Lugens Infestation Research Articles

Biochemical Defense Responses in Advanced Backcross-derived Rice Genotypes to Nilaparvata lugens (Stal) Infestation

BPH, Nilaparvata lugens (Delphacidae: Homoptera) infestation on most of the resistant and moderately resistant backcross derived rice genotypes and resistant checks (PTB 33 and BM 71) resulted in an increase in the phenolic content in the infested plants leaf sheath. The percentage increase in phenols in resistant and moderately resistant genotypes ranged from 14.8 % to 67.7 %. Upon infestation of BPH there was a decrease in total reducing sugars in all the resistant and moderately resistant genotypes. The highest quantity of reducing sugars was present in healthy susceptible check TN1 compared to all the resistant and moderately resistant backcross derived rice genotypes. The ascorbic acid content in the resistant and moderately resistant genotypes decreased after BPH infestation and percentage decrease ranged from 16% to 36%. The total N content in the infested resistant and moderately resistant genotypes decreased over healthy genotypes. Decrease in the N content was highest in the susceptible check TN1 (35.2%). In the resistant checks slight decrease in the N content was observed. Potassium and Phosphorous (%) increased in the resistant genotypes and resistant checks, but not in susceptible check TN1. The plants responded defensively upon infestation, resulting in production of higher amount of phenolics, potassium, phosphorous and reduced level of nitrogen, reducing sugars and ascorbic acid.

Transcriptome-wide N6-methyladenosine profiling reveals growth-defense trade-offs in the response of rice to brown planthopper (Nilaparvata lugens) infestation.

N6-Methyladenosine (m6A) is a common messenger RNA (mRNA) modification that affects various physiological processes in stress responses. However, the role of m6A modifications in plants responses to herbivore stress remains unclear. Here, we found that an infestation of brown planthopper (Nilaparvata lugens) female adults enhanced the resistance of rice to N. lugens. The m6A methylome analysis of N. lugens-infested and uninfested rice samples was performed to explore the interaction between rice and N. lugens. The m6A methylation mainly occurred in genes that were actively expressed in rice following N. lugens infestation, while an analysis of the whole-genomic mRNA distribution of m6A showed that N. lugens infestation caused an overall decrease in the number of m6A methylation sites across the chromosomes. The m6A methylation of genes involved in the m6A modification machinery and several defense-related phytohormones (jasmonic acid and salicylic acid) pathways was increased in N. lugens-infested rice compared to that in uninfested rice. In contrast, m6A modification levels of growth-related phytohormone (auxin and gibberellin) biosynthesis-related genes were significantly attenuated during N. lugens infestation, accompanied by the down-regulated expression of these transcripts, indicating that rice growth was restricted during N. lugens attack to rapidly optimize resource allocation for plant defense. Integrative analysis of the differential patterns of m6A methylation and the corresponding transcripts showed a positive correlation between m6A methylation and transcriptional regulation. The m6A modification is an important strategy for regulating the expression of genes involved in rice defense and growth during rice-N. lugens interactions. These findings provide new ideas for formulating strategies to control herbivorous pests. © 2024 Society of Chemical Industry.

Pyramiding BPH genes in rice maintains resistance against the brown planthopper under climate change.

Nilaparvata lugens (brown planthopper; BPH) is a significant rice pest in Asia, causing substantial yield losses. Pyramiding BPH resistance genes with diverse resistance traits into rice cultivars is an effective strategy for pest management. However, the response of pyramiding combinations to environmental changes remains unclear. To address this knowledge gap, we investigated three pyramiding rice lines (BPH2 + 32, BPH9 + 32, and BPH18 + 32) in the context of varying climate change conditions, ensuring sufficient N. lugens-rice interactions. Thus, we set three environmental conditions [30/25 °C (day/night) with 500 ppm CO2 concentration, 32/27 °C (day/night) with 600 ppm CO2 concentration, and 35/30 °C (day/night) with 1000 ppm CO2 concentration]. All three pyramiding rice lines maintained the insect resistant ability under the three environmental settings. In particular, the BPH18 + 32 rice line exhibited stronger antibiotic and antixenosis effects against N. lugens. In addition, BPH18 + 32 rice line had better shoot resilience under N. lugens infestation, whereas the performance of the other two selected pyramiding rice lines varied. Thus, although BPH2, BPH9, and BPH18 represent three alleles at the same locus, their resistance levels against N. lugens may vary under distinct climate change scenarios, as evidenced by the performance of N. lugens on the three pyramiding rice lines. Our findings indicate that all three tested pyramiding rice lines maintained their insect resistance in the face of diverse climate change scenarios. However, these lines exhibited varied repellent responses and resilience capacities in response to climate change. Thus, the combination of pyramiding genes needs to be considered for future breeding programs. © 2023 Society of Chemical Industry.

