal data on vector abundance or insecticide resistance. As a first step in incorporating this information, available published data on insecticide resistance in Africa has now been collated and incorporated into this decision support system. Data also are incorporated onto the openly available Mapping Malaria Risk in Africa (MARA) Web site (http://www.mara.org.za). New data, from a range of vector population-monitoring initiatives, can now be incorporated into this open access database to allow a spatial understanding of resistance distribution and its potential impact on disease transmission to benefit vector control programs.

An initial survey of the cattle grub Dermatobia hominis (L. Jr.) in Nicaragua

After the civil war and the Hurricane-Mitch disaster, cattlemen in Nicaragua were forced to transport their cattle from lowland areas to higher, dryer areas of the country. These areas are natural ecological niches for the cattle grub Dermatobia hominis (L. Jr.) (Diptera: Cuterebridae). To determine the importance of this infestation, the Agricultural and Livestock-Forestry Ministry selected a central area of Nicaragua to run a pioneer survey program to acquire information about hosts involved, number of cases, treatments applied and general knowledge of 42 farmers about the life cycle of the parasite. The subjects were either farm owners or farm managers. Ninety-five percentage of the farms indicated cases of D. hominis infestation in their animals, with cattle being the most affected host (100% of the affected farms). There was poor understanding of the D. hominis life cycle, vectors and control methods. A misuse of insecticides for the treatment of larval infestation by D. hominis was indicated.