Effect of selected fungicides and Bio-Pesticides on the mycelial colony growth of the Helminthosporium oryzae. brown spot of rice

Helminthosporium oryzae, a fungal pathogen causing Brown Spot of Rice is one of the disastrous biotic factors responsible for 16–43% yield in rice. To control in vitro fungal growth of this pathogen, four fungicides viz. Mencozeb, Thiophanate Methyl, Iprovalicarb + Propineb and Propineb were used with four different concentrations: 50, 100, 150 and 200 ppm. Plant extracts of five species as Azadirachta indica, Calotropisprocera, Allium sativum, Datura stramonium and Zingiber officinale were also tested with three doses (5, 10 and 15 ml). While, 24 isolates of Bacterial isolates were investigated for their antagonistic effect. The in vitro results of the four fungicides contributed that Mancozeb and Thiophanate Methyl inhibited the colony growth at the higher doses (150 and 200 ppm) with no linear colony growth. However, Propineb was found moderately effective at (5.00 mm) and Iprovalicarb + Propineb was less effective (7.25 mm). Similarly, the in-vitro efficacy of the five plant extracts against H. oryzae at different doses revealed that Zingiber officinale and Allium sativum were more effective at high doses (00.00 mm, 2. mm). Also, Datura stramonium (4.62 mm) Azadirachta indica (18.00 mm) and Calotropisprocera (12.00 mm) performed better as compared to the control (40.00 mm). The results revealed that out of 24 isolates, 4 isolates of bacteria Agrobacterium spp, Xanthomonas, Erwinia, Streptomyces has inhibited the linear colony growth of H. oryzae up to 1-2 mm. This study can be useful for controlling the fungal disease as the two fungicides Mancozeb and Thiophanate Methyl were more effective and the Zingiber officinale and Allium sativum plant extracts were highly effective against the brown spot of rice. Biocontrol also reduced leaner colony Helminthosporium oryzae.     

Appraisal of plant extracts and streptomycin sulfate against citrus canker disease

Abstract

Plant extracts and streptomycin sulfate were evaluated against Xanthomonas axonopodis pv. citri. In first experiment, Azadirachta indica, Allium cepa, Catharanthus roseus, Allium sativum, Zingiber officinale (Roscoe) were investigated in vitro through inhibition zone technique against the growth of X. a. pv. citri. Results indicated that A. indica exhibited statistically significant inhibition (4?cm) zone over control. In second experiment, A. indica and streptomycin sulfate disjointedly and in amalgamation were evaluated in vitro. Streptomycin alone and in permutation with A. indica articulated significant inhibition of the bacterium. In third study, streptomycin sulfate and A. indica (S) and in combination were evaluated against citrus canker disease in green house. Results showed that streptomycin sulfate reduced disease significantly than control. In fourth experiment, streptomycin sulfate, A. indica, in combination and their interaction with days were evaluated under field condition. Streptomycin sulfate proved to be most effective and reduced the disease severity as compared to control.     

Toxicity,repellent and oviposition deterrent effects of select essential oils against the house fly Musca domestica

Essential oils from plants may provide environment-friendly alternatives to conventional synthetic insecticides. Here, toxic, repellent, and oviposition deterrent effects of essential oils of six plants: Allium sativum L. (Alliaceae), Azadirachta indica A. Juss. (Meliaceae), Cinnamomum cassia (L.) (Lauraceae), Eucalyptus camaldulensis Dehnh. (Myrtaceae), Piper nigrum L. (Piperaceae), and Thevetia peruviana (Pers.) (Apocynaceae), were evaluated against different life stages of Musca domestica. Bioassays revealed that the essential oils of A. indica, T. peruviana and E. camaldulensis exhibited: a) the highest toxicity on larvae (LC₅₀ = 169.72, 182.23 and 277.01 ppm, respectively), pupae (LC₅₀ = 150.56, 164.84 and 164.87 ppm, respectively) and adults (LC₅₀ = 166.69, 139.15 and 302.75 ppm, respectively) of M. domestica; b) the highest repellency (91.44, 72.19 and 72.80%, respectively) and oviposition deterrent (90.36, 88.82 and 89.13%, respectively) effects on adults of M. domestica, as compared to the other essential oils. Moreover, the speed of mortality caused by essential oils of A. indica (LT₅₀ = 16.85 and 17.06 h for larvae and adults, respectively) and T. peruviana (LT₅₀ = 16.46 and 18.58 h for larvae and adults, respectively) was faster than the rest of the essential oils. On the whole, it might be expected that the essential oils of A. indica, T. peruviana and E. camaldulensis could be developed into a new type of environment-friendly insecticides and/or repellents for the management of M. domestica.     

