Shahbaz Talib Sahi

Multiple Resistances Against Formulated Organophosphates, Pyrethroids, and Newer-Chemistry Insecticides in Populations of Helicoverpa armigera (Lepidoptera: Noctuidae) from Pakistan

ABSTRACT Field populations of Helicoverpa armigera Hübner from 15 localities across the Punjab, Pakistan, were assessed by the leaf dip method for resistance against formulated organophosphates, pyrethroids, and newer insecticide groups. Resistance levels in H. armigera have been incrementally increasing for organophosphate and pyrethroid insecticides after decades of use in Pakistan. Resistance ratios (RRs) documented for organophosphates were 24- to 116-fold for profenofos and 22- to 87-fold for chlorpyrifos. For pyrethroids, RRs were 3- to 69-fold for Cypermethrin and 3- to 27-fold for deltamethrin. Resistance levels against newer chemistries were 2- to 24-fold for chlorfenapyr, 1- to 22-fold for spinosad, 1- to 20-fold for indoxacarb, 1- to 18-fold for abamectin, and 1- to 16-fold for emamectin benzoate. Resistant populations of H. armigera were mainly in the southern part of the Punjab, Pakistan. The most resistant populations were collected from Pakpattan, Multan, and Muzzafargarh. Of the nine insecticides tested, LC50 and LC90 values were lower for newer insecticide groups; resistance levels were moderate to very high against organophosphates, very low to high against pyrethroids, and very low to low against the newerchemistry insecticides. These findings suggest that the newer-chemistry insecticides with different modes of action could be included in insecticide rotations or replace the older insecticides. Supplementing the use of synthetic insecticides with safer alternatives could help to successfully lower the farmers reliance on insecticides and the incidence of resistance due to repeated use of insecticides against major insect pests.

Different Eucalyptus Species Show Different Mechanisms of Tolerance to Salinity and Salinity × Hypoxia

ABSTRACT We studied the effect of sodium chloride (NaCl) salinity and oxygen deficiency stress on growth and leaf ionic composition of three Eucalyptus species [E. tereticornis, E. camaldulensis (Silverton), and E. camaldulensis (Local)]. Species were grown with control (no NaCl) and salinity (150 mol m−3 NaCl) under hypoxic and non-hypoxic conditions in nutrient solution with five replications following CRD. Species differed significantly in their response to salinity and hypoxia. Absolute shoot dry matter was significantly better in E. camaldulensis (Silverton) in salinity and in E. camaldulensis (Local) in saline hypoxic treatment. E. tereticornis was the most sensitive species to salinity and salinity × hypoxia in the root environment. Sodium (Na+) and chloride (Cl−) concentrations were significantly lower in E. camaldulensis (Local) in non-hypoxic saline treatment compared to the other two species. E. camaldulensis (Silverton) seems to have better tissue compartmentalization, whereas E. camaldulensis (local) seems to have better exclusion of Na+ at the root level.

INDUCTION OF RESISTANCE IN CHICKPEA (Cicer arietinum L.) AGAINST Ascochyta rabiei BY APPLYING CHEMICALS AND PLANT EXTRACTS

Since new fungicides are scarce in the market and because of environmental problems, researchers are now emphasizing other alternatives, such as the genetic potential of plants, resistance against pathogens, and the use of biotic and abiotic agents to develop induced or acquired resistance. We investigated the role of resistance-inducing substances (chemicals and plant extracts) in three chickpea cvs. C-44, Pb-91, and Bittle-98 in field experiments against Ascochyta blight disease. These cultivars were selected on the basis of better yield potential shown in previous experiments. Aqueous solution of salicylic acid (SA) at 0.5, 1.0, and 1.5 mM; acibenzolar-S-methyl (ASM) at 0.4, 0.8, and 1.2 mM; and KOH at 25, 50, and 75 mM were applied, whereas Azadirachta indica A. Juss., Datura metel L., and Allium sativum L. plant extracts were applied at 5, 10, and 15%. Disease reduction data was recorded at different intervals from 4 to 14 d after being induced and inoculated with the pathogen. Overall results revealed that significant disease reduction (79.3%) was provided by ASM in the cv. C-44 at 1.2 mM compared with SA, whereas the least significant was KOH. Maximum disease reduction (43.5%) against disease in the plant extracts was observed by applying A. indica leaf extract, but D. metel and A. sativum extracts were not effective. Our findings suggest that enhancing resistance before infecting chickpea plants could be an innovative control method for Ascochyta blight of chickpea.

