Effect of vibrational mating disruption on flight activity and oviposition to control the grapevine pest, Scaphoideustitanus.

The increasing demand for safe and sustainably produced food is leading to the development of strategies of pest control alternative to chemicals. One innovative method is Vibrational Mating Disruption (VMD) to disrupt insect communication in plants. VMD was proven effective in preventing mating of the grapevine pest Scaphoideus titanus, vector of flavescence dorée. However, the stress induced by VMD on the target species has the potential to influence other crucial aspects of the insect biology and ethology. Therefore, the goal of this study was to understand side effects of VMD on the flight activity and oviposition of S. titanus. The results of our experiments conducted in the greenhouse showed that in the presence of a receptive female, males fly more if exposed to vibrations than in the silent control but not differently from singles males in silence. Surprisingly, we found that also females subjected to VMD fly more than in the silence. Regarding oviposition, we found that mated females exposed to vibrations and single females (unmated) laid significantly fewer eggs than mated females in silence. In conclusion, this study shows the potential of VMD to interfere, besides with mating, with other important biological aspects of the pest species.

Insight into the evolutionary profile of radio-resistance among insects having intrinsically evolved defence against radiation toxicity.

Ionizing radiation (IR) has wide-ranging applications in various fields. In agriculture, pest control is one of the important applications, because insect pests have become a threat to the global agriculture industry. IR are used routinely to prevent crop loss and to protect stored food commodities. Radio-sterilization and disinfestation treatments are commonly used procedures for insect pest control. From various studies on insect radio-sterilization and disinfestation, it has been established that compared to vertebrates' insects have high levels of radiation resistance. Therefore, to achieve adequate radio-sterilization/disinfestation; exposure to high doses of IR is necessary. However, studies over decades made a presumption that radiation resistance is general among insects. Recent studies have shown that some insect orders are having high IR resistance and some insect orders are sensitive to IR. These studies have clarified that radiation resistance is not uniform throughout insect class. The present review is an attempt to insight at the evolutionary profile of insect species studied for radio-sterilization and disinfestation treatment and are having the trait of radio-resistance. From various studies on insect radiation resistance and after phylogenetic analysis of insect species it appears that the evolutionary near species have drastically different levels of radio-resistance and trait of radiation resistance appears to be independent of insect evolution.

Impact of IRS: Four-years of entomological surveillance of the Indian Visceral Leishmaniases elimination programme.

BACKGROUND: In 2005, Bangladesh, India and Nepal agreed to eliminate visceral leishmaniasis (VL) as a public health problem. The approach to this was through improved case detection and treatment, and controlling transmission by the sand fly vector Phlebotomus argentipes, with indoor residual spraying (IRS) of insecticide. Initially, India applied DDT with stirrup pumps for IRS, however, this did not reduce transmission. After 2015 onwards, the pyrethroid alpha-cypermethrin was applied with compression pumps, and entomological surveillance was initiated in 2016. METHODS: Eight sentinel sites were established in the Indian states of Bihar, Jharkhand and West Bengal. IRS coverage was monitored by household survey, quality of insecticide application was measured by HPLC, presence and abundance of the VL vector was monitored by CDC light traps, insecticide resistance was measured with WHO diagnostic assays and case incidence was determined from the VL case register KAMIS. RESULTS: Complete treatment of houses with IRS increased across all sites from 57% in 2016 to 70% of houses in 2019, rising to >80% if partial house IRS coverage is included (except West Bengal). The quality of insecticide application has improved compared to previous studies, average doses of insecticide on filters papers ranged from 1.52 times the target dose of 25mg/m2 alpha-cypermethrin in 2019 to 1.67 times in 2018. Resistance to DDT has continued to increase, but the vector was not resistant to carbamates, organophosphates or pyrethroids. The annual and seasonal abundance of P. argentipes declined between 2016 to 2019 with an overall infection rate of 0.03%. This was associated with a decline in VL incidence for the blocks represented by the sentinel sites from 1.16 per 10,000 population in 2016 to 0.51 per 10,000 in 2019. CONCLUSION: Through effective case detection and management reducing the infection reservoirs for P. argentipes in the human population combined with IRS keeping P. argentipes abundance and infectivity low has reduced VL transmission. This combination of effective case management and vector control has now brought India within reach of the VL elimination targets.

