Reduction In Aphid Population Research Articles

Eco-friendly and sustainable approaches against aphids management (Myzus persicae) and dissipation studies of imidacloprid in important cash crop capsicum under protected and open condition

Capsicum is generally infested with many biotic agents mainly sucking insects, among them the major is aphid (Myzus persicae). Chemical management is one of the most common strategies for their management. However, there are no recommended insecticides for insect management in polyhouse. An experiment was designed to assess the bio-potency of four popularly used insecticides (Imidacloprid-17.8SL, Acephate-75SP, Dimethoate-30EC and Buprofezin-25SC), a botanical (Neem oil 10000 ppm) and two entomopathogenic fungi (Metarhizium anisopliae 1.15%WP and Lecanicillium lecanii 1.15%WP) for two consecutive seasons. Most effective and the highest reduction of aphid population (78.14–81.92 %) were found in imidacloprid (17.8SL) treated plots. This effective molecule imidacloprid was further studied for its dissipation pattern under polyhouse and open condition and found that the imidacloprid residues in capsicum fruit dissipated below quantification limit (BQL) within 10days after final spray and the residues in the soil sampled at harvest time were found below the detection level. The half-lives of imidacloprid were 1.88 and 2.61 days under polyhouse and 1.07 and 1.52 days in open field at recommended doses (25 g a.i. ha−1) and double doses (50 g a.i. ha−1) of application respectively. The dietary exposure of imidacloprid on capsicum fruit under both conditions exposed that hazard quotient (HQ) values obtained from the different treatment doses have not exceeded the upper limit of toxicity (HQ < 1) and imidacloprid residues in the fruits were found below the existing MRL (Maximum Residue Limit) values (0.5 mg/kg) at 3 days after its final applications. Thus, imidacloprid may be considered as the effective chemical management option against aphids in capsicum under polyhouse and open field having no harmful effect on human consumption.

Geographic variation in evolutionary rescue under climate change in a crop pest-predator system.

Species distribution models (SDMs) are often built upon the "niche conservatism" assumption, such that they ignore the possibility of "evolutionary rescue" and may underestimate species' future range limits under climate change. We select aphids and ladybirds as model species and develop an eco-evolutionary model to explore evolutionary rescue in a predator-prey system under climate change. We model the adaptive change of species' thermal performances, accounting for biotic interactions. Our study suggests that, without considering evolutionary adaptation, the warming climate will result in a reduction in aphid populations and the extinction of ladybirds in large parts of the United States. However, when incorporating evolutionary adaptation into the model, aphids can adapt to climate change, whereas ladybirds demonstrate geographic variation in their evolutionary rescue potential. Specifically, ladybirds in southern regions are more likely to be rescued than those in the north. In certain northern regions, ladybirds do not avoid extinction due to severe warming trends and seasonality of the climate. While higher warming trends do prompt stronger evolutionary changes in phenotype, they also lead to reduced aphid population abundance such that ecology constrains ladybird population growth. Higher seasonality induces an ecological effect by limiting the length of reproductive season, thereby reducing the capacity for evolutionary rescue. Together, these findings reveal the complex interplay between ecological and evolutionary dynamics in the context of evolutionary adaptation to climate change.

Efficacy and Economics of Selected Chemicals and Bio-pesticides against Mustard Aphid [Lipaphis erysimi (Kaltenbach)] in Prayagraj, U.P., India

The study was carried out at central research farm in rabi season at Sam Higginbottom University of Agriculture Technology and Sciences. The efficacy of treatments was measured in terms of the reduction in aphid population. Imidacloprid 17.8 SL exhibited the highest population reduction (95.210), followed by Dimethoate 30 EC (82.887), Acetamiprid 20 SP (69.350), Neem oil 5% (48.767), N.S.K.E. (42.040), Verticillium lecanii 1.15 WP (39.95), Beauveria bassiana 1.15 WP (30.707), with the untreated plot showing the minimum reduction. The cost-benefit analysis of treatments revealed that. Imidacloprid 17.8 SL demonstrated the highest return (1:5.23), followed by Dimethoate 30 EC (1:4.26), Acetamiprid 20 SP (1:4.16), Neem oil 5% (1:3.67), N.S.K.E (1:3.45), Verticillium lecanii (1:2.77), and Beauveria bassiana (1:2.61). The control plot yielded the lowest return (1:1.56).

