Leaf Infestation Research Articles

ENVIRONMENTAL ASPECTS OF THE APPLICATION OF BIOLOGICAL PREPARATIONS IN THE APPLE PROTECTION SYSTEM IN THE RIGHT BANK FOREST STEPPE OF UKRAINE

Based on long-term monitoring of the phytosanitary state of apple plantations in the Right-Bank Forest-Steppe of Ukraine, the species composition of diseases was established, among which scab (Venturia inaegualis (Cooke) Wind) – 32.4 % and fruit rot (Monilia fructigena Pers.) – 23.7 %, mealy dew (Podosphaera leucotriche) – 21.7 %; bacteriosis (Erwinia amylovora) – 17.8 %. The features of the use of tank mixtures of microbiological fungicides based on fungal and bacterial bioagents for the protection of apple trees from diseases have been studied. It has been established that the microbiological preparation “Glyocladin BT” (Trichoderma (Gliocladium) virens) with a consumption rate (6.0 l/ha) provides a reduction in leaf infestation from scab and powdery mildew by 64.0–66.3 %, fruits by 31.4–40.0 %, the weight of fruits increases by 13.0–18.4 % and the yield of standard environmentally safe products by 12.0 and 14.2 %, and the yield by 4.6–5.8 t/ha. Microbiological preparations “Gaupsin BT” and “Pentafag-S” reduce the infection of apple leaves and fruits with bacterial burns by 56.3–70.0 %; fruit rot – by 66.8–80.0 %, while the yield and standard of apple fruits in the experimental variants exceed the control by 0.6–1.1 t/ha and 13.6–18.1 %, respectively.

The impact of the intensity of selective sanitary cutting in oak forests on the defeat of the pedunculated oak (Quercus Robur L.) trees by powdery mildew

The article assesses the impact of the intensity of selective sanitary cutting in oak forests on the defeat of oak trees by powdery mildew. The research methodology included visual estimation and detailed inspection of oak plantations. On their basis, the species composition of pathogens was identified, the degree of crown desiccation from a complex of factors and leaf infestation with powdery mildew and necrotic spots was assessed. The dispersive analysis was applied for data processing. The analysis of the long-term survey of the plots passed by selective sanitary cutting shows that the degree of damage to oak trees by powdery mildew on permanent test areas practically does not depend directly from selective sanitary cutting, in general, and from their intensity, in particular. The dynamics of the damage degree of the oak trees by powdery mildew changed almost synchronously in all test areas and in the control area. The results can be used in the practice of the Voronezh region forestry enterprises when carrying out forest pathology surveys.

Following the pest outbreak: preliminary findings on the landscape effect on Dasineura oleae and its parasitoids in central Italy

Dasineura oleae (Angelini, 1831) (Diptera: Cecidomyiidae), the olive leaf gall midge, is a pest of olive crops that was not problematic in Italy until 2016 when a massive infestation of this pest was reported in a small region in central Italy. We identified infested olive orchards using farmers’ reports and quantified the pest infestation level and parasitism rate in each field. We also explored the effect of the landscape on both the pest and parasitoids using the abundance of olive crops and semi-natural habitats and the Shannon index, estimated at four different scales (250 m, 500 m, 750 m and 1000 m buffers around the sampling points). The results showed a small-scale effect on the parasitism rate and a large-scale effect on leaf infestation mediated by the Shannon Index. Moreover, some preliminary results showed that the parasitism rate was high in sites where plants associated with D. oleae parasitoids were present in the adjacent semi-natural habitat. Further studies are needed to validate our findings on the effect of landscape and vegetation on the natural enemies of D. oleae in order to develop new suppression strategies.

