Insecticide Treatments Research Articles

Plague mitigation for prairie dog and black-footed ferret conservation: Degree and duration of flea control with 0.005% fipronil grain bait

Sylvatic plague, a primarily flea-borne zoonosis, is a significant threat to prairie dogs (Cynomys spp., PDs) and their specialized predators, endangered black-footed ferrets (Mustela nigripes, BFFs). Host-fed fipronil baits have proven effective in controlling fleas on PDs for the purposes of plague mitigation and BFF conservation. Currently, annual treatments are the norm. We tested the long-term efficacy of fipronil bait treatments with black-tailed PDs (C. ludovicianus, BTPDs) and BFFs in South Dakota, USA. During 2018–2020, we provided BTPDs on 21 sites with grain bait formula, laced with 0.005% fipronil (50 ​mg/kg); 18 non-treated sites functioned as baselines. In 2020–2022, we live-trapped, anesthetized, and combed BTPDs for fleas. Flea control was significant for at least 639–885 days. Flea abundance on the treated sites was < 0.5 fleas/BTPD for ∼750 days. During 2020–2022, we sampled BFFs for fleas on 4 BTPD colonies treated with fipronil grain bait and 8 non-treated colonies. Flea control was significant with BFFs, but flea abundance began to rebound within ∼240 days post-treatment. When feasible, the combination of insecticide treatments, such as fipronil baits, and BFF vaccination against plague provide a “two-pronged” protection approach for these endangered carnivores. If fipronil bait treatments are less effective with predatory BFFs than PDs, as found herein, the “two-pronged” approach might be used to protect BFFs and biennial fipronil bait treatments might be used to protect PDs. If BFF vaccination is not possible, or few BFFs can be vaccinated, annual fipronil bait treatments might be used as a precaution to protect BFFs. Flea densities might be surveyed to determine when/where more frequent treatments seem useful.

Preliminary investigations of the main Flavescence dor&amp;eacute;e vector Scaphoideus titanus and its first record in Kosovo

Scaphoideus titanus Ball is a major pest of grapevine in Europe, being the main vector of Flavescence dor&amp;eacute;e phytoplasma (FDp). The North American grapevine leafhopper was identified in neighboring countries, however, the FDp vector was not recorded and there is no available data on its presence in Kosovo. In 2021, initial investigations were conducted and field surveys were carried out in the region of Rahovec in order to evaluate the presence of S. titanus in Kosovarian vineyards. The survey was established in seventeen vineyards in different locations and grapevine varieties. In the middle of June, in each vineyard chosen for investigation were settled yellow sticky traps for surveying and sampling of leafhoppers. All plantations were subjected to fungicide treatment and no insecticide treatment was applied for S. titanus. The captures on the yellow sticky traps indicated that the North American grapevine leafhopper was present in Kosovo. Its population was different in investigated vineyards. Of the seventeen vineyards monitored, in twelve of them was captured the FDp vector, two sticky traps were damaged, and in three vineyards was not captured any specimen of Scaphoideus titanus. An average, of two up to forty-nine specimens of S. titanus per trap were collected over the surveyed period from the beginning of June until the end of September 2021. These results show only the distribution of S. titanus in the surveyed area. Furthermore, the presence of the North American grapevine leafhopper in Kosovo is an alert for urgent phytosanitary control of the quarantine phytoplasma Flavescence dor&amp;eacute;e (FD).

Pest-Defender Abundance under Evaluation of Ecofriendly Insecticides against Major Insect Pests of Rice in Eastern Uttar Pradesh Conditions