Improved vector control of Triatoma infestans limited by emerging pyrethroid resistance across an urban-to-rural gradient in the Argentine Chaco.

BACKGROUND: The sustainable elimination of Triatoma infestans in the Gran Chaco region represents an enduring challenge. Following the limited effects of a routine pyrethroid insecticide spraying campaign conducted over 2011-2013 (first period) in Avia Terai, an endemic municipality with approximately 2300 houses, we implemented a rapid-impact intervention package to suppress house infestation across the urban-to-rural gradient over 2015-2019 (second period). Here, we assess their impacts and whether persisting infestations were associated with pyrethroid resistance. METHODS: The 2011-2013 campaign achieved a limited detection and spray coverage across settings (< 68%), more so during the surveillance phase. Following community mobilization and school-based interventions, the 2015-2019 program assessed baseline house infestation using a stratified sampling strategy; sprayed all rural houses with suspension concentrate beta-cypermethrin, and selectively sprayed infested and adjacent houses in urban and peri-urban settings; and monitored house infestation and performed selective treatments over the follow-up. RESULTS: Over the first period, house infestation returned to pre-intervention levels within 3-4 years. The adjusted relative odds of house infestation between 2011-2013 and 2015-2016 differed very little (adj. OR: 1.17, 95% CI 0.91-1.51). Over the second period, infestation decreased significantly between 0 and 1 year post-spraying (YPS) (adj. OR: 0.36, 95% CI 0.28-0.46), with heterogeneous effects across the gradient. Mean bug abundance also dropped between 0 and 1 YPS and thereafter remained stable in rural and peri-urban areas. Using multiple regression models, house infestation and bug abundance at 1 YPS were 3-4 times higher if the house had been infested before treatment, or was scored as high-risk or non-participating. No low-risk house was ever infested. Persistent foci over two successive surveys increased from 30.0 to 59.3% across the gradient. Infestation was more concentrated in peridomestic rather than domestic habitats. Discriminating-dose bioassays showed incipient or moderate pyrethroid resistance in 7% of 28 triatomine populations collected over 2015-2016 and in 83% of 52 post-spraying populations. CONCLUSIONS: The intervention package was substantially more effective than the routine insecticide spraying campaign, though the effects were lower than predicted due to unexpected incipient or moderate pyrethroid resistance. Increased awareness and diagnosis of vector control failures in the Gran Chaco, including appropriate remedial actions, are greatly needed.

Pesticides Misused for Bed Bug Control: Comparing Professional and Nonprofessional Applications Reported to the National Pesticide Information Center, 2013-2017.

Objectives. To compare outcomes when pesticides are used to control bed bugs by professionals and nonprofessionals. Methods. All US National Pesticide Information Center inquiries from 2013 to 2017 were assessed to identify scenarios involving bed bugs and pesticide applications. Cases were evaluated with respect to types of applicators, misapplications, and human pesticide exposures. Results. Misapplications were more than twice as likely to be reported in cases involving nonprofessional applications (14%) as in cases involving professional applications (5%). Human exposures to pesticides were reported more often when pesticides were misapplied (70%) than when there were no apparent misapplications (31%). Conclusions. Both professionals and nonprofessionals may misuse pesticides to control bed bugs, which may increase the risks of exposure and adverse outcomes. Policy interventions may reduce pesticide incidents related to bed bug control by promoting professional involvement and adherence to product label instructions.

Assessing the combined effects of household type and insecticide effectiveness for kala-azar vector control using indoor residual spraying: a case study from North Bihar, India.

