Insect growth regulator effects of azadirachtin and neem oil on survivorship, development and fecundity of Aphis glycines (Homoptera: Aphididae) and its predator, Harmonia axyridis (Coleoptera: Coccinellidae)

BACKGROUND: Aphis glycines Matsumura, an invasive insect pest in North American soybeans, is fed upon by a key biological control agent, Harmonia axyridis Pallas. Although biological control is preferentially relied upon to suppress insect pests in organic agriculture, approved insecticides, such as neem, are periodically utilized to reduce damaging pest populations. The authors evaluated direct spray treatments of two neem formulations, azadirachtin and neem seed oil, under controlled conditions for effects on survivorship, development time and fecundity in A. glycines and H. axyridis. RESULTS: Both azadirachtin and neem seed oil significantly increased aphid nymphal mortality (80 and 77% respectively) while significantly increasing development time of those surviving to adulthood. First-instar H. axyridis survival to adulthood was also significantly reduced by both neem formulations, while only azadirachtin reduced third-instar survivorship. Azadirachtin increased H. axyridis development time to adult when applied to both instars, while neem oil only increased time to adult when applied to first instar. Neither neem formulation affected the fecundity of either insect. CONCLUSIONS: Results are discussed within the context of future laboratory and field studies aimed at clarifying if neem-derived insecticides can be effectively integrated with biological control for soybean aphid management in organic soybeans.     

Effect of buprofezin on adult life span,oviposition, egg hatch and progeny production of the cotton whitefly,Bemisia Tabaci

The 50% survival ofBemisia tabaci Genn. females was reduced to 5.9 days by exposure to bean seedlings treated with 1000 ppm buprofezinvs 8.9 days in the control. At lower concentrations ranging from 50 to 500 ppm, survival was extended to 11.8–14.2 days. Mean fecundity was significantly reduced on plants treated with 1000 ppm as compared with the control, whereas at 50 to 500 ppm the oviposition period was extended with a considerable increase in mean fecundity, irrespective of concentrations. Overall mean percent hatch dropped gradually from 25.8 to 12.9 with increase of concentration from 50 to 1000 ppm, as against 96.9% in the control. The survival of hatched nymphs was greatly affected at all buprofezin concentrations. No immature stages survived at 50, 100, 250 and 500 ppm; nymphal survival was 13.8, 7.0, 1.9 and 1.2%, respectively, as against 81.6% in the control.     

Impacts of atmospheric CO<Subscript>2</Subscript> concentrations and soil water on the population dynamics,fecundity and development of the bird cherry-oat aphid<Emphasis Type="Italic">Rhopalosiphum padi</Emphasis>

The impacts of elevated CO₂ and soil water on the population dynamics, adult fecundity and nymphal period of the bird cherry-oat aphidRhopalsiphum padi (Linnaeus) were evaluated in three experiments: (i)Combined effects of CO ₂ and soil water on aphid populations. Spring wheat was grown in pots at three CO₂ concentrations (350, 550 and 700 ppm) and three soil water levels (40%, 60% and 80% of field water capacity, FWC) in field open-top chambers (OTC) and infested with the bird cherry-oat aphid. Aphid population dynamics were recorded throughout the growing season; at the same time, adult fecundity and duration of the nymphal period were recorded. Chemical composition of spring wheat leaves was also analyzed. (ii)Indirect effects of CO ₂ concentrations and soil water on aphid adult fecundity and nymphal period. The experiment was conducted with the leaf discs method in the laboratory. Aphids were reared on leaf discs excised from the treated wheat in OTC with different CO₂ and soil water levels. (iii)Direct effects of CO ₂ concentrations on aphid adult fecundity and nymphal period. Aphids were reared on leaf discs excised from the wheat grown under natural conditions. The experiment was conducted with the leaf disc method in OTC with the three CO₂ concentrations. It was found that the direct effect of CO₂ concentration on aphid population parameters was minor. CO₂ and soil water affected aphid population indirectly through their effects on wheat characteristics. The aphid population under 550 ppm CO₂ was far larger than the one under 350 ppm CO₂, whereas the population under 700 ppm CO₂ was slightly higher than that under 550 ppm CO₂. The largest aphid population was obtained with the 60% soil water treatment, regardless of CO₂ treatment. The effects of CO₂ concentration on aphid population were, however, not significantly correlated with soil water level. Adult fecundity increased with CO₂ concentration, the highest fecundity being achieved under 60% FWC treatments. The nymphal period was not affected by CO₂ concentration. The shortest period occurred under 60% FWC. Atmospheric CO₂ and soil water had significant effects on the chemical composition of the wheat leaves. Aphid population size was positively correlated with leaf water content, concentrations of soluble proteins, soluble carbohydrates and starch, and negatively correlated with DIMBOA and tannins concentrations. http://www.phytoparasitica.org posting Oct. 20, 2003.     

