The fate, distribution and biological performance of insecticide residues in vegetable crops following seedling treatment

Carrot, cauliflower and radish seedlings raised in sand culture and treated with aqueous suspensions containing chlorfenvinphos, diazinon, iodofenphos or triazophos were planted into the field in 1982 and 1983 to compare the performance against cabbage root fly and carrot fly of these treatments with that of bow-wave applications of granular formulations at sowing. Initial residue concentrations were up to 4100 mg kg^-1 in the seedlings at planting. Thereafter the amounts of insecticides per root system declined. Residue concentrations in mature carrot and radish roots were smaller when plants had been treated as seedlings rather than by bow-wave application. Chlorfenvinphos was the most effective insecticide against both pests. Amounts of insecticide applied in transplanted seedlings were < 5% of the amounts applied by the bow-wave method but short-term control of cabbage root fly on radish was similar. Carrot fly damage was reduced by 60% by some of the seedling treatments after 16 wk in 1982 but in 1983 they were less effective. Pot experiments with chlorfenvinphos showed that most of the insecticide in the seedlings was transferred rapidly into the surrounding soil and it was concluded that the bioactivity resulted mainly from uniform distribution of the released insecticide between and around individual plants.     

A method of using the proportions of undamaged carrots or parsnips to estimate the relative population densities of carrot fly (Psila rosae) larvae, and its practical applications

The plant-to-plant distribution of carrot fly damage was studied on carrots and parsnips in field and microplot experiments. The observed data were well-fitted by the relationship In (–In q) = In L+ constant, where q is the proportion of undamaged roots and L is the number of larval mines in a sample and is proportional to the number of associated larvae, N. Hence, if N₁ and N₂ are the numbers of larvae at two levels of infestation on one occasion, the relative numbers present, N₂:N₁ are estimated by In q₂: In q₁ In this way the relative efficiencies of insecticide treatments can be determined within an experiment from only q₁ and q₂ and compared between occasions. A nomogram relating q₁, q₂ and treatment efficiency is provided. The method can also probably be used to compare the relative susceptibilities of host-plant cultivars to carrot fly attack. Guidance is given on the sample sizes needed to estimate q within 95% confidence limits and constraints on the application of the method are stated. An appropriate statistical procedure for analysing data sets on carrot fly infestations is by analysis of deviance and an example is given in an Appendix. The principles described can probably be adapted to other crop/pest problems.     

The protection of carrots against carrot fly (Psila rosae) with granular and emulsifiable concentrate formulations of chlorfenvinphos incorporated in gels used for drilling pre germinated seed in a sandy loam

Field experiments were done in a sandy loam in 1979 and 1980 to investigate the performance against carrot fly on carrots of e. c. and granular formulations of chlorfenvinphos incorporated in gels used for drilling pre-germinated seed. With 9·4–66·7 mg a. i./m row, the two formulations performed similarly in a natural hydrocolloid and a mineral colloid gel. Thus the emergence of carrot seedlings 6–7 wk after drilling was similar on plots with untreated gel and those with insecticide-treated gel and, about 6 months after drilling when > 90% of carrots grown without insecticide were damaged by carrot fly larvae, an approximately six-fold increase in dose of both formulations increased the estimated larval mortality from about 70 to 95%. Mean concentrations of residues of total (Z + E) isomers of chlorfenvinphos in harvested carrots treated with 9·4–56·5 mg a. i./m row were50% of the insecticide had been released into both gels.     

Integrating flood depth and plant resistance with chlorantraniliprole seed treatments for management of rice water weevil,Lissorhoptrus oryzophilus (Coleoptera: Curculionidae)

Chlorantraniliprole seed treatments in rice provide effective suppression of rice water weevil populations in the United States; however, heavy reliance on prophylactic insecticide treatments as a sole strategy could destabilize management programs for this insect. The present research evaluated the compatibility of seed treatments with two other potential management tactics—plant resistance and shallow flooding–by conducting two split‐plot experiments in 2009 and 2011. In both experiments, no substantial antagonism was found among the 3 different tactics. Statistical interactions in these experiments arose from the strong and persistent effects of chlorantraniliprole on larval densities rather than incompatibility of tactics. In 2009, weevil densities differed among varieties and were significantly lower on the cultivar “Jefferson.” In 2011, weevil densities were reduced significantly in shallow‐flooded plots compared to deep‐flooded plots. Significant reductions in weevil numbers by chlorantraniliprole seed treatments, even at application rates 5 fold lower than commercially recommended rates, demonstrated the potential to reduce application rates of this highly potent larvicide. These latter results suggest that future studies on the relationship between chlorantraniliprole seed treatment rate and weevil fitness are warranted.     