The present study was analyzed the abundance of pest: defender ratio (P:D) over check plot under evaluation of ecofriendly insecticides against the major insect pests of rice in eastern Uttar Pradesh conditions for two consecutive years (2014 and 2015) at farmer field of district Deoria under the supervision of Department of Entomology, B.R.D.P.G. College, Deoria, Uttar Pradesh, India. There were 10 treatments (09 insecticides + 01 check) evaluated under randomized block design (RBD) by transplanting method of rice cultivation on localized popular rice cultivar Samba Mahsuri (BPT-5204). The insecticide treatments comprise 9 insecticides (CartapHcl, 50 SP, Indoxacarb 14.5 SC, Imidacloprid 17.8 SL, Chlorpyriphos 20 EC, Thiamethoxam 25 WG, Chlorantraniliprole 18.5 SC, Azadirachtin (Neem Oil) 0.03 EC, Bacillus thuringiensis kurstaki (Btk) 3.5 WP, and combination of Neem Oil 0.03 EC + Btk 3.5 WP).This evaluation was observed most effective ecofriendly insecticides concerned to lowest pest: defender ratio (P:D), lowest abundance of pest: defender ratio (P:D) over check plot, and highest yield. The inferences of pest: defender abundance ratio (P:D) over check plot and yield of rice crop were based on non-significant ecofriendly insecticides for the lowest pest: defender ratio (P:D). There were 2 insecticides (Neem Oil + Btk and Imidacloprid) inference non-significant for the lowest abundance of pest: defender ratio (P:D) over check plot. The mean ranking and inference of abundance of pest: defender ratio (P:D) over check was similar to the inference of non-significant ecofriendly insecticides for lowest pest: defender ratio (P:D) as, Neem Oil + Btk and Imidacloprid respectively.

Infestation Suppression under Evaluation of Ecofriendly Insecticides against Major Insect Pests of Rice in Eastern Uttar Pradesh Conditions

The present study was undertaken to analysis the suppression of infestation over check plot under evaluation of ecofriendly insecticides against major insect pests of rice in eastern Uttar Pradesh conditions for the two consecutive years (2014 and 2015) at farmer field of district Deoria under the supervision of Department of Entomology, B.R.D.P.G. College, Deoria, Uttar Pradesh, India. There were 10 treatments (09 insecticides + 01 check) evaluated under randomized block design (RBD) by transplanting method of rice cultivation on localized popular rice cultivar Samba Mahsuri (BPT-5204). The insecticide treatments comprise 9 insecticides (CartapHcl, 50 SP, Indoxacarb 14.5 SC, Imidacloprid 17.8 SL, Chlorpyriphos 20 EC, Thiamethoxam 25 WG, Chlorantraniliprole 18.5 SC, Azadirachtin (Neem Oil) 0.03 EC, Bacillus thuringiensis kurstaki (Btk) 3.5 WP, and combination of Neem Oil 0.03 EC + Btk 3.5 WP). This evaluation was observed most effective ecofriendly insecticides concerned to lowest infestation, highest suppression of infestation over check plot, and highest yield. The inferences of suppression over check plot and yield of rice crop were based on non-significant ecofriendly insecticides for lowest infestation. There were 2 insecticides (CartapHcl and Imidacloprid) inference non-significant for highest suppression of infestation over check. There were 3 insecticides (CartapHcl, Imidacloprid, and Neem Oil + Btk) inference non-significant for lowest infestation and highest yield respectively. The mean ranking and inference of suppression over check were similar to inference of non-significant ecofriendly insecticides for lowest infestation as, Imidacloprid, CartapHcl, and Neem Oil + Btk respectively.

Evolutionary trade-offs associated with copy number variations in resistance alleles in Culex pipiens mosquitoes

Organophosphate and carbamate insecticides have largely been used worldwide to control mosquito populations. As a response, the same amino acid substitution in the ace-1 gene (G119S), conferring resistance to both insecticides, has been selected independently in many mosquito species. In Anopheles gambiae, it has recently been shown that the G119S mutation is actually part of homogeneous duplications that associate multiple resistance copies of the ace-1 gene. In this study, we showed that duplications of resistance copies of the ace-1 gene also exist in the Culex pipiens species complex. The number of copies is variable, and different numbers of copies are associated with different phenotypic trade-offs: we used a combination of bioassays and competition in population cages to show that having more resistance copies conferred higher resistance levels, but was also associated with higher selective disadvantage (or cost) in the absence of insecticide. These results further show the versatility of the genetic architecture of resistance to organophosphate and carbamate insecticides around the ace-1 locus and its role in fine-tuned adaptation to insecticide treatment variations.Graphical