Integration of Calneem® oil and parasitoids to control <Emphasis Type="BoldItalic">Cadra cautella</Emphasis> and <Emphasis Type="BoldItalic">Corcyra cephalonica</Emphasis> in stored grain cereals

The compatibility and protectant potential of Calneem® oil derived from the neem tree Azadirachta indica and two parasitoids, Habrobracon hebetor and Venturia canescens, for the control of the rice moth Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) and the tropical warehouse moth Cadra cautella Walker (Lepidoptera: Pyralidae) in stored rice and wheat, were evaluated in the laboratory. Calneem® oil (= neem oil) is a biopesticide produced, registered and marketed in Ghana by AQUA AGRIC Community Projects (AACP/Caldor Ghana Ltd., Tema). It contains 0.3% azadirachtin as its major active ingredient. The oil was emulsified with water using 0.07% soap. Fourth instar moth larvae were held in grain treated with neem oil only, grain treated with one of the parasitoids only, grain treated with a combination of neem and one of the parasitoids, and a control with untreated grain. Neem oil was applied at concentrations from 5,000 to 30,000 ppm. All samples were kept in growth cabinets maintained at 25°C and 65–70% r.h. Adult emergence was recorded after 4 weeks. Parasitoid or neem treatments alone reduced the emergence of C. cephalonica and C. cautella. In general, parasitoid releases were as effective as a combination of neem oil and parasitoids. At the lowest dose, 5,000 ppm, the combination of neem and parasitoid was more effective than the neem alone. The number of adults of H. hebetor and V. canescens that emerged in rice containing either parasitoids alone or in combination with neem oil was similar. This indicates minimal or no adverse effect of neem oil on the two parasitoids. It is thus possible to incorporate neem oil in a well-designed pest management program with parasitoids.     

Toxicity of neem to natural enemies of aphids

Neem [Azadirachta indica (A. Juss.)] seed oil (NSO) applied in three concentrations, 0.5%, 1% and 2%, to potted plants infested with green peach aphid,Myzus persicae (Sulzer), totally prevented adult eclosion of larval coccinellids,Coccinella undecimpunctata L., and reduced adult eclosion of syrphids,Eupeodes fumipennis (Thompson), to 11%, 7% and 0%, respectively, of the controls. Under the same conditions, NSO did not reduce the rate of parasitism ofM. persicae byDiaeretiella rapae (Mcintosh), but emergence of parasitoid adults from aphid mummies collected from treated plants was reduced to 35%, 24% and 0%, respectively, of the controls. Although topical treatment of predator larvae with NSO at concentrations of up to 5% did not affect survival, emergence of parasitoids from mummies dipped in aqueous emulsions of NSO at similar rates was reduced significantly. Under field conditions, sprays of NSO and neem seed extract to plants had no significant impact on the number of aphids parasitized. Although total numbers of predators were reduced, numbers of predators relative to aphid numbers were similar to those in controls. Neem insecticides may be suitable for use in integrated pest management programs, as under field use they appear to be relatively benign to aphid predators and parasitoids.     