Biology ofTrichogramma ostriniae (Hym.: trichogrammatidae) reared onOstrinia nubilalis (Lep.: pyralidae) and survey for additional hosts

Trichogramma ostriniae has been identified as a candidate for biological control ofOstrinia nubilalis. As little was known about the biology of this parasitoid when reared onO. nubilalis, we undertook experiments to quantify biological parameters important to mass-rearing and ase ofT. ostriniae. When reared continuously onO. nubilalis, femaleT. ostriniae on average lived 2.7 days and produced 24 progeny. Continuous access to honey resulted in a four-fold increase in longevity and fecundity and a significant increase in the percentage of females parasitizing eggs. Rates of fecundity and parasitism decreased with age of female. Likewise, emergence rates and percentage of female progeny decreased with age of parental female.T. ostriniae successfully parasitizedO. nubilalis eggs until the blackhead stage. Most parasitism of eggs and eclosion of adults occurred during the first half of photophase. Eggs of 13 Lepidopterans were parasitized byT. ostriniae. Eggs of the Noctuidae, Pyralidae, and Plutellidae experienced higher levels of parasitism than others tested.T. ostriniae appears to be similar to other species ofTrichogramma in several respects and does not possess any characteristics that limit its potential for mass rearing and use for augmentative biological control ofO. nubilalis.     

Differential Responses of Erysiphe polygoni Conidia to Living and Non-living Substrata

Conidial germination and appressorium formation of Erysiphe polygoni on living and non-living substrata have been studied. Among living hosts, peelings from bulbs and leaves of Allium sativum and Allium cepa, or from stems of Azadirachta indica and rhizomes of Curcuma longa supported good germination. Zingiber officinale rhizome peelings inhibited germination. Germination and appressorium formation were maximum on the host (Pisum sativum) as compared to some other leguminous hosts. Little morphological variation was noticed among appressoria developed on various substrata, although they differed in size. Conidial germination was enhanced in leaf extract of pea.     

Effect of mating combinations on the host parasitisation and sex allocation in solitary endoparasitoid,Aenasius arizonensis (Hymenoptera: Encyrtidae)

Aenasius arizonensis (Girault) is an important solitary endoparasitoid of Phenacoccus solenopsis Tinsley. To optimise the mass production of high-quality females, it is important to assess the influence of mating regimes on the progeny fitness and sex allocation. We, therefore, hypothesise that mating combinations in A. arizonensis adults emerged from different host instars may influence parasitism and sex allocation in the subsequent generation. Therefore, we compared three nymphal instars (1st, 2nd and 3rd) and adults host stages of P. solenopsis for parasitism and sex allocation by A. arizonensis. Further, F₁ female progeny of the parasitoid emerged from different host instars was henceforth evaluated for its fitness in six mating combinations. A. arizonensis females parasitised all the host stages except the 1st instar nymphs. The parasitised 2nd instar nymphs yielded only males, while the sex ratio in the later host instars was strongly female-biased. The parasitoid females preferred 3rd instar nymphs with respect to higher parasitism (74.0–84.0%) and produced more females in the F₁ progeny as compared to other host stages. F₁ females that emerged from 3rd instar nymphs produced significantly higher parasitism (74.0–79.0%). These mating combinations also yielded more female progeny in the F₂ generation. However, parasitism by F₁ females was significantly lower (9.0–12.0%) when mated with males that emerged from 2nd instar P. solenopsis nymphs. Moreover, latter combinations yielded only male progeny in F₂ generation. These findings can be used in laboratory mass rearing of this parasitoid vis-à-vis biological control of P. solenopsis.     