Integrating Metarhizium anisopliae entomopathogenic fungi with border cropping reduces black bean aphids (Aphis fabae) damage and enhances yield and quality of French bean

French bean growers, rely mainly on pesticides for pest management. The acceptable tolerance for pesticides residue in French beans is a major concern and has led to several tonnes of the crop continuously rejected and listed as unsafe for human consumption. There is growing demand for alternative approaches and products that are effective at managing pests without the side-effects associated with reliance on pesticides. A field study to determine the combined effects of Metarhizium anisopliae, (Metarril WP E9 and Biomagic) biopesticides and border crops (Sunflower and wheat) on aphid population, damage severity, growth, yield and quality of French bean. A two-factor experiment was conducted at the Egerton University, Kenya. First factor included two border crops (sunflower and wheat) and no border crop (control). Second factor included spraying Metarril WPE9 (2 × 108 cfu/g), Biomagic (2 × 108 cfu/ml) biopesticides, alpha-cypermethrin (synthetic insecticide) and water. Data on growth, yield and quality parameters were collected and analyzed using the SAS version 9.4M8. Results showed that M. anisopliae and border crop significantly (p < 0.0005) enhanced growth, yield and quality of French bean in both seasons. French bean grown with wheat or sunflower borders showed a significant reduction in aphid population (p < 0.0001) and damage severity (p < 0.0001) when sprayed with various treatments compared to the control. Plots with wheat border caused an increase in collar diameter of French bean. The plots (Metarril and wheat border) caused a 4 % and 5 % increase in marketable yield, a 2 % and 12 % reduction in non-marketable yield. To exploit the benefits of biopesticides, the study recommends their integration with and border crops. Thus, French bean growers could benefit more from fungal-based biopesticides in aphid-IPM approach, as it reduces pre-harvest intervals and residues compared to synthetic insecticides.

Compatibility of the Entomopathogenic Fungus Metarhizium anisopliae (Ascomycota: Hypocreales) and the Predatory Coccinellid Menochilus sexmaculatus (Col.: Coccinellidae) for Controlling Aphis gossypii (Hem.: Aphididae).

Metarhizium anisopliae (Ascomycota: Hypocreales) is an entomopathogenic fungus considered a key factor in developing integrated management of several insect pests on a variety of crops. The predatory coccinellid, Menochilus sexmaculatus (Col.: Coccinellidae), is also an important natural enemy that must be conserved for effective aphid control. Laboratory studies were conducted under controlled conditions to investigate the interaction between M. anisopliae isolate IRN. 1 and the coccinellid predator M. sexmaculatus in combating Aphis gossypii Glover (Hem.: Aphididae). The combined application of M. sexmaculatus and M. anisopliae led to significant reduction in aphid populations. The foraging behavior of M. sexmaculatus notably facilitated the dispersion of M. anisopliae conidia to uninfected plants, resulting 54 ± 1.3% decrease in aphid density after 10days. In both choice and non-choice experiments, female adult M. sexmaculatus to fungus-infected aphids was offered as prey and avoided as a food source during all starvation periods. However, live and dead non-fungus-infected aphids were fed upon. The result revealed the compatibility between M. sexmaculatus and M. anisopliae, which may provide a sustainable strategy for the effective management of A. gossypii in a cropping system.

Synergistic effects of Aphidius colemani (Hymenoptera: Aphidiidae) and Coccinella undecimpunctata (Coleoptera: Coccinellidae) releases for the biological control of Diuraphis noxia in wheat fields

