Compatibility and combined efficacy of entomopathogenic fungi and neonicotinoid insecticides against Myzus persicae (Sulzer): An ecofriendly approach

Efficacy of different entomopathogenic fungi (EPF) viz., Beauveria bassiana, Metarhizium anisopliae and Lecanicillium (=Verticillium) lecanii and neonicotinoid insecticides i.e., Imidacloprid, Thiamethoxam and Acetamiprid were evaluated alone and their 1:1 combination against Lipaphis erysimi prevalent in vegetable ecosystem. Among the entomopathogenic fungi, B. bassiana was found most promising registering lowest median lethal time (LT50) of 48.17, 48.92 and 48.87 h during the period of 2018, 2019 and 2020, respectively, followed by L. lecanii (49.57, 49.45 and 50.46 h), M. anisopliae (51.81, 51.67 and 51.63 h). Amongst the three neonicotinoids, Acetamiprid was found more efficacious than the Imidacloprid and Thiamethoxam. Blending of B. bassiana and Acetamiprid at half of their recommended dose took lowest (22.76, 23.48 and 23.06 h during 2018, 2019 and 2020, respectively) lethal time to kill the fifty per cent test population followed by L. lecanii + Acetamiprid (22.58, 22.68, 22.52 h) and M. anisopliae + Acetamiprid (22.61, 23.82, 23.60 h). Combinations of these entomopathogenic fungi and neonicotinoid insecticides had co-toxicity co-efficient values > 1 and lower LT50 values than each of their individual indicating the compatibility amongst them. Co-application of these EPF with sub-lethal concentration of neonicotinoids could not only be a green ecofriendly option against this sucking pest but also able to minimize the chemical insecticides load in the environment

Evaluation and economic analysis of ecofriendly biological approaches for the management of shoot and fruit borer (Earias vittella F.) of okra

During the years 2020 and 2021, the effects of various biopesticides and the egg parasitoid Trichogramma chilonis on the okra shoot and fruit borer were investigated in open fields. All interventions outperformed over the untreated control. The entomopathogenic bacterium Bacillus thuringiensis was the most promising biopesticide tested, with the lowest shoot (5.49% and 6.87% in 2020 and 2021, respectively) and fruit damage (4.95% and 5.65% in 2020 and 2021, respectively), followed by the entomopathogenic fungi Beauveria bassiana (7.08%, 8.04% shoot damage and 6.78% and 6.73% fruit damage during 2020 and 2021, respectively). Interestingly, all biopesticides evaluated were shown to be safe for the polyphagous predators occurring in the okra habitat, such as the ladybird beetles Menochilus sexmaculatus and Micraspis discolour and the spiders Marpissa spp. and Oxyopes lineatipes. However, emamectin benzoate 5% SG was the most effective treatment in terms of minimizing okra shoot and fruit damage, resulting in a maximum percent reduction over control (PROC) (85.54 and 80.90 against shoot damage and 76.60 and 71.33 against fruit damage during 2020 and 2021, respectively). Each treatment's economics were also analysed. The experimental plots treated with emamectin benzoate had the highest cost:benefit ratio (1:11.16), while B. thuringiensis had the highest (1:7.06) among the biopesticide / parasitoid releasing plots

Distribution, Host Range and Bionomics of Rhopalosiphum nymphaeae (Linnaeus, 1761) a Polyphagous Aphid in Aquatic Vegetables

The present study records the occurrence of water lily aphid, Rhopalosiphum nymphaeae (Linn, 1971) on different aquatic plants from Varanasi and adjoining regions, Uttar Pradesh, India for the fi rst time. Both nymphs and adults prefer to feed on petiole, leaf lamina and buds towards terminal portion of different aquatic plants. They suck the cell sap resulting in curling of leaves, stunted plant growth with lower number of fruits in water chestnut. Further, the honey dew deposited on the leaves favours the development of black sooty-mould and hinders the normal photosynthetic activity of the plants. Infestation of aphid started in the region on water chestnut during last week of October (1.35 aphids leaf-1) coinciding with the initiation of winter in the region and gradually increased with highest peak (21.95 aphids leaf-1) during fourth week of January. Amongst the different aquatic host plants under study in the region, olfactometer study showed significantly highest number of R. nymphaeae (28%) attraction towards lotus followed by of water chestnut (21.3%) and water lily (20%) and the least was with water hyacinth (4%). Amongst the biopesticides tested, L. lecanii @ 5 g lit-1was found most promising with lowest median lethal time (31.09 h) followed by neem oil (1%) (41.59 h) and M. anisopliae (43.95 h)

Parasitization preference of Diaeretiella rapae (Hymenoptera: Braconidae) among different aphids in vegetable ecosystem