YIELD AND QUALITY OF SPRING CAMELINA SEEDS IN THE CONDITIONS OF NORTHERN KAZAKHSTAN

The results of the studies on the effect of the use of biological and chemical preparations sown against the background of different sowing dates on the structure of the crop and the quality of seeds of camelina are reflected. The studies were carried out in 2018-2020 on the experimental plot of NJSC " S. Seifullin Kazakh Agrotechnical University" in Akmola region. As a result of the research, it was found that the highest in terms of yield structure were options with a sowing date of May 25-30. The maximum number of pods on average was noted in the late sowing options, both with the insecticidal (75.2 pcs/plant) and fungicidal (74.7 pcs/plant) treatment of crops sown with Extrasol treated seeds. The number of seeds in the pod did not depend on the combined use of the biological and chemical preparations, but had a slight increase in that indicator when sown at a later date (by 8.6 - 1.1%). The yield of spring camelina slightly changed depending on the use of each preparation separately and exceeded the control by 0.11-0.34 t/ha when sown on May 15-20 and by 0.54-0.76 t/ha when sown on May 25-30. Variants using Extrasol + Piktor significantly increased the yield of camelina seeds. According to the oil content, there was a slight increase in the fat content in the variants treated with the drugs, compared with the control. However, the use of the Extrasol + Piktor complex increased the oil content to 39.74 - 40.05%, which was higher than in the control and in the variant of the combined use of Extrasol with an insecticide and separately. The same pattern was noted for the protein content in the seeds.

Foliar Antibiotic Treatment Reduces Candidatus Liberibacter asiaticus Acquisition by the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae), but Does not Reduce Tree Infection Rate.

Huanglongbing (HLB), or citrus greening, is the most destructive disease of cultivated citrus worldwide. Candidatus Liberibacter asiaticus (CLas), the putative causal agent of HLB, is transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). In Florida, D. citri was first reported in 1998, and CLas was confirmed in 2005. Management of HLB relies on the use of insecticides to reduce vector populations. In 2016, antibiotics were approved to manage CLas infection in citrus. Diaphorina citri is host to several bacterial endosymbionts and reducing endosymbiont abundance is known to cause a corresponding reduction in host fitness. We hypothesized that applications of oxytetracycline and streptomycin would reduce: CLas populations in young and mature citrus trees, CLas acquisition by D. citri, and D. citri abundance. Our results indicate that treatment of citrus with oxytetracycline and streptomycin reduced acquisition of CLas by D. citri adults and emerging F1 nymphs as compared with that observed in trees treated only with insecticides, but not with antibiotics. However, under field conditions, neither antibiotic treatment frequency tested affected CLas infection of young or mature trees as compared with insecticide treatment alone (negative control); whereas trees enveloped with mesh screening that excluded vectors did prevent bacterial infection (positive control). Populations of D. citri were not consistently affected by antibiotic treatment under field conditions, as compared with an insecticide only comparison. Collectively, our results suggest that while foliar application of oxytetracycline and streptomycin to citrus reduces acquisition of CLas bacteria by the vector, even high frequency applications of these formulations under field conditions do not prevent or reduce tree infection.

Response of foliage- and ground-dwelling arthropods to insecticide application: Early step for cotton IPM in the Brazilian semiarid