Protection of rice against Nilaparvata lugens by direct toxicity of sodium selenate.

Nilaparvata lugens is one of the most notorious pest insects of cultured rice, and outbreaks of N. lugens cause high economic losses each year. While pest control by chemical pesticides is still the standard procedure for treating N. lugens infections, excessive use of these insecticides has led to the emergence of resistant strains and high pesticide residues in plants for human consumption and the environment. Therefore, novel and environment-friendly pest control strategies are needed. In previous studies, selenium was shown to protect selenium-accumulating plants from biotic stress. However, studies on nonaccumulator (crop) plants are lacking. In this study, rice plants (Oryza sativa, Nipponbare) were treated with sodium selenate by seed priming and foliar spray and then infested with N. lugens. Brown planthoppers feeding on these plants showed increased mortality compared to those feeding on control plants. Treatment of the plants with sodium selenate did not affect the enzymes involved in the biosynthesis of the plant stress hormones jasmonic acid and salicylic acid, suggesting that the observed insect mortality cannot be attributed to the activation of these hormonal plant defenses. Feeding assays using an artificial diet supplemented with sodium selenate revealed direct toxicity toward N. lugens. With a low concentration of 6.5 ± 1.5 µM sodium selenate, half of the insects were killed after 3 days. In summary, sodium selenate treatment of plants can be used as a potential alternative pest management strategy to protect rice against N. lugens infestation through direct toxicity.

Effects of exogenous plant growth regulator abscisic acid-induced resistance in rice on the expression of vitellogenin mRNA in Nilaparvata lugens (Hemiptera: Delphacidae) adult females.

Recent study showed that exogenous abscisic acid (ABA) acts as a regulator of plant resistance. This study investigated average injury scale and callose contents of rice, and vitellogenin ( Nlvg ) mRNA expression in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) adult females after third instar nymphs fed on exogenous ABA-treated susceptible [Taichung Native one (TN1)] and moderately resistant (IR42) rice cultivars. The results showed that exogenous ABA significantly decreased average injury scale of rice and Nlvg mRNA expression in N. lugens adults compared with the control (without ABA spraying). Nlvg mRNA expression in N. lugens adults decreased significantly after third instar nymphs fed on ABA-treated (5, 20, and 40 mg/liter) TN1 for 1 and 2 d, and for IR42, after fed on ABA-treated (20 and 40 mg/liter) rice plants for 1 d and after fed on ABA-treated (5, 20, and 40 mg/liter) rice for 2 d decreased significantly. The callose contents showed no significant change for TN1, while for IR42, significantly increased in roots and sheathes after N. lugens infestation under ABA treatments (20 and 40 mg/liter) compared with the control. The decrease of Nlvg mRNA expression may be partially attributed to the increase of callose content of plants. The results provide a profile for concerning the effects of ABA-induced rice plants’ defenses on phloem-feeding insects.

Intermediate herbivory intensity of an aboveground pest promotes soil labile resources and microbial biomass via modifying rice growth