Plant material as an alternative tool for management of aphid in country bean field

The aphids Aphis craccivora Koch attack country bean Lablab purpureus L. both in its vegetative and reproductive stages and cause severe damage. To develop an integrated management of aphid powders of black pepper, chili, turmeric, and coriander; oils of mahogany, neem, and eucalyptus; aqueous extracts of neem, basil, and garlic leaves; and water were evaluated in field conditions. The treatments were applied at 7?day intervals and aphid abundance per inflorescence was counted at 24, 48, and 72?h after treatment. All the plant materials reduced aphid abundance and flower infestation, ensuring a higher yield with larger and heavier pods. The neem oil treatment had the lowest abundance of aphid and consequently produced the highest marketable and gross yields. Predatory insects were abundant in the field, but their populations were lower in the treatments than the control. An economic analysis indicated that the highest gross return, net return, adjusted net return, and benefit-cost ratio were obtained from the mahogany oil treatment. The plant materials have insecticidal potential against aphids, and the oils of mahogany and neem showed better performances.     

Effects of neem (Azadirachta indica) extracts onLeptocorisa chinensis under choice and no-choice conditions

Two extracts from neem (Azadirachta indica A. Juss. (Meliaceae)) seeds, azadirachtin and oil, and a mixture of neem oil and abamectin, were tested on second-instar nymphs of the rice bugLeptocorisa chinensis (Dallas) (Hemiptera: Alydidae). To clarify the effect of spraying coverage on bioefficacy of test materials, experiments were conducted under choice and no-choice conditions in field cages. In a choice test, treatment with the mixture of neem oil and abamectin was most effective in reducing the survival ofL. chinensis, followed by azadirachtin at 60 ppm, 30 ppm and 3% neem oil, whereas all treatments except neem oil caused 100% mortality within 3 weeks in a no-choice test. When second-instar nymphs had choices of treated and untreated plants within a treatment, no differences in yield and sum of dead and stained grains were found between those two choices, indicating that nymphs neither caused significant reduction in yield nor reduced the quality of untreated plants. Regardless of treatment, the difference in overall yield between treated and untreated plants under choice conditions was not statistically significant (P>0.05). Our results indicate that neem-based formulations, used alone or in combination with abamectin, have the potential to be integrated into the existing programs to control the rice bug. http://www.phytoparasitica.org posting Aug. 28, 2005.     

The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 2: indirect effects of oil deposits

The primary mode of action of petroleum spray oils (PSOs) on pest insects is through direct contact. Indirect effects are, however, also possible, and deposits of the oils may influence pest populations by killing insects and/or by influencing their behaviour. The indirect effects of deposits of a new nC24 oil against the cotton aphid, Aphis gossypii Glover, were therefore determined. The effects of oil deposits on the acceptance of cotton as host plant by the aphids were assessed, as well as aphid mortality rates and their success in the establishment of colonies. The efficacy of deposits of a heavier oil (nC27) was also evaluated. Deposits of PSO were toxic to A. gossypii and remained effective until 8 days after spraying. Mortality decreased with time, so that, the older the deposit, the lower was the mortality. Significantly higher aphid mortalities were achieved on younger leaves than on mature ones. Thus, leaf age proved a significant factor in the efficacy of the deposits. Consecutive prophylactic applications (at 9 day intervals) did not have a cumulative effect, and their killing power proved to be independent of one another. Thus, applying the oil prior to aphid infestations would confer only minimal protection. The mortality inflicted by the deposits was not improved by increasing the molecular mass of the oil used (nC27 oil), but the toxic life of the oil deposit was increased. Oil deposits did not deter alates from landing on oil-sprayed plants. Oil deposits did, however, affect subsequent alate and nymphal survival, and thus the establishment of aphid colonies. The impact that the oils could have on the longer-term development of aphid populations in the field was thus demonstrated. First- and second-instar nymphs were the most susceptible life stages, with > 50% mortality compared with < 10% for the other stages. These nymphs did not show the typical signs of oil-induced mortality observed in aphids killed by direct oil applications, which suggests an alternative mode of action to that of the directly applied oil. Anoxia does not seem to be involved in either process, and alternative modes of action of the oil deposits are discussed. The implications of these findings for cotton aphid control are also considered, primarily in relation to the timing and frequency of oil application.     

