Biological Enemies Research Articles

Influence of the Surrounding Plants by Rapeseed Field on Population Density of Cabbage Aphid (Brevicoryne brassicae L.) and its Biological Enemies

The result revealed that the peak of population density of cabbage aphid Brevicoryne brassicae was 523.20 individuals/plant on 21 March in edges of rapeseed field and was 1141.67 individuals/plant in center of the field. Results revealed that population density of cabbage aphid in rapeseed fields surrounded by cover crops significantly were low compared with that of monoculture rapeseed. The location of rapeseed plants (in edges or in center) significantly affected (p

Prevalence of Gastrointestinal Parasites of Poultry Chicken Slaughtered and Sold in Uyo Metropolis, Akwa Ibom State, Nigeria

Gastrointestinal parasites (GIP) are important biological enemies causing poor health in poultry, thereby causing significant reduction in harvest. This study was aimed to assess the prevalence of gastrointestinal parasites of poultry chickens slaughtered in Uyo, Akwa Ibom State. One hundred and fifty (150) intestinal contents of poultry chickens slaughtered were collected from poultry dressing units in market within Uyo metropolis and kept in polythene bags, and then transported to the Animal and Environmental Biology laboratory of the University of Uyo for analysis. The gizzard, small and large intestine and caeca were assessed for GIP. The method employed in this assessment was Direct Wet Mount following other standard methods. The parasites were analyses by microscopic examination of the fecal smears, thereafter identification of parasite. Five species were encountered in this study: Ascaris galli (32.76%) had the highest, followed by of Eimeria tenella (25.86%), Raillietina tetragona (16.39%) and Histomonas meleagridisis (16.39%). The least was recorded in Heterakis gallinarum (10.34%). Among the 67 (male) and 83 (female) samples, 34.38% and 65.62% respectively recorded positive. Ascaris galli, being the most prevalent was seen in 38 samples and Histomonas meleagridisis (the lowest) was seen in only 12 samples. > 12 weeks age group recorded lowest prevalence (9.3%) while 8-12 weeks had highest (19.30%). This study reveals that 39.12% had single parasitic infection, while mixed had 60.94%. Based on these results, poultry in Uyo farms are affected with gastrointestinal parasitic infection. Therefore, it is recommended that farmer should improve upon their management skills and issues concerning hygiene.

Crops biological protection: Phytopathogens growth inhibition by the entomopathogens

Background: The safety of agrarian preparations used for crop protection is a critical issue. In these regards, the minimization of usage of chemical pesticides containing artificial harmful substances is very important. Thus, the elaboration of innovative harmless biopesticides, based on biological enemies of pests, is very desirable. Microbe-based biopesticides can significantly increase the quality of agricultural production. Objectives: This research aims to develop ecologically safe, entomopathogenic microbe based biopesticides for use in green agriculture to improve agricultural production qualityIt includes the quality of vegetables, cereals, and fruits, as well as meat, milk, and eggs from animals that consume plant-based feed cultivated using recommended methodologies. Context and purpose of this study: This article was devoted to the consideration of bactericide effect of non-cellular extracts of entomopathogens against the various phytopathogens, as the potential prospective innovation for elaboration of plant protection safe biopesticides. Results: The majority of the studied entomopathogens can synthesize the compounds which inhibit the growth of phytopathogens. Entomopathogenic strains BT 2675, BL 200-4, and LS 2728 were found to significantly inhibit the growth of phytopathogens such as Pectobacterium, Xanthomonas, Rhodococcus, Curtobacterium, and Pseudomonas genera. According to spectroscopy the antiphytopathogenic effect is caused by an active component which is probably lipoprotein complex. Further detailed research on this is planned. Conclusions: Non-cellular extracts of entomopathogenic Bacillus are effective against the various plant pathogens. The identified antimicrobial properties of non-cellular extracts of entomopathogenic can be potentially used for the elaboration of plant protection safe biopesticides. Keywords: Bacillus thuringiensis (BT), Brevibacillus laterosporus (BL), Lysinibacillus sphaericus (LS), non-cellular extract, phytopathogen, entomopathogen, safe biopesticide

Identification of Gonatophragmium mori Causing Mulberry Zonate Leaf Spot Disease and Characterization of Their Biological Enemies in Guangxi, China.