Cold storage effects on maternal and progeny quality of Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae)

This study determined the effects of cold storage on the survival, development and reproduction of the mymarid wasp, Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae). Following storage of the immature parasitoids within host eggs of the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) under a daily fluctuating temperature for up to 50 d, the quality of the parental and F₁ generations was assessed by examining several reproductive and developmental parameters indicating fitness. Immature wasps were stored for 20 d within the host without reducing their subsequent survival, development or progeny fitness parameters. After 30 d of storage, survival declined, post-storage developmental time was extended, and the fecundity of the adult females decreased. Storage for 40 d severely damaged G. ashmeadi, because it not only yielded a 12% survival rate, 44% female sterility and increased the proportion of progeny males by 155%, but it also reduced parasitism and fecundity by 70% and 73%, respectively. No wasps emerged after 50 d of storage. Cold storage affected the emergence pattern of the parental but not the F₁ and F₂ generations. Parental emergence was extended and the pattern displayed two additional peaks after the initial onset. Analysis of several demographic parameters for the parental and F₁ generations further confirmed that the quality of the adult parents declined after they had been stored as immatures for 30 d. The detrimental effects caused by cold storage of the parental generation do not extend to the F₁ generation. Our results indicate that short-term cold storage of G. ashmeadi within its host could be used for maintaining and accumulating these parasitoids during mass propagation for release in a control program.     

Host-age-dependent parasitism and reproductive success of Apanteles stantoni (Hymenoptera: Braconidae), a larval parasitoid of Diaphania indica (Lepidoptera: Pyralidae)

The relative suitability of five instars of Diaphania indica (Saunders) (Lepidoptera: Pyralidae) as a substrate for the development of a larval parasitoid, Apanteles stantoni Ashmead (Hymenoptera: Braconidae), was investigated. Maximum parasitism (22.25?±?1.21%) under laboratory conditions was observed in the early larval instars. The highest parasitoid emergence was recorded from the second (86.07?±?0.70%) and third (98.93?±?0.72%) instar larvae of D. indica, and that from the first larvae was 71.43?±?1.18%. The number of cocoons in each cluster, length and width of single cocoons, percentage emergence, sex ratio and adult longevity of A. stantoni collected from different instars of D. indica were also recorded. These results indicated that the life stage of the host when the parasitoid larvae complete their final instar is particularly important for their development. Therefore, considering the efficiency of parasitism and reproduction, the second-instar larvae of D. indica is the most suitable stage for mass rearing A. stantoni in the laboratory.     

Cytoplasmic effects on activity of individual anionic isoenzymes of peroxidase in crosses between two genotypes of flax (Linum usitatissimum L.)

Four anionic peroxidase isoenzymes in main stem tissues of flax (Linum usitatissimum L.) were separated electrophoretically on acrylamide gels and their individual activities measured spectrophotometrically in the gels. Activities were expressed in terms of areas of optical density peaks corresponding to the locations of the isoenzymes. Four isoenzymes were assayed for activity in this way in two inbred genotypes and their F₁, F₂, and first backcross progeny. Crosses were made in all combinations between the two parental genotypes and their reciprocal F₁ hybrids to produce 16 progenies of the generations above. Isoenzyme separations and assays for activity were carried out on individual plants of each of the 16 progenies. A model estimating cytoplasmic effects across segregating generations as differences between all progeny of the one compared to the other F₁ reciprocal hybrid, either in a male or a female direction, was fitted to the activity data by weighted least-squares procedures. Cytoplasmic effects transmitted through male gametes from the F₁ reciprocals were demonstrable for three of the four anionic peroxidase isoenzymes.Supported in part by the National Research Council of Canada.     