ABSTRACT The Russian wheat aphid, Diuraphis noxia, is a significant pest for grain crops worldwide. Bioagents such as the parasitoid, Aphidius colemani and the predator, Coccinella undecimpunctata have been shown to be effective against many aphid species. This study aimed to investigate the combined effect of releasing these two bioagents on controlling D. noxia without using pesticides. To achieve this, three systems of release were evaluated in the field: (1) the parasitoid A. colemani at rate of 4 mummies/m2, (2) the predator C. undecimpunctata at rate of 10 individuals (3rd larval instar)/m2, and (3) A. colemani (4 mummies/m2) + C. undecimpunctata (10 individuals/m2) and control. After four releases, the combination of A. colemani and C. undecimpunctata resulted in the highest percentage of reduction in aphid population, with a reduction of 95.58, 95.53% in 2020 and 2021, followed by 86.94, 83.92% in A. colemani plots and the lowest reduction percentage in C. undecimpunctata plots, with 65.1, 68.92%, in 2020 and 2021, respectively. Based on these results, it is recommended to use the combination of the two bioagents, A. colemani and C. undecimpunctata for controlling D. noxia in a wheat field. Therefore, the use of a combination of natural enemies, carefully timed and repeated releases, and consideration of intraguild predation dynamics can help to achieve effective biological control of aphids in wheat crops. The use of natural enemies such as A. colemani and C. undecimpunctata can reduce the application of pesticides and promote sustainable pest management practices.

Functional Response and Intraspecific Competition of Three Ladybird Species Feeding on Aphids on Goji Berry Plants in Laboratory and Semi-Field Conditions.

The aphid, Aphis gossypii Glover, is identified as a significant pest that causes severe damage to goji berries in China. To analyze the ladybird consumption of aphids, the functional responses of three ladybird species, Harmonia axyridis, Coccinella septempunctata, and Hippodamia variegata, and intraspecific competition among ladybird individuals were evaluated under laboratory conditions. Moreover, the practical impact of ladybirds on aphid population reduction was investigated in semi-field conditions. We found that all adult ladybirds of the three species exhibited a type II functional response toward aphids. According to Holling's disc equation, H. axyridis exhibited the highest searching efficiency (a = 0.79), while C. septempunctata had the shortest handling time (Th = 5.07 min) among the three ladybird species studied. Additionally, intraspecific competition had a greater impact on H. variegata (m = 0.41) compared to the other two ladybird species. The semi-field study demonstrated that H. axyridis (83.9% reduction) and C. septempunctata (78.7% reduction) exhibited higher efficacy in reducing aphid populations compared to H. variegata (27.3% reduction). This study suggests that H. axyridis and C. septempunctata exhibit potential as effective biological control agents against aphids on goji berry plants and highlights the importance of considering intraspecific competition. However, the results obtained from laboratory and semi-field studies cannot be directly extrapolated to field conditions due to the simplification of these experimental systems. Future field studies are crucial in ensuring the effective implementation of a biological control program.

Integrated Management of Cabbage Aphid (Brevicoryne brassicae L.)

The present investigation entitled “Integrated Management of Cabbage Aphid (Brevicoryne brassicae L.)” was carried out at Department of Entomology as well as field of Vegetable Research and Demonstration Block, College of Horticulture, VCSG Uttarakhand University of Horticulture and Forestry, Bharsar, Pauri Garhwal during 2022. Seasonal incidence of Cabbage aphid (Brevicoryne brassicae) revealed that the maximum numbers of aphid, (784.05 nymphs/plants and 506.32 adults/plants) were recorded during 23rd SMW viz., 2nd week of June. Correlation studies indicated that aphid population exhibited highly significant positive correlation with maximum temperature and minimum temperature and significant negative correlation with morning and evening relative humidity. While rainfall showed non-significant positive correlation with aphid population. Efficacy of different treatments (Cultural practices (Weeding) + Yellow sticky trap), (Garlic extract + Red pepper extract), (Onion extract + Yellow sticky trap), (Neem leaf extract + Cow urine), (Thiamethoxam 25 WG + Beauveria bassiana), (L-cyhalothrin 5 EC + Beauveria bassiana) and (Biological control + Mechanical control) were evaluated by two sprays at 3, 5 and 7 days interval against aphid (B. brassicae) during year 2022. After 1st and 2nd application highest reduction in aphid population (77.37 and 93.57) and maximum yield (5.85 kg/plot and 541.66 q/ha) over pre treatment was recorded in L-cyhalothrin 5 EC incorporated with Beauveria bassiana.

An eco-friendly approach of biocontrol of aphid (Aphis gossypii Glover) by Trichoderma harzianum.

