Systemic Insecticide Imidacloprid Research Articles

Enhancing Red Ginger Plant Growth through Eco-Friendly Pest Management: Synergistic Effects of Metarhizium anisopliae and Imidacloprid

This study explores the potential of a more environmentally friendly pest management approach for enhancing the vegetative growth of red ginger plants (Zingiber officinale Rosc.) by mitigating the damage caused by Lepidiota stigma (white grub) larvae. The study was conducted at the Experimental Garden of the Faculty of Agriculture, UPN “Veteran” Yogyakarta from April to August 2022, utilizing a factorial Completely Randomized Design. The application of the entomopathogenic fungus Metarhizium anisopliae at varying doses (0 g, 10 g, 20 g, and 30 g per 3 kg of planting media) and the systemic insecticide Imidacloprid (either absent or at a dose of 0.02 g per 3 kg of planting media) were the primary factors studied. Each treatment combination, executed on ten plants each infested with one larvae, was repeated thrice. The findings demonstrate that a combined application of M. anisopliae and Imidacloprid could significantly reduce the intensity of white grub damage to red ginger plants and improve their vegetative growth. Notably, a dose of M. anisopliae of 20 g per 3 kg of planting media maximized the plant height, leaf number, and tiller count. The findings highlight the potential of integrating biological and chemical controls for sustainable pest management and crop yield improvement, with broad implications for other similar agricultural contexts.

Integration of Metal-Organic Polyhedra onto a Nanophotonic Sensor for Real-Time Detection of Nitrogenous Organic Pollutants in Water.

The grave health and environmental consequences of water pollution demand new tools, including new sensing technologies, for the immediate detection of contaminants in situ. Herein, we report the integration of metal-organic cages or polyhedra (MOCs/MOPs) within a nanophotonic sensor for the rapid, direct, and real-time detection of small (<500 Da) pollutant molecules in water. The sensor, a bimodal waveguide silicon interferometer incorporating Rh(II)-based MOPs as specific chemical receptors, does not require sample pretreatment and enables minimal expenditure of time and reagents. We validated our sensor for the detection of two common pollutants: the industrial corrosion inhibitor 1,2,3-benzotriazole (BTA) and the systemic insecticide imidacloprid (IMD). The sensor offers a fast time-to-result response (15 min), high sensitivity, and high accuracy. The limit of detection (LOD) in tap water for BTA is 0.068 μg/mL and for IMD, 0.107 μg/mL, both of which are below the corresponding toxicity thresholds defined by the European Chemicals Agency (ECHA). By combining innovative chemical molecular receptors such as MOPs with state-of-the-art photonic sensing technologies, our research opens the path to implement competitive sensor devices for in situ environmental monitoring.

Trunk Injection with Insecticides Manages Xylotrechus chinensis (Chevrolat) (Coleoptera: Cerambycidae).

Xylotrechus chinensis (Chevrolat) (Coleoptera: Cerambycidae) is a serious wood-boring insect of mulberry trees (Morus spp.). Larvae of this species enter the trunk of the tree and feed on woody tissues. Xylotrechus chinensis is endemic in several Asian countries, while, in the last decade, it invaded Europe. In the present work, we evaluated trunk injection against this pest. The systemic insecticides fipronil, imidacloprid, and spirotetramat were used in the trials. Abamectin was used as a positive control since it has been found to be effective for the management of X. chinensis. Imidacloprid and fipronil proved to be highly effective against this species in both years (9.5 and 12.1 exit holes/tree in 2021, 5.0 and 8.8 exit holes/tree in 2022, respectively), while spirotetramat was the least effective. The lowest mean number of exit holes was recorded when abamectin was applied in both years (4.7 exit holes/tree in 2021 and 3.3 exit holes/tree in 2022). The percentage of exit holes was reduced by 76.1, 71.8, and 85.6% in trees treated with imidacloprid, fipronil, and abamectin, respectively, after two years of application, while spirotetramat caused a 37.4% reduction. Trunk injection with imidacloprid, fipronil, and abamectin could be used against X. chinensis for long-term control of mulberry trees.