Mulberry zonate leaf spot disease (MZLSD) is an important fungal disease of mulberry trees, which seriously affects the productivity and quality of mulberry leaves. MZLSD has been widely reported in sericultural production areas in Guangxi, China, in recent years. In this study, the causal agent of MZLSD was isolated from symptomatic samples and identified as Gonatophragmium mori (Acrospermaceae) based on morphological characterization and molecular analyses using nucleotide sequences of the internal transcribed spacer (ITS) and large subunit ribosomal DNA (LSU rDNA). Pathogenicity tests confirmed that G. mori is the pathogen responsible for MZLSD. Furthermore, we isolated antagonistic endophytic bacteria (AEB) from healthy mulberry leaves. Plate confrontation experiments showed that the lipopeptide crude extracts (LPCE) of three endophytic bacteria can inhibit the growth of G. mori, and the diameter of the antibacterial circle reaches more than 60 mm when their concentration of LPCE is 200 mg/ml. Light microscopy and scanning electron microscopy revealed that LPCE caused drastic changes in mycelial morphology. Fluorescence microscopy and transmission electron microscopy showed that the LPCE-induced apoptosis-like cell death in G. mori hyphae. Finally, based on morphological and molecular features, we identified the three isolates as Bacillus subtilis DS07, B. subtilis DS32, and B. velezensis Q6, respectively. To our knowledge, this is the first time to identify G. mori by combining characterization and molecular analyses, and we provide timely information about the use of biocontrol agents for suppression of G. mori.

Nematophagous Fungi Isolated from Municipal Waste-contaminated Soil in Medan City, North Sumatera: Morphological Identification, Phylogeny Analysis and Assessment as Root-knot Nematodes Biocontrol

Root-knot nematodes (RKNs) are groups of nematodes that cause significant diseases in horticultural and field crops. Chemical pesticides used to control RKNs could pollute environmental resources and ultimately affect human health. Therefore, eco-friendly efforts are needed. Previous research revealed that nematode-trapping fungi (NTFs) as the biological enemies of nematodes has been observed suppressing the nematode population. This study aimed to isolate NTF species from municipal waste-contaminated soil in Medan City, Indonesia, and identified them using morphological and molecular analysis. Furthermore, their biocontrol potential against Meloidogyne hapla Chitwood (Nematoda: Meloidogynidae) was assessed. Soil sample covered seven districts with seven repeats for isolation and in vitro assessment against M. hapla was done on CMA and observed after 12-72 hours. Three isolates were successfully obtained and proven effective in suppressing M. hapla by 97.7% (isolate sH51 and sH52) and 89.27% (isolate sH53). Morphological identification on PDA and genetic analysis of ITS concluded that sH51 is Drechslerella brochopaga Drechsler (Ascomycota: Orbiliaceae) and sH53 is Arthrobotrys thaumasius Drechsler (Ascomycota: Orbiliaceae). Morphological analysis for isolate sH52 reveals it as Arthrobotrys sinensis but is limited to Arthrobotrys sp. based on phylogeny analysis thus additional gen needs to be sequenced for confirmation.

Haar wavelet approach to study the control of biological pest model in Tea plants

n this study, we consider a novel approach called the Haar wavelet collocation method (HWCM) toexamine the mathematical model of pest propagation in tea plants and how biological enemies might controlthem. This model is in the form of a system of coupled ordinary differential equations (ODEs). When studyingthe system, we consider tea plants, pests that harm the plants, biological enemies that are their reasonablecompetitors of pests, self-reproduction of the tea plants, natural death of pests and natural enemies, etc. Byturning the Mathematical model into a system of non-linear algebraic equations, we use the properties ofthe Haar wavelets. The opted method can solve the biological pest management problem in tea plants. Thevalues of the unknown coefficients are recovered using the collocation method and Newton Raphson method.The Mathematica program acquires the numerical results, nature, and uniformity. The acquired findings showthat the current method is more accurate than those indicated in tables and graphs.