Aphid (Aphis gossypii) is one of the important pests of papaya crop. In this work, applications of Trichoderma harzianum and Beauveria bassiana (biocontrol agents) and malathion (insecticide) were conducted in vitro and in agrifields for testing their anti-aphid efficacy and compared their efficacy. Furthermore, the enzymatic mechanism of T. harzianum with respect to biocontrolling the pest was unearthed. The LD50 dose of T. harzianum and B. bassiana was 1.2 × 105 spores mL-1 and 1.0 × 106 spores mL-1 respectively after 48h of administration. The LT50 of T. harzianum also exhibited a lower effective time (47.70h) than B. bassiana (57.53h) for the same concentration of spores applied (1 × 105 spores mL-1). The pooled data analysis of two years (2019-2020) showed that the application of T. harzianum spores in agrifields exhibited 31.75 ± 13.00a percentage of reduction of aphid population whereas malathion exhibited 23.93 ± 1.30a%, in comparison to control. The statistical analysis indicated that the application of malathion exhibited the same efficacy as T. harzianum isolate and placed in the same category. In plate detection assay, T. harzianum produced a higher hydrolytic zone for chitinase (8.0 ± 0.4cm diameter) and protease (7.0 ± 0.4cm diameter) enzymes, than B. bassiana (1.3 ± 0.2cm and 1.1 ± 0.2cm respectively). Quantitative estimation of enzymes exhibited that T. harzianum produced 299 ± 11a μg mL-1 of chitinase, 519 ± 19a μg mL-1 of protease, and 65 ± 12a μg mL-1 of PR1, and on the other hand, B. bassiana yielded 124 ± 12b, 361 ± 23b, and 29 ± 18b μg mL-1 of chitinase, protease, and PR1 respectively. It indicated that T. harzianum was superior over the B. bassiana in terms of production capacity of all three enzymes. In conclusion, all the above experimental results suggested that T. harzianum showed better aphid-killing efficacy than B. bassiana. It also suggested that T. harzianum should replace hazardous chemical pesticide (malathion) for eco-friendly biocontrol of aphids.

Management of powdery mildew and aphid in organically grown Indian mustard (Brassica juncea L.) through different oils

All the cultivated Brassica species exhibited powdery mildew severity with highest (43.2%) on Brassica juncea followed by B. rapa (28.0%) which is widely cultivated in India. Yield losses from 10-90 per cent with reduction in 6.47 per cent oil content have been estimated from different Brassica species. Hence, the present study was carried out to evaluate different oils to manage powdery mildew disease and aphids in an organically grown mustard crop. Five oils (castor, groundnut, sunflower, neem and mustard oil) and ghee were evaluated against powdery mildew (Erysiphae cruciferarum) and aphid (Lipaphis erysimi) of Indian mustard (Brassica juncea). Castor oil 50 EC, neem oil 50 EC and mustard oil 50 EC and deshi ghee 50 EC (@ 100 ml/10 litre water) were effective over untreated control in reducing powdery mildew disease severity when applied as foliar spray (@ 5 ml/litre) in the experiment carried out in organic field (plot No. B-2 at Agronomy Instruction Farm, S. D. Agricultural University, Sardarkrushinagar). Maximum reduction in germinated conidia (66.0%) over control, disease severity (50.0%), area under disease progress curve (AUDPC) values (51.8%) and maximum increase over control in 1000 seed weight (16.7%) and seed yield (10.3%) was observed with neem oil. This was followed by the application of ghee which exhibited reduced disease severity (22.9%) and AUDPC values (30.6%) and increased seed yield (8.1%) and the application of castor oil 50 EC which exhibited an increased in seed yield (8.0%) and reduced powdery mildew severity (20.8%). Shortest log phase was observed with neem oil during 10th std. week. All the oils tested (castor, groundnut, sunflower, neem and mustard oil) and deshi ghee were effective in reducing aphid population (39.5 to 65.9%) and damage index (6.1 to 25.1%). A maximum reduction in aphid population (65.9%) over control and lowest aphid damage index (3.70) was observed with neem oil 50 EC 6 days after 2nd spray. Application of neem oil, castor oil and deshi ghee resulted in increased seed yield (8.1 to 10.4%). This information could be useful in devising strategies for powdery mildew and aphid management in organic cultivation, eco-friendly management and IPM of mustard.