Solitary, polyphagous, endoparasitoid Diaeretiella rapae (Mc’Intosh) is considered as one of the prominent parasitoid of aphids on several host plants under natural field conditions. However, knowledge about its affinity and host preference towards different prey aphids is very scanty. So the present study on host preference of D. rapae revealed differential response for its parasitization to different aphid species infesting vegetable crops. It preferred maximum to cruciferous aphids, viz. Myzus persicae (59%) followed by Brevicoryne brassicae (51%) and Lipaphis erysimi (46%) than the other vegetable aphids like Aphis craccivora (23.67%) and Aphis spiraecola (19.67%). Seasonal incidence of D. rapae also indicated that its first occurrence was observed on M. persicae (13.67%) and L. erysimi (5.67%) during second fortnight of January, 2013 whereas spiraecola feeding on brinjal parasitized last indicating the preference of cruciferous aphids over other vegetable aphids. However, among the cruciferous aphids, highest parasitoid emergence was observed from L. erysimi (88%) followed by B. brassicae (81%) and M. persicae (80%). Comparatively higher body size (2.81 ± 0.23 mm) and tibial length (0.51 ± 0.05 mm) of M. persicae by the parasitoid for its parasitization and variation in nutritional quality in L. erysimi as food substrate towards D. rapae for its higher emergence might be responsible for their preference over the other host aphids

Mechanisms of physical and biochemical basis of resistance against leaf-hopper (Amrasca biguttula biguttula) in different okra (Abelmoschus esculentus) genotypes

Different biophysical parameters, viz. trichomes, leaf length, angle between the mid-ribs, angle between the midribs and vein, mid-rib thickness, leaf angle, number of leaves/plant, plant height and biochemical parameter like total phenol content of leaves were studied in relation to the expression of reaction towards leaf hopper (Amrasca biguttula biguttula) in 10 okra [Abelmoschus esculentus (L.) Moench] genotypes. It was observed that genotype SB-6 had relatively lower number of trichomes on leaf lamina (10.11), mid-rib (7.17) and vein (8.05) as showed highly susceptible to jassids (17.57 jassids/leaf) as compared to tolerant genotype VROB-181 (5.43 jassids/leaf) which had 11.85, 9.17 and 9.95 trichomes per cm2, respectively. Susceptible cultivar SB-10 possessed higher mid-rib thickness (1.75 mm) and leaf length (25.65 cm) as compared to tolerant genotype VROB-181 (1.58 mm and 22.43 cm, respectively). Similarly, higher number of total leaves (31.9) per plant was also recorded from SB-6 as compared to other tolerant lines (VROB-181, VROB-178, VROR-160). Leaf length, plant height, angle between mid-ribs and total leaves showed a strong positive correlation (r value = 0.493, 0.499, 0.723 and 0.474, respectively) with jassid incidence. Amongst the biochemical parameter, total phenol content was highest in VROB-181 (75.04 mg/100 g) and the incidence of jassids was lowest than those of susceptible genotypes, viz. SB-6 (42.61 mg/100 g) and SB-10 (48.35 mg/100 g) and thereby establishing the significant negative correlation (r = - 0.577) with the jassid incidence and total phenol content

Field bioefficacy and residue dynamics of chlorantraniliprole (18.50% sc) in okra (Abelmoschus esculentus)

The okra fruit borer (Earias vittella) and sucking pests are a key limiting factor in okra cultivation due to their severe crop destruction behaviour. An experiment was conducted during 2019–20 to assess the bioefficacy of various new insecticides and persistence of chlorantraniliprole 18.50 sc residues in okra fruits at research farm of ICAR- Indian Institute of Vegetable Research, Varanasi, Uttar Pradesh. Among various treatments, chlorantraniliprole tested at 30 g a.i./ha was reported to be effective in reducing fruit damage by E. vittella (96%), as well as sucking pests infestation (87.81–1100%) with a significantly higher marketable fruit yield (8.88 t/ha) recorded under open field situations. Ethyl acetate was used to extract the chlorantraniliprole contaminants from the okra fruit matrix, and PSA and magnesium sulphate were used to clean up the matrix. The estimate for the limit of quantification (LOQ) was 0.01 mg/kg, and the average percent recoveries ranged from 83.67–89.00. The half-life was estimated 1.72 days. Based on the field bioefficacy against insect pests and residue status in okra fruits, it can be concluded that the chlorantraniliprole 30 g a.i./ha can be utilized in the okra ecosystem to successfully manage the sucking pest complex and fruit borer without posing any health risks to consumers

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Not AvailableThe prey preference of polyphagous predator, green lacewing (Chrysoperla zastrowi sillemi (Esben-Petersen)) was evaluated against five prey aphids viz., mustard aphid (Lipaphis erysimi), green peach aphid (Myzus persicae), cabbage aphid (Brevicoryne brassicae), black bean aphid (Aphis craccivora), spirea aphid (Aphis spiraecola) of agriculture importance and compared with eggs of Corcyra cephalonica (Stainton). Lacewing larvae preferred Myzus persicae most followed by Brevicoryne brassicae. The highest growth index (8.31), larval survival (94.50 %), larval weight (10.45 mg), pupal weight (8.78 mg), faster multiplication rate (0.051) and fecundity (183.4 per gravid female) of the predator were recorded on M. persicae. However, the chrysopid reared on Corcyra eggs performed best in all biological parameters and fitness, than on aphid preys. This study explores the possibilities of selecting the most suitable prey aphid species for its exploitation as supplement for mass multiplication of chrysopid during off-season or unavailability of Corcyra eggsICAR-IIV