Effect of temperature on host plant‐specific leaf‐ and root‐feeding performances: a comparison of grape phylloxera biotypes C and G

AbstractGrape phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera: Phylloxeridae), is a destructive pest for global viticulture. With the grafting of the susceptible cultivated grapevine (Vitis vinifera L., Vitaceae) on top of tolerant Vitis spp. rootstock, root infestation no longer causes vine death. These tolerant rootstock vines are hybrids of American species that are often highly susceptible to leaf infestation. Though leaf infestation is normally rarely seen on V. vinifera, some commercial vineyards have been showing high intensities of leaf galls for many years. In this study, two possible factors are investigated to explain these anomalies: (1) intra‐specific differences in phylloxera host plant specialization, and (2) improved environmental settings for infestation due to temperature increase. To study the former, a phylloxera biotyping assay was conducted after whole‐plant (both root and leaf) infestations, and for the latter, a temperature increase simulation was performed with potted plants in climate chambers. Both assays also contained a phylloxera control biotype C, obtained from an American rootstock hybrid (Vitis berlandieri Planch. × Vitis riparia Michx.). The biotyping assay showed that field‐sampled populations from V. vinifera leaf galls had innate advantages to infest the leaves of this host plant species compared to those of the American rootstock hybrid. This is therefore the first study to categorize a phylloxera population as biotype G, using controlled experimental conditions with biological pest control. At moderate temperatures (22 °C), infestation was similar as in the biotyping assay, but at higher temperatures (27 °C), biotype G seems to lose its comparative advantage to infest V. vinifera leaves. Specifically, at higher temperatures, insect performance in terms of leaf gall intensity, development, and egg‐laying of both biotype G and C is improved on American rootstock hybrids and worsened on V. vinifera compared to infestations at moderate temperatures. We discuss possible explanations for these findings and how these experimental results may be extrapolated to field settings.

Morpho-Biochemical Characteristics of Brinjal Germplasms Affect the Abundance And Infestation of Jassid

The tropical vegetable, brinjal is cultivated throughout the year in Bangladesh but the crop is infested by a number of insects including jassid. This study investigated the effects of different biophysical and biochemical characteristics of twelve brinjal germplasms on the abundance and infestation of jassid. The experiment was conducted during September 2018 to March 2019 in Gazipur, Bangladesh with twelve brinjal germplasms namely BD-7320, BD-7328, BD-9952, BD-10154, BD-10158, BARI Begun-1, BARI Begun-4, BARI Begun-5, BARI Begun- 6, BARI Begun-7, BARI Begun-8 and BARI Begun-9. The incidence of jassid was recorded from 3rd December to 26th March, and the lowest population was found on BARI Begun- 6. Among the biophysical traits, plant height, number of branch and leaf per plant, and leaf area exerted significant positive correlation; whereas trichome on lower and upper surfaces of leaf, spine per stem and leaf showed significant negative correlation with the abundance of jassid. On the other hand, moisture, reducing sugar, total sugar and protein content of the leaves and fruits, chlorophyll content of the leaves exerts significant positive correlation but ash and pH contents of the leaves and fruits were negatively correlated with the abundance of jassid. Jassids showed the lowest level of leaf infestation on BARI Begun-6, which could be for further analysis to develop jassid resistant brinjal. SAARC J. Agric., 19(1): 81-91 (2021)

Damage potential and control of the common mormon butterfly, Papilio polytes Cramer on citrus

Studies were conducted to know the damage potential and effect of insecticides on leaf area feeding and larval mortality of the common Mormon butterfly, Papilio polytes Cramer in the homestead garden and germplasm center of the Patuakhali Science and Technology University (PSTU) campus and in the laboratory, Department of Entomology, PSTU, Patuakhali, Bangladesh during October to December 2016. Ten Citrus host plants such as Kagoji lime-BAU-1, BAU-2, BAU-3, BAU-4, BARI kagoji, elachi lime, sweet orange, orange, jamir and pumelo were used as study materials. To determine the effects of insecticides on leaf area feeding and larval mortality, five treatments viz., T1 = Voliam flexi 300SC @ 0.5 ml/l of water, T2 = Voliam flexi 300SC @ 1.0 ml/l of water T3 = Bioneem Plus @ 0.5 ml/l of water, T4 = Bioneem Plus @ 1.0 ml/l of water T5 = control were applied. Under natural field conditions, the highest percentage of leaf infestation was recorded in orange, followed by BAU-3, BAU-4, malta and elachi lime, while the lowest percentage was in BARI kagoji on 23 and 30 November, 2016. At the top canopy, the highest percentage of leaf infestation was recorded in orange and elachi (56%), while the lowest was in BAU-4 (8%). At the middle canopy, the highest percentage of leaf infestation was recorded in orange (56%), while the lowest was in jambura (12%). At the lower canopy, the highest percentage of leaf infestation was recorded in BAU-3 (40%), while the lowest was in elachi (8%). At the top canopy, significantly the highest percentage of infested leaves per branch was observed in orange (51.39%) and the lowest percentage of infested leaves per branch was in BAU-4 kagoji lime (10.86%). At middle and lower canopies, no significant difference was observed in the percentage of infested leaves per branch among different citrus varieties. The lowest percentage (6%) of leaf area consumed by 4th instar larva was recorded in T2 (Voliam flexi 300SC @ 1.0 ml/l of water) treated leaf, while the highest percentage of leaf area consumption was found in T5 (control) at 3 HAT. The highest percent mortality (100%) of larvae was found in T2 treated citrus plant, while the lowest percent mortality was in the T3 (70%) treated plant. No mortality was recorded in the untreated control (T5) plant.
 J. Asiat. Soc. Bangladesh, Sci. 47(1): 35-46, June 2021