BACKGROUND: Indoor residual spraying (IRS) is the mainstay for vector control intervention of visceral leishmaniasis (VL) in India. Little is known on the control effects of IRS on different household types. Here, we assessed if IRS with insecticides has an equal residual and interventional effect on all household types in a village. We also developed a combined spatial-risk map and a sand fly, Phlebotomus argentipes density analytical model based on household characteristics, insecticide susceptibility and IRS-status to explore the spatio-temporal distributions of the vector at a micro-scale level. METHODS: This study was carried out in two villages of Mahnar block in Vaishali district, Bihar. IRS using two insecticides [dichlorodiphenyltrichloroethane (DDT 50%) and synthetic pyrethroid (SP 5%)] was evaluated for VL-vector (P. argentipes) control. Temporal residual efficacy of the insecticides on different wall-surface types was evaluated using the cone-bioassay technique according to WHO guidelines. Insecticide susceptibility of local P. argentipes was explored using the tube-bioassay method. Pre- and post-IRS sand fly densities were monitored in human dwellings and animal shelters using Centers for Disease Control light-traps installed between 18:00-6:00 h. A best-fit model for sand fly density analysis was developed using multiple logistic regression analysis. Geographical information system based spatial analysis techniques were employed to map the household type distribution of insecticide susceptibility of the vector, and IRS-status of the households to interpret the spatio-temporal distributions of P. argentipes. RESULTS: Phlebotomus argentipes was highly susceptible to SP (100%) but showed high resistance to DDT with a 49.1% mortality rate. SP-IRS has been reported as having better community acceptance than DDT-IRS in all household types. Residual efficacies were varied between wall-surfaces; both insecticides failed to achieve the duration of IRS effectiveness recommended by the WHO. Reduction in P. argentipes counts due to SP-IRS was higher than DDT-IRS between household groups (i.e. sprayed and sentinel), in all intervals post-IRS. Combined spatial risk-maps revealed a better control effect of SP-IRS on sand flies than DDT-IRS in all household types risk-zones. The multilevel logistic regression analysis explored five risk-factors that were strongly associated with the density of P. argentipes. CONCLUSIONS: The results contribute to furthering current understanding of IRS-practices for control of visceral leishmaniasis in endemic Bihar, which may help in future actions for improvements.

Negative Density-dependent Dispersal in Tsetse Flies: A Risk for Control Campaigns?

Tsetse flies are vectors of parasites that cause diseases responsible for significant economic losses and health issues in sub-Saharan Africa, including sleeping sickness in humans and nagana in domestic animals. Efficient vector-control campaigns require good knowledge of the demographic parameters of the targeted populations. In the last decade, population genetics emerged as a convenient way to measure population densities and dispersal in tsetse flies. Here, by revealing a strong negative density-dependent dispersal in two dimensions, we suggest that control campaigns might unleash dispersal from untreated areas. If confirmed by direct measurement of dispersal before and after control campaigns, area-wide and/or sequential treatments of neighboring sites will be necessary to prevent this issue.

Dynamics of bed bug infestations and control under disclosure policies.

Bed bugs have reemerged in the United States and worldwide over recent decades, presenting a major challenge to both public health practitioners and housing authorities. A number of municipalities have proposed or initiated policies to stem the bed bug epidemic, but little guidance is available to evaluate them. One contentious policy is disclosure, whereby landlords are obligated to notify potential tenants of current or prior bed bug infestations. Aimed to protect tenants from leasing an infested rental unit, disclosure also creates a kind of quarantine, partially and temporarily removing infested units from the market. Here, we develop a mathematical model for the spread of bed bugs in a generalized rental market, calibrate it to parameters of bed bug dispersion and housing turnover, and use it to evaluate the costs and benefits of disclosure policies to landlords. We find disclosure to be an effective control policy to curb infestation prevalence. Over the short term (within 5 years), disclosure policies result in modest increases in cost to landlords, while over the long term, reductions of infestation prevalence lead, on average, to savings. These results are insensitive to different assumptions regarding the prevalence of infestation, rate of introduction of bed bugs from other municipalities, and the strength of the quarantine effect created by disclosure. Beyond its application to bed bugs, our model offers a framework to evaluate policies to curtail the spread of household pests and is appropriate for systems in which spillover effects result in highly nonlinear cost-benefit relationships.