Chemical composition and bioactivities of thirteen non-host plant essential oils against Plutella xylostella L. (Lepidoptera: Plutellidae)

The diamondback moth (DBM), Plutella xylostella (L.), is a globally destructive pest of cruciferous vegetables. Excessive use of synthetic pesticides to control this species results in negative effects on the environment, human health, and nontargeted organisms. The essential oils (EOs) derived from plants may be developed as effective alternatives to conventional pesticides. In this study, thirteen EOs were extracted by hydrodistillation, respectively. Their chemical compositions were identified by gas chromatography-mass spectrometry (GC–MS). Furthermore, the biological activities of EOs such as toxicity, antifeedant activity, and growth inhibition effect, toward DBM larvae were investigated. Against DBM second-instar larvae, the most toxic EO was Pelargonium graveolens (LC₅₀ = 0.36 μg/μl) after 72 hr of exposure, followed by Polygonum hydropiper (LC₅₀ = 0.53 μg/μl). The Ocimum basilicum EO exhibited the highest antifeedant effect to third-instar larvae at at all set concentrations. At 15 μg/μl, the EOs of Acorus calamus, O. basilicum, and P. graveolens completely inhibited the feeding activities of larvae (100%). The Ruta graveolens EO showed the lowest relative growth rate and the highest growth inhibition rate towards third-instar larvae at diverse concentrations. And the EOs of P. hydropiper, A. calamus, and O. basilicum showed promising growth inhibition activities. Overall, the five EOs (P. graveolens, O. basilicum, R. graveolens, P. hydropiper, and A. calamus) showed moderate to high bioactivity, whereas eight EOs were found to be less active against DBM larvae. These results indicate that the five tested EOs are promising to be developed as novel botanical insecticides to control DBM population.     

In vitro efficacies of oils, silicas and plant preparations against the poultry red mite Dermanyssus gallinae

The aim of this study was to test the effectiveness of physically acting substances (oils and silicas) and plant preparations for the control of the poultry red mite Dermanyssus gallinae (De Geer 1778). Reproduction and survival of fed D. gallinae females were evaluated in vitro for a total of 168 h using the “area under the survival curve” (AUC) to compare survival of the mites between treatments. Four oils (two plant oils, one petroleum spray oil and diesel), one soap, three silicas (one synthetic amorphous silica, one diatomaceous earth (DE) and one DE with 2% pyrethrum extract) and seven plant preparations (derived from Chrysanthemum cineariaefolium, Allium sativum, Tanacetum vulgare, Yucca schidigera, Quillaja saponaria, Dryopteris filix-mas, and Thuja occidentalis) were tested at various concentrations. All the oils, diesel and soap significantly reduced D. gallinae survival. All silicas tested inhibited reproduction. DE significantly reduced mite survival, but amorphous silica was less effective in vitro. Except for pure A. sativum juice and the highest concentration of C. cineariaefolium extract, the plant preparations tested resulted in statistically insignificant control of D. gallinae.     

Some genetic aspects of the resistance of Spodoptera frugiperda to a nuclear polyhedrosis virus

A probit analysis of the dosage-response of two isolates of Spodoptera frugiperda to a single nuclear polyhedrosis virus revealed a greater than 5-fold difference in the LD₅₀. The response of F₁ progeny of reciprocal crosses between the two parental isolates demonstrated that resistance to the virus is not sex-linked. The LD₅₀ values of F₁ and F₂ backcrosses suggest that the major variation in resistance is due to a single gene or genes that lack dominance.     

