Morphological and Biochemical Responses Associated With Resistance to Earias Vittella Fab. (Lepidoptera: Noctuidae) In Okra Varieties

Response of morphological and biochemical traits against okra shoot and fruit borer in different okra varieties were studied. Among the fifteen okra varieties under test Kashi Satdhari was the most superior variety as it showed lowest (2.60) per cent shoot damage followed by D-1-87-5 (3.62%) and Pusa A-4 (4.24%). On the contrary, in Pusa Sawani highest level of shoot infestation (16.23%) followed by SB-2 (13.74%) as against Kashi Pragati (check) 10.08 per cent were recorded. Further, okra variety Kashi Satdhari (7.87%) showed lowest fruit infestation and was considered as least susceptible variety which was at par with NO-136 (8.77%), D-1-87-5 (9.12%) and Kashi Leela (9.38%). Amongst all the okra varieties evaluated for their susceptibility to fruit infestation, Pusa Sawani and VRO-03 showed relatively higher fruit infestation i.e. 35.17 and 33.41 per cent, respectively and registered as the most inferior varieties against (26.12%) Kashi Pragati (check). The correlation study between fruit infestation and morphological factors implied that primary branching and trichome length adversely affect the borer infestation. Further, phenol and phosphorus availability in host plant also showed negative effect on shoot and fruit borer infestation. Bangladesh J. Bot. 50(4): 1059-1066, 2021 (December)

Beauveria bassiana: as a potential microbial biocontrol agent for tea mosquito bug, Helopeltis theivora Waterhouse (Hemiptera: Miridae) in Dooars and Darjeeling, India

Background In the present study, the efficacy of two isolates of Beauveria bassiana namely, BKN20 and BKN1/14 was evaluated against the tea mosquito bug (TMB), Helopeltis theivora, Waterhouse (Hemiptera: Miridae) damaging harvestable shoots of tea plants in the Dooars and Darjeeling regions of West Bengal, India. Results Laboratory study revealed that, in both isolates, BKN20 was more pathogenic than BKN1/14, exhibiting 76% mortality of the test insect. The BKN20 isolate was formulated as an aqueous suspension (5%AS), and evaluated against TMB through micro-plot trials in tea plantations. The Micro-plot field study revealed a maximum of 72.19% reduction in the shoot damage due to TMB in plots sprayed with a 1000 ml/ha concentration of BKN20 5%AS containing 2 × 107 conidia/ml, as compared to the synthetic insecticide (Thiamethoxam 25%WG), where a 63.12% reduction in the shoots was recorded. Furthermore, different concentrations of the formulated BKN20 5%AS were evaluated against the test insect at 2 locations of tea gardens in the Dooars and Darjeeling regions. The results from both locations revealed that 1000 and 1200 ml/ha concentrations of BKN20 5%AS (each concentration containing 2 × 107 conidia/ml) significantly (p < 0.05) reduced the TMB population and they were more effective than Thiamethoxam 25%WG (120 g/ha). However, non-significant differences in crop yields were recorded. The formulation BKN20 5%AS was found to be non-pathogenic to non-target insects, i.e. natural enemies present in the tea ecosystem. BKN20 5%AS had no phytotoxic effect on the tea leaves, with acceptable organoleptic attributes. Conclusion The BKN20 isolate could be commercialized as an alternative microbial insecticide to reduce the load of chemical insecticides in the tea ecosystem.

Flumioxazin soil persistence under plastic mulch and effects of pretransplant applications on strawberry

