Béla Darvas

Cry1Ab toxin production of MON 810 transgenic maize

Levels of Cry1Ab toxin were detected in genetically modified maize of genetic event MON 810 against near isogenic maize as negative control by two commercial immunoassays. The immunoassays were characterized for their cross-reactivity (CR) between Cry1Ab protoxin and activated toxin, and were compared with each other for toxin detection in a reference plant sample. Cry1Ab toxin levels, corrected for active toxin content using the CR values obtained, were monitored in maize DK-440 BTY through the entire vegetation period. The toxin concentration was found to show a rapid rise in the leaves to 17.15 +/- 1.66 microg/g by the end of the fifth week of cultivation, followed by a gradual decline to 9.61 +/- 2.07 microg/g by the 16th week and a slight increase again to 13.51 +/- 1.96 microg/g during the last 2 weeks due to partial desiccation. Similar but lesser fluctuation of toxin levels was seen in the roots between 5.32 +/- 0.49 microg/g at the less differentiated V1 stage and 2.25 +/- 0.30 microg/g during plant development. In contrast, Cry1Ab toxin levels appeared to be stably 1.36 +/- 0.45, 4.98 +/- 0.31, 0.47 +/- 0.03, and 0.83 +/- 0.15 microg/g in the stem, anther wall, pollen, and grain, respectively. Toxin concentrations produced at the VT-R4 phenological stages under actual cultivation conditions were compared with each other in three different years within an 8-year period.

Forty Years with Glyphosate

Indeed, the two boasted pesticides show certain similarities in their history of discovery and fate. Both were synthesised first several decades prior to the discovery of their pesticide action. DDT and glyphosate were first described as chemical compounds 65 and 21 years before their discovery as pesticides, respectively. Both fulfilled extensive market need, therefore, both burst into mass application right after the discovery of their insecticide/herbicide activity. They both were, to some extent, connected to wars: a great part of the use of DDT was (and remains to be) hygienic, particularly after Word War II, but also the Vietnam War; while glyphosate plays an eminent role in the “drug war” (Plan Colombia) as a defoliant of marijuana fields in Mexico and South America. And last, not least, ecologically unfavourable characteristics of both was applauded as advantageous: the persistence of DDT had been seen initially as a benefit of long lasting activity, and the zwitterionic structure and consequent outstanding water solubility of glyphosate, unusual among pesticides, also used to be praised, before the environmental or ecotoxicological disadvantages of these characteristics were understood.

Monitoring Pesticide Residues in Surface and Ground Water in Hungary: Surveys in 1990–2015

Over 2000 surface, ground and raw drinking water samples have been analyzed in the frame of different monitoring projects in Hungary and watercourses in neighboring countries between 1990 and 2015. Effects of pesticide contamination on ecological farming and drinking water supply have been assessed. Main water pollutant ingredients of agricultural origin in Hungary are herbicides related to maize production. After EU pesticide re-registration, diazinon, atrazine, and trifluralin gradually disappeared as contaminants. High levels of water soluble pollutants (e.g., acetochlor) in surface water result in temporarily enhanced levels in raw drinking water as well. Extreme levels observed for herbicide residues were of agrochemical industrial origin.

Comparative aspects of cry toxin usage in insect control

Crystalline (Cry) endotoxins from Bacillus thuringiensis (Bt) and related toxins are currently being used as active ingredients of bacterial insecticides and as expressed proteins in genetically modified plants. While both approaches take advantage of the specificity of Cry toxins against various insect orders, there are characteristic differences between these technologies in (i) form of application; (ii) compatibility with agrotechnologies; (iii) composition of the active ingredients; and (iv) their environmental fate. The technical advantage of Bt plants is that they eliminate labor- and energy-demanding field applications of insecticides against insect pests manageable with Cry toxins. In turn, however, Bt plants continuously produce Cry toxin during vegetation. As a result, these Bt plants do not comply with the principle of integrated pest management, as Cry toxin administration cannot be limited to the duration of the occurrence of the insect pest targeted. Bt insecticides and Bt plants may also differ in their active ingredients (bacterial protoxins and plant-expressed preactivated toxin), which in addition to pesticide registration issues, has pronounced effects on Cry toxin resistance and environmental persistence in stubble.

Inter-laboratory comparison of Cry1Ab toxin quantification in MON 810 maize by enzyme-immunoassay

Abstract A laboratory ring trial was performed in four laboratories for determination of Cry1Ab toxin in leaf material of MON 810 maize using a standardised enzyme-linked immunoassay protocol. Statistical analysis was carried out by the ISO 5725-2 guidelines, sample standard deviation and standard error, within-laboratory and inter-laboratory SD and SE were calculated. Measured inter-laboratory average values were 12.5±4.0, 15.3±4.6 and 72.6±17.8 µg/g for three lyophilised samples, and 27.8±4.3 µg/g for a frozen sample, yet, Cry1Ab concentrations ranged 66.5–160.1% of the corresponding IA. Determined concentrations by in-house protocols were statistically not different in one laboratory and different in two laboratories from the corresponding values by the joint protocol. Results emphasise the importance of a standardised protocol among laboratories for comparable quantitative Cry1Ab toxin determination. However, even when using a standardised protocol, significant differences still occur among toxin concentrations detected in different laboratories, although with a smaller range of variation.