Two novel bioassays useful for the quick assessment of chemical effects on the behavior of mosquito larvae (Culicidae) and adult earthworms (Lumbricidae)

The behavior, i.e., observable response of an organism can serve as a useful indicator of environmental quality. In the absence of death and other sublethal effects, behavioral changes can represent early warning signs of toxic effects. In the present contribution, we present two novel bioassays useful for the quick assessment of chemical effects on the behavior of mosquito larvae (Culicidae) and adult earthworms (Lumbricidae). These bioassays could have applications in ecological risk assessment and laboratory based ecotoxicological testing. The novel assays are:•A bioassay for the assessment of chemical toxicity on the swimming, breathing and resting behavior of Culicidae larvae.•A bioassay for the assessment of chemical toxicity on the escape behavior of Lumbricidae in water.•These bioassays were carried out using the systemic insecticide imidacloprid and documented the relatively rapid onset of the neurotoxic effects of imidacloprid to experimental organisms.

Evaluation of IDM modules for tomato leaf curl disease management in Madhya Pradesh

Comparative suitability assessment field trials of fourdifferent IDM modules for the management of leaf curldisease of tomato were conducted at farmer’s field. The trialcites were located in Chorgarhi, Mankesher and Upani villageof district Sidhi, Madhya Pradesh. The trials were conductedduring 2014-15, 2015-16 and 2016-17 as On Farm Trial. Trendof results obtained during past three years of experimentationindicated that all the management modules tested were foundsuperior over predominant farmer’s practice (M1). Themodule M4 having tolerant variety, seed treatment withinsecticide, nursery raising in nylon net cages of 40 mesh,root dip of seedling with systemic insecticide Imidacloprid,as to enable nursery to be transplanted, remain uninfestableby white flies and thrips at least up to 2 weeks aftertransplanting. Further, initial roughing at 3 weeks aftertransplanting and two subsequent sprays of systemicinsecticide before flowering, at 25 and 45 DAT was foundeffective not only in reducing disease incidence butdecreased total number of white fly per plant as well. Thispackage of practice was also able to enhance tomato yieldwith favorable cost benefit ratio. Module 4 was followed bymodule T3, where most of the measures mentioned in module4 were followed except use of nylon net. Therefore, it is verymuch evident that the seed treatment with insecticide andseedling dip measures along with physical intervention todeploy nylon net to prevent assess of vectors to nurseriesinside the cage, hold the great promise to have an almostleaf curl free crop.

Imidacloprid Movement into Fungal Conidia Is Lethal to Mycophagous Beetles.

Simple SummarySome insects are beneficial to plants because they eat pest insects and disease-causing fungi; integrating the use of these insects into pest management can help to reduce the need for costly pesticide applications. Twenty-spotted ladybeetles eat plant pathogenic fungi, which helps to reduce disease severity for many economically important crops. In this study, we applied a systemic insecticide to the roots of pumpkin plants and monitored to see if it would be detectable in the spores of a plant pathogenic fungus and whether the insecticide-tainted fungal spores would hurt the ladybeetle larvae. We were able to chemically detect the systemic insecticide in the fungal spores up to 21 days after the plants had been treated with the fungus. We found that the ladybeetles raised on infected plants that had been treated with the systemic insecticide died more rapidly that ladybeetles that had been raised on uninfected or untreated plants. This study is the first to show that systemic insecticides can move from the roots of a plant, into a plant pathogenic fungus, and then have negative effects on a fungus-eating insect. It suggests that growers and land managers need to carefully consider the unintended consequences of insecticide applications.Applications of systemic pesticides can have unexpected direct and indirect effects on nontarget organisms, producing ecosystem-level impacts. We investigated whether a systemic insecticide (imidacloprid) could be absorbed by a plant pathogenic fungus infecting treated plants and whether the absorbed levels were high enough to have detrimental effects on the survival of a mycophagous beetle. Beetle larvae fed on these fungi were used to assess the survival effects of powdery mildew and imidacloprid in a factorial design. Fungal conidia were collected from treated and untreated plants and were tested for the presence and concentration of imidacloprid. The survival of beetles fed powdery mildew from imidacloprid-treated leaves was significantly lower than that of the beetles from all other treatments. Imidacloprid accumulated in fungal conidia and hyphae was detected at levels considered lethal to other insects, including coccinellid beetles. Water-soluble systemic insecticides may disrupt mycophagous insects as well as other nontarget organisms, with significant implications for biodiversity and ecosystem function.