Efficacy of Capsaicin Rich Botanicals on the Aphid Population in Lablab (Dolichos lablab L.) under Organic Production System

Aim: The growing concern for environmental safety and the demand for pesticide residue –free food worldwide have evoked interest in pest management through the use of botanicals, which offers a good alternative to manage the insect pests in an eco-friendly manner. This research was carried out to study the efficiency of botanicals on the aphid population in lablab under organic production system.&#x0D; Study Design: The study was carried out in Randomized Block Design (RBD) with eight treatments and three replications.&#x0D; Place and Duration of Study: The study was carried out at College Orchard, Department of Vegetable Science, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore during 2021 - 2022.&#x0D; Methodology: The study was performed using chilli extract with three concentrations (2.5, 5.0 and 7.5%) and compared with other botanicals such as neem oil, neem seed kernel extract, garlic extract and panchagavya. The aphid population was counted visually before and 1, 3, 5 and 7 days after spraying.&#x0D; Results: The results showed that after 7 days spraying 95.81 per cent of aphid population was reduced in T3 (7.5% chilli extract) followed by T2 &amp; T1 (5 % &amp; 2.5%) with a population reduction to the level of 95.62 and 91.54 per cent, respectively. This was followed by neem oil with a reduction of 83.50 per cent followed by garlic extract (79.74%), neem extract (76.94%) and panchagavya (62.81%). The inflorescence infestation was also lower in T3 (4.94) which were compared to control.&#x0D; Conclusion: The application of chilli extract resulted in reduction of aphid population in lablab under organic cultivation. Infloresecence infestation was also recorded minimum in chilli extract treated plots. The chilli extract is non-toxic to humans and does not harm the environment and hence this can be utilized as an alternative to chemical pesticides.

Preventable yield losses and management of mustard aphid, Lipaphis erysimi (Kaltenbach) in different cultivars of Brassica juncea (L.) Czern & Coss

The mustard aphid, Lipaphis erysimi (Kaltenbach) is a major pest of Brassica spp. and causes significant yield losses. We determined the current status of levels of infestation, yield loss due to aphids, and efficacy of biopesticides as well as neonicotinoids to manage L. erysimi in Brassica juncea. The reduction in the number of aphids after insecticide applications and seed yield differed significantly among treatments (insecticide protected and unprotected), across seasons, and treatment × season interactions in most test cultivars (cv.) viz., BSH 1, NRCDR 02, PDZM 31 and RH 725. The insecticide applications reduced the aphid populations by 51.4–99.6% across cultivars and seasons. Aphid population was significantly higher and seed yield lower under late-sown than early and timely-sown conditions in cv. PM 26. Seed treatment with different insecticides did not result in a significant reduction in the aphid population and protect the potential seed yield of B. juncea. Dimethoate was effective over the biopesticide treatments, and Beauveria bassiana performed best among the test biopesticides. Thiomethoxam and imidacloprid were best among the neonicotinoids for reduction in aphid population, protection of potential seed yield, and incremental benefit-cost ratio in cv. PM 30. The control of aphid populations could prevent 10.2–61.1% yield loss. The alternate use of B. bassiana @ 2 g/l, dimethoate 30 EC @ 1 ml/l, imidacloprid 17.8 SL @ 0.25 ml/l, or thiomethoxam 25 WG @ 0.2 g/l water based on the extent of aphid population effectively manages L. erysimi in B. juncea.