Distribution, abundance and natural enemies of the invasive tomato leafminer, Tuta absoluta (Meyrick) in Kenya.

Tuta absoluta (Meyrick) has become a serious menace to sustainable production of tomato in Kenya. A survey was conducted between April 2015 and June 2016 to determine its distribution, abundance, infestation, and damage levels on tomato, and associated natural enemies. Trap counts of T. absoluta moths were recorded in all surveyed 29 counties, which indicated its nationwide distribution irrespective of altitude. Tuta absoluta was present in both open fields and greenhouses. The highest moth/trap/day was 115.38 ± 15.90. Highest leaf infestation was 92.22% and the highest number of mines and larvae per leaf were 3.71 ± 0.28 and 2.16 ± 0.45, respectively. Trap captures in terms of moth/trap/day were linearly and positively related to leaf infestations in open fields (R2 = 0.81) and greenhouses (R2 = 0.61). Highest fruits' infestation and damage were 60.00 and 59.61%, respectively, while the highest number of mines per fruit was 7.50 ± 0.50. Nesidiocoris tenuis (Reuter) and Macrolophus pygmaeus (Rambur) were identified as predators of T. absoluta larvae. Nine species of larval parasitoids were recovered from infested foliage, with a combined parasitism of 7.26 ± 0.65%. Hockeria species was the most dominant (31.25%) and accounted for 12.88 ± 1.47% parasitism. Two species of larval parasitoids, Hockeria and Necremnus were obtained from sentinel plants with an average parasitism of 1.13 ± 0.25. The overall abundance and parasitism rates of recovered natural enemies were low to effectively control the field populations of T. absoluta. These findings form the basis of researching and developing effective and sustainable management strategies for the pest.

Evaluation of the Efficacy of Chemical Insecticides and Biopesticides against Flea Beetle in Cabbage (Brassica oleracea var. Capitata)

Aims: This study aimed to evaluate chemical insecticides and bio-pesticides against flea beetle in cabbage.
 Study Design: The experiment was laid out at a randomized complete block design with three replications.
 Place and Duration of Study: Experimental farm of Sher-e-Bangla Agricultural University, Bangladesh during the period from October 2017 to March 2018.
 Methodology: The experiment consisted of nine treatments viz. T1(Sevin 85 WP @ 2g/L of water), T2 (Decis 2.5 EC @ 1.0 ml/L of water), T3 (Voliam flexi @ 0.5 ml/L of water), T4 (Ripcord 10 EC @ 1.0 ml/L of water), T5 (Dursban 20EC @ 1 ml L-1 of water), T6 (Tobacco leaf extract @ 3 g L-1 of water), T7 (Neem seed kernel extract @ 3 g L-1 of water), T8 (Bioneem plus 1 EC @ 1 ml L-1 of water) and T9 (Untreated Control) were used at 7 days interval.
 Results: Stripped flea beetle(Phyllotreta striolata) and white-spotted flea beetle (Monolepta signata), these two species of flea beetle were found in the experimental field. Among all the treatments T4 (Ripcord 10EC)performed the best in managing flea beetles based on the lowest percentage of leaf infestation (5.84%), lowest no. of holes per plant (6.13), lowest percentage of head infestation by number (18.04) and highest percentage of infestation reduction over control on all parameters at vegetative stage of plant. Again, the lowest leaf infestation intensity (5.73%), lowest number of holes per infested head (14.00), lowest percentage of infestation of head by number (6.69) were achieved at harvesting stage from the same treatment (T4) whereas the highest values of all these parameters were achieved from untreated control treatment (T9). T4 treatment provided the best performance in yield where yield was increased (112.51 %) over control, giving maximum yield 75.76 tons ha-1. Bioneem plus 1 EC (T8) performed the best among the biopesticides while the neem seed kernel extract showed less effectivity against flea beetle.
 Conclusion: It is concluded that in case of chemical insecticides Ripcord 10EC while in case of biopesticides Bioneem plus 1 EC would be effective for flea beetle management.