Comparative insecticidal activity of different plant materials from six common plant species against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is one of the major insect pests of stored grains. Due to export legislation and zero-tolerance for live insect in trade commodities, extensive use of synthetic insecticides is in practice in order to eliminate pest infestations from the lots. Currently, the one and only acceptable chemical to be used in stored grain is phosphine but due to its excessive usage the stored grain pests are becoming resistant against it. Hence discovery of alternative compounds is much needed. In this study we have compared insecticidal efficacy of different plant materials from six commonly grown plants of Pakistan, viz. Allium sativum (Alliaceae), Zingiber officinale (Zingiberaceae), Cymbopogon citratus (Poaceae), Eucalyptus globulus (Myrtaceae), Nicotiana tabacum (Solanaceae), and Azadirachta indica (Meliaceae) against T. castaneum infesting stored wheat, rice, corn and gram pulse. Various plant parts were dried, powdered, and used as admixtures to the stored commodities in the experiments. The results have suggested that A. sativum (garlic) and Z. officinale (ginger) were more effective resulting into 15 times higher adult mortality and 4 to 5 times reduction in grain weight losses when mixed with rice grains. Similarly, A. indica when admixture with wheat checked the population growth in the resources resulting into 3.5 times less adult production compared to controls. A subsequent experiment was conducted to study the dose response of neem seed powder against the beetle pest infesting milled products. Surprisingly, better control was observed either at lowest (1% w/w) or the highest doses (5% w/w). This finding is of great interest to understand the underlying phenomenon which we assume is the ability of T. castaneum to feed selectively in flour mediums, however, further research on this aspect is required to be investigated. The results of this study support the use of botanicals for stored product pest management.     

Pyramided rice lines harbouring Allium sativum (asal) and Galanthus nivalis (gna) lectin genes impart enhanced resistance against major sap-sucking pests

We have developed transgene pyramided rice lines, endowed with enhanced resistance to major sap-sucking insects, through sexual crosses made between two stable transgenic rice lines containing Allium sativum (asal) and Galanthus nivalis (gna) lectin genes. Presence and expression of asal and gna genes in pyramided lines were confirmed by PCR and western blot analyses. Segregation analysis of F₂ progenies disclosed digenic (9:3:3:1) inheritance of the transgenes. Homozygous F₃ plants carrying asal and gna genes were identified employing genetic and molecular methods besides insect bioassays. Pyramided lines, infested with brown planthopper (BPH), green leafhopper (GLH) and whitebacked planthopper (WBPH), proved more effective in reducing insect survival, fecundity, feeding ability besides delayed development of insects as compared to the parental transgenics. Under infested conditions, pyramided lines were found superior to the parental transgenics in their seed yield potential. This study represents first report on pyramiding of two lectin genes into rice exhibiting enhanced resistance against major sucking pests. The pyramided lines appear promising and might serve as a novel genetic resource in rice breeding aimed at durable and broad based resistance against hoppers.     

Behavior of chromosomes after meiosis inCoprinus cinereus

The movement was investigated of a specific chromosome in the F₁ progeny of the basidiomyceteCoprinus cinereus. We focussed our attention on the smallest chromosome of the 5302 strain. We first constructed a chromosome-smallest library and screened it with a chromosome-specific clone, pRC 1. The pRC 1 probe hybridized only with the smallest chromosome of the 5302 strain, and it detected one band of different mobility in two parental strains. In the F₁ progeny, the probe hybridized with one to three chromosomes. Most of the hybridized chromosomes in the F₁ progeny were positioned in terms of mobility between the hybridized chromosomes of the two parental strains. Therefore, they were probably generated by meiotic recombination between homologous chromosomes of different sizes.     

Evaluation of the composition and fumigant toxicity against Plodia interpunctella of essential oils from Ajania potaninii and Ajania fruticulosa

Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae), is a worldwide omnivorous pest. It is the primary insect pest in many economically important stored crops. The insecticidal activity of essential oils (EOs) extracted from Ajania potaninii and Ajania fruticulosa were evaluated against Plodia interpunctella. EOs obtained by hydro-distillation were analyzed by GC–MS. Fumigant toxicity testing indicated that both EOs and their main components were toxic to P. interpunctella adults. 1,8-Cineole exhibited the strongest activity, having an LC₅₀ of 0.86 mg/L air and being twice as active as camphor. Myrtenol was also strongly toxic to P. interpunctella adults (LC₅₀ 0.99 mg/L air), while camphor, verbenol, borneol, and the two complete EOs exhibited lower toxicity. None of the EOs or main components exhibited significant toxicity against the larvae of P. interpunctella. This study provides evidence of the individual active substances accounting for the insecticidal activity of EOs from A. potaninii and A. fruticulosa. These EOs have potential as biological insecticides for controlling insect pest damage in stored crops.     