Common oils and insecticidal control and their resistance to Aleuroclava jasmini (Hem.: Aleyrodidae) on paper mulberry in Iran

Abstract

Aleuroclava jasmini (Hemiptera: Aleyrodidae) is a major insect pest of paper mulberry (Broussonetia papyrifera) in Iran, negatively affecting its production. Considering the importance of oils in the integrated management programs of such pests, the present study examined the possibility of whitefly control on paper mulberry plant to assess mortality rate (MR), synergistic rate (SR), resistance rate (RR), and lethal concentration for 50% of the population (LC₅₀) of oils and common insecticide in populations from four areas of Tehran, Iran (one susceptible and three non-susceptible). The best chemical treatments against A. jasmini adults and nymphs in paper mulberry plants were neem oil (1?ml L^?1) mixed with deltamethrin (0.5?ml L^?1) or with buprofezin (1?ml L^?1). The neem, akylarylpolyglyglycol ether and volk oils mixed with deltamethrin or buprofezin also had synergistic effects on adults and nymphs of A. jasmini, respectively, in Azadi, Shahrake Gharb, and Vanak areas (non-susceptible populations), but with higher concentrations (> LC₅₀) and lower SR than in Garm Dareh area (susceptible population). We observed that A. jasmini adults showed the greatest resistance to deltamethrin in Vanak area and nymphs of this pest to buprofezin in Shahrake Gharb area.     

Application of plant growth regulators mitigates chlorotic foliar injury by the black pecan aphid (Hemiptera: Aphididae)

BACKGROUND: Black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), feeding elicits localized chlorotic injury to pecan foliage [Carya illinoinensis (Wangenh.) K Koch] and apparent acceleration of leaf senescence and defoliation. The ability of certain plant growth regulators (PGRs) (forchlorfenuron, gibberellic acid and aviglycine) to prevent M. caryaefoliae from triggering pecan leaf chlorosis and senescence‐like processes was evaluated on two dates in both 2006 and 2007. Treatments were applied to orchard foliage and used in laboratory leaf‐disc bioassays to assess possible reduction in aphid‐elicited chlorosis and concomitant effects on aphid mortality and development. RESULTS: Foliage pretreated with forchlorfenuron + gibberellic acid prior to being challenged with aphids resulted in significantly less aphid‐elicited chlorosis than did control or aviglycine‐treated leaf discs. No PGR affected aphid mortality; however, development time was increased by forchlorfenuron + gibberellic acid in 2006 and by aviglycine + gibberellic acid on one date in 2007. CONCLUSION: Certain PGRs possess the potential for usage on pecan to protect foliar canopies from M. caryaefoliae via changes in the susceptibility of the host leaf to senescence‐like factors being introduced by feeding aphids. This protective effect on host foliage and the associated suppressive effect on development of feeding aphids might also be relevant to pest management programs on other aphid–crop systems in which aphid‐elicited chlorosis and senescence‐like processes can limit profitability. Published 2010 by John Wiley & Sons, Ltd.     

Effect of methoprene on the progeny production of Tribolium castaneum (Coleoptera: Tenebrionidae)

BACKGROUND: Tribolium castaneum (red flour beetle) is a serious insect pest of stored products around the world. Current control measures for this species have several limitations: loss of registration of insecticides, insecticide resistance and consumer concerns about chemical residues in food. The objective of this study was to determine whether methoprene affects progeny production of T. castaneum. Late‐instar larvae or young adults were exposed to methoprene‐treated wheat, and progeny production was determined. The pairing of male and female adults was performed as untreated × untreated, treated × untreated or treated × treated, to study sex‐based effects. RESULTS: There were three outcomes to late‐instar larvae held on methoprene‐treated wheat kernels (0.001 and 0.0165 ppm): (1) failure to emerge as an adult; (2) emergence as an adult, and almost no offspring produced; (3) emergence as an adult and normal production of offspring. Male larvae were more susceptible to methoprene than female larvae. In contrast, young adults exposed to methoprene (1.67–66.6 ppm) showed no reduction in offspring production. CONCLUSION: Methoprene concentrations will decline with time following its application. However, this research indicates that methoprene can still reduce populations of T. castaneum by reducing their progeny production, even if adults emerge. Copyright © 2011 Society of Chemical Industry     