Formation of volatiles in response to tea green leafhopper (Empoasca onukii Matsuda) herbivory in tea plants: a multi-omics study.

Combined transcriptome and metabolome analysis of fresh leaf infestation by tea green leafhoppers (Empoasca (Matsumurasca) onukii Matsuda) suggests roles for alternative pre-mRNA splicing and mRNAs in the regulation of aroma formation in tea plants. Oriental Beauty is a high-grade, oolong tea with a pronounced honey-like aroma and rich ripe fruit flavor that develops primarily as a result of the infestation of the fresh leaves by tea green leafhoppers (Empoasca (Matsumurasca) onukii Matsuda). Here, we used PacBio Iso-Seq and RNA-seq analyses to determine the full-length transcripts and gene expression profiles of fresh tea leaves in response to E. (M.) onukii herbivory. We investigated the relationship between RNA-seq, tea metabolites, and aroma response mechanisms in leaves infested by leafhoppers. We found 3644 differentially expressed genes, of which 2552 were up- and 1092 were down-regulated. A total of 49,913 alternative splicing events were predicted, including 324 differential AS events. Moreover, 3105 differentially expressed transcripts were also identified, of which 2295 were up- and 810 were down-regulated. The characterization of expression patterns of the key gene transcript isoforms involved in the aroma formation pathways identified 130 differentially expressed metabolites, 97 of which were up- and 33 were down-regulated. Two key aroma compounds (phenylacetaldehyde and 4-hydroxybenzaldehyde) were highly correlated with genes of the aroma formation pathways. Our results revealed that pre-mRNA AS plays a crucial role in the metabolic regulation surrounding aroma formation under leafhopper herbivory in tea plants.

Effect of weather parameters on the seasonal incidence of rice leaf folder (Cnaphalocrosis medinalis, Gunee)

Study was undertaken to determine the effect of weather parameters on rice leaf folder during 2015-16 at Krishi Vigyan Kendra Jagatsinghpur, Odisha. The leaf folder infestation was monitored through light trap catches and the infestation percentage was observed during crop period and correlated with weather parameters. Results indicated that the peak activity of rice leaf folder was in the third week of September with 25.39 per cent leaf infestation. It was associated with 30.71 0C to 22.79 0C maximum and minimum temperatures and 92.00 and 45.00 per cent morning and evening relative humidity with the association of 65.8 mm rainfall. The correlation study revealed that the number of rice Leaffolder infestation were significantly correlated with maximum temperature (r= 0.465) and minimum temperature (r=0.381). Increasing temperature within upper threshold of the species promoted leaf folder growth. and showed negative and non significant correlation with average rainfall (r = - 0. 15), morning relative humidity (r = - 0.14) and evening relative humidity (r = - 0. 12).