Plant bioactive volatile products and their efficiency in aphid control

The “farm-to-fork strategy” of the European Union aims to reduce dependency on pesticides and towards increased use of low-risk products, such as those based on botanical extracts. A product based on the mixture of the five natural compounds selected for their repellent or insecticidal properties, namely citral, (E)-anethole, farnesol, cis-jasmone and lemon essential oil, was evaluated against Myzus persicae Sulzer (Hemiptera: Aphididae). Three formulations were prepared using various surfactants at different ratios: the first one with Tween80, the second one with soy (Glycine max (l.) Merr.) lecithin and the third one with soy lecithin and sunflower oil (Helianthus annuus L.). The oil-in-water nanoemulsions at 1% were tested in a laboratory study with Petri dishes using a computer-controlled spraying apparatus (equivalent application of 200 l/ha). The mean efficacy was 45%, 71% and 63%, respectively, with a least statistically significant difference (LSD) at 5% comparing the first two formulations. A field experiment (in two pepper, Capsicum anuum L., greenhouses) at Torreblanca Exp. Stat. in Murcia (Spain) followed in April 2020 in which a reduction in aphid populations only occurred by spraying the product formulated with soy lecithin. Phytotoxicity was also observed but was lower in the formulation that contained sunflower oil. Nanoemulsions were characterised using a Zetasizer, and a polydispersion of 2–3 populations of particles, ranging from 15 to 341 nm in size, was found with the Tween80 formulation and bigger sizes (250–438 nm) with the soy lecithin and sunflower oil formulation, which were more stable (Z potential = −28.15 mV). The application of ultrasounds reduces the Z-average to 100 nm in the mixture product with stability for at least 14 days. Another field experiment was repeated in February and April 2021. The plants were sprayed sequentially with the following: a) mixture product at 0.5% formulated with soy lecithin and sunflower oil, b) 3% cottonseed (Gopsyppium hirsutum L.) oil in 3% soap water (Feb.) or 1.5% cottonseed oil in 1.5% soap water (Apr.) and c) cis-jasmone at 0.25% formulated with Tween80. The treatment with the mixture of bioactive volatiles (a) was not more effective than that of the fixed seed oil (b). In February, the instantaneous population growth rate (ri) of aphid populations showed a significant reduction when the plants were sprayed with cottonseed oil. Further research is recommended for the formulation and application methods of the products being developed.

Aphicidal activity of farnesol against the green peach aphid – Myzus persicae

AbstractBACKGROUNDMyzus persicae (Hemiptera: Aphididae) is considered one of most important agricultural pests in the world. It is one of the main pests in protected pepper crops under glasshouse conditions in Southeastern Spain, but its control is limited as a consequence of the few available authorized insecticides and their incompatibility with the natural enemies. Some essential oils and pure compounds such as anise (Pimpinella anisum) or farnesol are repellent and/or toxic to aphids. Their use as a botanical insecticides can be an alternative for aphid control in pepper.RESULTSThe effect of farnesol was evaluated against M. persicae in a new bioassay developed to test the contact effect (aqueous formulation of the products) on aphids in laboratory conditions. Aniseed essential oil, geraniol and (Z)‐jasmone at 0.6% causes an aphid mortality of &gt;50%; and farnesol was the most effective (93.67% mortality). Farnesol nanoemulsions between 0.2% and 0.6% were formulated with an IKA‐Labor Pilot dispersing machine (7940 rpm for 10 min) using Tween 80 as a surfactant. These formulations were tested on field experiments (glasshouse conditions) on pepper crops for 2 years. Foliar applications of farnesol at a concentration of 0.4% in field conditions causes a high reduction in aphid populations, with efficacies of ≈70–80% with respect to the control, similar to or even higher than the efficacy of the reference pyrethrin insecticide.CONCLUSIONFarnesol showed a great aphicidal effect against M. persicae. The use of this molecule in integrated pest management programs combined with natural enemies is a good option for future control of M. persicae. © 2022 Society of Chemical Industry.

Feasibility study on hexacopter UAV based sprayer for application of environment-friendly biopesticide in guava orchard