Consumption of residue containing cucurbitacin feeding stimulant and reduced rates of carbaryl insecticide by western corn rootworm (Coleoptera: Chrysomelidae).

Application of insecticide at a reduced rate with a cucurbitacin-based feeding stimulant is a viable alternative to a broadcast insecticide application for control of adult western corn rootworms, Diabrotica virgifera virgifera, LeConte. Because of the small amount of material applied, it is conceivable that a high density of beetles could consume all of the spray residue before economic control is achieved. A laboratory experiment was conducted to determine the amount of cucurbitacin-based spray residue consumed by beetles. Dried residue of four treatments were exposed to three groups of 10 rootworm beetles for 1 h each. Treatments consisted of a cucurbitacin-based adjuvant (Cidetrak CRW, Trécé, Salinas, CA) with carbaryl insecticide (Sevin XLR Plus, Rhone Poulenc, Research Triangle Park, NC) mixed at 0, 0.12, 1.2, and 12 g (AI)/liter. For the treatment with cucurbitacin adjuvant only (no insecticide), beetles consumed 0.029 mg beetle(-1) h(-1) of exposure. Approximately 54% of the beetles were recorded as feeding at any given time during the 60-min feeding period. However, when the spray residue contained carbaryl, no weight loss of treatment residue was measured, though the beetles were observed to feed from the residue during the first few minutes of exposure. When residue included insecticide, beetles quickly ceased feeding (within 20 min), and toxicity behavior was observed 30 min after initial exposure for up to 75% of the beetles, which were classified as moribund (unable to stand upright). Beetle mortality was recorded 24 h after exposure and demonstrated that male beetles (53% dead for three insecticide treatments) were more susceptible to carbaryl toxicity than female beetles (28% dead for three insecticide treatments). Regression analysis showed a significant positive relationship between mortality of female beetles and ovarian development. Based on the measurements of this experiment, it is unlikely that realistic beetle densities would consume enough spray residue to prevent economic control of the beetle population.     

Arabinogalactan-protein epitopes in somatic embryogenesis of Daucus carota L.

Two monoclonal antibodies (ZUM 15 and ZUM 18) directed against carrot (Daucus carota L.) seed arabinogalactan proteins (AGPs) were used to isolate specific AGP fractions. For both carrot and tomato (Lycopersicon esculentum Mill.) seed AGPs analyzed by crossedelectrophoresis, the ZUM 15 and ZUM 18 AGP fractions showed one identical peak. However, the Rf values for the two species were different: 0.82 for carrot seed AGPs and 0.52 for tomato seed AGPs. When the fractionated AGPs (carrot or tomato) were added to carrot cell lines they had a dramatic effect on the culture. One AGP fraction (ZUM 15 AGPs) was able to induce vacuolation of embryogenic cells. Those cells failed to produce embryos. The other AGP fraction (ZUM 18 AGPs) increased the percentage of embryognic cells from about 40% up to 80% within one week and this subsequently resulted in the formation of more embryos on hormone-free medium. This activity was higher than that of unfractionated carrot seed AGPs, while the optimum concentration was 50-fold lower. Since both ZUM 18 AGPs (carrot or tomato) yielded identical responses it can be concluded that neither the Rf value nor the source are essential for biological activity. The dose-response curve of ZUM 18 AGPs showed a sharp optimum. When the AGPs that also bound to the antibody ZUM 15 were removed, the dose-response curve of the remaining AGPs (containing only the ZUM 18 epitope, not the ZUM 15 epitope) resembled a saturation curve. Regardless of its concentration, the fraction in which AGP molecules contained both epitopes showed no appreciable embryogenesis-promoting activity. The biological activity of AGPs was therefore determined by the presence of embryogenesis-enhancing and-inhibiting epitopes. The inhibiting and enhancing epitopes can be located on separate molecules or one single AGP molecule.     