EFFECT OF DIFFERENT NATURAL MIXED MEDIA ON THE BIOLOGICAL CHARACTERISTICS OF THE GREEN LACEWING Chrysoperla carnea (STEPHENS)

The experiments were carried out in the laboratories of the mass rearing units of biological enemies Plant Protection Directorate / Ministry of Agriculture /Abu Ghraib in order to study the effect of different nutritional mixtures of media on some biological charecters of the adult predator Chrysoperla carnea(stephens). The results showed that the highest egg laying was obtained at the mixture (0.5 g yeast + 1.5 g Spirulina + 4g Honey + 0.5 Ml Water), reached to 881.33 eggs / female. In addition, the feeding on the mixture (0.5 g Spirulina + 4g Honey + 0.5 Ml Water) showed a positive effect in the incubation period of eggs, with an average of 3.54 days. The feeding on the mixture (0.5 g Ganoderma + 4g Honey + 0.5 Ml Water) resulted in better egg hatching ratio, reaching to 93.33%. A positive effect was shown with females’ survival when fed on the mixture (0.5 g yeast + 1.5 g Spirulina + 4g Honey + 0.5 Ml Water), the average longevity was 54 days. The longest male longevity was 36 days recorded at the mixed media of (0.5 g yeast + 1.5 g Spirulina + 4g Honey + 0.5 Ml Water). Longest post oviposition period was 5 days recorded at the mixed media of (1.5 g Spirulina + 4g Honey + 0.5 Ml Water). The longest period of eggs laying was at the mixture (Spiro Lina 1.5 g + yeast 0.5 g + honey 4 g + sterile distilled water 0.5 ml) was (46.47) days. Result indicated that some of the mixed media have a positive effect on the performance of aphid lion therefore; these combinations can be used in the quantitative mass rearing of the predator aphid lion.

Identification of Pathogenic Fusarium spp. Responsible for Root Rot of Angelica sinensis and Characterization of Their Biological Enemies in Dingxi, China.

Root rot is a serious disease in plantations of Angelica sinensis, severely reducing yield and quality and threatening sustainable production. Fusarium isolates (n = 32) were obtained from field samples of root rot tissue, leaves, and infected soil. Isolates were identified by comparison of the sequences of their internal transcribed spacer region and translation elongation factor 1-α to sequences of known species in the National Center for Biotechnology Information database. These Fusarium isolates include Fusarium tricinctum (43.75%), F. equiseti (31.25%), F. solani (9.37%), F. oxysporum (6.25%), F. acuminatum (6.25%), and F. incarnatum (3.12%). For pathogenicity testing under greenhouse conditions, seven isolates were selected based on a phylogenetic analysis, including four strains of F. tricinctum and one strain each of F. solani, F. oxysporum, and F. acuminatum. The seven isolates were all pathogenic but differed in their ability to infect: The four F. tricinctum strains were capable of causing root rot in A. sinensis at 100% incidence and were highly aggressive. Furthermore, the symptoms of root rot induced by those seven isolates were consistent with typical root rot cases in the field, but their disease severity varied. Observed histopathological preparations of F. tricinctum-infected seedlings and tissue slide results showed that this fungal species can penetrate epidermal cells and colonize the cortical cells where it induces necrosis and severe plasmolysis. Plate confrontation experiments showed that isolated rhizosphere bacteria inhibited the Fusarium pathogens that cause root rot in A. sinensis. Our results provide timely information about the use of biocontrol agents for suppression of root rot disease.

Study of the Factors Affecting Infestation Rate with Olive Moth Prays oleae (Bernard, 1788) in Three Olive Growing Locations Along the Syrian Coast

Wassouf, Y., A.N. Bashir and Gh. Ibrahim. 2022. Study of the Factors Affecting Infestation Rate with Olive Moth Prays oleae (Bernard, 1788) in Three Olive Growing Locations Along the Syrian Coast. Arab Journal of Plant Protection, 40(3): 193-200. https://doi.org/10.22268/AJPP-40.3.193200 This study aimed to investigate the effect of the most important factors affecting the infestation rate with the olive moth, Prays oleae (Lepidoptera: Yponomeutidae), in three olive growing locations in Lattakia and Tartus Governorates (Al-Sawda, Ain Shiqaq and AlBarqiah). The study was carried out during the period 2019-2020. Results obtained showed that the location had an effect on the infestation rate, and the highest average infestation rate was 33.53% in Al-Barqiah location, followed by 20.86% in Ain Shkak, and the lowest was 16.65% in Al-Sawda location. Results obtained also showed that the insect generation had an effect on the olive moth infestation rate; infestation of the phyllophagous generation was the highest, followed by the antophagous generation and the carpophagous generation in the three locations. The x2 (Chi-square) test showed that there were significant differences between the infestation rate and the total number of biological enemies, the number of predators and the parasitism rate in the three locations. Keywords: Biological factors, olive moth, predators, parasitoids, Ain Shkak, A-Sawda, Al-Barqieh, Syria

Análisis del manejo de las especies de tucuras (Orthoptera: Acrididae), plaga del agro en el partido de Laprida, Buenos Aires, Argentina