Foliage- and ground-dwelling arthropods provide ecosystem services, including decomposition and biological control of agricultural pests. Despite this, there is little information on the ground-dwelling arthropod community associated with cotton crops and about their role under pest control practices. Identifying these communities and their preservation would assist smallholder cotton growers in considering an Integrated Pest Management (IPM) approach to pest control. In this context, the strategy of using selective- or broad-spectrum insecticides (both applied only once the pests reached an economic threshold) was assessed using field plots set up within non-Bt cotton structured refuge of a grower field measuring the response of both foliage- and ground-dwelling arthropods and yield. The abundance, species richness, dominance indices, and foliage-dwelling predators and pest species and ground-dwelling predators and decomposers were compared between untreated and insecticide treatments, as was the crop yield. In response to pest monitoring, insecticides were applied 5 and 3 times during the 2018 and 2020 growing seasons, respectively. In 2018 and 2020, 16 and 12 foliage-dwelling predator arthropods and 43 and 47 ground-dwelling predator and decomposer arthropods were collected, respectively. During the 2018 season, broad-spectrum insecticide applications reduced the abundance of foliage-dwelling predators, but had no significant impact on the ground-dwelling community. Principal response curves (PRC) indicated a negative impact of broad-spectrum insecticides only on the foliage-dwelling community, particularly among the Formicidae and Araneae species. Insecticide applications in the 2020 season were only required at the end of the crop season and did not significantly influence the foliage- or ground-dwelling communities. The selective insecticide regime yielded as well as the broad-spectrum insecticide regimes higher yielded than untreated plots. These results demonstrated to the small landholders engaging conservation biological control for the first time, the advantages of an IPM approach to pest management.

Identification of Distinct Endosymbionts of Whiteflies-infesting Cassava (Manihot esculenta Crantz), using Diagnostic PCR and Sanger Sequencing

The study was conducted during March–December 2021 in Thiruvananthapuram, Kerala for the identification of distinct endosymbionts of cassava whiteflies (Bemisia tabaci (Gennadius) and Aleurodicus dispersus (Russell). Endosymbiotic bacteria found in whiteflies have been reported to interact and provide specific advantages to the hosts and they can be one of the reasons for whiteflies’ insecticidal resistance. In the present study, endosymbiotic bacteria were isolated from the insects, allowed to grow in media after insecticidal treatments and after observing colony morphology, distinct bacterial colonies were sub-cultured and selected for further molecular identification procedures. PCR analysis was carried out for bacteria using 16S rRNA primer, with an annealing temperature of 49°C and yielded fragments at 1500 bp. Based on the sequencing report the observations were that the culturable endosymbionts Providencia present in B. tabaci is resistant to chlorpyrifos and Paenibacillus alvei present in A. dispersus is resistant to imidacloprid and chlorpyrifos. Clostridium senegalens and Acinetobacter are found in control populations of Bemisia and Aleurodicus respectively.The sequences were submitted to NCBI and the accession numbers obtained were OP303253, OP303256, OP303254 and OP295124. Also, through diagnostic PCR using specific bacterial primers, presence of Portiera aleyrodidarum at fragment length of 1000 bp and Wolbachia at 650 bp in B. tabaci and Rickettsia at fragment length of 800 bp in A. dispersus are confirmed. The study could identify bacteria which are decisive in their presence and activity in whiteflies.

The Chickpea Pod Borer, Helicoverpa armigera (Hübner): Yield Loss Estimation and Biorational Insecticide Assessment in Morocco

Helicoverpa armigera (Hübner) is considered one of the most destructive insect pests of chickpea crops in Morocco; however, the extent of the yield loss it causes in Morocco is unknown. This study assessed the yield losses and pod damage caused by the chickpea pod borer H. armigera on four improved Kabuli varieties with insecticide treatment at two different locations. The second part of this study investigated the contact and systemic toxicity of different biological and selective insecticides in the control of the larvae of H. armigera under controlled laboratory and field conditions. The results demonstrated that the yield losses due to H. armigera infestation were in the range of 14.3–31.2%. Chickpea pod borer infestation resulted in losses in the total seed weight for all the chickpea varieties, with the highest yield losses for Zahor (F84-145C) being 31.18% at Allal Tazi followed by Farihane (F84-79C) with 27.38% at the Marchouch station. Emamectin benzoate at 250 g/ha showed a high level of larvicidal and systemic activity, with 100% mortality 24 h after application. Indoxacarb at 25 mL/100 L water, recorded 100% and 92% larval mortality in larvicidal and systemic activity, 48 h after application, respectively. The bioinsecticide spinosad in 30 mL/100 L water resulted in 88% and 92% larval mortality in contact and systemic activity, 48 h after application, respectively. Under field conditions, the two insecticides emamectin benzoate and indoxacarb were found to be highly effective in reducing the H. armigera larval population and pod damage after two sprays. Both insecticide treatments significantly increased grain yields compared with the untreated plots, with 25.8% and 24.5%, respectively. These findings showed that two applications of the selective chemical insecticides emamectin benzoate or indoxacarb with a week interval starting from the pod setting could be incorporated into the management strategies for the control of H. armigera.

