Mosambi
4. CROP PROTECTION
4.2 ENTOMOLOGY
(BBTV) DNA1, DNA2, DNA3 components and a set of primers from BBTV common stem loop region. The amplified products of putative replicase and coat protein genes were cloned. The putative rep-gene was sequenced.
It had 83% sequence homology with BBTV master rep-gene.
Amplification of viral genome could be achieved only in the tissues from the youngest unfurled leaves and meristem tips.
4.1.3.10 Orchids
Characterization of the virus infecting Cymbidium and Coelogyne. Two important viruses, namely, Cymbidium mosaic virus (CymMV) and Odontoglossum ring spot virus (ORSV) are ubiquitous with orchid cultivation in Sikkim and Darjeeling hills. CymMV and ORSV may infect orchid genera either singly or in combinations. Immunological studies detected mixed infection of CymMV and ORSV in Cymbidium and other orchid genera. Electron microscopic (EM) studies of the infected samples also revealed the presence of both flexuous filamentous particles of CymMV and rigid rods of ORSV. Besides these two viruses, a number of viruses having Rhabdovirus-, Potyvirus- and Badnavirus-like particles were found to be associated with different orchid species. EM studies of the leaf tissue of Cymbidium spp.
infected with mosaic streak disease and the leaf tissue of Coelogyne spp. infected with ring spot disease showed the presence of Rhabdovirus-like particles either alone or in combination with ORSV.
4.1.3.11 Tapping panel dryness of rubber
R-PAGE analysis of grafted trees revealed that TPD is graft transmissible. One hundred per cent (100%) transmission was observed when both stock and scion were from the affected source, up to 70% when the stock source was positive, up to 42% when the stock source was negative and the scion source was positive. In such case where both the stock and scion were from apparently healthy source, small percentage of plants showed the presence of TPD. Characterization of LMW-RNA -like bands associated with TPD is in progress.
InfoCrop, a crop-pest model was used to simulate crop losses due to leaf folder (Cnaphalocrosis medinalis), and stem borer on rainfed rice in Khulgad watershed, Almora, Uttarakhand. Yield loss data were then used to formulate iso- loss curves, which depicted various combinations of pest damage and crop age resulting in the same yield loss. The crop was found to be prone to leaf folder attack more up to 50 days after sowing than during later growth stages. The crop was prone to stem borer attack more during post-flowering stage than during pre-flowering stage.
4.2.1.2 Pulses
Field experiments on evaluation of different morphological characters of chickpea cultivars in relation to the damage caused by Helicoverpa armigera were undertaken during rabi. Mexico Local recorded the maximum height gain from 60 days to 90 days after sowing (DAS), i.e., 28.33 cm to 36.7 cm, respectively and the lowest height gain in the cultivar JG 62 (31 cm) at 90 DAS. At 100 DAS, the maximum number of leaves was observed in ICC 3279 (18.67 leaves per branch) and the lowest in Mexico Local (4 leaves/branch). Oviposition on Mexico Local ranged from 0.5 to 3.26 eggs/plant, when observed from 60 to 110 DAS, indicating that this cultivar was more preferred for oviposition. Relatively very less number of eggs was laid on BG 1103 (0.56 eggs/plant). At 125 DAS, Mexico Local recorded the maximum number of larvae (3.13) per plant. These results have concluded that plant height was negatively correlated with the number of branches and positively correlated with the number of leaves/branch.
Cultivars that recorded higher number of eggs, had recorded
higher egg and larval counts in subsequent generation too.
High humidity within the bushy plants attracted more female moths for oviposition, which was absent in spreading type of cultivars. The correlation between yield and total number of pods was found to be positive, whereas negative correlation occurred between yield and number of eggs, number of larvae and number of damaged pods.
In pigeonpea during kharif 2007 the population of borers was negligible and did not cross the economic threshold level.
4.2.1.3 Oilseeds
A total of 73 germplasm/cultivars of Brassica were screened against mustard aphid Lipaphis erysimi during rabi 2006-07. The minimum Mean Aphid Infestation Index (MAII) varied between 0.25 and 2.65 at flowering. At pod stage, the minimum MAII ranged between 0.5 and 4.5 when graded on a scale of 0 to 5. An insecticidal trial was conducted with oxydemeton methyl and imidacloprid at 40 g a.i./ha and 60 g a.i./ha; thiamethoxam at 20 g a.i./ha and 40 g a.i./ha; acetamiprid at 40 g a.i./ha; chlorpyriphos at 500 g a.i./ha and endosulfan at 700 g a.i./ha. All the treatments were found effective against the aphid up to 7 days after spraying. Thereafter, the aphid migrated from the plant because of the rise in temperature during February. The reduction percentages due to treatments ranged between 78% and 92%.