Non-pesticide alternatives for reducing feeding damage caused by the large pine weevil (Hylobius abietis L.)

The large pine weevil (Hylobius abietis L.) is an important pest of young forest stands in Europe. Larvae develop under the bark of freshly cut pine and spruce stumps, but maturing weevils feed on the bark of coniferous seedlings. Such seedlings frequently die because of bark consumption near the root collar. We tested the effect of three treatments (the insecticide alpha cypermethrin, a wax coating and a glue coating) on the feeding damage caused by H. abietis on Douglas fir (Pseudotsuga menziesii) and Norway spruce (Picea abies) seedlings under semi-natural conditions. In two experiments (one in 2016 and another in 2017) seedlings in cages were subjected to pine weevil feeding for 16 weeks under shaded outdoor conditions. The experiment in 2016 compared insecticide and wax treatments and an untreated control on Douglas fir and Norway spruce, and the experiment in 2017 compared insecticide, wax and glue treatments and an untreated control on Norway spruce. In both experiments, all treatments significantly reduced H. abietis feeding damage at week 8 at the end of both experiments (week 16); the effect of treatments was significant only on spruce seedlings. The damages on Douglas fir seedlings was less on treated seedlings than on untreated control seedlings but differences were not significant. Coating stems with glue and especially with wax was generally effective at reducing weevil damage and in most cases provided control that was not significantly different from that provided by insecticide treatment. Our results suggest that a wax coating has the potential to replace the protection of seedlings provided by insecticides.     

Effect of neonicotinoid synergists on entomopathogenic nematode fitness

In previous greenhouse and field studies, the neonicotinoid insecticide imidacloprid interacted synergistically with five entomopathogenic nematode species against five scarab species. Two other neonicotinoids, thiamethoxam and acetamiprid, showed a weaker interaction with nematodes in scarab larvae. Entomopathogenic nematodes have the potential to recycle in hosts after inundative applications, thereby increasing the persistence of nematodes and insect control. Thus we investigated the effect of neonicotinoids on nematode fitness after tank mixing and after combined applications. Tank mixing only had a negative effect on nematode survival and infectivity in a few nematode–insecticide combinations and only if both insecticide concentration and exposure time were several times higher than typical for field applications. Combined application of nematodes with imidacloprid generally had no negative effect on the percentage of scarab cadavers producing progeny or the number of nematode progeny emerging per cadaver. In experiments with a synergistic increase in scarab mortality, the total number of progeny in combination treatments was up to four times higher than in nematodes only treatments. Similarly, nematode populations in soil from combination treatments were 13.2 times greater than for nematodes only treatments at 28 days after treatment. Combined imidacloprid–nematode applications did not affect the pathogenicity or infectivity of the nematode progeny. Combining thiamethoxam with nematodes had no negative effects on nematode reproduction in the majority of treatments. However, due to the weaker interaction of thiamethoxam and nematodes on scarab mortality, the total number of nematode progeny per treatment generally did not increase compared with nematodes only treatments. The demonstrated tank mix compatibility of imidacloprid and nematodes improves the feasibility of combining these agents for curative white grub control. The positive effect of imidacloprid on nematode reproduction after combined application may increase the likelihood of infection of white grubs by subsequent generations of nematodes, thereby improving their field persistence and biological control potential.     