Impact of Planting Date and Insecticide Application Methods on Melanaphis sorghi (Hemiptera: Aphididae) Infestation and Forage Type Sorghum Yield.

Studies on the management of the invasive Melanaphis sorghi are essential to refining integrated pest management strategies against M. sorghi in forage sorghum in the USA. The objective of this study was to determine the impact of planting date (early planting and late planting) and in-furrow and foliar insecticide application of flupyradifurone, on M. sorghi infestation and forage sorghum yield in Tifton, Georgia and Florence, South Carolina, USA, in 2020 and 2021. Early planted sorghum supported slightly higher aphid density and severity of infestation as evident in the greater cumulative insect days values in the early planted sorghum at both Florence and Tifton in 2020 and 2021. A single foliar application reduced aphid infestations below the threshold level of 50 aphids per leaf. In contrast, in-furrow insecticidal application in selected plots at both locations significantly suppressed M. sorghi density to near-zero levels. Yield results in Florence in 2020 showed that sorghum yield was over 50% greater in early planted plots compared to late planted plots. Both insecticide treatments (foliar and in-furrow) resulted in significantly higher yield than untreated plots. These data indicate that early planting coupled with in-furrow and foliar insecticide applications can suppress M. sorghi infestations and improve silage production in forage sorghum in the USA.

Management of Melanaphis sorghi (Hemiptera: Aphididae) in grain sorghum with early planting and in-furrow flupyradifurone application

Melanaphis sorghi is a key pest of sorghum production across the southern USA, where it causes serious damage that can lead to 100% grain yield loss in severe situations. Studies aiming to refine IPM strategies are crucial to improve management of this invasive pest. Here, the authors investigated the impact of planting date and insecticide application methods, including in-furrow vs. foliar applications, on M. sorghi infestation and grain sorghum yield. Field trials with four insecticide treatments (untreated, flupyradifurone in-furrow at 117 g/ha, flupyradifurone in-furrow at 146 g/ha, and flupyradifurone foliar at 73 g/ha) and two planting dates (mid-April to early May = early planting and late May to early June = late planting) were conducted on grain sorghum at Tifton, Georgia and Florence, South Carolina, in 2020 and 2021. Generally, early planted sorghum supported higher aphid density and severity of infestation as evident in the greater cumulative insect days in early planted sorghum in both Florence and Tifton. While a single foliar insecticide application immediately reduced infestations below the economic threshold, the lower rate in-furrow insecticide application significantly suppressed aphid density to near zero levels. These results suggest that foliar insecticide applications suppressed aphid densities, but were less consistent compared to in-furrow applications. Early planting dates and in-furrow insecticide treatments resulted in highest grain yield in both study locations. These data strongly suggest that planting early and using an in-furrow insecticide is the most consistent way to suppress M. sorghi infestations and improve grain yield in sorghum production in southern USA.

Participatory development of practical, affordable, insecticide-treated mosquito proofing for a range of housing designs in rural southern Tanzania