Aim: To study the feasibility of hexacopter UAV based sprayer for application of environment-friendly biopesticide in guava orchard. Methodology: Field experiments were conducted in Punjab (India) during 2020. UAV was evaluated for spraying environment-friendly bio-pesticidein guava orchard. UAV was operated at 2.0 m height above the tree top.The water and oil sensitive papers were fixed on the outer side as well as inside of selected guava trees at four different canopies. Organic neem seed kernel based azadirachtin 0.15% EC biopesticide was used at recommended dose. After spraying, all water and oil sensitive papers were collected for further laboratory analysis. All spray quality parameters, i.e., coverage (%), droplet density (droplets cm-2), droplet size (µm) and uniformity coefficient were determined. For the efficacy of drone sprayer insects were counted before and 1, 2, 7 days after spray (DAS) and reduction in number of insects was calculated. Results: The on-flight field capacity of spraying with UAV was 3.0-3.3 ha h-1 whereas actual field capacity was found to be 2.0-2.3 ha h-1. The total mean coverage area was found in the range of 2.67-10.67%. The maximum coverage was at the top canopy (inner and outer) of tree which was significantly higher than all other observation points on the canopy. The mean droplet density was found in the range of 14.67-28.33 droplets cm-2. The highest droplet density (28.33 droplets cm-2) was found at the top outer side of the tree canopy. The volume median diameter was found in the range of 208.0-418.3 µm whereas, number median diameter was in the range of 138 to 269 µm. The percent reduction in aphid population 1, 2 and 7 days after spray (DAS) was 38.06, 68.28 and 62.69%, respectively whereas it was 47.95, 78.69 and 70.90% with knapsack sprayer. Interpretation: Hexacopter UAV sprayer is effective in terms of quality of spray and effective control of aphid population.

Efficacy of some indigenous products against cowpea aphid, Aphis craccivora Koch

An experiment was conducted in field during 2017-18 for efficiency evaluation of seven indigenous products along with a check (imidacloprid 17.8 SL at 20g a.i /ha) to manage Aphis craccivora Koch on cowpea. In the bio-efficacy study, leaf extract of Polygonum hydropiper at 5% was found to be most effective and efficient in aphid population reduction (up to 77.48%), followed by neem oil at 1% (74.11%), Ocimum sanctum leaf extract at 5% (74.00%), Murraya koenigii leaf extract at 5% (70.96%), ash at 10 kg/ha (68.04%), river sand + neem leaf powder at 10 kg/ha (3:1 ratio) (44.48%) and ash + river sand at 10 kg/ha (5:1 ratio) (42.53%) after 7 days of spraying.

Identification of novel aphid-killing bacteria to protect plants.

SummaryAphids, including the peach‐potato aphid, Myzus persicae, are major insect pests of agriculture and horticulture, and aphid control measures are limited. There is therefore an urgent need to develop alternative and more sustainable means of control. Recent studies have shown that environmental microbes have varying abilities to kill insects. We screened a range of environmental bacteria isolates for their abilities to kill target aphid species. Tests demonstrated the killing aptitude of these bacteria against six aphid genera (including Myzus persicae). No single bacterial strain was identified that was consistently toxic to insecticide‐resistant aphid clones than susceptible clones, suggesting resistance to chemicals is not strongly correlated with bacterial challenge. Pseudomonas fluorescens PpR24 proved the most toxic to almost all aphid clones whilst exhibiting the ability to survive for over three weeks on three plant species at populations of 5–6 log CFU cm−2 leaf. Application of PpR24 to plants immediately prior to introducing aphids onto the plants led to a 68%, 57% and 69% reduction in aphid populations, after 21 days, on Capsicum annuum, Arabidopsis thaliana and Beta vulgaris respectively. Together, these findings provide new insights into aphid susceptibility to bacterial infection with the aim of utilizing bacteria as effective biocontrol agents.

Efficacy of plant derived and synthetic insecticides against cabbage aphid, Brevicoryne brassicae (L.) (Homoptera: Aphididae) and their effect on coccinellid predators