A field trial to estimate the increase in seed yield and other components of mustard due to pollination by Apis mellifera and other pollinators on a recently released variety of Brassica juncea JD 6 revealed an increase in seed yield by 25%; number of pods per plant by 33.2%; number of seeds per pod by 20.2% and 1000-seed weight by 33.3%.
4.2.1.4 Cotton
A field experiment to evaluate insecticides against major insect pests of cotton was conducted during kharif, 2007 on variety P-8-6. Four sprays were required to suppress the population of insect pests throughout the crop season. Thiomethoxam 25 WG @ 100 g a.i./ha, caused the highest reduction in the population of Bemisia tabaci by 82.2% and 84.4%, and in the population of Amrasca biguttula by 84.8% and 84.1% at seven days after first spray and second spray, respectively. However, it was on a par with imidacloprid 17.8 SL @ 20 g a.i./ha and acetamiprid 20 SP @ 25 g a.i./ha.
Spinosad 45% SC @ 75 g a.i./ha was found to be superior against bollworm Earias spp. with the highest
Isoloss curves for leaf folder damage in rice in Khulgad watershed in Almora, Uttarakhand
reduction in larval population (72.3%) at seven days, minimum damage to fruiting bodies (19.3%) and green bolls (11.8%) after third spray, and was on a par with emamectin benzoate 5% SG @ 11 g a.i./ha and profenophos 50 EC @ 75 g a.i./ha.
Similarly, after fourth spray, the highest reduction in larval population, (83.4%) and the lowest damage to fruiting body (5.3%) and green boll (3.3%) were recorded with spinosad 45% SC @ 37.5 g a.i./ha + profenophos 50 EC @ 500 g a.i./
ha. The minimum pink bollworm (P. gossypiella) infested open boll damage (9.8%), loculi damage (18.1%) and the highest yield of 2.78 t/ha were observed in treatment with spinosad 45% SC @ 37.5 g a.i./ha + profenophos 50 EC @ 500 g a.i./ha followed by emamectin benzoate 5% SG @ 11 g a.i./ha used as a third spray, as against those observed in the untreated control (1.79 t/ha).
4.2.1.5 Soybean
Ninety soybean lines (PYT- I =18, PYT- II = 22, IVT = 42 and AVT II = 8) were evaluated during kharif against stem fly and yellow mosaic virus (YMV) disease transmitted by whitefly. Variety DS 2207, which showed resistance consistently for the last three years, was identified as a promising source of resistance.
4.2.1.6 Vegetables
An insecticidal trial on okra variety Pusa Anamika with seven treatments and baby-corn as border crop along with a control having no baby corn was conducted during 2007. Five treatments had the seed treated with either thiamethoxam (70WS) or imidacloprid (70WS) @ 3 g a.i./kg with abamectin (1.8 EC), spinosad (45 SC), emamectin (5% SG) and Econeem (10,000 ppm of Azadirachtin) in different combinations. All the seed treated plants exhibited significantly less number of leafhoppers Amrasca biguttula biguttula (4.0 - 8.3/15 plants) compared to baby-corn check (12/15 plants) as well as control (22/15 plants) at 35 days after sowing. Okra border cropped with baby-corn without any insecticidal intervention was also found effective in managing leafhopper with 12.0, 11.3, 19.7 and 30.0 leafhoppers at 35th, 43rd, 50th and 57th day after sowing, respectively, as compared to control where the population count was 22.0, 33.0, 56.0 and 67.0 leafhoppers/
15 plants, respectively.
Six insecticides, viz., alphamethrin, cypermethrin, endosulfan, spinosad, emamectin and Neem Baan, were evaluated against fruit fly in bittergourd variety Chaman (F1 hybrid). Per cent infestation (number-by-number basis) due to Bactrocera cucurbitae varied from 7.8 to 16.4 against 17.5%
in control. On weight-by-weight basis, alphamethrin @ 20 g a.i./ha was the most effective followed by emamectin benzoate
@ 15 g a.i./ha and Neem Baan (1500 ppm) @ 1ml/l.
Modern synthetic insecticides and botanicals were evaluated against the tobacco caterpillar (TC), Spodoptera litura in the seed crop of cabbage when transplanted in early August.