Quantifying the Impact of Excluding Insecticide Classes From Cotton Integrated Pest Management Programs in the U.S. Mid-South.

Current assessments from the U.S. Environmental Protection Agency suggest that some current insecticides may be lost or severely restricted in the near future. An experiment was conducted from 2014 to 2015 at two locations in Mississippi to determine the impact of losses of insecticide classes on integrated pest management of insect pests in cotton. The treatments included cotton treated with all available classes of insecticides, cotton treated with all classes except neonicotinoids, cotton treated with all classes except pyrethroids, cotton treated with all classes except carbamates and organophosphates, and an untreated control. Plots were scouted weekly and insecticide applications were made with the most efficacious and economical insecticides for each treatment when that treatment reached threshold for a particular insect pest(s). The primary insects at both locations were tobacco thrips and tarnished plant bugs. Thrips pressure was similar at both locations and generally showed that all insecticide treatments provided a similar level of protection compared with the untreated control. At the Stoneville location where tarnished plant bug pressure was greatest, cotton yields and economic returns differed between plots where all classes of insecticides were applied compared with the untreated control and where neonicotinoids were excluded. However, in Starkville where tarnished plant bug pressure was less, there were no differences among treatments. Although yield and economic returns were similar in high tarnished plant bug pressure areas when using all classes compared with managing without pyrethroids or organophosphates, a rotation among all insecticide classes should be beneficial for resistance management in Mid-South cotton production.

Standardising visual control devices for Tsetse: East and Central African Savannah species Glossina swynnertoni, Glossina morsitans centralis and Glossina pallidipes.

BACKGROUND: This study focused on the savannah tsetse species Glossina swynnertoni and G. morsitans centralis, both efficient vectors of human and animal trypanosomiasis in, respectively, East and Central Africa. The aim was to develop long-lasting, practical and cost-effective visually attractive devices that induce the strongest landing responses in these two species for use as insecticide-impregnated tools in population suppression. METHODS AND FINDINGS: Trials were conducted in different seasons and years in Tanzania (G. swynnertoni) and in Angola and the Democratic Republic of the Congo (DRC, G. m. centralis) to measure the performance of traps (pyramidal and epsilon) and targets of different sizes, shapes and colours, with and without chemical baits, at different population densities and under different environmental conditions. Adhesive film was used to catch flies landing on devices at the remote locations to compare tsetse-landing efficiencies. Landing rates by G. m. centralis in both Angola and the DRC were highest on blue-black 1 m2 oblong and 0.5 m2 square and oblong targets but were not significantly different from landings on the pyramidal trap. Landings by G. swynnertoni on 0.5 m2 blue-black oblong targets were likewise not significantly lower than on equivalent 1 m2 square targets. The length of target horizontal edge was closely correlated with landing rate. Blue-black 0.5 m2 targets performed better than equivalents in all-blue for both G. swynnertoni and G. m. centralis, although not consistently. Baiting with chemicals increased the proportion of G. m. centralis entering pyramidal traps. CONCLUSIONS: This study confirms earlier findings on G. swynnertoni that smaller visual targets, down to 0.5 m2, would be as efficient as using 1 m2 targets for population management of this species. This is also the case for G. m. centralis. An insecticide-impregnated pyramidal trap would also constitute an effective control device for G. m. centralis.

Resistance to deltamethrin by domestic and wild Triatoma infestans populations in the municipality of Toro Toro, Potosi, Bolivia.