Efficacy and Profitability of Insecticide Treatments for Tomato Spotted Wilt Management on Peanut in South Carolina.

Tomato spotted wilt (TSW) is a common and serious disease of peanut (Arachis hypogaea L.) caused by Tomato spotted wilt virus (TSWV; family Tospoviridae, genus Orthotospovirus). Management frequently uses an integrated approach, with cultivar resistance and application of in-furrow insecticide as two critical components. In-furrow insecticides help suppress thrips, which can injure and stunt young growing plants and transmit TSWV, with postemergent application of acephate capable of providing additional thrips control. To examine effects of systemic insecticides (imidacloprid, imidacloprid plus fluopyram, phorate, and acephate) on TSW management, yield, and economic return across cultivar susceptibilities (susceptible, moderately susceptible, and resistant) in South Carolina, a meta-analysis was used to synthesize results from 32 studies conducted between 2009 and 2018. Although efficacy and magnitude of individual treatments varied with susceptibility, imidacloprid increased, whereas phorate generally decreased TSW incidence relative to nontreated controls. In-furrow treatments followed by acephate further reduced TSW incidence and increased profitability. All examined treatments improved yield compared with untreated peanuts except for susceptible cultivars treated with imidacloprid. Imidacloprid plus fluopyram increased yield more than imidacloprid alone for the susceptible group, although there was little difference between these treatments in association with moderately susceptible cultivars. When comparing individual applications, phorate was overall the most profitable option across susceptibilities, although imidacloprid plus fluopyram exhibited analogous profitability for susceptible cultivars. Results from this study can be used to assist producer selection of management options for TSW in peanut.

Combined Effects of Hemlock Woolly Adelgid (Adelges tsugae) Infestation and Treatment with Imidacloprid on Eastern Hemlock (Tsuga canadensis) Leaf Radiometry

Abstract The neonicotinoid systemic insecticide imidacloprid has proven to be an effective treatment for the prevention and control of hemlock woolly adelgid (Adelges tsugae Annand) in southeastern populations of eastern hemlock (Tsuga canadensis L.). Recent studies have demonstrated that imidacloprid and A. tsugae both stimulate salicylic acid-dependent physiological responses in plant tissues responsible for plant defenses against pathogens, timing of developmental outcomes including flowering and leaf senescence, and resilience to abiotic stressors. We evaluated the interacting effects of A. tsugae presence/absence and treatment with imidacloprid on leaf optical properties indicative of photosynthetic potential, photosynthetic efficiency, and tissue senescence. Our results indicated that A. tsugae changes lower canopy leaf optical properties indicative of reduced photosynthetic potential/efficiency and accelerated senescence in mature leaves. Imidacloprid was associated with declines in photosynthetic potential and showed a largely similar, though less pronounced, effect on leaf spectral properties to that of A. tsugae.