At one month stage of the crop, 42.92% plant infestation of TC was recorded. It was followed by two fortnightly sprays of different insecticides. After one month of these sprays, minimum TC infestation was recorded in the case of endosulfan (0.05%), followed by cypermethrin (0.01%) sprays. Maximum net yield of cabbage, i.e., 59.8 t/ha was however, recorded in the case of cypermethrin followed by Bt and endosulfan.
Comparative effectiveness of modern synthetic insecticides and botanicals against Spodoptera litura
Insecticides Per cent plant infestation (DAT) Cabbage
0 28 yield (t/ ha)
Dharek 4g DLP/l 16.00 (23.21) 14.30 (22.26) 53.00 Bt (Halt @ 1g/l) 14.30 (21.72) 10.70 (19.37) 58.20 Dimilin(0.01%) 18.30 (25.04) 13.10 (21.16) 55.40 Endosulfan(0.05%) 16.40 (23.05) 2.80 (9.21) 57.40 Neem (Neem-excel 17.10 (23.04) 16.80 (22.88) 50.45 (0.015%)
Cypermethrin (0.01%) 14.80 (22.38) 10.30 (17.17) 59.80 Thiamethoxam (0.02%) 15.70 (23.17) 15.60 (22.78) 54.00 Control 29.20 (32.47) 15.70 (23.29) 48.10
SE 6.83 5.74 7.18
CD(P=0.05) NS 11.93 NS
DAT- Days after treatment. Figures in the parentheses are arc sin √ per cent x+0.5 transformation
In the seed crop of cauliflower, maximum seed yield obtained was 364. 3 kg/ha when carbofuran was applied @ 0.5 g/plant, 15 days after transplanting. It was followed by need based rogor (0.05%) sprays against cabbage aphid (CA), Brevicoryne brassicae, endosulfan (0.05%) spray on 25th April against cabbage butterfly (CB), Pieris brassicae and another endosulfan spray against thrips in the first week of May.
Maximum seed yield of cabbage, i.e., 1384.33 kg/ha was obtained when monthly, cypermethrin (0.01%) sprays were given at the vegetative stage, followed by two endosulfan sprays at the reproductive stage.
4.2.1.7 Storage entomology
Studies on the efficacy of various extracts of Caesalpinia crista as grain protectant against
Callasobruchus chinensis infesting green gram were undertaken. Significantly reduced egg laying was observed in all the treatments. Methanol extract was more effective at various concentrations when observed 30 days, 60days and 90 days after treatments followed by butanol and hexane extracts. No adult emergence was observed in any of the treatments after 30 days and 60 days except from seeds treated with hexane extract, although adult emergence was observed in all the treatments except in higher concentration of butanol extract when experiment was conducted 90 days after treatment. There was no adverse effect of these extracts on the viability of the seeds even after 180 days of treatment.
Susceptibility to commercial formulation of deltamethrin was reduced by 3.4 times after 5 generations in the larvae of Trogoderma granarium. Toxicity of commercial formulations of bifenthrin, malathion and dichlorvos when studied against F1 and F6 larvae of T. granarium indicated that bifenthrin, although most toxic to F1, was least toxic to the F6 generation.
4.2.2 Biological Control
Economic mass production of Bacillus thuringiensis was attempted on four media including defatted mustard cake, defatted cotton seed extract, bone meal and nutrient broth for their ability to produce higher amounts of spores. The highest spore count of B. thuringiensis var. kurstaki HD-1 was observed in the case of media prepared using cotton seed extract followed by mustard extract based media and nutrient broth + Mg, while the least growth of B. thuringiensis var.
kurstaki HD-1 was noticed in bone meal extract based media.
Studies on the comparative life history of Zygogramma bicolorata on two weeds, namely, Parthenium hysterophorus (exotic) and Xanthium strumarium (indigenous), were carried out in the laboratory. The beetle could complete its development in 26.94 ± 3.88 days and 34.59 ± 3.51 days at 28 + 1°C and 45-65% R.H., when fed on P. hysterophorus and X. strumarium, respectively. Females lived longer than males in both cases and laid more number of eggs when P. hysterophorus was provided as food material. These studies provide an evidence of the oligophagous nature of Z. bicolorata.
4.2.3 Insect Physiology
Investigations on baseline susceptibility of H. armigera populations collected on Bt cotton from Mansa, Muktsar, Bhatinda, Hisar and Raichur to Cry1Ac toxin indicated a variation of 57-fold in the insect susceptibility compared to
that of the most tolerant population, thus showing no evidence of resistance development.
The genetic inheritance of Cry1Ac resistance was examined in H. armigera by intermating resistant and susceptible populations. Reciprocal F1 crosses were done by mating susceptible Vadodara female × Bharuch male (SR) and susceptible Vadodara male × Bharuch female (RS).