BACKGROUND: Chemical control with pyrethroid insecticides has been effective in reducing endemic areas of distribution of Triatoma infestans in the Southern Cone, as well as Bolivia; this had considerably reduced the infestation of households in a large part of the territory. Nowadays, areas such as the Chaco and the Inter-Andean Valleys are regions where the reach of vector control strategies is becoming limited, and infestations of insecticide-treated households are reported more often. The objective of this study was to determine if the persistence of T. infestans stems from changes in the susceptibility of its toxicological profile in four communities in the municipality of Toro Toro, Potosi, Bolivia. METHODS: Susceptibility to deltamethrin of wild and domestic populations of T. infestans was evaluated in two stages (16 populations before and 13 populations after spraying) among DUs (structures in the intra- and peridomicile) and wild ecotopes, in four communities. Serial dilutions of deltamethrin in acetone (0.2 µl) were applied topically on standardized first-stage nymphs. Dose-response results were analyzed with the software PoloPlus and the relationships between lethal doses (LD) and resistance ratios (RR50) were determined. RESULTS: Different degrees of RR50 were detected among the populations before and after spraying (25.66-54.70 and 21.91-40.67, respectively), as well as in different ecotopes within a DU (DU JC 3, 28.06-36.13, in mixed structures of corrals and chicken coops; and DU JG 3, 46.27-25.70, in kitchen roofs), or in the wild environment of the community JG Sil (29.21-40.67). The mortality of insects undergoing diagnostic dose (DD) was never higher than 34%. CONCLUSION: The results obtained in this study showed resistance of T. infestans to deltamethrin in four communities, hence the complexity of this phenomenon is not only limited to the level of communities, but also applies to the microgeographical level, as in different ecotopes present within the DUs. This phenomenon should be considered while planning the activities of control programs.

Insecticide resistance, control failure likelihood and the First Law of Geography.

Insecticide resistance is a broadly recognized ecological backlash resulting from insecticide use and is widely reported among arthropod pest species with well-recognized underlying mechanisms and consequences. Nonetheless, insecticide resistance is the subject of evolving conceptual views that introduces a different concept useful if recognized in its own right - the risk or likelihood of control failure. Here we suggest an experimental approach to assess the likelihood of control failure of an insecticide allowing for consistent decision-making regarding management of insecticide resistance. We also challenge the current emphasis on limited spatial sampling of arthropod populations for resistance diagnosis in favor of comprehensive spatial sampling. This necessarily requires larger population sampling - aiming to use spatial analysis in area-wide surveys - to recognize focal points of insecticide resistance and/or control failure that will better direct management efforts. The continuous geographical scale of such surveys will depend on the arthropod pest species, the pattern of insecticide use and many other potential factors. Regardless, distance dependence among sampling sites should still hold, following the maxim that the closer two things are, the more they resemble each other, which is the basis of Tobler's First Law of Geography. © 2016 Society of Chemical Industry.

Assessment of the Housing Improvement Program for Chagas Disease Control in the Northwestern municipalities of Rio Grande do Sul, Brazil.

INTRODUCTION:: The Housing Improvement Program for Chagas Disease Control (HIPCDC) was established in 2001 in Northwestern Rio Grande do Sul State, aiming to improve the conditions of the domiciliary and peridomiciliary environments to make them resistant to triatomine colonization. This study aimed to assess the impact of the HIPCDC on triatomine control by developing local population and authority awareness on the issue. METHODS:: The study was conducted by means of questionnaires applied to local authorities and the program beneficiaries. Three municipalities - Ajuricaba, Coronel Barros, and Crissiumal - were visited. RESULTS:: A program coordinator from each municipality and 62 individuals from selected households were interviewed. The authorities reported difficulties in the implementation of the program due to differences between the project development period and financial resource availability, in addition to a lack of understanding by the community not included in the program. As for the houses, most improvements were made in the peridomiciliary environments; moreover, construction of 4 new residences, as well as the renovation of others, was also reported. Regarding suggestions to the program, requests for better planning (44.9%) and renovation quality (36.7%) were highlighted. With reference to the presence of triatomine bugs, prior to the HIPCDC adaptations, 12.9% of the respondents reported coming across at least one specimen at home, as compared to 22.6% who found these insects in peridomiciliary areas. CONCLUSIONS:: Despite reports of difficulties in carrying out the HIPCDC, there was an improvement in the housing conditions, with no triatomine occurrence reports after the program implementation.