The importance of aboveground herbivores for modifying belowground ecosystems has prompted numerous studies; however, studies can be biased by context dependent conditions which lead to extremely inconsistent results. So far, the impacts of herbivory intensity by important rice pests on rice paddy soil ecosystems are lacking. The aim of this study was to test the hypothesis that intermediate herbivory intensity of the brown planthopper (Nilaparvata lugens Stal) could promote soil labile resources and microbial biomass, while high intensity would show a reverse pattern, by mediating rice plant growth. This study will also help the development of integrative pest management. Four hopper infestation density treatments (0, 4, 8 and 12 nymphs per rice plant) and two infestation duration treatments (9 and 15 days after N. lugens infestation, DAI 9 and DAI 15) were established in a glasshouse experiment. Soil and plant were sampled destructively from four replicates and analysed for soil labile resources availability, soil microbial biomass and plant performance, respectively. The infestation density significantly affected both shoot and root mass of rice (P < 0.05), soil dissolved organic carbon (DOC) and nitrogen (DON), and microbial biomass carbon (MBC) and nitrogen (MBN), and the effects were further enhanced by prolonged infestation duration. Compared to the control (CK) without N. lugens, plant dry mass, DOC, DON, MBC and MBN increased under low (LD) and moderate hopper densities (MD) but decreased under high density (HD) on DAI 9. Moreover, the LD treatment exerted the most promotional effects on DAI 15. Rice root to shoot ratio generally increased in treatments subjected to herbivory. The labile resources and microbial biomass showed close relationships with both shoot and root mass across treatments, in particular with root mass on DAI 15. Such a trend indicated that the shift of photosynthate allocation to belowground contributed to changes of soil resource availability and microbial biomass. Intermediate herbivory intensity showed positive effects on rice seedling performance and, further, promoted soil labile resource availability and microbial biomass. The importance of extrapolating temporal and spatial scale, i.e. from the short-term greenhouse experiment to an entire rice growing season in the field, was highlighted.

Study of the relationship between the content of the rare earth element Eu in rice plants and in Nilaparvata lugens (Hemiptera: Delphacidae)

Abstract The current study investigated changes in the content of the rare earth element Europium (Eu) in roots, shoots and leaves of rice plants and in Nilaparvata lugens Stål (Hemiptera: Delphacidae) using an Eu marker and hydroponic culture. The results showed that N. lugens infestation significantly reduced Eu content in roots, shoots and leaves of two rice varieties, Shenyou 1 and Xieyou 963. The Eu content in roots, shoots and leaves of the susceptible variety, Shenyou 1, was significantly higher than that in the resistant variety, Xieyou 963. The Eu content of N. lugens fed on Shenyou 1 was significantly higher than of those fed on Xieyou 963. In addition, the Eu level was elevated at a higher density of N. lugens infestation. Eu content in the bodies of N. lugens was related to their weight and honeydew excretion, with a significant positive correlation. Thus, Eu content in the bodies of N. lugens can be considered an index of the amount of phloem sap taken in by N. lugens because the amount of honeydew excretion is proportional to the amount of phloem sap consumed. The ratios of Eu content in N. lugens to that in roots, shoots and leaves of rice plants were elevated at a higher N. lugens infestation density. That ratio was maximal in leaves, was intermediate in shoots and was minimal in roots. There was no significant difference in ratios between the two plant varieties. An Eu marker may be useful in the screening of resistant varieties and in the study of the mechanisms of resistance.

Physiological Responses to &lt;I&gt;Nilaparvata lugens&lt;/I&gt; in Susceptible and Resistant Rice Varieties: Allocation of Assimilates Between Shoots and Roots

Nilaparvata lugens (Stål) is a typical vascular feeder, primarily sucking the phloem sap of host plants. Its feeding on rice, Oryza sativa L., plants changes the pattern of allocation of assimilates between roots and shoots, and the root:shoot (R/S) ratio of assimilates is often measured as an index of physiological responses to N. lugens. The current study investigated changes in the R/S ratio of biomass, sucrose, and soluble sugar contents of rice plants in a susceptible variety (TN1) and a resistant variety (Xieyou 963). The results demonstrated that root and shoot biomasses in the two varieties linearly decreased with the increase of N. lugens infestation density. However, the relationship between changes in the R/ S ratio ofbiomass and N. lugens density differed between rice varieties, with the R/S increasing with infestation density in TN1 and decreasing in Xieyou 963. Sucrose and soluble sugar contents and their R/S values were also significantly different between the two varieties. Compared with the control that was not infested by N. lugens, the R/S values of sucrose and soluble sugar at 3 days after infestation (DAI) increased but decreased at 6 DAI in TN1. The R/S values of sucrose and soluble sugar were higher at 6 DAI than those at 3 DAI in TN1, whereas these values were lower at 6 DAI than at 3 DAI in Xieyou 963. These contrasting results suggest that physiological responses to N. lugens infestation differ between the susceptible and tolerant rice varieties.