Effects of Neem Seed Derivatives on Brown Planthopper Symbiotes

Populations of intracellular symbiotes declined significantly in brachypterous females of the brown planthopper,Nilaparvata lugens (Stål), which were stressed during nymphal development by caging them on IR20 rice plants treated with 3% neem oil, 5% neem seed kernel aqueous extract, or 10% neem cake aqueous extract. In addition, nymphs grew poorly and symbiote populations in prospective females declined, when reared on rice plants grown in soil treated with neem cake; this indicates systemic action of bioac-tive neem constituents. Addition of custard-apple oil to neem oil did not enhance the inhibitory effects. The effects of neem derivatives on the symbiotes may be either host-mediated — possibly through disturbed neuroendocrine homeostasis, or direct — leading to perturbations of host-symbiote equilibrium.     

Outbreak of oriental yellow scale insect,Aonidiella orientalis (Newstead) (Homoptera: Diaspididae), on neem in Sudan

Scale insects were observed in neem trees (Azadirachta indica A. Juss) planted in Shambatarea near the bank of the Nile in Khartoum State and along Blue Nile Street in Wad Medani, Gezira State, Sudan in October 2014. Specimens of neem leaves and twigs, which were highly infested with scale insects and showing signs of wilting, were collected from different parts of the tree canopies and sent to the Insect Collection Unit at the Agricultural Research Corporation, Gezira Research Station, Sudan for identification. The pest was morphologically identified as Aonidiella orientalis (Newstead) (Hemiptera: Diaspididae). An endoparasitoid was observed to emerge from the scale insect and was identified as an encyrtid wasp. Aonidiella orientalis had been recorded previously in Shambatarea in 1969 and this paper presents the results of surveys carried out following the initial observations in Khartoum and Gezira States. This was a major outbreak, affecting the majority of the 1685 surveyed neem trees and causing damage on 62.7% of them.     

Laboratory evaluation of a botanical natural product (<Emphasis Type="Italic">AkseBio2</Emphasis>) against the pear psylla<Emphasis Type="Italic">Cacopsylla pyri</Emphasis>

A botanical natural product,AkseBio2, was evaluated under laboratory conditions for its oviposition deterrent, ovicidal and larvicidal (nymphicidal) effects against the pear psyllaCacopsylla pyri (L.) (Hemiptera: Psyllidae). The product exhibited a strong oviposition deterrent effect for winterform and summerform females and caused a reduction in the total number of eggs laid in both choice and no-choice assays. Significant mortalities in freshly laid eggs (0–48 h) and various nymphal stages of the pest were recorded in toxicity assays. At a concentration of 0.1% (formulation), the highest biological activity of the product was recorded against the young (1st and 2nd) nymphal stages (up to 87.4% mortality) in comparison with the other biological stages of the pest. It was less active against the older (3rd-5th) nymphs, causing 62.1% mortality at the same concentration. In assays with non-target organisms, a significant negative effect was not observed. There were no significant changes on treated plants up to 7 days after treatment in any trial, nor was there any phytotoxicity on plant tissue as a result ofAkseBio2 treatments. The results suggest that the product can be used in psylla control instead of synthetic insecticides and may serve as an integrated pest management (IPM) component in pear orchards. http://www.phytoparasitica.org posting July 14, 2004.     

Life history performance of Aphis gossypii Glover (Aphididae) on seven cucumber cultivars

The cotton aphid, Aphis gossypii Glover (Aphididae) is an important pest of indoor and outdoor cucumber crops in Iran. We studied the life history performance of A. gossypii on seven cucumber cultivars (Negin, Pierro, Davos II, Royal safa, Dominus (Ps), Super pretty and TN-94-203) at 27 ± 1 ºC, 50% ± 10% RH and a photoperiod of 16:8 (L:D) h. The developmental time for the nymphal stages ranged from 4.27 days on Pierro to 4.47 days on Negin, but differences among cultivars were not statistically significant. The lowest and highest survival rates for immature stages were 68.33% and 95% on Royal safa and TN-94-203, respectively. The total fecundity of A. gossypii significantly differed among cultivars, being the highest on Pierro (44.66 nymphs/female) and the lowest on Dominus (Ps) (69.89 nymphs/female). The lowest intrinsic rate of natural increase (r_m) was obtained on Negin, and the highest on Super pretty. The generation time (T) was shortest on Pierro (7.41 days) and longest on Negin (8.32 days). According to our results, Super pretty and Negin were partially susceptible and resistant to A. gossypii, respectively. The findings of this study provide direction to design a more comprehensive integrated pest management program for this pest.     