BackgroundInsecticidal mosquito-proof netting screens could combine the best features of insecticide-treated nets (ITNs) and indoor residual spraying (IRS), the two most important front line vector control interventions in Africa today, and also overcome the most important limitations of these methods. This study engaged members of a rural Tanzanian community in developing and evaluating simple, affordable and scalable procedures for installing readily available screening materials on eave gaps and windows of their own houses, and then treating those screens with a widely used IRS formulation of the organophosphate insecticide pirimiphos-methyl (PM).MethodsA cohort of 54 households recruited upon consent, following which the structural features and occupant demographics of their houses were surveyed. Indoor mosquito densities were surveyed longitudinally, for approximately 3 months before and over 5 months after participatory house modification and screening using locally available materials. Each house was randomly assigned to one of three study arms: (1) No screens installed until the end of the study (negative control), (2) untreated screens installed, and (3) screened installed and then treated with PM, the insecticidal activity of which was subsequently assessed using standard cone assays.ResultsAlmost all (52) recruited households participated until the end, at which point all houses had been successfully screened. In most cases, screening was only installed after making enabling structural modifications that were accepted by the enrolled households. Compared to unscreened houses, houses with either treated or untreated screens both almost entirely excluded Anopheles arabiensis (Relative reduction (RR) ≥ 98%, P < < 0.0001), the most abundant local malaria vector. However, screens were far less effective against Culex quinquefasciatus (RR ≤ 46%, P < < 0.0001), a non-malaria vector causing considerable biting nuisance, regardless of their treatment status. While PM did not augment household level protection by screens against either mosquito species (P = 0.676 and 0.831, respectively), 8 months after treatment it still caused 73% and 89% mortality among susceptible insectary-reared Anopheles gambiae following exposures of 3 and 30 min, respectively.ConclusionsParticipatory approaches to mosquito proofing houses may be acceptable and effective, and installed screens may be suitable targets for residual insecticide treatments.

Bio-Efficacy of Chemical Insecticides Against Defoliators Spodoptera litura and Achaea janata in Castor

Field experiments on bio-efficacy of chemical insecticides against defoliators Spodoptera litura and Achaea janata in castor was carried out at Main Oilseeds Research Station, Junagadh Agricultural University, Junagadh during consecutive three year i.e. 2015-16, 2016-17 and 2017-2018. All the treatments were significantly superior over untreated check. Results of the experiment indicated that lowest number of larvae per plant for S. litura and A. janata was recorded in the treatment of chlorantraniliprole 18.5 SC 0.006% (0.42 &amp; 0.22 larvae/plant), which was at par with the most of the insecticidal treatments except the treatment of poneem after three days of the first spray. More or less similar trend was observed after 7 and 14 days of first spray as well as 3,7 and 14 days after second spray. The highest net return was recorded in treatment of indoxacarb 14.5 SC 0.0073% (Rs. 31870/-) followed by the treatment chlorantraniliprole 18.5 SC 0.006% (Rs. 31080/-), spinosad 45 SC 0.009% (Rs.29240/-) and emamectin benzoate 5 % WG 0.002 % (Rs. 26232/-). Looking to the ICBR, the treatment of profenophos 40 % + cypermethrin 4% 44 EC noted the highest ICBR i.e. (1:11.60) followed by the treatment of chlorpyriphos 20 EC 0.05% (1: 10.20), indoxacarb 14.5 SC 0.0073% (1:9.30) and emamectin benzoate 5 % WG 0.002 % (1:7.30).

Diversity of Arthropods in Relation to Insecticide and Biopesticide Treatments in Okra

Present study was carried out during 2019 at the Vegetable Research Farm, Punjab Agricultural University, Ludhiana to generate information on diversity of invertebrates in okra. Study revealed that okra crop was harboured by 27 invertebrate species belonging to 11 orders and 26 families. Of these, maximum belonged to order Hemiptera followed by Coleoptera. Higher values of Shannon-Wiener index (1.75, 1.84) and Simpson’s index (0.26, 0.17), respectively were recorded for both phytophagous arthropods and predators in untreated control plots. This is followed by neem/ other insecticides treated plots. Imidacloprid lowered the arthropod population. Occurrence of predators and phytophagous arthropods revealed a significant positive correlation with temperature (r=+0.37 to +0.99) and relative humidity (r=+0.04 to +0.80) except for few hemipterans and coleopterans.