Widespread occurrence and spatial distribution of glyphosate, atrazine, and neonicotinoids pesticides in the St. Lawrence and tributary rivers

The occurrence and spatial distribution of selected pesticides were investigated along a 200-km reach of the St. Lawrence River (SLR) and tributaries in Quebec, Canada. Surface water samples (n = 68) were collected in the summer 2017 and analyzed for glyphosate, atrazine (ATZ), 8 systemic insecticides (acetamiprid, clothianidin, dinotefuran, fipronil, imidacloprid, nitenpyram, thiacloprid, and thiamethoxam) and some metabolites. Overall, 99% of the surface water samples were positive to at least one of the targeted pesticides. The most recurrent compounds were glyphosate (detection frequency: 84%), ATZ (82%), thiamethoxam (59%), desethylatrazine (DEA: 47%), and clothianidin (46%). Glyphosate displayed variable levels (4–3,000 ng L−1), with higher concentrations in south tributaries (e.g., Nicolet and Yamaska). In positive samples, the sum of ATZ and DEA varied between 5 and 860 ng L−1, and the sum of 6 priority neonicotinoids between 1.5 and 115 ng L−1. From Repentigny to the Sorel Islands, the spatial distribution of pesticides within the St. Lawrence River was governed by the different upstream sources (i.e., Great Lakes vs. Ottawa River) due to the limited mixing of the different water masses. Cross-sectional patterns revealed higher concentrations of glyphosate and neonicotinoids in the north portions of transects, while the middle and south portions showed higher levels of atrazine. In Lake St. Pierre and further downstream, cross-sections revealed higher levels of the targeted pesticides near the southern portions of the SLR. This may be due to the higher contributions from south shore tributaries impacted by major agricultural areas, compared to north shore tributaries with forest land and less cropland use. Surface water samples were compliant with guidelines for the protection of aquatic life (chronic effects) for glyphosate and atrazine. However, 31% of the samples were found to surpass the guideline value of 8.3 ng L−1 for the sum of six priority neonicotinoids.

Efficacy of Two Systemic Insecticides With Stem Gall Wasp, Zapatella davisae (Hymenoptera: Cynipidae) on Black Oak.

Black oak, Quercus velutina Lamarck, is the dominant deciduous tree on Cape Cod, Nantucket, and Martha's Vineyard, Massachusetts, and in recent years it has experienced widespread mortality and severe canopy loss due to infestations of a stem gall wasp, Zapatella davisae Buffington and Melika (Hymenoptera: Cynipidae). A single application of systemic insecticides emamectin benzoate and imidacloprid was found to reduce or prevent further accumulation of Z. davisae damage on infested black oak during a 1-yr trial.

Lobate lac scale, Paratachardina pseudolobata (Hemiptera: Keriidae), in Hawaii's urban landscape: Hosts and management

AbstractThe lobate lac scale,Paratachardina pseudolobataKondo &amp;amp; Gullan, is a recent insect invader to Hawaii that was first found in October 2012 on Oahu, Hawaii. It infests young branches of woody plants (usually less than 2 cm in diameter), forming a mass that appears as a dark crust, resulting in an unhealthy appearance, defoliation of leaves, and death of some plant species. This insect has infested many native and non-native plant species on Oahu, and the number of infested plant species is increasing. Our recent survey results, reported in this article, revealed 28 new host plant species in addition to 83 host species that we had reported previously, making 111 host plant species in Oahu's urban landscape. Efficacy and longevity of preventive treatment using the systemic insecticides imidacloprid and emamectin benzoate, delivered through trunk injection, against lobate lac scale on Chinese banyan,Ficus microcarpa, and curative treatment using imidacloprid on weeping banyan,Ficus benjamina, were evaluated. Forty-five Chinese banyans and 10 weeping banyans were included in this study. Our findings suggest that imidacloprid delivered via trunk injection is effective in preventing lobate lac scale infestation for at least 22 months post-treatment, and also in reducing lobate lac scale infestation curatively for at least 20 months post-treatment. This study provides an update on lobate lac scale's host species in Hawaii's urban landscape, and an effective preventive and curative management strategy against this pest.

