Defensive Responses of Rice Genotypes for Resistance Against Rice Leaffolder Cnaphalocrocis medinalis

The experiment was carried out to assess the reaction of different categories of rice genotypes viz., resistant, susceptible, hybrid, scented, popular and wild in response to the infestation by rice leaffolder （RLF）, Cnaphalocrocis medinalis （Guenee） and to explore the possible use of these genotypes in developing RLF-resistant rice varieties. The changes of various biochemical constituents such as leaf soluble protein, phenol, ortho-dihydroxy phenol, tannin and enzymes viz., peroxidase, phenyl alanine ammonia lyase （PAL） were assessed spectrophotometrically in all the rice genotypes before and after RLF infestation. The protein profile was analyzed using sodium dodecyl sulphate-poly acrylamide gel electrophoresis （SDS-PAGE） method. A significant constituent of biochemical content such as tannin, phenol and ortho-dihydroxy phenol has been increased along with enzyme activities of peroxidase and PAL in the infested resistant （Ptb 33, TKM6 and LFR831311） and wild rice genotypes （Oryza minuta and O. rhizomatis）. A decrease in leaf protein content was evident invariably in all the infested rice genotypes. It is also evident that the contents of biochemicals such as phenol, ortho- dihydroxy phenol and tannin were negatively correlated with leaffolder damage. However, leaf protein content was positively correlated with the damage by rice leaffolder. SDS-PAGE analysis for total protein profiling of healthy and C. medinalis-infested genotypes revealed the enhanced expression of a high molecular weight （〉 97 kDa） protein in all the genotypes. Besides, there was also an increased induction of a 38 kDa protein in C. medinalis infested resistant genotypes, which was absent in uninfested plants. The present investigation proved that the elevated levels of biochemicals and enzymes may play a vital role in rice plants resistance to RLF.

Susceptibility of <i>Culex quinquefasciatus</i>(Diptera: Culicidae) to malathion in Sargodha district, Pakistan

The present study was designed to evaluate the susceptibility of Culex quinquefasciatuns against malathion in Sargodha district of Pakistan. The activities of detoxifying enzymes i.e., β-esterases, GSTs and monooxygenases were also estimated. Our results revealed 100 percent mortality in insecticide treated groups after 24 hours of exposure. There was no difference in the activities of insecticide detoxifying enzymes between control and treated groups. We concluded from our work that malathion is still effective against C. quinquefasciatuns in the area for control of mosquito population.

Defensive Role of Plant Latex on Insect Pests’ Suppression: A Critical Review

Over 350 million years have passed since the documentation of the first interaction between plants and insects. Numerous plant defense qualities and associated counter-adaptive features have developed as a result of these interactions between insects and plants. These characteristics might be either morphological or biological in nature. One of the most significant and useful biochemical characteristics in plants is latex. Latex has a sticky property due to presence of secondary metabolites in it, which aids in entangling or sealing the mouthparts of small insects. These metabolites also chemically interact with the insects interfering with crucial bodily processes. Plant latex has amazing properties that help protect plants from insects and inhibit them in general. It may be possible to control insect pests in a natural, secure, and long-lasting manner by correctly identifying plant latex with strong insecticidal properties and developing formulations of plant latex.

Biological performance of BollgardⅡ Bt-resistant vs susceptible population of pink bollworm,Pectinophora gossypiella(Saunders)on non-toxic diet