Reaction of resistant and susceptible rice genotypes against brown planthopper (Nilaparvata lugens)

The study was carried out to assess the reaction of different rice genotypes in response to brown planthopper (BPH)Nilaparvata lugens (Stal.) attack and the possible use of these genotypes in BPH management. The resistant genotypes PTB 33, ADT 45 and ASD 7 and the moderately resistant genotypes CO 43 and KAU 1661 recorded the lowest nymphal preference, fecundity, feeding rate, survival, growth index, population buildup and plant dry weight loss per mg of insect dry weight produced, and more unhatched eggs, longer nymphal development period, days to wilt and higher Functional Plant Loss Index compared with the susceptible genotype TN1. In resistant and moderately resistant genotypes, a greater accumulation of defense enzymes such as peroxidase and polyphenol oxidase in response toN. lugens infestation was recorded one day after infestation, and more pathogenesis-related protein and chitinase activity was noted 3 days after infestation. The activity was sustained for more than a week after infestation compared with the susceptible genotype TN1.

Role of ethylene signaling in the production of rice volatiles induced by the rice brown planthopper Nilaparvata lugens

Ethylene signaling pathway plays an important role in induced plant direct defense against herbivores and pathogens; however, up to now, only few researches have focused on its role in induced plant indirect defense, i.e. the release of herbivore-induced volatiles, and the results are variable. Using a model system consisting of rice plants, the rice brown planthopper Nilaparvata lugens and its egg parasitoid Anagrus nilaparvatae, we examined the role of ethylene signaling in the production of rice volatiles induced by N. lugens by measuring both the timing of herbivore-induced ethylene levels and the relationships between ethylene, rice volatiles and attraction of the parasitoid. N. lugens infestation significantly enhanced the release of ethylene during 2–24 h after infestation. Plants treated with ethephon, a compound that breaks down to release ethylene at cytoplasmic pH, released volatiles profiles similar to those released by N. lugens-infested plants, and both of them showed an equal attraction of the parasitoid. Moreover, pretreatment with 1-MCP, an inhibitor of ethylene perception, reduced the release of most of rice volatiles whose amount was enhanced by N. lugens infestation and decreased the attractiveness to the parasitoid. These results demonstrate that ethylene signaling is required for the production of rice volatiles induced by N. lugens.

Time of occurrence of hopperburn symptom on rice following root and leaf cutting and fertilizer application with brown planthopper, Nilaparvata lugens (stål) infestation

The manifestation of brown planthopper Nilaparvata lugens (Stål) hopperburn damage was investigated with damage due to rice leaffolder, Cnaphalocrocis medinalis (Guenée) simulated by leaf cutting and root pests by root cutting. Plants were grown under hydroponic culture, with a nutrient solution (PK) foliar applied to assess the effect on the onset of the damage symptoms. The effect of both root and leaf removal on the time (days) before hopperburn symptoms (DHS) depended on the rice variety. DHS was significantly shortened with TN1 variety (BPH susceptible), but not with root cutting. Removal of both leaves and roots from Xieyou 63 variety (BPH tolerant), did not affect DHS. However, multiple comparisons of means of combined treatments for leaf and root cutting showed that removal of two thirds of root and leaves significantly shortened DHS. Foliar P sprays with root cutting had no impact of DHS on TN1 compared to no spray, but with leaf cutting DHS of TN1 was shortened significantly. In contrast to TN1, foliar P sprays significantly prolonged DHS of Xieyou 63. For the two rice varieties, foliar K sprays did not affect DHS, nor did doubling P and K concentrations in hydroponics solutions with TN1 under root removal. There was a significant interaction between leaf removal and doubling P and K with leaf cutting, the DHS being shortest for the combined treatment of two thirds of leaf cut and double K. Doubling P and K concentrations did not affect DHS of Xieyou 63 with both root and leaf removal. The understanding of the relationship between DHS and root/leaf cutting, and application of P and K fertilizer for two rice varieties can provide valuable information for determining a control threshold of BPH when two pests coexist and for rational application of fertilizers. A high damage rate of rice leaves by C. medinalis can enhance the damage inflicted by BPH due to an interaction effect. Thus the control threshold of BPH should be decreased when C. medinalis outbreaks occur. In contrast, the threshold of BPH should be increased when there is a low damage rate caused by C. medinalis. The variety that delays DHS indicates that it has some tolerance to BPH infestation, thus control threshold should be increased or pesticide application be reduced.