Bioactive polar natural compounds from garlic and onions

Bioactive natural compounds from garlic and onions have been the focus of researches for decades, firstly due to their pharmacological effects, and secondly due to their defence properties against plant diseases. In fact, garlic and onion, belonging to Allium genus, are among the oldest food plants known since ancient times and used as ingredient of many recipes and for therapeutic properties. These plants are well known to produce bioactive apolar sulphur compounds but less is known about their polar natural compounds, such as phenols, sapogenins and saponins, that are more stable to cooking, So, we continued our work on the discovery of polar bioactive metabolites from Allium with the isolation of a number of sapogenins and saponins from the wild onion species Allium elburzense, Allium hirtifolium, Allium atroviolaceum, and Allium minutiflorum, and, more recently, from the cultivated white onion, Allium cepa, and garlic, Allium sativum. In particular, the sapogenins and saponins isolated from A. elburzense and A. hirtifolium, named elburzensosides and hirtifoliosides respectively, exhibited significant antispasmodic properties. In addition, the saponins named minutosides isolated from A. minutiflorum showed promising antimicrobial activity. More recently the phytochemical analysis of A. cepa and A. sativum has been undertaken and afforded the characterization of saponins, phenols and N-cynnamic amides which showed significant antifungal activity.     

Combining ability analysis over F1-F5 generations in diallel crosses of bread wheat

Summary Combining ability studies for grain yield and its primary component traits in diallel crosses involving seven diverse wheat cultivars of bread wheat (Triticum aestivum L.) over generations F₁-F₅ are reported. The general and specific combining ability variances were significant in all generations for all the traits except specific combining ability variance for number of spikes per plant in the F₅. The ratio of general to specific combining ability variances was significant for all the traits except grain yield in all the generations. This indicated an equal role of additive and non-additive gene effects in the inheritance of grain yield, and the predominance of the former for its component traits. The presence of significant specific combining ability variances in even the advanced generations may be the result of an additive x additive type of epistasis or evolutionary divergence among progenies in the same parental array. The relative breeding values of the parental varieties, as indicated by their general combining ability effects, did not vary much over the generations. The cheap and reliable procedure observed for making the choice of parents, selecting hybrids and predicting advanced generation (F₅) bulk hybrid performance was the determination of breeding values of the parents on the relative performance of their F₂ progeny bulks.     

Estimating the number of genetic elements that defer senescence inDrosophila

Summary Although many different physiological and biochemical changes characterize the process of senescence, little is understood of the genetic elements that determine its age of onset. We provide here the first estimates of the number of genetic factors that extend longevity inDrosophila melanogaster. Life span was measured in F₁, F₂ and backcrosses of true-breeding long and short-lived stocks ofD. melanogaster, established by selection. Estimates of the number of effective factors delaying senescence range from about 0.3 to 1.5, indicating control by a single factor. The distribution of longevity shows this to arise as selection acts on the short-lived parental stock. Life span is extended at the cost of early fecundity.     

Apomixis in Taraxacum paludosum (section Palustria, Asteraceae): Recombinations of apomixis elements in inter-sectional crosses

Recent studies have shown independent control of apomixis elements (restitution/diplospory, parthenogenesis and autonomous endosperm) in Taraxacum sect. Ruderalia. We studied inheritance of apomixis elements in the section Palustria using the crosses between various sections used as mother plants and apomictic T. paludosum (sect. Palustria) as pollen donor. Non-apomictic plants prevailed in F₁ progeny, and a high incidence of sterility was observed. Triploid non-apomictic F₁ hybrids were backcrossed with diploids (sects. Ruderalia, Palustria) and tetraploids (sects. Palustria, Piesis), and produced various types of progeny. These F₁ hybrids were classified into three types depending on the occurrence of parthenogenesis along with restitution, and the occurrence of various progeny in particular crosses (i.e. within the same mother plant) was observed. The results indicate the independent genetic control of all apomixis elements in T. paludosum, and recombinations during a restitutional megasporogenesis in hybrids.