Relationships of Helicoverpa armigera, Ostrinia nubilalis and Fusarium verticillioides on MON 810 Maize.

MON 810 maize was developed against Ostrinia nubilalis and is suggested to indirectly decrease Fusarium spp. infestation in maize ears. To evaluate this effect, co-occurrence of insect and fungal pests on MON 810 maize was studied. During 2009, exceptionally high maize ear infestation occurred in Julianna-major (Hungary). From investigation of some thousands of maize ears, the majority of the larval damage originated from Helicoverpa armigera larvae, while O. nubilalis larvae contributed significant damage only at a single plot. Fusarium verticillioides infection appeared only in a small portion (∼20–30%) of the insect damaged cobs. H. armigera and O. nubilalis larvae feeding on F. verticillioides mycelia can distribute its conidia with their fecal pellets. MON 810 maize showed 100% efficacy against O. nubilalis in the stem, but lower efficacy against O. nubilalis and H. armigera in maize ears. The ∼Cry1Ab toxin content of maize silk, the entry site of H. armigera, was lower than that in the leaves/stem/husk leaves of MON 810. Fusarium-infected MON 810 cobs are rarely found and only after larval damage by O. nubilalis. H. armigera larvae could not tolerate well F. verticillioides infected food and attempted to move out from the infected cobs. For further feeding they re-entered the maize ears through the 8–12 husk leaves, but in the case of the MON 810 variety, they usually could not reach the kernels. Apical damage on cobs resulted in only a minor (about one-tenth of the cob) decrease in yield.

Effects of the pyrimidine-containing cytochrome P-450 inhibitor, fenarimol, on the formation of 20-OH ecdysone in flies

The effect of fenarimol, a pyrimidine-containing cytochrome P-450 inhibitor, was tested in vitro on brain-ring gland complexes ofCalliphora vicina (Dipt., Calliphoridae), and on microsomes prepared from the fat body of 0-h wandering stage larvae ofNeobellieria bullata (Dipt., Sacrophagidae). Fenarimol had no influence on the formation of ecdysone, but it was an effective inhibitor of cytochrome P-450-dependent ecdysone 20-monooxygenase.

Ecdysone 20-monooxygenase systems in flesh-flies (diptera: sarcophagidae), Neobellieria bullata and Parasarcophaga argyrostoma

Abstract 1. 1. The ecdysone 20-monooxygenase activity is the highest in fat bodies of 0 hr third instar wandering stage flesh-fly larvae. 2. 2. After the white prepuparial stage, activity of ecdysone 20-monooxygenase systems decreases, almost to zero. 3. 3. Microsomal ecdysone 20-monooxygenase activity is maximal at pH 7.2 and 30°C, is dependent on an NADPH-regenerating system and is strongly inhibited by 0.01% Tween 80. 4. 4. Microsomal ecdysone 20-monooxygenase activity exhibits variation in activity during development, with peaks at birth, in the middle of the second instar, and at the beginning of wandering behaviour in the third instar.

Inhibitory effect of an in vivo activated soft analogue of A‐phenyl‐B‐triazolium metyrapone during pupariation in Sarcophaga bullata

Experiments with the ovoviviparous fleshfly Sarcophaga bullata (Parker) (Dipt., Sarcophagidae), showed that the compound 4‐(dodecanoyloxymethyl)‐1‐(2‐methyl‐1‐oxo‐1‐phenyl‐2‐propyl)‐(1,2,4‐triazolium) chloride (NKI‐42002) was an in vivo inhibitor of the cytochrome P‐450‐dependent monooxygenase system (MFO) during pupariation. The hard analogue of A‐phenyl‐B‐triazolium metyrapone and the soft analogue of A‐phenyl‐B‐imidazolium metyrapone showed no specific activity. Our results suggest that the soft quaternary group may help the transport of A‐phenyl‐B‐triazolium metyrapone to the MFO system.

Study on Soil Mobility of Two Neonicotinoid Insecticides

Movement of two neonicotinoid insecticide active ingredients, clothianidin (CLO) and thiamethoxam (TMX), was investigated in different soil types (sand, clay, or loam) and in pumice. Elution profiles were determined to explore differences in binding capacity. Soil characterized by high organic matter content retained the ingredients, whereas high clay content resulted in long release of compounds. Decrease in concentration was strongly influenced by soil types: both CLO and TMX were retained in loam and clay soils and showed ready elution through sandy soil and pumice. Elution capability of the active ingredients in sandy soil correlated with their water solubility, indicating approximately 30% higher rapidity for TMX than for CLO. Soil organic carbon-water partitioning coefficients () determined were in good agreement with literature values with somewhat lower value for CLO in sandy soil and substantially higher values for TMX in clay soil. High mobility of these neonicotinoid active ingredients in given soil types urges stronger precautionary approach taken during their application.