Sibmating was also done for maintaining purity of both resistant and susceptible lines. Progenies of both F1 hybrid and sibmating were subjected to bioassay using seven concentrations ranging from 0.001 µg/g to 3.0 µg/g diet using the diet incorporation method. On the basis of the 4-day mortality data, the LC50 was estimated and the degree of dominance calculated to determine the mode of inheritance.
F2 hybrids were subjected to bioassay and the mortality data analyzed, and the degree of dominance (D) was estimated.
The responses of F1 progeny from reciprocal crosses differed statistically from each other indicating that the inheritance of Cry1Ac resistance is sex influenced and semidominant.
Inheritance of MVP Bt Cry1Ac in Helicoverpa armigera
Cross Female (@&) × LC50 FL at 95% D-value Male (B&) (µg/gm diet)
1. S x S 0.0028 0.0004-0.0065 -
2. R x R 0.638 0.411-1.02 -
Reciprocal F1 Hybrid
3 S × R 0.146 0.089-0.226 0.299
4 R × S 0.55 0.304-1.09 0.782
F2 Hybrid
9 (S × R) × (S × R) 0.39 0.23-0.686 -
10 (R × S) × (R × S) 0.286 0.18-0.428 -
R (Resistant) = Bharuch population ; S (Susceptible) = Vadodara population
Investigations on toxicity of Cry toxins to neonates of cabbage butterfly Pieris brassicae and Diacrisia obliqua indicated that Cry1Ac was more toxic (LC50= 0.065 µg/ml) than Cry1Ab (LC50= 0.20 µg/ml) to neonates of P. brassicae than to D. Obliqua while Cry1B was more toxic (LC50= 1.82 µg/ml) than Cry1C (LC50= 2.43 µg/ml) to neonates of D.
obliqua on a four-day bioassay. Bioassays on a seven -day basis were more sensitive to differentiate toxicities of Cry1B and Cry1C against D. obliqua.
Eighty-seven germplasm accessions of cereals (rice, maize, barley, wheat and oats) received from NBPGR, DRR and other sources were assayed in the laboratory for trypsin
CNSL (Cashewnut shell liquid) oil and partially hydrogenated preparations were evaluated at 1% concentration for their insecticidal properties against H. armigera neonates by ‘artificial-diet-surface-incorporation’ method in a ‘no- choice’ assay. CNSL-treatments resulted in delayed larval- and pupal-periods and deformed larvae. Hydrogenated-CNSL was more active than CNSL and exhibited 75% mortality till pupation as against 20% and 23.3% in aqueous and acetone blanks, respectively. The insecticidal activity is attributed to stomach poisoning in ‘diet-surface-incorporation’, while no contact toxicity by ‘direct-spray’ method was recorded against five-day old larvae.
IGR activity of hexane, methanol and chloroform extracts of Andrographis paniculata was evaluated against S.
litura larvae through diet incorporation method and compared with that of azadirachtin 50%. Treatment with various concentrations of methanol extract and azadirachtin resulted in formation of abnormal adults while hexane and chloroform extracts resulted in only 33.3% normal adult formation at a concentration of 0.07%.
and chymotrypsin inhibitory activities using synthetic substrate BApNA, and expressed as TIU and CIU, respectively. Among these five barley accessions had high trypsin inhibitory activity (~ 40 TIU/mg protein). Trypsin inhibitory activity was more compared to chymotrypsin inhibitory activity in all the cereals tested. Only one accession of maize (51705) had comparable activity (30.50 TIU) as that of barley. The trypsin inhibitory activity of rice, wheat and oats accessions was below 10 TIU/
mg of seed protein. Hence, barley seed is a potential source for isolation of protease inhibitors for use in transgenic studies aimed at insect pest management.
Trypsin inhibitory activity of barley accessions
Barley accessions TIU/mg seed protein CIU/mg seed protein
IC 82680 43.96 15.97
IC 82512 43.04 8.79
IC 82506 44.02 5.08
IC 79590 39.81 8.38
IC 60712 35.44 6.34
Laboratory studies on the effect of dihydrodillapiole on pyrethroid resistance associated esterase inhibition in third instar larvae of Spodoptera litura populations from Delhi and Guntur indicated that α-naphthyl acetate hydrolysable esterase activity (µmoles/mg protein/min) in Delhi population was less compared to that of Guntur population.
