Synergistic effect of naturally occurring Granulosis virus isolates (PbGV) with phagostimulants against the cabbage butterfly, Pieris brassicae (L.) for its eco-friendly management

Background To manage the cabbage butterfly, Pierisbrassicae (L.) (Lepidoptera: Pieridae), it is not wise to use insecticides on leafy vegetables which are eaten mostly fresh. During the past decades, the efforts to manage the pest, through chemical insecticides have raised serious health. Investigations were carried out to isolate naturally occurring GVs (PbGV) as a potent biopesticide against P.brassicae and to explore their efficacy with the application of phagostimulants. Results Among the four naturally occurring isolates obtained from Northwestern Himalayas, Sudhmahadev isolate was found to be the most promising based on virulence and speed of kill against all the instars tested in the laboratory, showing the natural incidence of PbGV infection in field conditions. In concentration and time–response bioassay, all the isolates of P.brassicae Granulosis virus were found high virulent against second instar larvae of cabbage butterfly. Therefore, for enhanced efficacy of PBGV, its combined application with phagostimulants (Lepidiumsativum + Teepol + jaggery) or sticker (Teepol + jaggery), applied in field trials, resulted into greater mortality of larval instars than the single one. Overall, the results indicated that the introduction of a more isolates PBGV strain into populations of P.brassicae could be of vital importance for eco-friendly suppression of this pest globally with the combination of phagostimulants. The application virus alone with the pre-standardized concentration of 1 × 1012 OBs/ha did not reduce the larval population density to the desirable extent in the greenhouse chamber and therefore was not included in field experiments. Overall, the most promising treatments in reducing the larval population of the pest were PbGV + Teepol + B.thuringiensis (93.49 and 91.39%) and PbGV + Teepol + L.sativum (88.79 and 86.97%) over control in both greenhouse and field trials, respectively. Conclusions In this study, the native isolates of PbGV from different target locations to test their efficacy against different instars of P.brassicae were explored. Using native PBGV isolates with phagostimulant combinations played an important role for regulating the pest effectively. These phagostimulants not only protected the OBs from degradation in the presence of sunlight but also increased the speed of killing. The biocontrol potential of PbGV in both laboratory and field conditions indicated that baculoviruses are sustainable alternative to chemical insecticides.

Effect of Larval Density of Helicoverpa armigera (Hubner) on Pod Damage and Yield of Chickpea

Background: Chickpea (Cicer arietinum L.) is cultivated in almost all parts of world covering more than 50 countries spread over Asia, Africa Europe, Australia, north America and South America countries and is the second most important food legumes crop after common bean (Phaseolus vulgaris L.). Chickpea has played a major role in realization of pulse Revolution in india making the country near self-sufficient in pluses. Gram is extensively grow in india. Due to its high nutritional value and its ability to fix atmospheric nitrogen, its more widely cultivated rabi pulse crop. The gram pod borer Helicoverpa armigera (Hubner) is most important pest of chickpea. Many pesticides were so far tested against this pest but due to over use of these pesticides resistance, residue and resurgence problems arises, beside destruction of natural enemies. Methods: To determination of per cent pod damage and yield of chickpea due to different larval density of H. armigera is an important tool to reduce the cost of cultivation by avoiding the unnecessary use of pesticides. Therefore, a pot experiment was conducted in arranged in a completed randomized design with four replications. The pots were placed under natural field conditions and take observation at Research farm, Rajasthan Agricultural Research Institute, Durgapura, Jaipur during 2015-16 and 2016-17. Result: The results revealed that least per cent pod damage (29.05, 24.78%) was recorded when the larval population was one per plant, while the maximum pod damage (64.55 and 67.76%) was recorded during 2015-16 and 2016-17, respectively. The simple liner correlation analysis indicated that there was a significant positive correlation (r= 0.989 and 0.999) between the larval density and per cent pod damage. Further, a significant correlation was noticed between larval density and number of healthy pods per plant, reduction in yield, yield per plant, total number of pod and damaged pods were -0.964, -0.976; 0.98, 0.986; -0.98, -0.986; 0.117, 0.126 and; 0.985 and 0.992, respectively during 2015-16 and 2016-17.