Assessment of the performance of some new insecticides for the control of the vine mealybug Planococcus ficus in a Tunisian vineyard

Mealybugs (Hemiptera: Pseudococcidae) cause major economic losses in many Tunisian grapegrowing areas. In an attempt to improve management strategies for the Vine Mealybug (VM) Planococcus ficus (Signoret), three insecticides, imidacloprid, Prev-Am® and spirotetramat, were evaluated for their effect on this insect on vine, with reference to methidathion. The systemic insecticide spirotetramat (Movento® 150 OD) provided the greatest control performance of the VM populations, compared to the contact insecticide methidathion, the systemic insecticide imidacloprid applied through furrow irrigated system, and to Prev-Am®, a new contact biopesticide. Three weeks after treatment, VM eggs and adult females were missing from spirotetramat-treated vines. Additionally, spirotetramat supplied a long-residual activity against VM populations and prevented further spread of these insects on vine leaves. Therefore, this new systemic insecticide could be incorporated in an Integrated Pest Management program for VM control in Tunisian vineyards. Despite its short-residual activity, Prev-Am® was shown to be more effective than both methidathion and imidacloprid, mainly on VM eggs and L3 nymphs, and resulted in the highest level of VM L1-L2 nymph decrease on vine trunks. Hence, this biopesticide might prove useful for VM management in vineyards.

Productivity enhancement of lentil (Lens culinaris Medik) through integrated crop management technologies

The frontline demonstrations were conducted on 45 farmer's fields in the five adopted villages of Bundelkhand region of Madhya Pradesh during rabi seasons of 2010 to 2012 in rainfed condition on medium to heavy soil with medium fertility status under blackgram − lentil cropping system to study the productivity enhancement of lentil through improved production technologies. The results revealed that integrated crop management practices reduced the wilt disease incidence in lentil from 20.7 to 4.9 per cent (76.3 per cent), spray of systemic insecticide imidacloprid 17.8 SL reduced the aphid population from 17.0 to 7.6 per plant (55.2 per cent) in various years. The average 22- 27 pods per plant were obtained under improved technology over to farmer's practices (17-21). The seed yields of lentil under improved technology ranged between 5.02 to 10.5 q ha-1 with average yield of 8.63 q ha-1 which was 30.5 per cent higher over the farmer's practice (6.61 q ha-1). However, maximum average net returns (Rs.21666 ha-1) as well as benefit cost ratio (3.47) were recorded under improved technologies as compared to farmer's practice (Rs.15278 ha-1 and 2.96).

Long-Term Effects of Imidacloprid on Eastern Hemlock Canopy Arthropod Biodiversity in New England

Abstract The systemic insecticide imidacloprid is commonly used to protect trees against attack by the Adelges tsugae (Hemlock Woolly Adelgid [HWA]), an invasive pest that threatens Tsuga canadensis (Eastern Hemlock) and T. caroliniana (Carolina Hemlock) in eastern North America. Although there have been some studies documenting the short-term (1–3 years) impact of imidacloprid on non-target arthropods in hemlock systems, almost nothing is known about the impact over longer time scales. Here, using a set of trees which were experimentally treated 3 and 9 years prior to this study, we found that while the impact of imidacloprid on HWA may be approaching the limits of detection and efficacy on trees treated 9 years ago, there is still an intermittently detectable impact on HWA density. Similarly, 9 years after application there is a subtle but detectable increase in arthropod richness and a shift in canopy-arthropod community composition. Results from the 3-year treated trees were, however, ambiguous, but m...

A preliminary study of the content and distribution of pesticide residues in soil samples from the Kathmandu valley, Nepal .

