Greenhouse whitefly (Trialeurodes vaporariorum), green peach aphid (Myzus persicae) and cabbage aphid (Brevicoryne brassicae) are the three major sucking pests that infect hill crops in North Western Himalayan region and cause severe yield losses. Chemical management tactics are the widely practiced methods for management of these pests in the locality. However, knowledge about the efficacy of different pesticides against these native populations is lacking. In view of this, seven insecticides against whitefly and six against aphids were tested for their bio-efficacy under laboratory conditions. The results showed that, field populations of greenhouse whitefly were highly susceptible to three insecticides; Thiomethaxam> Imidacloprid> Pymetrozine with LC50 values 12.30, 18.62 and 22.38 ppm respectively. Whereas, LC50 values of botanical insecticides NSKE and nimbicidine were very high; 524.81ppm and 4365.16ppm respectively, indicating their non-suitability against greenhouse whitefly management. The susceptibility for B. brassicae, a major pest of crucifers is in the following order; Thiomethaxam> Imidacloprid> Indoxacarb> Pymetrozine> Nimbicidine> NSKE and Thiomethaxam was the most toxic insecticide with LC50 and LC90 values as low as 0.024ppm and 0.25ppm respectively. Green peach aphid (M. persicae) was highly susceptible to Thiomathaxam and was followed by Pymetrozine, indoxacarb, Imidacloprid, Nimbicidine and NSKE respectively. The LC50 values of Thiomethaxam and Pymetrozine were at par with a recorded value of 2.54ppm and 2.57ppm, respectively. The three sucking pests under study are well known for their resistance development mechanisms against several groups of insecticides. But, the level of susceptibility that was recorded in our study indicates presence of susceptible population of these sucking pests in Indian Himalayan region that could help to maintain a refugee or buffer populations against development of insecticide resistant strains.
Abstract The present investigation was aimed to assess the best organic pest management practices in soybean and Indian rape cultivation systems in the mid‐Himalayas. Based on the preliminary laboratory assays, promising treatments were selected for field assays for 3 years. It was observed that Parthenium leaf extract 5% provided significantly higher pest reduction in field condition with 76.8% at 7 DAT (days after treatment) against sucking bug, Chauliops choprai infesting soybean. In case of mustard aphids ( Lipaphis erysimi ) infesting Indian rape, Nimbicidine 5 ml L −1 was found superior with 61.5% pest reduction, followed by 5% seed extract of Melia azedarach at 7 DAT in field condition. Contrary to pest reduction, the pooled yield data analysis showed that among organic treatments, spraying of Nimbicidine @ 5 ml L −1 recorded significantly superior yield over control with yield advantage of 29%, followed by M. azedarach seed extract 5% and 10%, both recording 21% yield advantage in case of soybean. Nimbicidine was also superior for Indian rape crop with yield advantage of 51%, followed by Beauveria bassiana @ 3 g L −1 with 44% and 5% seed extract of M. azedarach with 33% yield advantage compared to control. Hence, Parthenium leaf extract 5% and Nimbicidine are recommended for effective control of C. choprai and L . erysimi infesting soybean and Indian rape, respectively. But to achieve higher yield, Nimbicidine is the best among organic management of those pests for both crops. These results suggest good organic pest management options in organic farming system.