Effect of modified meridic diet on the development and growth of tomato fruitworm Helicoverpa armigera (Lepidoptera: Noctuidae)

The efficacy of one new modified and two old meridic diets on Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) for rearing six successive generations was studied. Duration of larval development for insects fed on the modified diet was considerably shortened as most of them went through only five stadia before pupation, while the per cent pupation and per cent eclosion were relatively higher than on other diets. The lowest pupal mortality (6.33 ± 0.13%) was recorded in the F1 generation reared on the modified diet, whereas the highest pupal mortality (19.49 ± 0.15%) was observed in insects reared on a natural diet in the F6 generation. Blending of chickpea Cicer arietinum L. and red kidney bean Phaseolus vulgaris L. flours with tomato paste proved highly favorable for adult reproduction. These results suggest that the vitality of the tomato fruitworm did not decline obviously after rearing on a modified diet for several generations.

Transgenic expression of antifungal pathogenesis-related proteins against phytopathogenic fungi – 15 years of success

ABSTRACTBeing sessile organisms, plants are continuously challenged by phytopathogenic fungi, contributing the largest share in loss due to plant disease. Plants naturally possess a well-developed and programmed protein-based defense system, capable of producing antimicrobial cationic peptides to ward off pathogen attack. Numerous genes encoding antifungal proteins have been isolated, cloned, sequenced and transgenically expressed against multiple phytopathogenic fungi successfully. Genetic engineering technology has been widely utilized to produce transgenic plants with enhanced resistance against pathogens. Pathogenesis-related proteins (PR-proteins) is a group of the most important inducible defense-related antifungal proteins, including defensins, thionins, osomtin-like proteins, thaumatin-like proteins, chitinases, glucanases, oxalate oxidase or oxalate oxidase-like proteins and lipid transfer proteins. Transgenic plants have been developed by imparting the artificial expression of genes encoding ant...

Antagonistic Potential of Trichoderma Isolates and Manures Against Fusarium Wilt of Tomato

ABSTRACT Fusarium oxysporum f. sp. lycopersici induces wilt disease in tomato (Solanum lycopersicum L.), causing large loss in yield quality and quantity. In vivo and in vitro studies were conducted to evaluate effects of natural, cheaply available cow, horse, chicken, or sheep manure and the antagonistic isolates of Trichoderma viride and T. harzianum against F. oxysporum f. sp. lycopersici on tomato cv. Money Maker. The combination of Trichoderma isolates and cow manure performed best in vivo in controlling disease incidence of Fusarium wilt of tomato. Both isolates of Trichoderma and cow manure were evaluated in vitro and in vivo individually and in combination. In vitro the T. viride and cow manure mix produced the best pathogen inhibition. In vivo the T. viride, T. harzianum and cow manure mix produced the best inhibition. Different manures and Trichoderma spp. may be able to be used to control wilt disease in tomato and are likely more environmentally safe compared to synthetic chemicals.

Evaluation of Antifungal Effect of Different Plant Extracts for the Management of Late Blight of Potato Caused by Phytophthorain festans (Mont.) de Bary

Abstract In protective disease management Neem (Azadrachta indica) leaf extract was the most effective followed by Garlic (Allium sativum) extract but Neem (Azadrachtaindica) oil was least effective on all the five varieties (Cardinal, Karoda, Rodio, Shanan and Siply Red). Most effective dose of Neem (Azadrachta indica) leaf extract and all other plant extracts was 3 % followed by 2 % and 1 % being least effective while7 days spray interval was most effective as compared to 14, 21 and 28 days. In curative disease management program Neem (Azadrachta indica) leaf extract @3 % was most effective followed by Garlic (Allium sativum) extract @3 % while euclyptus (Eucalyptusglobulus) leaf extarct @3% being least effective on all the five varieties (Cardinal, Karoda, Rodio, Shanan and Siply Red). Three consecutive sprays after disease appearance were most effective among all the tested plant extracts followed by 2 and 1 sprays.