The increasing use of pesticides for agricultural production is causing soil pollution problems in different parts of Nepal. Uncontaminated agricultural soils are of great importance as they have a direct impact on food security and human health. The objective of this study was to investigate the quality and quantity of pesticides in soil samples from districts near the capital city of Kathmandu, from where fruit and vegetables are brought to the city for consumption. A questionnaire survey was carried out in four districts around Kathmandu city to investigate the types of pesticides that are most commonly used in these districts. A total of 15 soil samples were taken at a depth of 10 cm and four complete soil profiles were sampled at three different depths (10 cm, 30 cm and 50 cm) on the farms of those who were interviewed. A total of four replicates of each soil sample were extracted and analyzed. The pH, soil texture and organic carbon content of the soil samples were analyzed to understand the general soil characteristics. The QuEChERS method used for the analysis of food samples was modified and applied to the soil samples. An HPLC-MS/MS was used for the qualification and quantification of the pesticide residues in the soil samples. The questionnaire survey revealed that carbendazim, chlorpyrifos-methyl, parathion-methyl, imidacloprid, metalaxyl, dimethoate, omethoate and dichlorvos were the most commonly used pesticides in the area studied. The chemical analysis showed that soil samples from all the districts except Kathmandu city were contaminated with various pesticides. The soil samples collected at the depth of 10 cm were found to be contaminated with the fungicide carbendazim and the insecticide chlorpyrifos-methyl at rates of up to 0.038 mg kg&lt;sup&gt;-1&lt;/sup&gt; and the systemic insecticide imidacloprid was found at up to 0.016 mg kg&lt;sup&gt;-1&lt;/sup&gt;. The study of soil samples taken at different depths (10 cm, 30 cm and 50 cm) showed that pesticides were homogenously distributed with soil depth. The recovery between 77.5-112%, linearity between 0.01 mg kg&lt;sup&gt;-l&lt;/sup&gt; - 2 mg kg&lt;sup&gt;-l&lt;/sup&gt; with correlation factors R2 higher than 0.99 and LOQ between 0.2 µg kg&lt;sup&gt;-1&lt;/sup&gt;- 6.25 µg kg&lt;sup&gt;-l&lt;/sup&gt; were found. Some samples were contaminated with parathion-methyl, a highly carcinogenic organophosphorous insecticide, even though these pesticides had already been banned. For the first time, this study provides information about soil contamination levels due to pesticides in Central Nepal and shows that further research and information campaigns for farmers are necessary.

First Record of a Native Heteropteran Preying on the Introduced Eucalyptus Pest,Thaumastocoris peregrinus(Hemiptera: Thaumastocoridae), in Brazil