Assimilation efficiencies of slugs on different food materials

Summary The relative assimilation efficiencies of two common British species of slug, Limax flavus (L.) and Arion hortensis (Fér.), were studied in the laboratory using a gravimetric method. Results are given for adult slugs feeding on carrot root and potato tuber at 5°, 10°, 15°, and 20° C, and for L. flavus juveniles of known age feeding on potato at 10° and 15° C. A few results are also provided for Agriolimax reticulatus (Müller) feeding on both potato and carrot at 15° C.High mean assimilation efficiencies of 76.94 and 76.87% were obtained for L. flavus feeding on carrot and potato respectively. The equivalent results for A. hortensis were 88.60 and 89.42%. For A. reticulatus at 15° C the figures were 76.1 and 71.9%. Ingestion rates and assimilation rates are given for the first two species at all temperatures. Assimilation efficiency was found to be independent of temperature for L. flavus but not for A. hortensis. Ingestion rate and assimilation rate were temperature dependent in all cases except for A. hortensis feeding on potato. A. hortensis was more efficient at consuming both carrot and potato per gram live weight. All species consumed more potato than carrot per gram live weight.Juvenile L. flavus were found to have higher assimilation efficiencies and ingestion rates than the adults per gram live weight.Linear regression equations were determined from the relationship between dry weight of food consumed, and dry weight of faeces produced from that food for L. flavus.It is concluded that food quality and age of slug may be the factors most strongly influencing assimilation efficiency in this group.     

The Influence of the Arrangement of Neighbours on the Spatial Component of Resource Capture by an Individual Plant in Even-aged Monocultures

Data from experiments using extensive row-spacing treatments(Benjamin and Sutherland, 1992) were analysed to indicate thatmorphological responses to micro-spatial heterogeneity in resourcelevel are important in determining the growth response of field-growncarrot plants to the spatial distribution of neighbours. Thisinformation is important for the simulation of the growth ofindividual plants in response to the presence of neighbours.Copyright1993, 1999 Academic Press Crop yield, plant weight, plant density, plant spacing, plant arrangement, row crop, carrot, Daucus carota L., mathematical model, neighbourhood     

Modification by cis-diamminedichloroplatinum (II) of the radiation dose-response curve for intestinal crypt cells in mice

The effect of cis-diamminedichloroplatinum (II) (c-DDP) on the shape of the radiation dose-response curve for mouse duodenal crypt cells was investigated. A priming X-ray dose was followed 18 h later by graded test doses (single doses or five equal fractions at 3-h intervals) with or without c-DDP. Curves were fitted by a linear quadratic (LQ) relationship. The drug modified the dose-response curve by enhancing both the alpha and the beta terms. Repair kinetics were analyzed in split-dose experiments. c-DDP caused a minor, nonsignificant decrease in the rate of repair after irradiation. The survival ratio after split-dose irradiation, when the same X-ray doses were given, was actually slightly increased by the drug. This paradoxical effect can be explained by the fact that c-DDP mainly increased the beta term in the LQ relationship. There was no significant increase in crypt cell survival when split-drug doses were given alone at increasing intervals, suggesting no cellular repair after c-DDP treatment. The data are discussed in the light of the recently proposed "lethal and potentially lethal" (LPL) unified repair model of Curtis.     

小菜蛾对杀虫剂的敏感性与其抗药性的相关性

在开展云南省通海县小菜蛾Plutella xylostella(L.)种群对11种杀虫剂的敏感性的同时,对小菜蛾抗药性进行了测定,并分析二者之间的相关性,结果表明:小菜蛾对杀虫剂的敏感性与其抗药性总体上呈现负相关,即随着抗药性的增加,小菜蛾对杀虫剂的敏感性呈下降趋势,但相关性并不显著。如在无抗性至高抗性的杀虫剂之间,其敏感性并无明显的变化,处理间无差异,只有对其极高抗性的阿维菌素、虫酰肼和高效氯氰菊酯才表现出明显的下降趋势。因此,在实际生产过程中,一种药剂是否因抗药性增加而不能使用,还应该参照田间防治效果。     

Effects of the mixture of avermectin and imidacloprid on mortality and developmental stability of Copera annulata (Odonata: Zygoptera) larvae

The present study explored the effects of mixture of avermectin and imidacloprid on the level of fluctuating asymmetry (FA) and mortality of Copera annulata larvae. The results showed that the mortality of larval damselflies treated with different concentrations of insecticide did not differ significantly. However, we found that the levels of FA of two traits were significantly different with different treatments but the others did not show any differences. Explicitly, FA of two traits increased with increasing pesticide concentration. There was a significantly negative relationship between first femur length and the absolute difference between its right and left sides. There was no relationship with respect to the absolute difference between the right and left sides of all traits and their body size. FA was not associated with mortality. Our results emphasized that insecticide had potential effects on bilaterally symmetrical traits of damselfly larvae, although they were no longer treated with insecticide during the last rearing.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 44–50.     