Identification of resistant sources in chickpea against chickpea blight disease

Cheapest way to control gram blight is the use of resistant cultivars. Forty-eight genotypes comprising of black and white chickpea cultivars were collected from Ayube Agricultural Research Institute, Faisalabad. Genotypes were sown in augmented design in a way that after every two genotypes of test germplasm, there was a check (spreader) row. Artificial inoculation was used to screen out germplasm. Among 48 lines, 10 and 11 lines showed resistant and moderately resistant response, respectively. Most of the lines showed susceptible to highly susceptible response while others exhibited moderately susceptible. Sixteen lines were highly susceptible and eight were susceptible. Three lines displayed moderately susceptible response. Ranges of percent disease severity on resistant and moderately resistant advanced lines were; 3.75–10 and 12.5–20, respectively. And, these ranges for highly susceptible, susceptible and moderately susceptible genotypes were; 56.25–81.25, 40–45 and 665–752.5, respectively. Maximum and minimum ranges of area under chickpea disease progress curve (AUDPC) for resistant and moderately resistant advanced lines were; 70–192.5 and 210–367.5, respectively. Highly susceptible, susceptible and moderately susceptible genotypes showed AUDPC as 1085–1715, 787.5–910 and 647.5–735, respectively. Resistant and moderately resistant advanced lines had AUDPC 70–227.5 and 245–420, respectively. While, AUDPC values for highly susceptible, susceptible and moderately susceptible genotypes remained as 1172.5–1750, 805–962.5 and 665–752.5, respectively.

Pectobacterium punjabense sp. nov., isolated from blackleg symptoms of potato plants in Pakistan

Pectobacterium isolates SS95T, SS54 and SS56 were collected from a potato field in the Chiniot district in the plains of the Punjab province, Pakistan. Sequencing of the gapA barcode revealed that these strains belong to a novel phylogenetic group separated from P.ectobacterium wasabiae and Pectobacterium parmentieri species. Furthermore, multilocus sequence analyses of 13 housekeeping genes (fusA, rpoD, acnA, purA, gyrB, recA, mdh, mtlD, groEL, secY, glyA, gapA and rplB) clearly distinguished the type strain, SS95T, from its closest relatives, i.e. P. parmentieri RNS 08-42-1AT and P. wasabiae CFBP3304T, as well as from all the other known Pectobacteriumspecies. In silico DNA-DNA hybridization (<44.1 %) and average nucleotide identity (<90.75 %) values of strain SS95T compared with other Pectobacterium type strains supported the delineation of a new species. Genomic and phenotypic comparisons permitted the identification of additional traits that distinguished the Pakistani isolates from all other known Pectobacterium type strains. The name Pectobacterium punjabense sp. nov. is proposed for this taxon with the type strain SS95T (=CFBP 8604T=LMG 30622T).

Effect of Different Inoculum Levels of Ascochyta lentis on Growth and Yield Attributes of Lentil Plant

Effect of different inoculums levels (103, 5x103, 104, 5x104 spores/ml) of A. lentis was studied on growth and yield parameters of four lines of lentil. Results showed that among these lines one (ILL-358) showed microsperma resistant, one (ILL-4605) macrosperma resistant, one (ILL-5580) microsperma susceptible and the remaining one (ILL-6002) macrosperma susceptible response over control. Plant height was the minimum in case of all the four lentil lines are at 5spores/ml. Similarly no. of leaflets, no. of pods/ plant, no. of grains/pod and 100 grain weight were reduced with increased level of spores concentration from 103 spore/ml to 5x104 spore/ml. Size and frequency of lesions/pods showed positive correlation with increasing spore concentrations.