Assessment of the housing improvement program for chagas disease control in the northwestern municipalities of Rio Grande do Sul, Brazil

Abstract INTRODUCTION: The Housing Improvement Program for Chagas Disease Control (HIPCDC) was established in 2001 in Northwestern Rio Grande do Sul State, aiming to improve the conditions of the domiciliary and peridomiciliary environments to make them resistant to triatomine colonization. This study aimed to assess the impact of the HIPCDC on triatomine control by developing local population and authority awareness on the issue. METHODS: The study was conducted by means of questionnaires applied to local authorities and the program beneficiaries. Three municipalities - Ajuricaba, Coronel Barros, and Crissiumal - were visited. RESULTS: A program coordinator from each municipality and 62 individuals from selected households were interviewed. The authorities reported difficulties in the implementation of the program due to differences between the project development period and financial resource availability, in addition to a lack of understanding by the community not included in the program. As for the houses, most improvements were made in the peridomiciliary environments; moreover, construction of 4 new residences, as well as the renovation of others, was also reported. Regarding suggestions to the program, requests for better planning (44.9%) and renovation quality (36.7%) were highlighted. With reference to the presence of triatomine bugs, prior to the HIPCDC adaptations, 12.9% of the respondents reported coming across at least one specimen at home, as compared to 22.6% who found these insects in peridomiciliary areas. CONCLUSIONS: Despite reports of difficulties in carrying out the HIPCDC, there was an improvement in the housing conditions, with no triatomine occurrence reports after the program implementation.

The impact of insecticide-treated cloth targets on the survival of Stegomyia polynesiensis (= Aedes polynesiensis) under laboratory and semi-field conditions in French Polynesia.

The impact of deltamethrin-impregnated cloth targets on Stegomyia polynesiensis (= Aedes polynesiensis) (Marks) (Diptera: Culicidae) was assessed under laboratory and semi-field settings in French Polynesia. Stegomyia polynesiensis females were released into small laboratory cages and large field cages containing either a deltamethrin-treated or an untreated navy blue cloth, and mosquito knock-down and mortality were assessed. The 24-h mortality rate in mosquitoes exposed to the insecticide-treated target in small cages was 98.0%. These mosquitoes also demonstrated significantly higher levels of knock-down than those exposed to the untreated target. Mortality in field cages was assessed at 24 and 48 h. The 24-h mortality rate in mosquitoes exposed to the control target was 31.2%, whereas that in those exposed to the deltamethrin-treated target was 54.3%. The 48-h mortality rate was also elevated in mosquitoes exposed to the deltamethrin-treated target, but this result did not differ significantly from that observed in mosquitoes exposed to the control target. The significant suppression of female S. polynesiensis by deltamethrin-treated resting targets in this study indicates that these targets could play a role in the control of an important disease vector in the South Pacific region.

Comparative Field Evaluation of Different Traps for Collecting Adult Phlebotomine Sand Flies (Diptera: Psychodidae) in an Endemic Area of Cutaneous Leishmaniasis in Quintana Roo, Mexico.