EFFICACY OF VARIOUS INSECTICIDES AGAINST MAJOR INSECT PESTS OF SUMMER SQUASH (Cucurbita pepo) IN DHADING DISTRICT, NEPAL

Red pumpkin beetle, fruit fly, flea beetle, whitefly, squash bug, melon aphid, etc. are the major insect pests of summer squash resulting in a huge loss in quality and quantity to farmers A field trial was conducted to find out the comparative efficacy of various insecticides against the major insect pests of summer squash from January to June 2020 in Dhading district, Nepal. The experiment was laid in Randomized Complete Block Design (RCBD) with four different insecticides i.e. Imidachloropid 17.8 SL @1.5ml/l, Spinosad 45SC @1ml/L, Azadiractin (Nimbecidine) 500ppm @ 5 ml/L, Jholmol @ 1:5 concentrations, and normal water spray as control as five treatments. The treatments were replicated four times and ‘Anna 303’ variety of summer squash was used under study. The results revealed that, among all the insecticides evaluated at all the four sprays, Imidachloropid recorded the maximum reduction in the population of red pumpkin beetle (RPB) (about 90%), other insects (about 88%) and also showed minimum leaf infestation % (28.5%), and leaf damage % per plant (15.63%) and Spinosad being at par with Imidachloropid followed by Azadirachtin and Jholmol respectively. Imidachloropid and Spinosad also showed comparatively lower fruit infestation by fruit fly i.e. 18.5% and 20.5 % respectively than other insecticides. Both Imidachloropid and Spinosad treated plots were statistically (p<0.05) similar and significantly superior over other treatments for yield (52.11 and 50.31Mt ha-1 respectively), for fruit length (37.62 and 37.12cm respectively) and fruit diameter (26.78 and 26.51cm respectively). A negative and strong correlation was found between yield and mean population of RPB and other insects, leaf infestation % per plant, leaf damage % per plant, and fruit infestation % per plant whereas fruit length and diameter showed a positive correlation with yield. The benefit-cost ratio was highest for plot treated with Imidachloropid (4.21) followed by Spinosad, Azadiractin, Jholmol, and Control. Thus, Imidachloropid was the most effective and economic in controlling the major insect pests of summer squash.

Potato Tuberworm Phthorimaea operculella (Zeller) (Lepidoptera: Gelechioidea) Leaf Infestation Effects Performance of Conspecific Larvae on Harvested Tubers by Inducing Chemical Defenses.

Simple SummaryAboveground herbivory can affect belowground herbivore performance by changing plant chemicals. However, it is not clear how leaf feeding affects tuber-feeder performance in tuber-plants. We evaluated the effect of foliar feeding of the potato tuberworm P. operculella on the performance of conspecific larvae feeding on harvested tubers and measured the phytochemical changes in leaves, roots, and tubers. We found that aboveground P. operculella leaf feeding negatively affected the performance of conspecific tuber-feeding larvae, likely due to the increased α-chaconine and glycoalkaloids in tubers, suggesting that plant chemicals were reallocated among different tissues, with greater changes in metabolic profiles in leaves and tubers compared with roots. Thus, aboveground feeding by P. operculella during the growing season can change tuber resistance against the potato tuberworm during the warehouse storage of tubers.Conspecific aboveground and belowground herbivores can interact with each other, mediated by plant secondary chemicals; however, little attention has been paid to the interaction between leaf feeders and tuber-feeders. Here, we evaluated the effect of the foliar feeding of P. operculella larvae on the development of conspecific larvae feeding on harvested tubers by determining the nutrition and defense metabolites in the whole plant (leaf, root and tuber). We found that leaf feeding negatively affected tuber larval performance by increasing the female larval developmental time and reducing the male pupal weight. In addition, aboveground herbivory increased α-chaconine and glycoalkaloids in tubers and α-solanine in leaves, but decreased α-chaconine and glycoalkaloids in leaves. Aboveground herbivory also altered the levels of soluble sugar, soluble protein, starch, carbon (C), nitrogen (N), as well as the C:N ratio in both leaves and tubers. Aboveground P. operculella infestations could affect the performance of conspecific larvae feeding on harvested tubers by inducing glycoalkaloids in the host plant. Our findings indicate that field leaf herbivory should be considered when assessing the quality of potato tubers and their responses to pests during storage.