The bronze bug, Thaumastocoris peregrinus Carpintero & Dellape, 2006 (Hemiptera: Thau mastocoridae), is a threat to commercial plan tations of Eucalyptus (Myrtales: Myrtaceae) in Argentina, Australia, Brazil, Chile, Kenya, South Africa, Uruguay and Zimbabwe (Carpintero & Dellape 2006; Martinez & Bianchi 2010; Nadel et al. 2010; Noack et al. 2011). Thaumastocoris peregrinus is a typically gregarious sucking insect with nymphs and adults of different generations overlapping throughout the year (Noack & Rose 2007; Wilcken et al. 2010). Adults are about 3 mm long, with a flattened light brown body (Noack et al. 2011). Females lay about 60 black eggs usually in clusters on leaves, branches and at the base of host plant trunks (Jacobs & Neser 2005; Noack & Rose 2007). The high reproductive capacity of T. peregrinus facilitates rapid colonization and infestation. The pest initially causes silvering of the leaves, which subsequently shift to brown and red coloration, and this makes the trees look bronzed (Jacobs & Neser 2005). These canopy coloration changes al low identification of the presence of T. peregrinus before leaf drop and plant death occurs. The mechanism that induces plant death is not known, but the symptoms of feeding by nymphs and adults of T. peregrinus on eucalyptus leaves are similar to those of Cardiaspina psyllids (He miptera: Psyllidae) (Woodburn & Lewis 1973; Crawford & Wilkens 1996). The psyllids insert their stylets through the apertures of stomata to reach food supply causing cell degeneration of the mesophyll tissue that resembles the process of leaf senescence (Crawford & Wilkens 1996). The use of the systemic insecticide imidaclo prid injected into the trunk has been shown effec tive to control T. peregrinus in field tests (Noack et al. 2009), but chemical control in forest planta tions is questionable due to potentially adverse environmental impacts and high costs (Zanuncio et al. 1994). Thus, biological control, such as the introduction or enhancement of populations of predators, parasitoids and pathogens, is impor tant (Silva 2000). Pest control with natural en emies is growing in popularity; and heteropteran predators are important agents of biological con trol in integrated pest management programs (Molina-Rugama et al. 1997; Lemos et al. 2003). Here, we report the occurrence of the preda tory stinkbug, Supputius cincticeps Stal, 1860 (Hemiptera: Pentatomidae), nymphs feeding on T. peregrinus nymphs and adults in Lages, Santa Catarina State, Brazil. Nymphs and eggs of S. cincticeps, and nymphs and adults of T. peregri nus were found on Eucalyptus viminalis Labill (Myrtales: Myrtaceae) trees at the Centro de Ciencias Agroveterinârias of the Universidade do Estado de Santa Catarina (CAV-UDESC) (Fig. 1) in the urban perimeter of Lages, Santa Cata rina State, Brazil (27°47'S, 50°18'W) in January and February 2011. There were high densities of eggs, nymphs and adults of T. peregrinus on the eucalypts. The infested trees exhibited silver colored leaves (Fig. 1), but defoliation was not high. Damage by Gonipterus scutellatus Gyllen hal, 1833 (Coleoptera: Curculionidae) weevils to E. viminalis leaves was also observed (Fig. 2), in dicating the coexistence of the bronze bug with other eucalyptus pests, causing multifaceted and potentially more severe damage. Adults of T. peregrinus were collected, stored in 70% alcohol and observed under stereomicro

Laboratory Evaluation of Oral Treatment of Rodents with Systemic Insecticides for Control of Bloodfeeding Sand Flies (Diptera: Psychodidae)

The purpose of this study was to evaluate the efficacy of oral treatment of rodents with diets containing the systemic insecticides ivermectin, abamectin, imidacloprid, or spinosad, to control bloodfeeding sand flies. We found that diets containing concentrations higher than 10 mg/kg abamectin were not palatable to rodents, and that a diet containing 10 mg/kg abamectin (a palatable concentration) did not cause 100% mortality of bloodfeeding sand flies. Treatment of rodents with imidacloprid was effective for less than 3 days post-treatment. Treatment of rodents with diets containing 20 mg/kg ivermectin or 5000 mg/kg spinosad caused 100% mortality of bloodfeeding sand flies for at least 1 week. The efficacy of ivermectin and spinosad also were not reduced when combined with the fluorescent tracer dye rhodamine B in a single diet. We also did not observe significant benefits by increasing the feeding period of the rodents from 3 to 6 or 9 days. We conclude that ivermectin and spinosad are effective as rodent systemic insecticides against bloodfeeding sand flies, and suggest that weekly treatment of wild rodent reservoirs of Leishmania major with bait containing one of these systemic insecticides could be a useful tool as part of a sand fly control program.

Differences in ecological impacts of systemic insecticides with different physicochemical properties on biocenosis of experimental paddy fields