Responses in nutrient uptake in rice roots to infestation of brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

This study investigates the uptake of nitrogen (N), phosphorus (P), and potassium (K) by rice roots as a response to infestation by the rice brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae) at two developmental stages (i.e. beginning-heading and grain-filling) of two rice varieties, Zhendao 2 (japonics rice) and Xieyou 63 (hybrid indica rice), respectively. The results show that the impact of N. lugens infestation at the beginning-heading stage on N, P, and K uptake was not only more serious, but also that the recovery rate of root uptake after the removal of N. lugens was slower, as compared to the grain-filling stage. The percent reduction of N uptake following N. lugens infestations at the beginning-heading stage of Xieyou 63 was significantly greater in comparison to Zhendao 2 at the same stage. There was no significant difference in N uptake between two developmental stages, but P and K uptake by roots following N. lugens infestation were significantly different between the two developmental stages. The maximum reduction of K uptake was shown at the beginning-heading stage in both rice varieties. The recovery rate of N, P, and K uptake by roots after the removal of N. lugens from rice plants varied with the rice variety, developmental stage of rice and infestation duration. In Xieyou 63, the recovery rate of K uptake by roots of the plants infested at the beginning-heading stage was slower than that at the grain-filling stage. Plants of Zhendao 2 infested at the two developmental stages had showed slower recovery rate of K uptake compared with N and P uptakes. These findings partially explain the virulence of N. lugens feeding on rice plants, and thus may have important implications for integrated management of N. lugens.

Comparison of the Effects of Brown Planthopper, &lt;I&gt;Nilaparvata lugens&lt;/I&gt; (Stål) (Homoptera:Delphacidae), and Rice Leaffolder, &lt;I&gt;Cnaphalocrocis medinalis&lt;/I&gt; Guenee (Lepidoptera: Pyralidae), Infestations and Simulated Damage on Nutrient Uptake by the Roots of Rice Plants

Abstract Changes of the uptake function of rice roots to nitrogen (N), phosphorus (P), and potassium (K) in a hydroponics culture solution were studied in three experiments: a single factor experiment involving rice leaffolder, Cnaphalocrocis medinalis, larval infestations or simulated damages (cutting of leaves); paired combinations of two factors (leaf and root cuts); and combination of three factors (Nilaparvata lugens infestation and leaf and root removal). In the single-factor experiment, both C. medinalis feeding and leaf cutting significantly reduced the uptake of N by rice roots compared with the control. There were no significant differences in N concentration in hydroponics culture solution between treatments of one, two, and four larvae per hill, but there were significant differences between two rates of leaf cutting. Also, C. medinalis feeding and the cutting of leaves reduced the uptake of P by roots significantly but did not affect K uptake except when two-thirds of the leaf area was remove...

Attraction of the Parasitoid Anagrus nilaparvatae to Rice Volatiles Induced by the Rice Brown Planthopper Nilaparvata lugens

Anagrus nilaparvatae, an egg parasitoid of the rice brown planthopper Nilaparvata lugens, was attracted to volatiles released from N. lugens-infested plants, whereas there was no attraction to volatiles from undamaged plants, artificially damaged plants, or volatiles from N. lugens nymphs, female adults, eggs, honeydew, and exuvia. There was no difference in attractiveness between plants infested by N. lugens nymphs or those infested by gravid females. Attraction was correlated with time after infestation and host density; attraction was only evident between 6 and 24 hr after infestation by 10 adult females per plant, but not before or after. Similarly, after 24 hr of infestation, wasps were attracted to plants with 10 to 20 female planthoppers, but not to plants with lower or higher numbers of female planthoppers. The attractive time periods and densities may be correlated with the survival chances of the wasps' offspring, which do not survive if the plants die before the wasps emerge. Wasps were also attracted to undamaged mature leaves of a rice plant when one of the other mature leaves had been infested by 10 N. lugens for 1 d, implying that the volatile cues involved in host location by the parasitoid are systemically released. Collection and analyses of volatiles revealed that 1 d of N. lugens infestation did not result in the emission of new compounds or an increase in the total amount of volatiles, but rather the proportions among the compounds in the blend were altered. The total amounts and proportions of the chemicals were also affected by infestation duration. These changes in volatile profiles might provide the wasps with specific information on host habitat quality and thus could explain the observed behavioral responses of the parasitoid.