Background The pink bollworm,Pectinophora gossypiella(Saunders),is a devastating global pest of cotton that has caused substantial economic damage to Bt Bollgard-Ⅱ~?cotton plants in recent years due to the evolution of Bt resistance.The associated fitness cost is assumed to be one of the factors delaying the development of resistance against Bt transgenic crops.Hence,the present study was undertaken to assess the biological performance of pink bollworms by comparing the life history and demographic parameters of a resistant(Field-R)and susceptible(Lab-S)population.Results Prolonged larval duration(23.40 days in Field-R vs 18.80 days in Lab-S population),total life cycle(male=50.00 vs 42.80 days;female=53.60 vs 46.20 days),reduced fecundity(100.60 vs 154.20 eggs/female)and fertility(88.00 vs 138.00 fertile eggs/female)was observed.The demographic parameters indicated a significant reduction in the net reproductive rate(184.27 vs 276.72),innate capacity for increase in number(0.11 vs 0.15),finite rate of increase in number(1.12 vs 1.16 female progenies produced/female/day),weekly multiplication rate(2.16 vs 2.86),potential fecundity(545.06 vs 634.11 eggs),number of hypothetical F_2 females(33955.65 vs 76572.41),but longer mean length of generation(47.54 vs 37.74 days)and population doubling time(6.30 vs 4.62 days)in Field-R compared with Lab-S population.A stage-specific life to ble demonstrated the differences in survival rates between susceptible and resistant populations at various life stages,with the resistant population having higher generation mortality(0.22vs 0.19).Conclusions The study confirms the involvement of fitness costs associated with Bt resistance in P.gossypiella.Despite reduced reproductive fitness,the resistant population tried prolonging the larval stage as a compensatory mechanism to repair the damaged host tissues due to Bt intoxication and for accumulation of enough nutrient reserves for normal pupation and adult emergence.Presence of a high proportion of double Bt-resistant larvae in the field coupled with continued noncompliance with refug planting certainly favours the flaring up of this monophagous pest despite the observed fitness costs.The resistance cannot be effectively reversed unless suitable alternative management strategies are deployed.

球孢白僵菌对油桐尺蛾的生物效力(英文)

分别在2005年和2006年的5、6月份,在Kamalpur和Hunterpara茶园、孟加拉西部以及印度地区对一种昆虫致病真菌球孢白僵菌对油桐尺蛾Buzura(=Biston)suppressaria Guen.的生物效力进行了评估。以农场主常用的化学杀虫剂40%SP灭多虫和25%EC氯氰菊酯作为标准检测物。试验中球孢白僵菌浓度为1.50 g,2.00 g和2.5 g/lit.of water;灭多虫和氯氰菊酯浓度分别为0.75 mL,1.00 mL和1.50 mL,和0.50 mL,1.00 mL和1.50 mL/lit.of water。在喷洒2.5 g/lit.of water球孢白僵菌3天后,Kamalpur和Hunterpara茶园中油桐尺蛾种群个体数分别降低了88.00%和84.00%。死的毛虫变成黑色,垂悬在叶片上。并且发现球孢白僵菌的杀虫活性与高剂量的灭多虫和氯氰菊酯的相当。

黄钩尺蛾在四个茶树无性系品种上的生长和存活(英文)

在实验室条件下,对食叶害虫黄钩尺蛾Hyposidra infixaria Walker在4个茶树Camellia sinensis无性系品种(TV1,TV9,TV25和Teenali17)上的生长和存活进行了研究,以确定其最适合寄生的茶树无性系品种。结果表明:在TV25上的黄钩尺蛾幼虫期(15.78d)比在TV1(18.14d),TV9(18.00d)和Teenali17(17.00d)上显著缩短。黄钩尺蛾按幼期龄数分为5龄型和6龄型两类。6龄型幼虫在TV25上的发生率显著高于其在其他3个无性系品种上的发生率。在TV25上黄钩尺蛾幼虫和蛹的体重也显著高于在其他3个无性系品种上的。同样地,以TV25为食的黄钩尺蛾未成熟阶段的存活率显著高于其以其他3个无性系品种为食的存活率。基于生长参数和存活率,我们发现TV25是黄钩尺蛾最适合寄生的茶树无性系品种。

Differential Aphid Colony Establishment in <i>Dolichos lablab</i>Varieties Correlated with Some Plant Specific Factors That Impact on Aphid Fecundity

Aphid establishes colony in the selective plant parts like vine, leaf petiole, leaflet, inflorescence, and tender fruit in Dolichos lablab Linn but not the entire plant. In this study, the aphid colony establishment in vine is focused to understand the differential resistance response between two varieties. At the early stage of aphid infestation, the aphid colony establishment was significantly different between two genotypes (p value = 0.00) and abbreviated as “resistant” variety that supported lower aphid proliferation (mean value = 48.2 ± 2.2) and “susceptible” variety that supported comparatively higher aphid proliferation (mean value = 215.5 ± 16.9). The total aphid number was significantly different between the two varieties, realized at the early infestation stage when both “antixenosis” and “antibiosis” defense mechanisms were working on. Some plant specific factors like vine diameter, wet/ dry weight ratio of vine, phloem sap pressure, the compactness of the vine, wet/dry weight ratio of leaflet, length of leaf petiole, diameter of leaflet vein were identified as modulating factors. The impact of resistant variety on aphid was also investigated for better understanding of aphid defense mechanism.