Determining the optimal timing of foliar insecticide applications for control of soybean aphid (Hemiptera: Aphididae) on soybean

Field experiments were performed over 3 yr to examine the impact of insecticide application timing to control soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), populations and to prevent soybean yield losses. Experiments were conducted in early and late-planted soybean, Glycine max (L.) Merr. Insecticide applications were made based on soybean growth stages. In 2001, applications were made at V1, V3, R2, and R3 growth stages; in 2002 and 2003, applications were made at R2, R3, and R4 stages. Additional treatments consisted of an unsprayed control and a multiple spray treatment that received insecticide applications at 7-10-d intervals. Soybean aphid densities were recorded throughout the growing season, and yields were measured. Soybean aphid populations varied considerably across years and planting dates. In general, late-planted soybean exhibited higher aphid pressure than early planted soybean, and experiments in 2002 had lower aphid numbers than those in 2001 and 2003. The multiple spray treatment significantly increased yield over the control in four of the six experiments, the exceptions being 2002 late planted and 2003 early planted. This suggests that soybean aphid populations were not large enough to cause yield losses in these two experiments. The R3 spray treatment increased yield in three of the six experiments (2001 late planting, 2002 early planting, and 2003 late planting), the R2 spray treatment increased yield in two of six experiments (2001 and 2003 late plantings), and the V1 application increased yield over the control in the 2001 late-planted experiment. Results suggest that when aphid populations are high insecticide applications made at R2 and R3 plant stages are most effective in preventing yield loss.     

A review of the dose-response induction of DNA adducts by aflatoxin B1 and its implications to quantitative cancer-risk assessment

The induction of DNA adducts by aflatoxin B₁ in the liver has been extensively reviewed in a quantitative cancer-risk assessment of aflatoxins (CDHS, 1990). Rat is the most sensitive species for aflatoxin tumorigenesis and liver is the most sensitive site. In vitro DNA-adduct studies were mostly on adduct identification and specificity of binding. In vivo studies provided dose-response relationship of aflatoxin B₁, binding to DNA and DNA-adduct formation. Most in vivo studies were conducted in rats. The dose-response curves of DNA-adduct induction after ingestion or injection treatments in this species were reviewed. A linear dose-response relationship was observed in both injection and ingestion studies at low doses. For cancer-risk assessment, this observation is consistent with the assumption of the linear dose-response risk-assessment model for genotoxic agents, and justifies the use of this model for quantitative cancer-risk assessment for aflatoxins.     

Effects of autumn kaolin and pyrethrin treatments on the spring population of Dysaphis plantaginea in apple orchards

The impact of treatments with the pyrethrin insecticide Pyrethrum FS and the repellent kaolin product Surround^® WP to control the autumn forms of Dysaphis plantaginea Pass. (Hom., Aphididae), a major insect pest of apple, was assessed in 1‐year field experiments in Switzerland. Single and multiple applications of pyrethrin and kaolin were tested at different dates after apple harvesting in autumn 2002 when sexuales of the rosy apple aphid were present. Repeated applications of Surround^® WP in autumn significantly reduced the number of females in autumn and, consequently, the number of hatched fundatrices in spring. Single kaolin treatments were less effective. Unexpectedly, neither single nor multiple applications of the contact insecticide Pyrethrum FS had a knock‐down effect on females in autumn. However, pyrethrin significantly reduced the number of hatched fundatrices in spring. Neither pesticide completely controlled the rosy apple aphid but with a more detailed analysis of factors influencing the efficacy of autumn treatments a new approach to control this serious pest could be achieved.     

Reduction of the nocturnal rise in pineal melatonin levels in rats exposed to 60-Hz electric fields in utero and for 23 days after birth

Rats exposed to 60-Hz electric fields of either 10, 65, or 130 kV/m from conception to 23 days of age exhibited reduced peak nighttime pineal melatonin contents compared to unexposed controls. As a group, the exposed rats also exhibited a phase delay, estimated at approximately 1.4 hours, in the occurrence of the nocturnal melatonin peak. No clear dose-response relationship was noticed over the range of electric field strengths used as treatments in these experiments. These are the first studies concerned with the effects of electric field exposure on the pineal melatonin rhythm in immature rats. The findings are generally consistent with those obtained using adult rats, where electric field exposure has been shown to abolish the nighttime rhythm in pineal melatonin concentrations.     