Monitoring of damage and distribution of invasive fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) on maize crop in Karo, North Sumatera, Indonesia

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is an invasive pest from America and has recently become an important pest in Indonesia. In their new environment, these pests have very high migratory and adaptive skills, as well as aggressive feeding habits. The aim of this research was to monitor the distribution, percentage of attacks, and damage caused by S. frugiperda on maize fields in the Karo District of North Sumatra Province. The study was conducted using a survey method at various altitudes and the sample unit was determined using the diagonal method. Each sample unit has a size of 2 × 2 m2. The age of maize crop used as the sample is 2-4; 5-6; 7-8; 9-10; and 11 weeks after planting (wap). Symptoms of attack, number of larvae population, and percentage of FAW attack were observed directly on plants. The results showed that FAW spread evenly at various altitudes, with the highest population at an altitude of 500-1,000 m.a.s.l at the age of 2-4 wap with a larval population density of 14.20 individual/unit sample. The highest percentage of attack was found at an altitude of 500-1,000 m.a.s.l, namely 82% at 2-4 wap. The highest attack on leaves occurred at an altitude of 500-1,000 m.a.s.l (70.6%) at the age of 2-4 wap.

Effects of Irrigation Levels on the Yield of Chickpea (Cicer Arietinum Linn) Due to Incidence of Helicoverpa Armigera

Effects of four different irrigation levels viz., One irrigation at 50 per cent flowering stage, one irrigation at grain filling/pod initiation stage, two irrigations (one at 50 per cent flowering + one at grain filling stage), control (without irrigation) on the incidence of gram pod borer, Helicoverpa armigera (Hubner) on chickpea were studied during Rabi, 2014-15 and 2015-16 at Research Farm, College of Agriculture, Bikaner (Rajasthan), India. Results revealed that the highest mean larval population (3.12 larvae per 5 plants) and maximum pod damage (33.24%) were recorded in the crop which was irrigated twice viz., one at 50 per cent flowering stage and second at grain filling stage. The lowest larval population (2.03 larvae per 5 plants) with minimum pod damage (8.34%) was recorded in the crop where irrigation was not given. The maximum seed yield (11.05 q/ha) was obtained from the crop which was irrigated two times and minimum seed yield (7.56 q/ha) was obtained in control. Bangladesh J. Bot. 50(4): 1203-1207, 2021 (December)

Relationship between Weather Parameters and Incidence of Gram Pod Borer, Helicoverpa armigera on Chickpea

Background: Chickpea, Cicer arietinum which is considered as a “King of pulses” get adversely affected by several biotic and abiotic stresses, out of which gram pod borer, Helicoverpa armigera (Hübner) is the major one. The damage caused by H. armigera starts from vegetative growth and continues till maturity of the crop. This pest is causes 25 to 70 per cent pod damage in chickpea but in favorable conditions pod damage goes upto 95 per cent. Methods: Present study was carried out during, rabi, 2014-15 and 2015-16 at Research Farm, College of Agriculture, Bikaner (Rajasthan). Correlation coefficient was worked out with weather parameters such as temperature (maximum and minimum), relative humidity (maximum and minimum), rainfall and sunshine hours. Multiple linear forms of regression model were also used to assess the effect of the weather parameters on the incidence of pod borer. Result: The studies revealed that peak larval population of gram pod borer was recorded in the second fortnight of February thereafter, population declined abruptly. The larval population of pod borer on chickpea occurred low at vegetative and flowering stages and high at pod formation as well as at grain developmental stages. The temperature (maximum and minimum) and sunshine hours had significant positive correlation with larval population during rabi, 2015-16. The maximum relative humidity showed significant negative correlation during rabi, 2015-16 whereas, minimum relative humidity showed significant negative correlation with larval population during both the seasons. The rainfall showed significant positive correlation during rabi, 2014-15.

Weather based prediction of Chickpea Helicoverpa armigera population in Bundelkhand agroclimatic zone of Madhya Pradesh

An attempt was made to find out the impact of rainfall, temperature and growing degree day (GDD) on the larval incidence and peak population of Helicoverpa armigera on chickpea and its growth in the Bundelkhand Agroclimatic zone of Madhya Pradesh. Besides, an attempt was also made to examine the association with weather variables of rising and falling phase of the larval population of Helicoverpa armigera. It was found that there was not any significant impact of monthly (September and October) rainfall on the larval population but the monthly rainfall of January and February significantly influenced the incidence of the pod borer and GDD plays a vital role in increasing and decreasing of its peak population. Minimum temperature and rainfall play a crucial role for larval incidence and its population growth. Growing degree day from 1st January to 15th February were presented in relation to the number of peak larval population in chickpea. The correlation of weather factors with larval population was also presented and different weather parameters were screened for its prediction and management. A multiple regression equation was also developed. It was found that if the cumulative growing degree day from 1st January to 15th February 350 degree day and weekly minimum temperature ranged from 6 to 12 C along with number of rainfall events 5 days, then number of larval population of H. armigera in chickpea is high and vice-versa. This study will be very useful not only for forecasting the peak larval population of H. armigera in chickpea but in formulating effective pest management strategies too.