PS-3 Effects of Feeding Rates on Diflubenzuron Efficacy Against Filth Flies (Diptera: Muscidae) in Manure of Beef Heifers

Abstract The objective of the current study is to determine the effect of feeding rates on the efficacy of diflubenzuron against filth fly development in the manure of beef heifers. Twelve Angus × Hereford crossbred heifers (263 kg ± 16.2 kg BW) were used in a completely randomized design and heifers were assigned to a 2 x 2 factorial arrangement of treatments to evaluate the efficacy of diflubenzuron against horn flies Haematobia irritans (L.), stable flies Stomoxys calcitrans and house fly Musca domestica utilizing fecal bioassays. Treatments consisted of 2 insecticidal treatments [Diflubenzuron (DFB; 0.10 mg per kg BW) and no DFB (CNT)] in a factorial arrangement with 2 dietary fed regimens [1.5% BW alfalfa hay cubes and 3.0% BW alfalfa hay cubes]. All heifers receiving DFB treatments were dosed daily beginning on day 0 and continuing through day 7. Manure samples were collected daily prior to DFB offering and for 11 consecutive days. Efficacy calculations were developed utilizing standard filth fly fecal bioassays accounting for control performance. A treatment × day interaction (P ≤ 0.01) was observed for all species largely associated with the presence of DFB and associated with the on-set of efficacy (day 0–2) and wash out (day 8–10) of the product. Feeding regimen did not (P &amp;gt; 0.05) influence DFB performance against any of the fly species evaluated. Formulations of DFB appear to handle a wide range of animal intake scenarios under controlled situations.

Does IPPM bear fruit? Evaluating reduced‐risk insecticide programmes on pests, pollinators and marketable yield

Abstract Integrated pest and pollinator management (IPPM) has been touted as a novel approach to control pests while mitigating negative effects of insecticides on pollinators. In addition to non‐chemical approaches, IPPM programmes focus on insecticide treatments with low bee toxicity, threshold‐based applications and restricted timings to avoid sprays during pollinator foraging. However, the singular and combined effect of this approach on pollination services and pest management is understudied and generally lacks field validation. In two field studies, we evaluated the effect of IPPM insecticide programmes on striped cucumber beetle (Acalymma vittatum) management, pollination and watermelon yield. The first trial (2020) featured insecticide treatments representing a factorial combination of (1) products varying in bee toxicity (bifenthrin, cyclaniliprole and acetamiprid), (2) application frequencies (weekly vs. threshold‐based) and (3) application timings (AM vs. PM), as well as an untreated control. These data were then used to inform a second trial (2021) that applied two insecticide treatments (IPPM based or grower standard) to commercial‐scale (20–30 acres) fields in collaboration with regional watermelon farms. Weekly beetle densities, pollinator visitation and yield data were collected to determine programme efficacy. Overall, beetle infestations were successfully managed with all insecticide treatments, none of which compromised marketable yield. In 2020, threshold‐based insecticide programmes offered statistically similar levels of pest control but required 20%–80% fewer applications compared to a weekly programme. Furthermore, pollinator visitation was increased in threshold‐based programmes by ~42% across all products. The on‐farm validation trial in 2021 upheld these findings; IPPM fields had effective beetle control but with 1–7 fewer insecticide applications compared to grower standard fields. IPPM fields also had 62% greater pollinator visitation and 49% more melons during harvest compared to grower standard fields. Synthesis and applications. Our study demonstrates the capacity of IPPM programmes to manage pests while mitigating negative effects on pollinators. In particular, administering insecticide applications by pest thresholds led to the greatest enhancement in pollinator function. These findings also suggest that growers can benefit from this approach with reduced insecticide costs while encouraging pollination in pollinator‐dependent crops.

Selection of Reference Genes for Normalization of qRT‒PCR Analysis in the Soybean Aphid Aphis glycines Matsumura (Hemiptera: Aphididae).