Changes of Zeatin Riboside Content in Rice Plants due to Infestation by Nilaparvata lugens (Homoptera: Delphacidae)

The effect of Nilaparvata lugens (Stål) (Homoptera: Delphacidae), infestation on the content of zeatin ribosides (ZR) in rice plants was investigated with enzyme-linked immunosorbent assay. Hydroponics experiments were conducted on 'Zhendao 2' rice, in which plants were subjected to N. lugens infestation at three nonhopperburn-causing densities (15, 30, and 60 nymphs per hill) for 2, 4, 6, and 8 d and at one hopperburn-causing density (240 nymphs per hill) for 2, 4, and 6 d, respectively. When rice plants were infested at the nonhopperburn-causing densities, ZR content in leaves varied significantly with the infestation density. Compared with the control plants, ZR content in rice leaves decreased significantly after infestation by 60 nymphs per hill for 2 d, but it tended to increase due to prolonged infestation at all the nonhopperburn-causing densities. In contrast, ZR content in rice roots significantly reduced after the plants being infested at the density of 15 nymphs for 2 d and at all densities for prolonged duration, except for the plants infested by 60 nymphs for 6 and 8 d, in which the ZR content increased or did not change significantly. However, infestation at the hopperburn-causing density caused significant reduction in ZR content in rice roots, regardless of infestation duration, and in rice leaves from the plants subjected to 2-d infestation. These results are discussed in relation to the possible physiological reaction of rice plants to N. lugens infestation and the resultant severe damage or hopperburn.

Nutrient uptake of rice roots in response to infestation of Nilaparvata lugens (Stål) (Homoptera: Delphacidae).

This study investigated the uptake of three macronutrients, including nitrogen (N), phosphorus (P), and potassium (K), by rice roots in response to different infestation levels of Nilaparvata lugens (Stål) (Homoptera: Delphacidae). Hydroponics experiments were conducted on the rice variety 'Zhendao 2' (moderately resistant to Tryporyza incertulas, Lepidoptera: Pyralidae) and the variety 'Xiushui 63' (susceptible to N. lugens). In 'Zhendao 2', N. lugens infestation significantly influenced the uptake of P and K but not N, with P and K uptake decreasing as the duration of N. lugens infestation increased. In 'Xiushui 63', N. lugens infestation influenced N, P, and K uptake to a different degree, depending on the infestation level, in which infestation for 2, 4, 6, and 8 d at a density of 60 nymphs did not affect N uptake, but such infestation levels significantly influenced the uptake of P and K. After the removal of N. lugens from rice plants, the N uptake recovered from infestation faster than that for P and K in the variety 'Zhendao 2', whereas the recovery rate of K uptake was faster than that for N and P in the variety 'Xiushui 63'. The recovery rate of the nutrient uptake was negatively correlated to the density and duration of infestation. The experimental results demonstrated that N, P, and K uptake of rice roots were largely not influenced by N. lugens infestation when the pest density was controlled below 15 nymphs per hill. This infestation level was in agreement with the proposed economic thresholds for control measures against the N. lugens infestation on rice plants.

Photosynthesis and translocation of assimilates in rice plants following phloem feeding by the planthopper Nilaparvata lugens (Homoptera: Delphacidae).

Experiments were conducted to measure the effect of feeding by the planthopper Nilaparvata lugens (Stål) on photosynthesis and the translocation of assimilates in rice plants, Oryza sativa L. We used mature japonica rice plants and applied the 13CO2 feeding method to evaluate those physiological effects. The photosynthetic rate was suppressed by N. lugens infestation, especially at the lower leaf position, with rates 30% lower than that of control plants at the booting stage. Leaf nitrogen concentration in infested plants was also lower than that in control plants. After flowering, the chlorophyll content and total plant dry weight were reduced by N. lugens. Stem and sheath dry weights were significantly reduced by N. lugens infestation, whereas panicle dry weight was not affected. Little effect was found on disruption in translocation of assimilates, even when 13CO2 was supplied to the infested leaves. Results suggested that removal of assimilates and reduction in photosynthesis by N. lugens have the greatest effect on growth and yield of rice plants as compared with the disruption in the translocation of assimilates. Plant death can occur by N. lugens infestation if the amount of energy supplied is less than that required for tissue maintenance.