Weeds are managed in Florida strawberry production systems with plastic mulches, fumigants, and herbicides. There are limited post-transplant options to control weeds that emerge in the planting holes in the plastic-covered beds, but flumioxazin at 107 g ai ha−1 can be applied pretransplant under the plastic mulch to control broadleaf and grass weeds. Three research trials were conducted in Balm and Dover, FL, in 2017 and 2018 to evaluate tolerance of the strawberry cultivar ‘Radiance’ to flumioxazin rates ranging from 54 to 6,854 g ha−1 and to estimate herbicide persistence under the plastic mulch. Shoot damage was observed at 428 to 857 g ha−1 (4× and 8× the label rate, respectively), but a significant increase in the number of dead plants was not observed until the treatment rate was 857 g ha−1 at one site and 3,427 g ha−1 at a second site (8× and 32× the label rate, respectively). Berry yields were unaffected by rates lower than 857 g ha−1. Flumioxazin persisted throughout the growing season (approximately 150 d) with no reduction in soil concentration. We conclude that applied at the label rate, flumioxazin is a safe pretransplant weed management option for season-long weed control in strawberry with no yield reduction at rates below 8× the label rate. Caution is recommended for growers who plant a second crop on the same bed.

EFFICACY OF COMMERCIAL INSECTICIDES AGAINST FRUIT AND SHOOT BORER, LEUCINODES ORBONALIS GUENEE OF BRINJAL, SOLANUM MELONGENA L. IN DHADING, NEPAL

A study was conducted from January to June 2019 in Dhading district to identify the effective commercial insecticide against fruit and shoot borer of brinjal (Leucinodes orbonalis). A field experiment was conducted in Randomized Completely Block Design with five treatments (T1: Spinosad @ 1 ml/ 3 liters, T2: Chlorantraniliprole 1 ml/ 3 liters, T3: Cypermethrin 3 ml/ 1 liter, T4: Neem 3 ml/ 1 liter and T5: Control) and four replications. Result indicated that the fruit infestation percent and shoot damage reduction percent, fruit infestation reduction percent were highly significant with the application of insecticides. The shoot damage percent and fruit damage percent was the lowest with spinosad followed by chlorantraniliprole, cypermethrin and Neem. Thus, spinosad is the most effective insecticides for the management of fruit and shoot borer of brinjal in field conditions.

Evaluating the Potential of WorldView-3 Data to Classify Different Shoot Damage Ratios of Pinus yunnanensis

Tomicus yunnanensis Kirkendall and Faccoli and Tomicus minor Hartig have caused serious shoot damage in Yunnan pine (Pinus yunnanensis Faranch) forests in the Yunnan province of China. However, very few remote sensing studies have been conducted to detect the different shoot damage ratios of individual trees. The aim of the study was to evaluate the suitability of eight-band WorldView-3 satellite image for detecting different shoot damage ratios (e.g., “healthy”, “slightly”, “moderately”, and “severely”). An object-based supervised classification method was used in this study. The tree crowns were delineated on a 0.3 m pan-sharpened worldview-3 image as reference data. Besides the original eight bands, normalized two-band indices were derived as spectral variables. For classifying individual trees, three classifiers—multinomial logistic regression (MLR), a stepwise linear discriminant analysis (SDA), and random forest (RF)—were evaluated and compared in this study. Results showed that SDA classifier based on all spectral variables had the highest classification accuracy (78.33%, Kappa = 0.712). Compared to original eight bands of Worldview-3, normalized two-band indices could improve the overall accuracy. Furthermore, the shoot damage ratio was a good indicator for detecting different levels of individual damaged trees. We concluded that the Worldview-3 satellite data were suitable to classify different levels of damaged trees; therefore, the best mapping results of damaged trees was predicted based on the best classification model which is very useful for forest managers to take the appropriate measures to decrease shoot beetle damage in Yunnan pine forests.