The soybean aphid Aphis glycines Matsumura is a predominant insect pest in Asia and North America and causes great losses to soybean. The release of genome data for A. glycines will facilitate gene function research in the future. However, suitable reference genes for A. glycines under various experimental conditions are scarce. To search for appropriate reference genes for A. glycines, nine candidate reference genes, including Act, α-Tub, β-Tub, RPS12, RPS18, RPL5, RPL27, EF1α, and Fer, were tested under six experimental conditions to evaluate their suitability for use in the normalization of qRT‒PCR data. Results showed that EF1α and RPS12 were optimal for the developmental stages of A. glycines, RPS18 and RPS12 were appropriate for wing dimorphism, β-Tub and RPS18 were suitable for different tissues and RPL5, and α-Tub could be used for normalization at different temperatures. β-Tub and EF1α could be proposed as reference genes for insecticide treatment, and RPL5 and RPS12 were found to be the most stable reference genes in different photoperiods. The results provide appropriate reference genes for analyzing gene expression in A. glycines and contribute to future research on the molecular physiology and biochemistry of A. glycines.

Nutritional stress exacerbates impact of a novel insecticide on solitary bees' behaviour, reproduction and survival.

Pesticide exposure and food stress are major threats to bees, but their potential synergistic impacts under field-realistic conditions remain poorly understood and are not considered in current pesticide risk assessments. We conducted a semi-field experiment to examine the single and interactive effects of the novel insecticide flupyradifurone (FPF) and nutritional stress on fitness proxies in the solitary bee Osmia bicornis. Individually marked bees were released into flight cages with monocultures of buckwheat, wild mustard or purple tansy, which were assigned to an insecticide treatment (FPF or control) in a crossed design. Nutritional stress, which was high in bees foraging on buckwheat, intermediate on wild mustard and low on purple tansy, modulated the impact of insecticide exposure. Within the first day after application of FPF, mortality of bees feeding on buckwheat was 29 times higher compared with control treatments, while mortality of FPF exposed and control bees was similar in the other two plant species. Moreover, we found negative synergistic impacts of FPF and nutritional stress on offspring production, flight activity, flight duration and flower visitation frequency. These results reveal that environmental policies and risk assessment schemes that ignore interactions among anthropogenic stressors will fail to adequately protect bees and the pollination services they provide.

Application of insecticides on peppermint (Mentha × piperita L.) induces lignin accumulation in leaves by consuming phenolic acids and thus potentially deteriorates quality

Irrational use of pesticides may lead to physiological and metabolic disorders in different crops. However, there are limited investigations on impacts of insecticides on physiology and biochemistry, secondary metabolic pathways, and associated quality of medicinal plants such as peppermint (Mentha × piperita L.). In this study, target metabolites in peppermint were monitored following foliar spraying of five insecticides: imidacloprid, pyriproxyfen, acetamiprid, chlorantraniliprole, and chlorfenapyr. Compared with the control, all insecticide treatments caused a significant loss of soluble protein (decreased by 22.3–38.7%) in peppermint leaves. Insecticides induced an increase in the levels of phytohormones jasmonic acid and abscisic acid in response to these chemical stresses. Among them, imidacloprid increased jasmonic acid by 388.3%, and pyriproxyfen increased abscisic acid by 98.8%. The contents of phenylpropanoid metabolites, including rutin, quercetin, apigenin, caffeic acid, 4-hydroxybenzoic acid, ferulic acid, syringic acid, and sinapic acid showed a decreasing trend, with pyriproxyfen decreasing the levels of quercetin and 4-hydroxybenzoic acid by 78.8% and 72.6%, respectively. Combined with correlation analysis, the content of lignin in leaves shows different degrees of negative correlations with several phenolic acids. It could be inferred that insecticides may trigger plant defense mechanisms that accumulate lignin (increased by 24.6–49.1%) in leaves by consuming phenolic acids to barricade absorption of insecticides. Through constructing networks between phytohormones and secondary metabolites, peppermint may regulate the contents of caffeic acid, 4-hydroxybenzoic acid, and sinapic acid by the antagonistic effect between salicylic acid and abscisic acid in response to insecticidal stresses. Principal component analysis and systemic cluster analysis revealed that the most pronounced changes in physiological indexes and metabolites were caused by the pyriproxyfen treatment. In conclusion, this study improves our understanding of the mechanism by which insecticides affect plant physiological and metabolic processes, thus potentially altering the quality and therapeutic value of peppermint as an example.