Development of weather based prediction model for leaf roller population of Sesame in Bundelkhand zone of Madhya Pradesh

Field experiment was conducted during twelve consecutive Kharif seasons from 1995 to 2006 at Zonal Agricultural Research Station, Tikamgarh to find out the impact of weather parameters on the incidence and activity of Antigastra catalaunalis (Dupnocbel) in Sesame cv JT-7. The analysis revealed that the pest activity started to buildup from 30th standard meteorological week and remained up to 40th standard meteorological weeks (SMW). Larval population has been correlated with weather data and correlation coefficient, regression equations were worked out for development of weather based prediction model. Significant positive correlation with maximum and mean temperature (maximum, minimum) and negative relationships with rainfall was observed. Best fitted polynomial models were developed using the whole season data which explained 60 to 90 per cent variability due to weather parameters. The multiple regression technique has been used for developing predictive model using larval population and weather data not only for the corresponding week but also for preceding weeks. The prediction model for leaf roller explained 88% variability of the pest population. The model predicted peak larval population was in good agreement with observed peak larval population.

Larval densities of the protected Striped lychnis moth Shargacucullia lychnis (Lepidoptera: Noctuidae) in Buckinghamshire

Natural history information is essential for ecologically-relevant inferences about (adaptive) responses in organismal biology. Yet, natural history data can be difficult to obtain, particularly for the developmental stages of holometabolous insects. This gap can compromise our ability to design controlled experiments that provide useful understanding of insect responses to changing environments and precludes our ability to understand how natural populations may respond to unpredictable climatic changes in their natural environment. In this study, we collated data from previous reports from the Butterfly Conservation Upper Thames Branch on the larval population density of Shargacucullia lychnis (Lepidoptera: Noctuidae) in Buckinghamshire. In the UK, S. lychnis is a protected species, for which natural history information can be invaluable for its effective conservation. We report here that the natural range of larval densities observed for S. lychnis across locations and years is 0.001 to 6.417 larvae per spike. More importantly, S. lychnis larval density has overall declined from 1996 to 2020, which could support previous reports of a contraction in population range for this species. Overall, this study provides invaluable information about larval population density for an important protected Lepidopteran species of the UK.

Population Dynamics of Fall Armyworm, Spodoptera frugiperda (J. E. Smith) on Sorghum

The study on seasonal incidence of fall armyworm was carried out during kharif, 2019 at Agricultural college farm, Bapatla. The oviposition of fall armyworm was observed from 34th SMW (Standard Meterological Week) and reached its peak during 40th SMW (0.03 egg masses plant-1). The larval population of fall armyworm was commenced during 35th SMW and increased gradually to a peak of 1.67 larvae plant-1 during 41st SMW. The maximum plant infestation (60.00%) and leaf damage severity rating (3.13) of fall armyworm was observed during 41st SMW. The peak activity of natural enemies was observed during 41st SMW which coincides with the larval population of fall armyworm. The correlation analysis indicated that eggmasses of fall armyworm was positively correlated with minimum temperature(r= 0.668) and wind speed (r= 0.529) while, the larval population showed significant positive correlation with maximum temperature (r= 0.029). The plant infestation caused by fall armyworm had shown significant negative correlation with maximum temperature (r= -0.633) and positive correlation with morning relative humidity (r= 0.678) and evening relative humidity (r= 0.664) whereas, the leaf damage severity rating exhibited significant positive correlation with evening relative humidity (r= 0.691). The multiple regression analysis revealed that the influence of weather parameters on the incidence of fall armyworm and natural enemies in sorghum ecosystem was more than 65% and 40%, respectively.

Influence of prevailing weather parameters on population dynamics of fruit borer, Helicoverpa armigera (Hübner) on tomato in Haryana

A field experiment was conducted for two years (2016-17 and 2017-18) at Entomological Research Area, Department of Entomology, CCS Haryana Agricultural University, Hisar to ascertain the influence of various meteorological parameters on population fluctuations of Helicoverpa armigera on tomato. The maximum oviposition (4.60 eggs/ plant) was recorded during 15th standard meteorologicalweek (SMW) whereas larval population was at peak (4.91 larvae/ plant) during 16th SMW. The larval population showed significant positive correlation with maximum temperature (r=0.617*) and highly significant negative correlation with morning (r=-0.784**) as well as evening relative humidity (r=-0.814**). Maximum eggs parasitization (12.85 %) by Trichogramma sp. was recorded during 16th SMW. These trichogrammatid parasitoids exhibited non-significant correlation with weather parameters and highly significant positive correlation (r=0.976**) with egg counts of H. armigera. Multiple linear regression analysis showed that 77 per cent (R2=0.77) variability in larval population was accounted by weather parameters particularly maximum temperature, morning and evening relative humidity.