Grasshoppers are among the dominant insects in most grassland systems. These insects’ communities tend to exhibit temporal variations in the distribution and abundance of their species, and during outbreak years cause important economic loss in both implanted pastures and crops. In the study area, Laprida county, as well as in other areas of Buenos Aires province, this pest problem has been recognized since last century. The aim of this study was to analyze the pest management of grasshoppers made by farmers and related institutions in Laprida using both qualitative (interviews and documentary observation) and quantitative methods (surveys). About 80% of surveyed farmers considered that grasshoppers are the main pest in the region, and 60% of them apply chemical insecticides against this pest, mainly on crops. Besides, only 12.8% of surveyed farmers are aware of nonchemical alternatives for pest control, such us biological control and natural enemies. Most of the interviewed farmers acknowledged the importance of preventive management through systematic grasshopper monitoring and spot treatments in risky areas. Additionally, farmers showed interest in the implementation of more environmentally-safer strategies such as biological control.

Dynamics of Fractional Model of Biological Pest Control in Tea Plants with Beddington–DeAngelis Functional Response

In this study, we depicted the spread of pests in tea plants and their control by biological enemies in the frame of a fractional-order model, and its dynamics are surveyed in terms of boundedness, uniqueness, and the existence of the solutions. To reduce the harm to the tea plant, a harvesting term is introduced into the equation that estimates the growth of tea leaves. We analyzed various points of equilibrium of the projected model and derived the conditions for the stability of these equilibrium points. The complex nature is examined by changing the values of various parameters and fractional derivatives. Numerical computations are conducted to strengthen the theoretical findings.

The relationship between personality traits and dysfunctional attitudes of medical staff in the pandemic period

In recent years, the study of medical employees’ mental health has become an important debated topic in the literature around the world, but little information is available on the extent to which social, psychological, and organizational factors affect the degree of exhaustion, leading to behavioral changes. The pandemic period that has affected (negatively impacted) the whole world in the last year, represented even more a degree of stress for the medical staff, who imminently and directly confronted the biological enemy. Medical employees are frequently exposed to both physical and mental risks. Shocking events and the likelihood of failure encountered during the work schedule can cause mental changes and an emotional imbalance.

Non-native Microstegium vimineum populations collapse with fungal leaf spot disease outbreak

Non-native plants may meet little resistance in the novel range if they leave their biological enemies at home. As a result, species invasion can be rapid and appear unlimited. However, with time, organisms may acquire novel enemies in the novel range, or home-range enemies also may colonize the novel range. For plants, several authors have suggested that enemy release may give way to enemy acquisition in which pathogens accumulate and suppresses non-native plants. The ‘naturalization’ that occurs with acquired enemies may take decades to develop, yet most species invasion research lasts less than 4 years, and data tracking plant invasion before and after the appearance of pathogens are rare. Microstegium vimineum is an Asian grass that has invaded deciduous forest habitats in the southern Midwestern and Southeastern USA and is currently expanding in the Northeastern USA. We recorded widespread expansions in M. populations in North Carolina and Georgia (USA) between 2009 and 2011 but noticed that a fungal pathogen (indicated by leaf lesions; Bipolaris sp.) appeared on several of the populations in 2011. In 2019, we re-sampled these populations to determine whether the appearance of the fungal pathogen corresponded with a suppression of M. vimineum expansion. We found the once-expanding M. vimineum populations in retreat in 2019, and the plant population contractions were greater (and seed production lesser) where the fungal leaf spot disease was most extensive. These results suggest that enemy acquisition suppressed an active non-native plant invasion. We also found that where M. vimineum populations declined (or disappeared) native plants appeared to fill in the gap. Hence, whereby exotic species may gain advantage in novel habitat with the loss of their native-range pathogens, with longer time spans, enemy release may give way to enemy acquisition and native populations may recover if they are immune to the pathogens.

Paraleyrodes minei Iaccarino (Hemiptera: Aleyrodidae)- a new invasive pest threat to Andaman and Nicobar Islands, India

An invasive whitefly, Paraleyrodes minei Iaccarino is newly recorded from the Andaman and Nicobar Islands, India, and found infesting Callophylum inophyllum, Morinda citrifolia and Psidium guajava. The plant family Calophyllaceae is recorded as new host for P. minei. The puparial and adults identification characteristics and pest impact of Paraleyrodes minei in India are discussed. Biological information and natural enemies so far recorded are provided.