An emerging pest of radish, striped flea beetle Phyllotreta striolata (Fabricius), from Northern India: incidence, diagnosis and molecular analysis

Severe incidence of striped flea beetle, Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidae) in radish is being reported from Delhi National Capital Region and Haryana. The larvae and adult of this species were found to damage both roots and leaves of radish, respectively. Overall there was an average 63.02 percent leaf infestation and 53.96 percent root infestation in the radish fields surveyed, which was above the economic threshold level (25% infestation). Infestation was also observed on other cruciferous crops like turnip, mustard, cabbage and cauliflower in National Capital Region and Haryana. In the present study, we have furnished the species diagnosis, sexual dimorphism, nature of damage and illustrations of various stages of the pest. DNA barcoding was employed to confirm the species identity and molecular phylogenetic studies based on mt CO I sequences from across the world showed that there were two clusters; the Old World and the New World. The biology of the pest and the importance of studies on area specific population dynamics for formulating management strategies are discussed.

COMPARATIVE EFFICACY OF SOME NEWER INSECTICIDES AGAINST RICE LEAF FOLDER (CNAPHALOCROSIS MEDINALIS GUEN.) AND THEIR EFFECTS ON NATURAL ENEMIES IN RICE ECOSYSTEM

In the present study, some new generation insecticides were evaluated against rice leaf folder (RFL) infestation and their toxic effects were also observed on some natural enemies in the rice ecosystem. Data were collected on percent hill infestation, percent leaf infestation, number of moths/sweep, grain yield (t/ha) and abundances of natural enemies/m2. Results clearly showed that Serput (Bifenthrin) 2.5EC @ 2.0 ml/L water resulted in the greatest reduction of RFL and increased the grain yield compared to the untreated control which was followed by Envoy (Fipronil) 50SC @ 1.0 ml/L, Libsen (Spinosad) 45SC @ 0.40 ml/L, Acemida (Acephate + Imidacloprid) 51.8WDG @ 1.0 g/L, Suspend (Emamectin benzoate) 5SG @ 1.0 g/L, Combi-DT (Deltamethrin + Triazophos) 36EC @ 0.50 ml/L and Altima plus (Thiamethoxam + Emamectin benzoate) 40WG @ 0.20 g/L respectively. To know the toxic effect of selected insecticides, abundances (number/m2) of some natural enemies were counted at 7 days after given each spray. It was found that the highest numbers of natural enemies (m2) were recorded in the untreated control plot. In all field trials, the harmful effects of the seven insecticides were in the following rank order (least harmful to most harmful): Suspend 5SG, Serput 2.5EC, Envoy 50SC, Libsen 45SC, Acemida 51.8WDG, Altima plus 40WG and Combi-DT 36EC. Based on the reduction in rice leaf folder infestation, increase in grain yield and compatibility with natural enemies, Serput 2.5EC @ 2.0 ml/L proved to be the best among all the selected insecticides.

Seasonal incidence of major insect pests in the multi-storey farming of Mahaneem, pulses and castor in south west Haryana

In the present study, no. of insect pest infestation was observed on the Mahaneem (Ailanthus excelsa) plant. Themajor loss in the form of mean infestation level in castor was observed by red hairy caterpillar, Amsacta moorei (30% defoliation); castor semilooper, Achaea janata (25% defoliation); tobacco caterpillar, Spodoptera litura (55%defoliation) and leafhopper, Empoasca flavescens (20 % leaf infestation). It was noticed that castor shoot and capsule borer Conogethes punctiferalis infestation was only 8 percent capsule damage, however, its damage was 25% on capsule in monocrop of castor. The major infestation in the pulses i.e. urd bean, cowpea and mung bean was observed by spotted pod borer Maruca testulalis 80 percent pod damage, red hairy caterpillar (25% defoliation) and leafhopper Empoasca kerri (27% leaf infestation). It was concluded in the present study that there was no effect on the incidence of insect pests on mahaneem, pulses and castor except castor capsule borer damage. It might be due to least host preference of this insect towards multi-storey farming system plantation. The study proved successful multi-storey farming system of Mahaneem, pulses and castor in reference to insect pests attack in south west Haryana.