Entomopathogenic fungi disturbed the larval growth and feeding performance of Ocinara varians （Lepidoptera： Bombycidae）larvae

Feeding experiments using three strains ofentomopathogenic fungi, Beauveria bassiana, Metarhizium anisopliae and Isaria fumosorosea were conducted with newly moulted 3rd-5th instar Ocinara varians Walker larvae in the laboratory. The mortality of larvae immersed individually in spore suspension （1 × 10^7 spores/mL） of all the strains was 〉 80% except 5th instar larvae treated with M. anisopliae which transformed into pupae, but did not result in adult emergence. The growth （total body mass）, consumption, relative consumption rate and relative growth rate, were reduced at all three larval stages, while developmental time was extended in infected larvae with concurrent significant increase in approximate digestibility in infected larvae. Conversion of digested food （ECD） and ingested food （ECI） values declined in infected larvae as compared to the healthy larvae （control）. The 5th instar larvae treated with M. anisopliae showed higher ECD and ECI values than control. Based on mortality and growth inhibition it can be suggested that all the studied fungal strains have a high potential for biocontrol and could be developed into biocontrol agents against O. varians.

Comparative demography of Liriomyza sativae Blanchard （Diptera： Agromyzidae） on cucumber at seven constant temperatures

Reproduction and population parameters of vegetable leafminer, Liriomyza sativae Blanchard were measured on cucumber （Cucumis sativus L.） at seven constant temperatures （10, 15, 20, 25, 30, 35 and 40℃）. No eggs were found at 10℃ and flies died after exposure to 40℃. The significantly highest intrinsic rate of natural increase （rm）, net reproductive rate （R0） and finite rate of increase （λ） ofL. sativae were obtained at 25℃ as 0.196, 52.452, and 1.216, respectively. The above-mentioned parameters decreased at 15℃ and 135℃ and this reduction at 35℃ was strong. Doubling time （DT） varied significantly with temperature. The shortest doubling time was obtained at 25℃. Mean generation time （T） decreased significantly with increasing temperature between 15℃ and 35℃. Percentage of immature ages in the stable age distribution was more than 95% at all temperatures. Female longevity was greater than male at all temperatures. Liriomyza sativae lived for a long time at 15℃, whereas at 35℃ had lower survival rates. The effect of temperature on reproduction, especially the intrinsic rate of increase of L. sativae would be useful for predicting its longterm population fluctuation over several generations.

Biology and life table parameters of the mushroom pest, Pediculaster fletchmanni （Acari： Siteroptidae）, at three constant temperatures

This paper is concerned with the bionomics and demography of Pediculaster fletchmanni Wicht （Acari： Siteroptidae） under controlled conditions （20 ± l, 22 ± 1 and 25 ± 1℃, 70% ± 5% relative humidity and a photoperiod of 16L ： 8D hours）. Glass Petri dishes inoculated with Trichoderma sp. mycelia were used as substrate and food source. The mean developmental time of the egg and the active larva did not differ significantly at the various constant temperatures, but these periods were significantly different for the quiescent larval stage. The preoviposition period ranged from 2.3 to 2.8 days, the ovipositional period increased with temperature increase, and all females died immediately after oviposition. The development of active larvae was the fastest of all life stages. The developmental threshold ranged between 5.25-14.22℃ the highest value being observed for the quiescent larval development. For immature development required 89.29 degree-days. Values of rm （intrinsic rate of increase） were 0.229, 0.398 and 0.386 for 20, 22 and 25℃ respectively. Finite rates of increase （λ） increased along with increasing temperature from 20-25℃ consequently the population doubling time （D） and mean generation time （T） showed significant differences with increasing temperature.

Botanicals, selective insecticides, and predators to control Diaphorina citri （Hemiptera： Liviidae） in citrus orchards

The Asian citrus psyllid （ACP） Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing （HLB） or citrus greening devastating and economically im- portant disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecti- cides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin （Neem）, Tropane （Datura）, Spirotetramat, Spinetoram, and broad- spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old ＂Kinow＂ Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, aver- age 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Ane- glei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides.