Bottom‐up effects mediated by an organic soil amendment on the cabbage aphid pests Myzus persicae and Brevicoryne brassicae

Earthworm‐produced compost or vermicompost has been shown to increase resistance of plants to a variety of insect pests, but it is still unclear whether this resistance is dose dependent and whether the mechanisms responsible are the same for insect species with differing feeding habits and preferences. Therefore, we tested the effects of plants grown in various vermicompost concentrations (0, 20, 40, and 60%) on the preference and performance of generalist, Myzus persicae L., and specialist, Brevicoryne brassicae L. (both Hemiptera: Aphididae), aphid pests. Preference was evaluated with leaf disk (apterous) and whole plant (alate) choice assays. After 24 h of feeding, there was no significant negative effect on the feeding preference noted for apterae of either species of any of the treatments tested. To the contrary, apterae B. brassicae showed a significant preference for vermicompost treatments over control leaf disks. Alate M. persicae preferred alighting on control plants over vermicompost‐grown plants, but B. brassicae showed no preference toward any of the treatments tested. Both aphid species deposited significantly more nymphs on control plants than on those grown in 20% vermicompost. Furthermore, plants grown in soil amended with 20% vermicompost significantly suppressed mass accumulation, as well as numbers of adults and nymphs of both aphid species compared to controls. These data clearly show that vermicompost soil amendments can significantly influence pest aphid preference and performance on plants and that these effects are not dose dependent, but rather species and morph dependent.     

Effects of integrating companion cropping and nitrogen application on the performance and infestation of collards by Brevicoryne brassicae

Sustainable management of cabbage aphids, Brevicoryne brassicae (L.) (Hemiptera: Aphididae), is a major goal for collard, Brassica oleracea (L.) var. acephala (Brassicaceae), growers globally. Host finding ability of insect pests is significantly affected by diversified cropping systems, and this approach is being utilized currently as a pest management tool. Soil nutrition and its interaction with the cropping systems could have a significant effect on the general performance of collards and the infestation by cabbage aphids. In a search for a sustainable cabbage aphid control, a two‐season field experiment was carried out with two intercrops, collards and chilli, Capsicum frutescens (L.) (Solanaceae), and collards and spring onions, Allium cepa (L.) (Alliaceae), and a collard monoculture. For each of the cropping systems, nitrogen (N) was applied to the soil as a top‐dress at 20, 25, 30, and 35 g per collard plant. The response factors monitored were collard yield (fresh weight) and aphid infestation on collards. Spring onion‐collard intercrop had the lowest aphid density and the highest yield. Collard monoculture had the highest aphid infestation and the lowest yield. High levels of N led to increased infestation of collards by aphids, but also led to a significant increase in the yield of collards. Significant interactions between the N rates and the cropping systems were observed on some sampling dates, with the highest yield being realized under a combination of spring onion‐collard intercrop at a N rate of 30 g per plant. High aphid density led to a decrease in the yield of collards. It was concluded that with a spring onion‐collard intercrop, the soil N level could be raised from the blanket rate of 20–30 g per plant and this would lead to an increase in yield.     

Feeding behavior and performance of Nasonovia ribisnigri on grafts,detached leaves,and leaf disks of resistant and susceptible lettuce

Aphids are dependent on the phloem sap of plants as their only source of nutrients. Host‐plant resistance in lettuce, Lactuca sativa L. (Asteraceae), mediated by the Nr gene is used to control the lettuce aphid Nasonovia ribisnigri (Mosely) (Hemiptera: Aphididae). The resistance is located in the phloem; however, the exact mechanism of resistance is unknown. In this study, we investigated whether the resistance factor (or factors) is synthesized in the root or in the shoot. The feeding behavior and performance of avirulent N. ribisnigri were studied on grafts of resistant and susceptible lettuce. In addition, the persistence of resistance in excised lettuce tissue was measured, by studying the feeding behavior and performance of N. ribisnigri on detached leaves and leaf disks of resistant lettuce. It appears that the resistance factor encoded by the Nr gene is produced in the shoots: aphid feeding was reduced on resistant shoots grafted on susceptible roots, whereas aphids were able to feed on grafts of susceptible shoots on resistant roots. Partial loss of resistance was observed after detachment of leaves and excision of leaf disks from resistant plants. Aphids fed longer on excised resistant plant tissue compared with intact resistant plants; however, compared with excised plant tissue of the susceptible cultivar, the time spent on feeding was shorter, indicating resistance was not completely lost. Our findings caution against the use of excised leaf material for aphid resistance bioassays.     

Activation of ethylene‐related genes in response to aphid feeding on resistant and susceptible melon and tomato plants

The simple gaseous compound ethylene (ET) has long been recognized as a common component of plant responses to insect feeding and pathogen attack. However, it is presently uncertain whether it plays a role in host–plant resistance to piercing–sucking insects such as aphids. In these experiments, we investigated the expression of key ET‐associated genes in resistant and susceptible interactions in two model systems: the tomato‐Mi‐Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae: Macrosiphini) system and the melon‐virus aphid transmission gene (Vat)‐Aphis gossypii Glover (Hemiptera: Aphididiae: Aphidini) system. We examined expression patterns of genes associated with ET synthesis, perception, signal transduction, and downstream response. When compared with control plants, plants infested with aphids showed marked differences in gene expression. In particular, ET signaling pathway genes and downstream response genes were highly upregulated in the resistant interaction between A. gossypii and Vat⁺, indicating ET may play a role in Vat‐mediated host–plant resistance. A key integrator between the ET and jasmonic acid pathways (Cm‐ERF1) showed the strongest response.     

Feeding behavior of Myzus persicae on asparagus species susceptible and resistant to Asparagus virus 1

Asparagus virus 1 (AV‐1) infects Asparagus officinalis L. (Asparagaceae) in the field worldwide. However, various wild relatives of A. officinalis are resistant to AV‐1. Here we study the behavior of the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), on 19 AV‐1‐resistant wild relatives of A. officinalis. We focus on behavior that is associated with regular cell penetration, relevant for inoculation of AV‐1, and sieve element penetration to check for vector resistance and its potential influence on AV‐1 transmission. Parameters, relevant for the transmission of non‐persistent viruses and host plant acceptance, were obtained by the electrical penetration graph technique. Furthermore, phylloclade architecture of A. officinalis and its wild relatives was examined to study its influence on aphid behavior. Behavior of M. persicae displays many cell penetrations and long ingestion periods on A. officinalis, compared to the generally shorter cell penetrations (reduced potential for virus transmission) and reduced or no ingestion (phloem‐located aphid resistance) on wild relatives. Because effects on aphid behavior are not consistent throughout the group of the tested wild relatives of A. officinalis, with some wild relatives being susceptible to M. persicae, a common genetic background for AV‐1 and aphid resistance appears to be unlikely. However, the reduced potential of virus transmission as well as aphid resistance shown by some wild relatives may be useful for future breeding programs.     

Feeding behaviour and performance of different populations of the black currant‐lettuce aphid,Nasonovia ribisnigri,on resistant and susceptible lettuce

When crops are bred for resistance to herbivores, these herbivores are under strong selection pressure to overcome this resistance, which may result in the emergence of virulent biotypes. This is a growing problem for crop species attacked by aphids. The Nr‐gene in lettuce confers near‐complete resistance against the black currant‐lettuce aphid, Nasonovia ribisnigri (Mosely) (Hemiptera: Aphididae). Since 2007, populations of N. ribisnigri have been reported in several locations in Europe to infest resistant lettuce varieties that possess the Nr‐gene. The objective of this study was to analyse the behaviour and level of virulence of several N. ribisnigri populations observed to have colonized Nr‐locus‐containing lettuce lines. We analysed the stylet penetration and feeding behaviour, and the performance of these N. ribisnigri populations on resistant and susceptible lettuce lines. Large variation in the degree of virulence to the Nr‐locus‐containing lettuce lines was found among populations of the Nr:1 biotype. The German population was highly virulent on the Nr‐containing resistant lettuce lines, and showed similar feeding behaviour and performance on both the susceptible and resistant lettuces. The French population from Paris was the second most virulent, though reproduction on the resistant lines was reduced. The French population from Perpignan and a population from Belgium, however, showed reduced performance and feeding rate on the resistant compared to the susceptible lettuces. The lettuce background in which the Nr‐gene is expressed influences the level of resistance to the various Nr:1 aphid populations, because the performance and feeding behaviour differed between the aphids on the cultivars (romaine lettuce) compared to the near‐isogenic lines (butterhead/iceberg lettuce). This study also shows that being able to feed on a plant not automatically implies that a population can successfully develop on that plant, because aphids showed phloem ingestion during the 8‐h recording period on resistant lettuce, but were not able to survive and reproduce on the same lettuce line.     

Determining the host‐plant resistance mechanisms for Mamestra brassicae (Lepidoptera: Noctuidae) pest in cabbage

Six cabbage (Brassica oleracea var. capitata) varieties with different levels of resistance to Mamestra brassicae (Lepidoptera: Noctuidae) were investigated in order to assess whether antibiosis and antixenosis mechanisms are involved in the resistance to this pest or not. Four experiments were conducted to determine the effect of variety and plant ontogeny on larval behaviour, adult oviposition and leaf damages in non‐choice and choice tests. Larval survival, time to development and larval weights differed depending on the varieties and plant stages that we tested. At the pre‐head stage, larval mortality was higher, larvae died faster, time to pupation was shorter, pupae were lighter and the percentage of viable pupae and growth index (GI) values were lower than larvae reared from plants at the head stage. The commercial hybrid ‘Corazón de buey’ and the local variety named ‘BRS0535’ exhibited antibiosis to M. brassicae as they reduced its survival and growth and delayed its development time. In addition, these varieties were the most resistant after artificial infestation in terms of head foliage consumption and number of larvae per plant. Oviposition tests demonstrated that resistance found in ‘Corazón de buey’ and BRS0535 could be also based on antixenosis mechanisms as they resulted in fewer egg batches on plants, whereas BRS0402 could be classified as resistant because M. brassicae larvae showed less preference for it. Thus, resistance to M. brassicae found in cabbage crops may be due to the joint action of several factors involving antibiosis and antixenosis. We found significant differences in the resistance of BRS0535 depending on the plant ontogeny as it loses its resistance while developing. Further studies are required to identify the mechanism of antibiotic resistance which is present in this variety at the pre‐head stage and the changes that occur in plant defence as it grows.     

Effects of Rag1 aphid‐resistant soybean on mortality,development, and preference of brown marmorated stink bug

The brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), poses a new threat to soybean, Glycine max (L.) Merrill (Fabaceae), production in the north central USA. As H. halys continues to spread and increase in abundance in the region, the interaction between H. halys and management tactics deployed for other pests must be determined. Currently, the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is the most abundant and damaging insect pest of soybean in the region. Aphid‐resistant soybean, mainly with the Rag1 gene, is commercially available for management of A. glycines. Here, experiments were performed to evaluate the effects of Rag1 aphid‐resistant soybean on the mortality, development, and preference of H. halys. In a no‐choice test, mortality of H. halys reared on Rag1 aphid‐resistant soybean pods was significantly lower than when reared on aphid‐susceptible soybean pods (28 vs. 53%). Development time, adult weight, and proportion females of surviving adults did not differ when reared on Rag1 aphid‐resistant or aphid‐susceptible soybean pods. In choice tests, H. halys exhibited a preference for Rag1 aphid‐resistant over aphid‐susceptible soybean pods after 4 h, but not after 24 h. Halyomorpha halys exhibited no preference when tested with vegetative‐stage or reproductive‐stage soybean plants. The preference by H. halys for Rag1 aphid‐resistant soybean pods and the decreased mortality when reared on these pods suggests that the use of Rag1 aphid‐resistant soybean may favor this emerging pest in the north central USA.     

The distribution of aphids in response to variation among individual host plants: Uroleucon rudbeckiae (Homoptera: Aphididae) andRudbeckia laciniata (Asteraceae)

Abstract. 1. An investigation was conducted to determine the effects of variation among individual plants of Rudbeckia laciniata L. on the distribution and abundance of the aphid Uroleucon rudbeckiae (Fitch).
2. Wild plants were examined repeatedly for up to 2¹/₂ years to obtain information about plant growth and flowering, and about aphid densities on individual plants.
3. Aphid densities on individual plants were positively associated with several measures of plant vigour, including height, growth since previous year, and occurrence of flowers.
4. The colonization of plants by alate aphids was more highly correlated with plant height than with plant exposure. Aphid densities on individual plants were more strongly associated with plant height than with number of colonists.
5. In all years there were many hosts which were never colonized by aphids. Some of these plants produced shoots but did not flower. Experimental infestation of these plants showed that they were unsuitable for aphid growth and reproduction. Some plants which did flower and which escaped aphid infestation were nevertheless suitable hosts. Previously unsuitable host individuals were able to support aphids when grown under glass-house conditions.     

寄主植物-蚜虫-天敌三重营养关系的化学生态学研究进展

综述了寄主植物－蚜虫－天敌三重营养关系的化学生态学研究,重点阐述了3个研究热点：①植物挥发性物质在蚜虫及其天敌选择寄主行为过程中的作用;②蚜虫信息素和蜜露对蚜虫天敌寄主选择行为的影响;③植物挥发性物质对蚜虫信息系作用的影响。对寄主植物－蚜虫－天敌三重营养关系的全面了解,将为蚜虫的综合治疗提供新思维。     

Mi‐mediated aphid resistance in tomato: tissue localization and impact on the feeding behavior of two potato aphid clones with differing levels of virulence

The Mi‐1.2 gene in tomato, Solanum lycopersicum L. (Solanaceae), confers resistance against several herbivores, including the potato aphid, Macrosiphum euphorbiae (Thomas) (Hemiptera: Sternorrhyncha: Aphididae) and the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodidae). Previous studies on the tissue localization of resistance have given varying results; whitefly resistance was attributed to factors localized in the mesophyll or epidermis, whereas aphid resistance was attributed to factors localized in the phloem. Our study utilizes the direct current electrical penetration graph (DC‐EPG) technique to compare aphid feeding behavior on resistant (Mi‐1.2+) and susceptible (Mi‐1.2?) tomato plants. This study also compares the impact of resistance on the feeding behavior of two aphid clones that vary in their virulence, or their ability to survive and reproduce on resistant plants. Previous work had shown that the avirulent WU11 clone is almost completely inhibited by resistance, whereas the semi‐virulent WU12 clone can colonize resistant hosts. Here, DC‐EPG analysis shows that both aphid clones take longer to initiate cell sampling and to establish a confirmed sieve element phase on resistant plants than on susceptible hosts, and have shorter ingestion periods on resistant plants. However, the magnitude of these deterrent effects is far less for the semi‐virulent clone than for the avirulent aphids. In particular, the WU12 clone is less sensitive to factors that limit sieve element ingestion, showing shorter non‐probe duration and rapidly establishing sustained phloem ingestion on resistant plants when compared to the WU11 clone. We conclude that, in addition to previously described factors in the phloem that inhibit ingestion, Mi‐mediated aphid resistance also involves factors (possibly in the mesophyll and/or epidermis) that delay initiation of phloem salivation, and that act in the intercellular spaces to deter the first cell sampling. Furthermore, the relative effectiveness of these components of resistance differs among insect populations.     

Comparison of feeding behaviour of two Brassica pests Brevicoryne brassicae and Myzus persicae on wild and cultivated brassica species

Feeding behaviour of the specialist Brassicae aphid, Brevicoryne brassicae (L) (cabbage aphid) and the generalist, Myzus persicae, (Sulzer) (peach potato aphid) was monitored electronically on the susceptible cauliflower, Brassica oleracea var. botrytis cv Newton Seale, and a range of 17 Brassica species, B. carinata, B. juncea, B. nigra, B. macrocarpa, and B. villosa var. drepanensis and cultivated brassica varieties, B. oleracea, B. campestris and B. napus. Aphids, monitored for 10 h on the underside of leaves, performed recognisable feeding behaviour on all brassica species. The main differences in feeding behaviour, between M. persicae and B. brassicae, on the susceptible cauliflower Newton Seale, were fewer probes, shorter times to initially reach the phloem but longer times to establish sustained phloem ingestion and the longer times spent, by M. persicae, in xylem ingestion.Feeding behaviour on the range of brassica species tested indicated that generalist and specialist aphids are influenced differently by the host plant. A longer time spent in xylem ingestion was again the major difference in the feeding behaviour of the two aphids. In addition, rejection of passive phloem ingestion, by M. persicae, was not related so closely to increased time spent in non probing activities, as for B. brassicae. This observation indicates that M. persicae does not generally accept or reject brassica species due to the presence of phagostimulants, such as glucosinolates at the leaf surface or along the stylet pathway, unless the concentration is very high. Differences in feeding strategies employed by generalist and specialist aphids on the same plants are discussed.     

Role of host‐plant selection in resistance of wild Solanum species to Macrosiphum euphorbiae and Myzus persicae

Damage to potatoes by Macrosiphum euphorbiae (Thomas) and Myzus persicae (Sulzer) (both Hemiptera: Aphididae) can be controlled through plant resistance. We used ethological experiments and electric penetration graph (EPG) analysis to evaluate the role of host selection in the previously assessed resistance levels of Solanum accessions: Solanum circaeifolium Bitter subsp. capsicibaccatum (Cárdenas) (PI210036), S. chomatophilum Bitter (PI243340 and PI310990), S. okadae Hawkes & Hjert. (PI458367), S. oplocense Hawkes (PI473368), S. pinnatisectum Dunal (PI186553), S. polyadenium Greenm. (PI230463), S. tarijense Hawkes (PI414150), and S. trifidum Correll (PI255538), to M. euphorbiae and M. persicae. Through multivariate analysis, we grouped behavioural variables into factors, which we related to host selection behaviours, and then evaluated whether factors varied between each accession and the susceptible S. tuberosum. None of the factors obtained by ethological experiments differed among accessions. Four of six and three of five factors obtained through EPG varied among accessions for M. euphorbiae and M. persicae, respectively, and were used to suggest resistance characteristics. The resistance to M. persicae of both S. chomatophilum accessions was associated with pathway activity disturbance. Solanum tarijense and S. polyadenium resistance to M. persicae resulted from leaf surface characteristics, which may be trichomes. Solanum oplocense and S. trifidum resistance to M. euphorbiae resulted from the wound response system, whereas S. pinnatisectum resistance may stem from nutritionally unbalanced or toxic phloem sap. Solanum polyadenium resistance to M. euphorbiae was phloem‐based. Solanum circaeifolium ssp. capsicibaccatum resistance to M. persicae, and the resistance of PI243340 S. chomatophilum and S. tarijense to M. euphorbiae were not related to host selection and therefore were presumably due to physiologically active compounds.     

Reproductive rate of the Indian mustard aphid (Lipaphis erysimi pseudobrassicae) on different Brassica oilseeds: colmparisons with Swedish strains of mustard (Lipaphis erysimi erysimf) and cabbage aphid (Brevicoryne brassicae)

The reproductive rate of the Indian mustard aphid (Lipaphis erysimi pseudobrassicae), a serious pest on Brassica oilseeds in India, was compared with that of Swedish strains of mustard aphid (L. e. erysimi) and cabbage aphid (Brevicoryne brassicae) on six common Indian and Swedish Brassica oilseed cultivars. There were clear differences between L. e. erysimi and L. e. pseudobrassicae in the relative suitability of the cultivars, emphasisipg the biological differences between these aphids. B. brassicae had similar reproductive rates on all cultivars.
In addition, the reproductive rate of L. e. pseudobrassicae was measured on both young and old plants of the six Brassica oilseed cultivars and 14 Indian rai (B. juncea) cultivars. Among the six Brassica cultivars, the reproductive rates were highest on turnip rape and toria (B. campestris), and lowest on yellow sarson (B. campestris) and rai (B. juncea). The ranking of the cultivars was similar for young and old plants. There were no significant differences between the rai (B. juncea) cultivars tested, neither among young nor among old plants. These results from laboratory studies are compared with field data from India on the relative susceptibility of different Brassica oilseed cultivars to L. e. pseudobrassicae.     

Compatibility of insect management strategies: Diuraphis noxia abundance on susceptible and resistant barley in the presence of parasitoids

Russian wheat aphid, Diuraphis noxia, and parasitoid abundance was monitored on field-grown barley, Hordeum vulgare L., varying in D. noxia susceptibility, to address the applicability of previous laboratory assessments of barley seedling resistance and parasitoid compatibility. Study sites were representative of the barley production region of the High Plains in the western USA, where D. noxia and its parasitoids occur. D. noxia abundance on resistant barley lines, characterized as partially tolerant and antibiotic to the aphid, was lower than on more susceptible lines. Parasitism by Diaeretiella rapae, Aphelinus albipodus, and A. asychis differed in seasonal occurrence and abundance. D. rapae mummies occurred sooner than aphelinid mummies, and there were larger increases in aphelinid mummies than in D. rapae mummies during seed head development. But in regard to plant resistance, parasitoid abundance, relative to D. noxia abundance, was similar on resistant and susceptible barley lines. Based on the susceptibility of commercial barley to D. noxia, the seasonal abundance of D. noxia and its parasitoids, and the compatibility of resistant barley and D. noxia parasitoids, the use of resistant barley in areas of parasitoid establishment is justified.     