Evaluation of brinjal cultivars against mealybug coccidohystrixinsolita (Green) and its natural enemies

A experiment was conducted to study the response of brinj al cultivars to mealybug Coccidohystrix insolita and its natural enemies at the College of Agriculture, Vellayani, Kerala. Among the tested cultivars, Pusa Uttam recorded the lowest mean incidence (38.58) which was statistically on par with Pusa Purple Long (41.67). The evaluated cultivar, Udit harbored maximum number of mealybugs (127.58) which was statistically on par with Pink Long (116.75) and Haritha (115.50). The tested brinjal cultivars were categorized based on mean % leaf infestation. Pusa Purple Long was included under the category resistant whereas Pusa Uttam and Ponni were in the group moderately resistant; Pusa Kaushal, Pusa Shyamla and Neelima were moderately susceptible whereas hybrids Green Long and Pink Long fell under susceptible category. Cultivars, Udit and Haritha were found to be highly susceptible. The cultivars Haritha (3.92) attracted more number of predatory coccinellid beetles whereas the least occurence of spiders was observed in Pusa Purple Long (1.42).

Surveillance of pea leaf miner (P. horticola) infesting pea (Pisum sativum) in relation with abiotic factors

To study the seasonal incidence of insect pests of pea (P. sativum) the investigation was carried out during Rabi session of 2016-17 and 2017-18, at Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi. The incidence of pests infesting pea was recorded from 50th SMW to 11th SMW. During the observation it was found that P. horticola showed its appearance in the field from 1st to 11th SMW with peak population (71% leaf infestation) in 7th SMW. When population was correlated with abiotic factors it was found that there was positive association with maximum temperature (r = 0.759**), minimum temperature (r = 0.672**), wind speed (r = 0.449).and sunshine hours (r =0.583*) whereas a negative relationship was maintained with morning relative humidity (r =-0.496) and evening relative humidity (r=-0.515), during 2016- 17. Similarly, during 2017-18 there was a positive association with maximum temperature (r = 0.360), minimum temperature (r =0.431), wind speed (r = 0.544*) and sunshine hours(r=0.493) whereas a negative relationship was maintained with morning relative humidity (r =-0.277) and evening relative humidity (r=-0.365).

Screening of jute varieties against jute apion (Apion corchori Marshall) and its management using chemical and botanical pesticides

The experiment was conducted in the field laboratory of the Department of Entomology, Bangladesh Agricultural University, Mymensingh on the screening of resistant variety against jute apion, Apion corchori (Marshall) and its management by using some chemical and botanical pesticides during April to August 2014. Eleven jute varieties were selected to conduct varietal preference and tested against jute apion in field condition. Among the eleven varieties, O-9897 showed the higher leaf infestation than others showing statistically similar result with O-72 and O-795. Mean percent of leaf infestation was 55.64 in O-9897 while 28.07 in BJRI Deshi pat-5, 24.89 in CVL-1, 22.11 in BJRI Deshi pat-7, 29.64 in CC-45, 24.08 in BJRI Deshi pat-8, 27.99 in D-154, 51.42 in O-795, 26.37 in BJRI Deshi pat-6, 55.53 in O-72 and 39.45 in CVE-3. The lowest leaf infestation was found in BJRI Deshi pat-7 (22.11%) which was statistically similar to BJRI Deshi pat-8 (24.08%). The same trend of results was observed in case of the number of knot plant-1 and the highest knot was recorded in O-795 followed by O-72. Data revealed that the variety O-9897 was highly susceptible to jute apion followed by O-72 and O-795 whereas BJRI Deshi pat -7 had the resistant potentiality against jute apion followed by BJRI Deshi pat-8 and CVL-1. The overall preference rank of the varieties based on their resistance against jute apion was in the following order: BJRI Deshi pat-7>BJRI Deshi pat-8>CVL-1 > BJRI Deshi pat-6> D-154>BJRI Deshi pat-5> CC-45>CVE-3>O-795>O-72>O-9897. In the management study, two synthetic insecticides viz., Limper 10EC, Diginol 60EC and two botanicals viz., Neem oil and Mahogany oil were evaluated. Considering different parameters, comparatively less leaf infestation percent, number of hole leaf-1 and number of knot plant-1 was found with Diginol 60EC treated plot followed by Limper 10EC treated plot. The highest infestation was found in the control plot followed by Mahogany oil applied plot. The rank of the efficacy of the treatments was Diginol>Limper>Neem oil>Mahogany oil>control. It could be concluded that BJRI Deshi pat-7, BJRI Deshi pat-8 and CVL-1 was comparatively more resistant variety considering both leaf damage and number of knot plant-1 and local variety O-9897 followed by O-72 and O-795 was highly susceptible to Jute apion. This finding would be helpful to motivate the people to use botanical insecticides i.e., Neem oil for the management of jute apion in environmentally safe condition.
 J Bangladesh Agril Univ 17(3): 274–280, 2019