Insecticide resistance associated esterases in Delhi population of S. litura were inhibited by pre-treatment with dihydrodillapiole and the reduction was instantaneous initially and sustained for about 3 h post treatment and equilibrated at 4 hr post treatment. The esterase activity of Guntur population increased within 3 h and this increase was almost double. The highest increase was 1.28 µmoles / mg/min at 2 h post treatment. Subsequently, the esterase activity reduced to values lower than 0.70 µmoles at 4 h to 12 h post treatment in Guntur population. At a later stage, there was a clear trend of regaining esterase activity to the initial level. The variation observed was clearly triphasic, suggesting homeostatic regulation of esterase activity, though suppressed by dihydrodillapiole transiently.
4.2.4 Insect Toxicology
Laboratory studies on the susceptibility of different populations of S. litura to various insecticides revealed that the larvae from Bangalore and Guntur were 3.56, 1.1, 1.8 and 1.9 folds and 10.4, 4.8, 17.2 and 7.8 folds resistant to cypermethrin, fenvalarate, lambdacyhalothrin and emamectin
benzoate, respectively, compared to Delhi population.
However, Bangalore population was susceptible to profenophos and indoxacarb.
Relative resistance of S. litura populations from various locations to synthetic insecticides
Insecticides LC50 (%)
Delhi Bangalore Guntur
Cypermethrin 0.0112 0.0399 (3.56) 0.1162 (10.37) Fenvalerate 0.0314 0.0361 (1.14) 0.1503 (4.78) Lambdacyhalothrin 0.0110 0.0202 (1.84) 0.1896 (17.24) Profenophos 0.0662 0.0302 (0.46) 0.1490 (2.25) Indoxacarb 0.0051 0.0033 (0.64) 0.0073 (1.43) Emamectin benzoate 0.0035 0.0066 (1.88) 0.0274 (7.82) Note: Figures in parantheses are fold change with respect to Delhi population taken as unity
Effect of extracts of Andrographis paniculata on normal adult emergence
Extract Concentration (%)
0.007 0.01 0.03 0.05 0.07
Hexane 61.1 50.0 50.0 44.44 33.33
Methanol - - - - -
Chloroform 72.28 55.56 38.89 36.66 33.33
Azadirachtin 50% - - - - -
Control 94.75
Pratylenchus thornei and Xiphinema insigne (8 each), Rotylenchulus reniformis (5), Hemicycliophora typica (3), Hemicriconemoides mangifaere (2) and Tylenchorhynchus annulatus (1). The nematode bio-diversity studied in three districts (Mahasumund, Dhantari and Durg) of Chhatisgarh revealed predominant population of rice-root nematode Hirschmanniella oryzae encountered with 100%
frequency distribution.
The distribution of plant parasitic and beneficial nematodes in Gujarat was mapped.
4.3.1.2 Entomopathogenic nematodes
New EPN strains isolated.
Four strains of Steinernema, one each from Uttar Pradesh and Jammu and Kashmir and two from West Bengal were isolated. Based on the morphological and morphometrical features of the infective juveniles and males and females of the two generations, the strains were identified as S. riobrave from Uttar Pradesh; S. carpocapsae from Jammu and Kashmir; and S.
tami and S. carpocapsae from West Bengal. S. riobrave was characterized by having paired horn-like structures on the lip regions of its infective juveniles with the presence of additional pair of papillae on its males and the presence of tail mucro only in second generation females.
Insecticidal fractions purified. Two insecticidal fractions were purified from Photorhabdus luminescens, a symbiotic bacteria residing in the gut of nematode Heterorhabditis indica (IARI strain). Hundred per cent mortality to the neonates of Galleria mellonella larvae was recorded in PD1C and PD3 after 60 h and 72 h, respectively, when fed orally. PD1C when further denatured and fed to the larvae showed a delayed inception of mortality starting at 72 h (60%), 84 h (90%), 96 h (100%). Remaining fractions did not show oral toxicity upon denaturing.
Ecological characterization of S. riobrave. The infectivity and development of S. riobrave was studied at six different temperature conditions (10 °C, 15 °C, 20 °C, 25 °C, 30 °C and 35 °C). The optimum temperature for the infectivity and reproduction of the nematode was found to be 30 oC with an optimal range of 25-35 °C. To know the optimum moisture required for the species, its infectivity was recorded at different Toxicity of commercial formulations of nine
insecticides, viz., endosulfan, metasystox, thiomethoxam, imidacloprid, acetamiprid, chlorpyrifos, fipronil and dimethyl demeton was studied in the laboratory against mustard aphid L. erysimi. Results showed thiomethoxam to be the most toxic while endosulfan was the least toxic.