Feeding deterrency of flavonoids and related phenolics towards Schizaphis graminum and Myzus persicae: Aphid feeding deterrents in wheat

A number of naturally occurring flavonoids have been tested for their feeding deterrent activity against two aphid species, Schizaphis graminum and Myzus persicae. Most flavonoids, including a number of dihydrochalcones related to phloretin, showed strong deterrency at concentrations well within the range often found in plants. Flavanone and flavone glycosides showed weak feeding deterrency relative to their corresponding aglycones. S. graminum and M. persicae responded similarly towards the compounds tested. The feeding deterrency of wheat extracts towards S. graminum was confined to the phenolic fraction, which included the flavone tricin. The more polar phenolic fraction showed the strongest feeding deterrency towards S. graminum.     

Silicon‐mediated resistance against specialist insects in sap‐sucking and leaf‐chewing guilds in the Si non‐accumulator collard

Soil amendment with Silicon (Si) can increase plant resistance against insect herbivores, but the underlying mechanisms remain unclear. The mechanical resistance hypothesis (MRH) states that Si accumulated in epidermal cells directly and passively protects against herbivores by creating a mechanical barrier. The physiological resistance hypothesis (PRH) states that Si enhances resistance by activating plant biochemical and physiological processes. We tested both hypotheses by manipulating Si fertilization of the Si non‐accumulator collard, Brassica oleracea L. cv. acephala (Brassicaceae). Then, we assessed functional and ultrastructural plant responses and the developmental and reproductive performance of the leaf‐chewing larvae of the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), and the sap‐sucking cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae). There was a 20% increase in leaf Si content. Silicon deposition in epidermal cells was identified by confocal microscopy and directly coincided with lower performance of P. xylostella, but did not affect B. brassicae. On the other hand, we found no unequivocal evidence that Si‐mediated changes in primary and secondary metabolism improved plant resistance against the insects. Negative mechanical effects of Si on the insects may have masked beneficial effects of increased water, nitrogen, and mineral contents in Si‐treated collards. Silicon did not change leaf contents of hemicellulose, cellulose, and lignin. Although Si‐mediated increases in leaf glucosinolates (GLS) correlated with lower larval performance and higher oviposition preference of P. xylostella, both P. xylostella and B. brassicae are highly specialized in overcoming such secondary metabolites. Thus, mechanical resistance may have impaired P. xylostella, rather than the Si‐mediated increase in GLS. We suggest that the PRH may depend on the degree of insect feeding specialization, so that toxic Si‐mediated defenses may be more efficient against unadapted polyphagous herbivores. For them, a toxic barrier may be added to the mechanical resistance.     

Fluctuations in peroxidase and catalase activities of resistant and susceptible black gram (Vigna mungo (L.) Hepper) genotypes elicited by Bemisia tabaci (Gennadius) feeding

Whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleryrodidae), is a serious pest of black gram, (Vigna mungo (L.) Hepper), an important legume pulse crop grown in north India. This research investigated the potential role of selected plant oxidative enzymes in resistance/susceptibility to whitefly in nine black gram genotypes. Oxidative enzyme activity was estimated spectrophotometrically from leaf samples collected at 30 and 50 d after sowing (DAS) from whitefly infested and uninfested plants. The enzymes showed different activity levels at different times after the infestation. The results indicated that in general, whitefly infestation increased the activities of peroxidase and decreased the catalase activity. Resistant genotypes NDU 5-7 and KU 99-20 recorded higher peroxidase and catalase activities at 30 and 50 DAS under whitefly-stress conditions as compared with non-stressed plants. The results suggest that the enhanced activities of the enzymes may contribute to bioprotection of black gram plants against B. tabaci infestation. The potential mechanisms to explain the correlation of resistance to whitefly in black gram genotypes with higher activities of oxidative enzymes are also discussed.