EVALUATION OF SOME COMMONLY AVAILABLE BRINJAL VARIETIES AND HYBRIDS AGAINST LEUCINODES ARBONALIS

Some commonly used varieties and hybrids of brinjal were evaluated against shoot and fruit borer, Leucinodes orbonalis Guenee during late kharif 2015-16 in insectary premises, Department of Entomology, S.V. Agricultural college, Tirupati. Eleven varieties and hybrids of brinjal were tested against shoot and fruit borer, Leucinodes orbonalis. The shoot damage was ranged from 4.06 to 15. 37 per cent in different cultivars. The lower shoot damage was recorded in Arka Neelakanth (4.06%), CVK (4.66%), Shyamala (5.30%), PHB-909 (6.06%) and Arka Keshav (6.46%). The mean fruit damage comparatively was less in hybrid Shyamala, Arka Neelakanth. In these two lines, on number basis, the mean per cent damaged fruits were 23 to 26 per cent. On weight basis also, similar results were obtained (22 to 23 % mean fruit damage). The highest mean fruit damage was recorded in CVK variety (65.83% on number basis and 59.55% on weight basis) followed by Ranjitha hybrid and Arka Kusumakar variety (58 to 59% and 53 to 57% on number and weight basis respectively) at 100 days after transplanting. In remaining lines also, above 35 per cent fruit damage was recorded. Plant height, number of branches, leaves and leaf area did not show any impact on the damage by L. orbonalis. Density of trichomes was found to have negative impact on L. orbonalis. The highest number of trichomes (201 per cm2 leaf area) was recorded on Shyamala. The lowest were in Arka Kusumakar which was highly susceptible one. However, in many of the tested lines, above 150 trichomes/cm2 leaf area were noted.

Comparative assessment of apricot seedlings for drought resistance and winter hardiness in Dagestan

The article presents a comparative analysis of the water-holding ability of leaves (WAL) and its connection with the freezing of the shoots of apricot seedlings of various ecological and geographical origins. A non-linear relationship was found between the WAL of the leaves of apricot seedlings and the freezing of the shoots. It was revealed that seedlings with shoot damage to the average level, WAL are higher (12-15% water content in leaves after 24 hours) than those with slightly submerged (0.8-6%). In severely freezing genotypes (freezing 60-100%), on the contrary, is lower than winter-hardy. The correlation before the peak was 0.79 *, after the peak -0.98 *, significant at the 0.05 significance level.

Evaluation of Oil Extracts from Three Indigenous Botanicals against Field Pest of Solanum Species

Oil extract of three plant insecticides, Acalypha godseffiana, Annona muricata and Petiveria alliaceae were evaluated as protectant against field pest of three major Solanum species cultivated in Nigeria. The experimental design was laid out in a completely randomized block design with each treatment replicated three times. The results indicated low level in severity of shoot damage among Solanum macrocarpon bio-pesticide treated plants and their interactions. Higher fruit damage severity (13.93%) was reflected in untreated S. macrocarpon interactions. Findings from the study reflected a coefficient of determination (R2) = 0.18 between plant oil treatments and fruit yield of eggplant species, which implies that 18% of the variance in fruit yield of eggplant species can be attributed to the plant oil treatments. Further screening of the active components of the botanicals for insecticidal potency is hereby recommended.

Appraisal of resistant genotypes against brinjal shoot and fruit borer (BSFB), Leucinodes orbonalis, Guenee

The main purpose of this study was to find out the best variety of brinjal having resistance to BSFB. A pot experiment was carried out at the germplasm centre, Agrotechnology Discipline, Khulna University, Khulna during February 2014 to August 2014. The experiment was laid out in CRD using thirteen varieties with five replications. The varieties were V1=BARI begun-1, V2=BARI begun-4, V3=BARI begun-5, V4=BARI begun-6, V5=BARI begun-7, V6=BARI begun-8, V7=BARI begun-9, V8=BARI begun-10, V9=Makra, V10=Muktokashi, V11=Lalita, V12=Hazra, V13=Chaga. Data were collected on total number of shoot, total number of infested shoot, percentage of shoot damage, percentage of shoot infestation reduction, numbers of larvae per infested shoot, total number of fruit, percentage of fruit damage, percentage of fruit infestation reduction, numbers of larvae per infested fruit. Results have shown that the minimum shoot infestation was found in BARI begun-6 (29.60%, 32.40%, 29.86% and 29.38%, respectively at four different stages of eggplant). Percent of fruit infestation was minimum in V4 (BARI begun-6) (25.16%, 27.42% and 25.40% at three stages respectively).J. Bangladesh Agril. Univ. 16(2): 227-231, August 2018