Abstract Background The inadvertent observation of a substantial population reduction of greenhouse whiteflies infecting Salvia divinorum plants grown in a polyhouse sparked a flurry of inquiries on the cause of the population decline. The entomopathogenic fungus (EPF) ( Alternaria alternata strain VLH1) infecting greenhouse whitefly on S. divinorum plants was isolated and morphologically and molecularly characterised using multilocus sequence typing. Results The fungus was found to be highly virulent against sucking pests; with LC 50 values ranging from 1.7 × 10 4 to 2.5 × 10 6 spores per ml for the Mustard aphid ( Lipaphis erysimi Kaltenbach) and soybean sucking bug ( Chauliops choprai Sweet and Schaeffer), respectively. In the lepidopteran larvae treated with a concentration of 3 × 10 5 spores per ml, the fungus induced developmental abnormalities such as aberrant larval to pupal moulting, defective pupae, and deformed adults. Pathogenicity studies on the two beneficial insects ( Coccinella septempunctata (Linn.) and Apis mellifera L.) and 11 host plants revealed no disease signs, indicating that it is safe for use in pest management in hill agriculture. The chitinolytic activity of the fungus and its crude protein extracts was reported in studies conducted against target insect pests, with the highest chitinase enzyme production (117.7 U/ml) on the fourth day of inoculation. Furthermore, over a 96-h period, third instar Helicoverpa armigera (Hubn.) larvae fed on a protein fraction-amended artificial diet showed a significant decrease in nutritional physiology indices such as relative growth rate, relative consumption rate, efficiency of ingested food conversion, efficiency of digested food conversion, and approximate digestibility. Moreover, the polyhouse and open-field studies against two sucking pests; Myzus persicae (Sulz.) infesting capsicum in polyhouse and L. erysimi infesting Indian rapeseed in open-field conditions showed, 81.14% and 63.14% mortality rates, respectively, at 3 × 10 7 spore/ml concentration. Conclusions Entomopathogenic fungus (EPF) was reported to be an effective biocontrol agent, which caused direct mortality in sucking pests to developmental abnormalities in lepidopteran insects. Despite positive findings in in vitro and in vivo bioassay investigations against various insect pests, the fungus still has to be inspected before it can be used on a broad scale for biological pest management.
Okra [Abelmoschus esculentus (L.) Moench] is an often cross-pollinated crop with up to 19–42% of cross pollination assisted by insects and planned pollination may improve the economic fruit yield and biological parameters. The present study was carried out during rainy (kharif) seasons of 2021 and 2022 at Research Farm of ICAR-Vivekananda Parvatiya Krishi Anusandhan Sansthan, Hawalbagh, Almora, Uttarakhand to assess the pollinator diversity and possible results (both biological and economical) of planned bee pollination. The study on floral visitors of okra recorded 28 insect spp. belonging to four insect orders, among which five spp., viz. Apis cerana indica (Fabricius) 1798, Apis mellifera (Linnaeus) 1758, Bombus haemorrhoidalis (Smith) 1852, Lithurgus atratus (Smith) 1853 and Xylocopa latipes (Drury) 1773 were predominant. The foraging activity and pollination behaviour showed that two non-Apis bee species (X. latipes and B. haemorrhoidalis) were swift flyers and visited more numbers of flowers per unit time. It was noticed that, peak period of pollinator’s visitation was between 9.00–11.00 h accounting to 113.76±7.65 insects/m2/10 min, during which stigma receptivity and pollen germination were at its peak. Assessment of yield related parameters of insect pollinated flowers showed superior quality fruits with better capsule length (17.4–20.9 cm), capsule girth (6.56–7.84 cm), seeds/capsule (51.4–60.6), test weight of 100-seeds (7.05–8.38 g) and even the seed yield (1.86–3.04 tonnes/hectare) than closed control and hand pollination (emasculated and cross pollinated). In conclusion, ecological engineering of okra fields enhances the pollination rate and ultimately the yield and seed quality.
The VL Lahsun 2 is promising genotype as it has quality bulbs having high yield potential and resistance to purple blotch. This will help, in turn, improve the productivity of garlic in hilly areas of North-West Himalayas and overcome shortage of long day cultivars suitable for this region. Moreover, the variety has less storage loss and attractive foliage growth and good seed (bulb) production ability. Being used as a spice or condiment throughout India, it also helps improve the socio-economic status of hill farmers in North-West Himalayas.
The brown plant hopper (BPH), Nilaparvata lugens Stal (Homopterous: Delphacidae) is one of the lethal pests in rice. In the present study, genome wide distributed Simple Sequence Repeats (SSR) were identified and analysed. The screening of 1.2 Gb of BPH genome resulted in identification of 271785 SSRs. Out of these, 3231 SSRs were from genic region. Microsatellite distribution in genome was found to be 238.2 SSRs per Mb. Altogether the microsatellite motifs contribute only 7.45Mb of BPH genome. Trinucleotide repeats were most abundant representing 50.8% of total genomic microsatellites. Longer repeat motifs were found to be least abundant in the genome representing 1.1% and 0.5% for pentanucleotide and hexanucleotide, respectively. SSR markers identified from this study can be useful for diversity analysis and genetic map development of BPH.
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