Cabbage aphid, Brevicoryne brassicae (L.) is one of the major insect pests of brassica crops worldwide. Mainly insecticides are being used for its management which poses hazardous effects on the environment and the applicator. Low efficacy and non-target effect of the available insecticide are the main challenge in the management of the pest in Ethiopia. The use of bio-rational and neonicotinoid pesticides is a promising alternative as they are less vulnerable to resistance development and relatively safe to the environment and the applicator. This study was carried out in 2018/19 cropping season to evaluate the efficacy of plant derived and synthetic insecticides for the management of cabbage aphid and their effect on coccinellid predators on Ethiopian kale. Ten treatments including six synthetic and two botanical insecticides were tested in comparison with the standard check dimethoate 40% EC and the untreated control in Randomized Complete Block Design with three replications. Significant (P&lt;0.05) differences were observed among the treatments in terms of cabbage aphid population reduction and their effect on coccinellid beetles. The botanical mix (Garlic+onion+pepper) and imidacloprid were at par with each other and found to be the best treatment with 93.79% and 91.04% efficacy, respectively. The maximum leaf yield was obtained from imidacloprid (14.18 t/ha) followed by botanical mix (13.45 t/ha) and lufenuron (12.42 t/ha). The highest yield increment over control was obtained from imidacloprid (3.1 t/ha), followed by botanical mix (2.37 t/ha). The botanical mix, imidacloprid and neem seed extract were highly effective in aphid control as well as less hazardous to ladybird beetle (Coccinella septempunctata L.). The highest cost benefit ratio was recorded with profenofos (1:1.14) followed by lufenuron (1:0.2), spinosad and nimbecidine (1:0.18). Results of the current study demonstrated that imidacloprid and plant-based insecticides can reduce aphid populations equally to conventional insecticides and could be used as an alternative component for the integrated pest management (IPM) of cabbage aphid, Brevicoryne brassicae (L.) on kale crop under field condition of smallholder farming system.

Field efficacy of bio-rational insecticides against major pestiferous insects of cabbage

The major pestiferous insects during both crop seasons included aphids and diamond back moth; while, flea beetles and painted bug attained pest status during 2015-16; besides, tobacco caterpillar was noticed during 2016-17. Maximum reduction in aphid population (45.81 and 54.07%, respectively, at 1 and 3 DAS) was recorded for A. indica oil followed by Spinosad 45%SC; same schedule had maximum reduction of flea beetle population 1-DAS (50.03%); while, 3 and 7 days after spray Spinosad 45%SC followed by Spinosad 45%SC gave significantly higher reduction (75.21 and 64.62%, respectively). Maximum reduction of painted bug population (68.37% at 3DAS) was due to A. incida oil followed by Sl-NPV. Treatment schedule of Spinosad 45%SC followed by Spinosad 45%SC was most effective against DBM during both crop seasons with significantly lowest pooled larval population per plant being 0.82 and 1.0, 3 and 7 days after first spray; likewise, 1.62, 0.92, and 0.90, 1, 3 and 7 days after second spray. Similarly, against tobacco caterpillar, treatment schedule Spinosad 45%SC followed by Spinosad 45%SC was most effective at 3 DAS (0.71 larvae/plant); while, schedules A. indica oil followed by Spinosad 45%SC and A. indica oil followed by Sl-NPV were equally effective 7 DAS during crop season 2016-17 (0.90 larvae/plant).

Transgenic Expression of dsRNA Targeting the Pentalonia nigronervosa acetylcholinesterase Gene in Banana and Plantain Reduces Aphid Populations.

The banana aphid, Pentalonia nigronervosa, is the sole insect vector of banana bunchy top virus (BBTV), the causal agent of banana bunchy top disease. The aphid acquires and transmits BBTV while feeding on infected banana plants. RNA interference (RNAi) enables the generation of pest and disease-resistant crops; however, its effectiveness relies on the identification of pivotal gene sequences to target and silence. Acetylcholinesterase (AChE) is an essential enzyme responsible for the hydrolytic metabolism of the neurotransmitter acetylcholine in animals. In this study, the AChE gene of the banana aphid was targeted for silencing by RNAi through transgenic expression of AChE dsRNA in banana and plantain plants. The efficacy of dsRNA was first assessed using an artificial feeding assay. In vitro aphid feeding on a diet containing 7.5% sucrose, and sulfate complexes of trace metals supported aphid growth and reproduction. When AChE dsRNA was included in the diet, a dose of 500 ng/μL was lethal to the aphids. Transgenic banana cv. Cavendish Williams and plantain cvs. Gonja Manjaya and Orishele expressing AChE dsRNA were regenerated and assessed for transgene integration and copy number. When aphids were maintained on elite transgenic events, there was a 67.8%, 46.7%, and 75.6% reduction in aphid populations growing on Cavendish Williams, Gonja Manjaya, and Orishele cultivars, respectively, compared to those raised on nontransgenic control plants. These results suggest that RNAi targeting an essential aphid gene could be a useful means of reducing both aphid infestation and potentially the spread of the disease they transmit.