Phlebotominae are the vectors of Leishmania parasites. It is important to have available surveillance and collection methods for the sand fly vectors. The objectives of the present study were to evaluate and compare traps for the collection of sand fly species and to analyze trap catches along months and transects. Field evaluations over a year were conducted in an endemic area of leishmaniasis in the state of Quintana Roo, Mexico. A randomized-block design was implemented in study area with tropical rainforest vegetation. The study design utilized 4 transects with 11 trap types: 1) Centers for Disease Control and Prevention (CDC) light trap with incandescent bulb (CDC-I), 2) CDC light trap with blue light-emitting diodes (LEDs) (CDC-B), 3) CDC light trap with white LEDs (CDC-W), 4) CDC light trap with red LEDs (CDC-R), 5) CDC light trap with green LEDs (CDC-G), 6) Disney trap, 7) Disney trap with white LEDs, 8) sticky panels, 9) sticky panels with white LEDs, 10) delta-like trap, and 11) delta-like trap with white LEDs. A total of 1,014 specimens of 13 species and 2 genera (Lutzomyia and Brumptomyia) were collected. There were significant differences in the mean number of sand flies caught with the 11 traps; CDC-I was (P  =  0.0000) more effective than the other traps. Other traps exhibited the following results: CDC-W (17.46%), CDC-B (15.68%), CDC-G (14.89%), and CDC-R (14.30%). The relative abundance of different species varied according to trap types used, and the CDC-I trap attracted more specimens of the known vectors of Leishmania spp., such as like Lutzomyia cruciata, Lu. shannoni, and Lu. ovallesi. Disney trap captured more specimens of Lu. olmeca olmeca. Based on abundance and number of species, CDC light traps and Disney traps appeared to be good candidates for use in vector surveillance programs in this endemic area of Mexico.

Effects of environmental factors and storage conditions on the performance of Olyset® Plus against sand flies in WHO cone bioassays.

BACKGROUND: Leishmaniasis, visceral and cutaneous, is seen in Turkey and has both public and veterinary importance. So far, four Leishmania species and their vectors have been detected in Turkey. Vector control is essential in endemic areas and several personal protection methods are available including long-lasting insecticidal nets (LLINs). In this study, we aimed to measure the effects of usage and storage conditions on LLINs in a village-scale study. METHODS: Olyset(®) Plus bed nets were set up in different climatic conditions (rain, exposed to sunlight and humidity) and collected after 6 months. The effectiveness of bed nets were tested by WHO's cone test method using wild-caught sand flies. RESULTS: Bed nets, which were placed directly exposed to sunlight (A1, A2) showed lower (17.2%) knock down effect compared to bed nets placed indoors (A3, B1). Twenty-four hour mortality was 100% for the five study groups (A2, A3, B1, C1, C2) whereas group A1 was found to have a lower mortality rate (44.4%). CONCLUSION: Bed nets need to avoid direct exposure to sunlight. When used and stored in appropriate conditions (cool, well-ventilated place away from sunlight) they can be used as an effective vector control tool in endemic areas.

The cumulative damage index method: a new method for evaluating the effectiveness of control measures for Plutella xylostella (Lepidoptera: Plutellidae).

BACKGROUND: All previously and currently used methods for effectiveness evaluation of control measures for the diamondback moth (DBM) do not simultaneously take the actual damage and population size into consideration. Here, we propose a new method, the cumulative damage index method, in which the number of larvae and their amount of food consumption are simultaneously included in the calculation of the theoretical cumulative damage index (T) and actual cumulative damage index (A). Evaluation was based on the reduced degree of damage calculated according to indexes T and A. RESULTS: Based on the new method, the corrected effectiveness of the combined use of biological measures, chemical insecticides, Bacillus thuringiensis (Bt) and P. xylostella granulosis virus (PxGV) on DBM was 35.85, 2.37, 12.50 and 11.77% respectively. Under the action of natural factors, the Population Developmental Index (I) of DBM was 5.1 ± 1.4; under the integrated actions of natural factors and these four types of measure, index I of DBM was 0.34 ± 0.1, 6.1 ± 1.5, 2.1 ± 0.5 and 1.1 ± 0.3 respectively. The sole effectiveness of Trichogramma spp. when integrated with other natural factors, integrated biological measures and chemical insecticides was 21.43 ± 1.69%, 45.27 ± 4.09% and 20.68 ± 2.60% respectively. CONCLUSIONS: There was some difference between the effectiveness evaluated by the new method and index I, and the actual damage caused by DBM could be reflected well by index A. The new method is more scientifically appropriate and practical for effectiveness evaluation than existing methods. © 2014 Society of Chemical Industry.