Release from natural enemies mitigates inbreeding depression in native and invasive Silene latifolia populations.

Inbreeding and enemy infestation are common in plants and can synergistically reduce their performance. This inbreeding ×environment (I × E) interaction may be of particular importance for the success of plant invasions if introduced populations experience a release from attack by natural enemies relative to their native conspecifics. Here, we investigate whether inbreeding affects plant infestation damage, whether inbreeding depression in growth and reproduction is mitigated by enemy release, and whether this effect is more pronounced in invasive than native plant populations. We used the invader Silene latifolia and its natural enemies as a study system. We performed two generations of experimental out‐ and inbreeding within eight native (European) and eight invasive (North American) populations under controlled conditions using field‐collected seeds. Subsequently, we exposed the offspring to an enemy exclusion and inclusion treatment in a common garden in the species’ native range to assess the interactive effects of population origin (range), breeding treatment, and enemy treatment on infestation damage, growth, and reproduction. Inbreeding increased flower and leaf infestation damage in plants from both ranges, but had opposing effects on fruit damage in native versus invasive plants. Inbreeding significantly reduced plant fitness; whereby, inbreeding depression in fruit number was higher in enemy inclusions than exclusions. This effect was equally pronounced in populations from both distribution ranges. Moreover, the magnitude of inbreeding depression in fruit number was lower in invasive than native populations. These results support that inbreeding has the potential to reduce plant defenses in S. latifolia, which magnifies inbreeding depression in the presence of enemies. However, future studies are necessary to further explore whether enemy release in the invaded habitat has actually decreased inbreeding depression and thus facilitated the persistence of inbred founder populations and invasion success.

Impact of Soil Fertility Management Practices on Insect Pests and Diseases of Maize in Southwest Cote d’Ivoire

Objectives : Integrated soil fertility management (ISFM) is essential for sustainable management of tropical soils. However, soil fertility management is able to affect plant susceptibility to pests and diseases. The study investigated impact of soil fertilization practices on maize pests and diseases during two identical and simultaneous trials setup in South-West Cote d'Ivoire. Methodology and Results : Experiments were laid out using complete randomized block designs with three replicates and four treatments: (1) control; (2) chemical fertilization; (3) fertilization with cattle manure; (4) association “maize + legume” combined with chemical fertilization. Overall, 22 insect species collected and two diseases (maize streak disease and curvularia leaf spots) observed at both sites. Only cattle manure clearly increased pest and disease damages. The use of cattle manure significantly increased leaf infestation rate and maize streak disease frequency at both sites. Similar impact of NPK and cattle manure was obtained on maize yields either in monocropping or in mix cropping. Conclusions and application of findings : This study clearly confirmed that ISFM is able to affect plant susceptibility to pests and diseases. Cattle manure attracted a diversity of insects of diverse functional groups such as air-borne pests. These latter affected some plant parts; in this case, maize leaves which infestation rate significantly increased. This attraction for multitude insects may increase vector-borne diseases such as maize streak which frequency significantly increased at both sites. Consequently, despite the potential of cattle manure to increase maize yield, their use as organic fertilizer requires to take some precautions. So, the promotion of cattle manure as organic fertilizer in substitution of chemical fertilizer in tropical regions where it is available is encouraged. However, it should be converted into compost or pre-treated for optimal use in agriculture. Finally, mix cropping could be suggested for optimization of economic profit. Keywords : Maize, leaf infestation, maize streak disease, soil fertility management, cattle manure