The environmental risks of pesticides are typically determined by laboratory single-species tests based on OECD test guidelines, even if biodiversity should also be taken into consideration. To evaluate how realistic these assessments are, ecological changes caused by the systemic insecticides imidacloprid and fipronil, which have different physicochemical properties, when applied at recommended commercial rates on rice fields were monitored using experimental paddy mesocosms. A total of 178 species were observed. There were no significant differences in abundance of crop arthropods among the experimental paddies. However, zooplankton, benthic and neuston communities in imidacloprid-treated field had significantly less abundance of species than control and fipronil fields. Significant differences in abundance of nekton community were also found between both insecticide-treated paddies and control. Influences on the growth of medaka fish were also found in both adults and their fries. Both Principal Response Curve analysis (PRC) and Detrended Correspondence Analysis (DCA) showed the time series variations in community structure among treatments, in particular for imidacloprid during the middle stage of the experimental period. These results show the ecological effect-concentrations (LOEC~1μg/l) of these insecticides in mesocosms, especially imidacloprid, are clearly different from their laboratory tests. We suggest that differences in the duration of the recovery process among groups of species are due to different physicochemical properties of the insecticides. Therefore, realistic prediction and assessment of pesticide effects at the community level should consider not only the sensitivity traits and interaction among species but also the differences in physicochemical characteristics of each pesticide.

Potential risks of systemic imidacloprid to parasitoid natural enemies of a cerambycid attacking Eucalyptus

A community of insect herbivores has established on eucalyptus species in California following their introduction from Australia. A number of the species are under complete or partial biological control. A response to introduction of additional pest species into the complex has been the application of systemic insecticides to infested trees. Natural enemies that have been introduced to control the various pest species feed on the nectar of treated trees, and thus may be affected by these pesticides. In this study, Eucalyptus rudis trees were treated at label rates with the neonicotinoid systemic insecticide imidacloprid and nectar sampled at 5 months post-treatment during the spring bloom. The concentration of imidacloprid and its toxic metabolites in nectar was measured by ELISA at 660 ppb. Adults of the encyrtid egg parasitoid Avetianella longoi that were fed floral nectar collected from treated trees had significantly lower survival and reproductive fitness than adults fed nectar from untreated trees. In feeding bioassays, in which the adults were fed a range of concentrations of imidacloprid in sugar water, the LC 50 for A. longoi was 212 ppb imidacloprid. Bioassays were also conducted with the braconid larval parasitoid, Syngaster lepidus. The LC 50 for S. lepidus was 288 ppb imidacloprid. The insecticide appears to be concentrating in the nectar at higher levels than reported from other plant species and at concentrations exceeding the LC 50 for two important parasitoids. If tree treatments become widespread as a result of continual introductions of new eucalypt herbivores, established biological control programs could be at significant risk.

Efficacy and Uptake of Soil-Applied Imidacloprid in the Control of Asian Citrus Psyllid and a Citrus Leafminer, Two Foliar-Feeding Citrus Pests

The systemic neonicotinoid insecticide imidacloprid, Admire Pro, was applied to 3- and 4-yr-old nonbearing 'Rio Red' grapefruit, Citrus x paradisi Macfad., trees in 2006 and 2007, respectively, to determine its effects in the control of two major citrus pests, the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), and a citrus leafminer Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae). Young flush shoots were randomly collected weekly for 13 and 11 wk in 2006 and 2007, respectively, to determine the infestation levels and densities of immature stages of both Asian citrus psyllid and P. citrella. Additional flush shoot samples were collected in 2007 and titers of imidacloprid in leaf tissue were determined using an enzyme-linked immunosorbent assay. Soil application of imidacloprid significantly reduced the infestation levels and densities of both pests on flush shoots, starting from the second week post application. The effects of the neonicotinoid insecticide were similar in both years. Analysis of imidacloprid concentration in leaf tissue showed a gradual increase during the first 3 wk, and titers remained well above 200 ppb for 11 wk postapplication. Significant positive correlations were obtained between imidacloprid titers in leaf tissue and the percentage of control levels achieved for both pests. A high level of suppression of both P. citrella and Asian citrus psyllid populations on citrus trees was associated with imidacloprid titer in leaf tissue >200 ppb, which was reached 2 wk after soil treatment. Although soil application of imidacloprid did not provide rapid knockdown of Asian citrus psyllid and P. citrella populations, it resulted in chronic residues in leaf tissue and long-term suppression of both pests.