Chemical Defence of a Seagrass against Microfoulers and Its Seasonal Dynamics

In marine environments bacterial microfoulers are an important determinant for the settlement of algal and animal macrofoulers. At the same time fouling is usually subject to seasonal fluctuation. Additionally, the seagrass Zostera marina is prone to microfouling, although this marine spermatophyte is known to be chemically defended against bacterial settlers. Spermatophytes are often capable of induced or activated defences against biological enemies such as pathogens or herbivores, but it is still unknown whether they can fine-tune their antifouling-defence according to settlement pressure. We therefore assessed the seasonality of bacterial settlement pressure, defence against microsettlers and concentrations of a previously identified defence compound, rosmarinic acid, on surfaces of Z. marina. All examined variables peaked in summer, while they tended to be lower in spring and autumn. The seasonality of defence activity and rosmarinic acid surface concentration was positively correlated with the seasonal fluctuation of fouling pressure, which suggests that Z. marina can adjust its defence level to the relatively high bacterial fouling pressure in summer. Besides of biotic factors the seasonal change of environmental factors, such as nitrogen supply, and in particular temperature, also affected the defence level, either directly or through indirect effects on the microbial settlers.

Interplay between fungicides and parasites: Tebuconazole, but not copper, suppresses infection in a Daphnia-Metschnikowia experimental model.

Natural populations are commonly exposed to complex stress scenarios, including anthropogenic contamination and their biological enemies (e.g., parasites). The study of the pollutant-parasite interplay is especially important, given the need for adequate regulations to promote improved ecosystem protection. In this study, a host-parasite model system (Daphnia spp. and the microparasitic yeast Metschnikowia bicuspidata) was used to explore the reciprocal effects of contamination by common agrochemical fungicides (copper sulphate and tebuconazole) and parasite challenge. We conducted 21-day life history experiments with two host clones exposed to copper (0.00, 25.0, 28.8 and 33.1 μg L-1) or tebuconazole (0.00, 154, 192 and 240 μg L-1), in the absence or presence of the parasite. For each contaminant, the experimental design consisted of 2 Daphnia clones × 4 contaminant concentrations × 2 parasite treatments × 20 replicates = 320 experimental units. Copper and tebuconazole decreased Daphnia survival or reproduction, respectively, whilst the parasite strongly reduced host survival. Most importantly, while copper and parasite effects were mostly independent, tebuconazole suppressed infection. In a follow-up experiment, we tested the effect of a lower range of tebuconazole concentrations (0.00, 6.25, 12.5, 25.0, 50.0 and 100 μg L-1) crossed with increasing parasite challenge (2 Daphnia clones × 6 contaminant concentrations × 2 parasite levels × 20 replicates = 480 experimental units). Suppression of infection was confirmed at environmentally relevant concentrations (> 6.25 μg L-1), irrespective of the numbers of parasite challenge. The ecological consequences of such a suppression of infection include interferences in host population dynamics and diversity, as well as community structure and energy flow across the food web, which could upscale to ecosystem level given the important role of parasites.

Increased potential for wound activated production of Prostaglandin E2 and related toxic compounds in non-native populations of Gracilaria vermiculophylla

The capacity of the East Asian seaweed Gracilaria vermiculophylla (“Ogonori”) for production of prostaglandin E2 from arachidonic acid occasionally causes food poisoning after ingestion. During the last two decades the alga has been introduced to Europe and North America. Non-native populations have been shown to be generally less palatable to marine herbivores than native populations. We hypothesized that the difference in palatability among populations could be due to differences in the algal content of prostaglandins. We therefore compared the capacity for wound-activated production of prostaglandins and other eicosatetraenoid oxylipins among five native populations in East Asia and seven non-native populations in Europe and NW Mexico, using a targeted metabolomics approach. In two independent experiments non-native populations exhibited a significant tendency to produce more eicosatetraenoids than native populations after acclimation to identical conditions and subsequent artificial wounding. Fourteen out of 15 eicosatetraenoids that were detected in experiment I and all 19 eicosatetraenoids that were detected in experiment II reached higher mean concentrations in non-native than in native specimens. Wounding of non-native specimens resulted on average in 390% more 15-keto-PGE2, in 90% more PGE2, in 37% more PGA2 and in 96% more 7,8-di-hydroxy-eicosatetraenoic acid than wounding of native specimens. Not only PGE2, but also PGA2 and dihydroxylated eicosatetraenoic acid are known to deter various biological enemies of G. vermiculophylla that cause tissue or cell wounding, and in the present study the latter two compounds also repelled the mesograzer Littorina brevicula. Non-native populations of G. vermiculophylla are thus more defended against herbivory than native populations. This increased capacity for activated chemical defense may have contributed to their invasion success and at the same time it poses an elevated risk for human food safety.

Population genetic structure of sexual and parthenogenetic damselflies inferred from mitochondrial and nuclear markers.

It has been postulated that obligate asexual lineages may persist in the long term if they escape from negative interactions with either sexual lineages or biological enemies; and thus, parthenogenetic populations will be more likely to occur in places that are difficult for sexuals to colonize, or those in which biological interactions are rare, such as islands or island-like habitats. Ischnura hastata is the only known example of natural parthenogenesis within the insect order Odonata, and it represents also a typical example of geographic parthenogenesis, as sexual populations are widely distributed in North America, whereas parthenogenetic populations of this species have only been found at the Azores archipelago. In order to gain insight in the origin and distribution of parthenogenetic I. hastata lineages, we have used microsatellites, mitochondrial and nuclear DNA sequence data, to examine the population genetic structure of this species over a wide geographic area. Our results suggest that sexual populations of I. hastata in North America conform to a large subdivided population that has gone through a recent spatial expansion. A recent single long distance dispersal event, followed by a demographic expansion, is the most parsimonious hypothesis explaining the origin of the parthenogenetic population of this species in the Azores islands.

Multispecies interactions among a plant parasite, a pollinator and a seed predator affect the reproductive output of an invasive plant, Cytisus scoparius

AbstractInteractions between species pairs are almost always mediated by interactions with other species. The outcomes of these multispecies interactions are often difficult to predict and are rarely studied. In addition to their theoretical importance, multispecies interactions are also important for management situations. Where multiple agents are used to control invasive species, interactions between agents may either enhance or reduce the impacts on the target species, or may simply have additive effects. In this study, conducted in a Mediterranean‐type woodland in Australia, we examined how the interaction between an invasive legume, Cytisus scoparius (Leguminosae), its pollinator, Apis mellifera and a seed predator, Bruchidius villosus (Bruchidae), are modified by a native hemiparasitic vine, Cassytha pubescens (Loranthaceae). The parasite had a direct negative effect on C. scoparius, reducing flowering by 50% and consequently fruit and seed production. Despite having fewer flowers, infected plants had the same proportion of ‘tripped’ flowers, an indirect measure of pollinator visitation, as uninfected plants; although fruit formed on infected plants it was more likely to abort prematurely. Seed predation by B. villosus was lower on parasite‐infected C. scoparius plants than in uninfected plants. Although Ca. pubescens had an antagonistic effect on B. villosus, in consort, the two agents reduced overall seed production by an average of 62%. The acquired parasite Ca. pubescens was more effective in reducing reproductive output than the introduced seed predator, B. villosus, and shows potential as a biocontrol agent for C. scoparius. We documented a subadditive effect of two biological enemies on the invasive species, where the acquired parasite had a stronger effect than the introduced seed predator.

Detection of genotoxicants in Brassicales using endogenous DNA as a surrogate target and adducts determined by 32P-postlabelling as an experimental end point

Some plants use electrophilic metabolites as a defence against biological enemies. Some of them may react with DNA. We devised a new model to test this hypothesis. Plant tissue was homogenised. After incubation of the homogenate at 37°C for varying periods, the plant DNA was analysed for the presence of adducts using the (32)P-postlabelling technique. Adducts were detected with all Brassicales studied. Broccoli was investigated in detail. Adducts were absent in DNA isolated immediately after homogenisation of the plant. Subsequently, five characteristic adduct spots were formed in the homogenate, the maximum being reached after nearly 4 h. Adduct formation was low when broccoli was steamed before homogenisation, but was re-established when myrosinase was added to the homogenate, indicating that the active constituents were glucosinolates. Broccoli juice was mutagenic to Salmonella typhimurium, forming the same adduct spots in these target cells as in plant homogenate, but the relative intensity of the individual spots varied between both models. The patterns of adduct spots formed in homogenates of 15 other Brassicales species and tissues were similar to those detected with broccoli florets heads. However, the relative intensities of the spots varied. Sporadically, some spots were missing or additional spots appeared. These results, therefore, suggest that several different glucosinolates contribute to the adduct formation.