Evaluation of entomopathogenic nematodes for suppression of carrot weevil

The potential of entomopathogenic nematodes as biologicalcontrol agents for carrot weevil (Listronotus oregonensis) was evaluated throughboth laboratory and field experiments. In thelaboratory, Steinernema carpocapsae, S. riobrave, S. feltiae, Heterorhabditis megidis, H. bacteriophora, and a control (water only) werecompared in sand and muck soil against adults,and in sand against larvae. All nematodespecies produced high levels of larvalmortality. S. carpocapsae producedsignificantly greater adult mortality in sandthan other species or the untreated control. H. bacteriophora caused low adultmortality in sand, but the greatest adultmortality among treatments in a similar testthat used muck soil; S. carpocapsae wasranked second on muck soil. Other speciesconsistently produced intermediate (H.megidis and S. riobrave) or low (S.feltiae) levels of mortality on bothsubstrates. In the field, we compared theeffect of early season vs. late seasonapplications of H. bacteriophora or S. carpocapsae on carrot weevil mortality andparsley survival and yield. Significantdifferences among treatments in plant survivaland yield were not found; however treatmentsinvolving H. bacteriophora had higherplant survival than other treatments. Earlierapplication of this species was associated withhigher plant survival. S. carpocapsaetreatments had similar plant survival to thecontrol. Mortality of larvae and combinedstages of carrot weevil was significantlygreater at 1 week following H.bacteriophora application than for othertreatments. H. bacteriophora also showedgreater persistence than S. carpocapsaein treated plots. We conclude that H.bacteriophora is a good candidate for furtherevaluation as a biological control agentagainst carrot weevil on muck soils in theGreat Lakes region.     

The potential of reflective mulching in combination with insecticide sprays for control of aphid-borne viruses of iris and tulip in Tasmania

Silver coloured plastic mulches and weekly insecticide sprays were examined individually and in combination for efficacy in reducing spread of tulip breaking potyvirus (TBV) in tulip, and these plus mineral oil treatments, alone and in combination with insecticide and mulch, were evaluated for their effect on iris mild mosaic potyvirus (IMMV) spread in bulbous iris. In the iris trial, significant reductions in virus spread were noted for all treatments, with the combined treatment of mulch and insecticide giving the best virus control. However, with little virus spread there were no significant treatment effects on TBV spread in tulips. Reduced numbers of aphid vectors were trapped over unsprayed mulched than non-mulched plots. Mulch treatments had no effect on stem length or harvested bulb weight while the insecticide treatment (tulips only) and treatments incorporating mineral oil significantly reduced both stem length and bulb weight. This work suggests that enhanced virus management in flowerbulb production may be achieved by incorporating reflective mulches in current virus control strategies.     

Effect of poultry manure on the growth,yield and root-knot nematode (Meloidogyne spp.) infestation of carrot (Daucus carota L.)

Currently, synthetic pesticides which are highly detrimental to man and the environment are the principal means of nematode control. However, the use of organic amendments might provide a sustainable control option as nematicidal properties have been identified in many animal wastes. A field experiment was carried out to determine the effectiveness of different levels of poultry manure (PM) applications on root-knot nematode infestation of carrot. There were four treatments (0, 2, 4 and 6?t/ha of PM) laid out in a randomised complete block design with four replications. The various levels of PM were worked into the soil on raised beds before carrot seeds were sown. Data were taken on growth performance (plant height, number of leaves and canopy spread), yield characteristics (root weight, root length and root girth) and infestation (root-galling index and nematode population in the soil). PM significantly reduced both root galling and nematode population with 4?t/ha significantly increasing yield characters of carrot. Since PM significantly reduced (p?<?0.05) nematode infestation and promoted growth and yield of carrot, farmers are encouraged to use it preferably at 4?t/ha.