Comparative effect of integrated pest management and farmers' standard pest control practice for managing insect pests on cabbage (Brassica spp.)

BACKGROUND: Studies were conducted on experimental cabbage plantings in 2009 and on experimental and commercial plantings in 2010, comparing farmers' current chemical standard pesticide practices with an integrated pest management (IPM) program based on the use of neem (Aza‐Direct) and DiPel (Bacillus thuringiensis). In experimental plantings, the IPM program used six or eight applications of neem and DiPel on a rotational basis. The standard‐practice treatments consisted of six or eight applications of carbaryl and malathion or control treatment. RESULTS: The IPM treatments reduced pest populations and damage, resulting in a better yield than with the standard chemical or control treatment. When IPM treatment included three applications of neem plus three applications of DiPel (on a rotational basis in experimental fields), it again reduced the pest population and damage and produced a better yield than the standard practice. The lower input costs of the IPM program resulted in better economic returns in both trials. CONCLUSIONS: The IPM components neem and DiPel are suitable for use in an IPM program for managing insect pests on cabbage (Brassica spp.). Copyright © 2011 Society of Chemical Industry     

Using bioassays with the green peach aphid (Myzus persicae) to determine residual activity of two systemically soil-applied neonicotinoid insecticides in field-grown tobacco

Duration of systemic pesticide activity under field conditions has wide implications for pest management. Our aim was to determine the duration of activity of systemic insecticides commonly used in cultivated tobacco (Nicotiana tabacum) by measuring the levels of insect infestations on field plots and effects on reproduction and survival of the green peach aphid (Myzus persicae) in controlled bioassays using field grown leaves. Plants were treated with different concentrations of two systemic neonicotinoid pesticides, imidacloprid and thiamethoxam, and grown in small field plots. Our results show that these materials are effective under field conditions against aphids for at least 13 weeks after transplant. Pesticides also affected aphid reproduction and nymph survival in bioassays, although some aphids survived on pesticide-treated leaves. We also observed that leaf age affected aphid survival. We showed that neonicotinoids were very effective against M. persicae, aphids are a useful organism to assess pesticide efficacy early in the growing season, but plant characteristics are more important than pesticide concentration in the second half of the growing season.     

Insects associated with the banana aphid <Emphasis Type="Italic">Pentalonia nigronervosa</Emphasis> Coquerel (Hemiptera: Aphididae) in banana plantations with special emphasis on the ant community

Ant attendance, well known behavior form towards aphid species was studied in case of the banana aphid Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae) populations in four plantations in the coastal area of Carmel (Israel), where the aphid is a major pest on banana. The study characterizes the ant community the extent of attendance and the natural enemies associate with the aphid. The ants and natural enemies were sampled on mats and suckers. The ant community in the plantations was also studied by using different ant baits. In addition, the ants’ impact on the density of the banana aphid population and the potential role of local natural enemies was evaluated in artificially infested potted banana plants set in the plantation with or without a glue barrier. More than 80% of the aphid colonies on the mats were attended by ants. Ten of the twelve ant species detected in the plantations were observed attending the banana aphid. Seventeen species of potential natural enemies of the aphid, mostly belonging to the families Syrphidae, Cecidomyiidae and Coccinellidae, were found in the aphid colonies. When ant attendance on infested potted banana plants was excluded, the number of natural enemies was higher, while the aphid density was lower, than recorded on the control plants. Our finding suggest that the ants, especially the invasive species, lower the pressure of natural enemies on the aphid population and but also probably remove large quantity of honeydew which is the source of the main damage caused by the banana aphid in the local plantations.     

Movement of phorate and metabolites from treated leaflets to aphid colonies on broad bean plants

Aphid colonies were established on one second-node leaflet of young broad bean plants and sublethal treatments of ¹⁴C-labelled phorate were applied to the adjacent leaflets. After 3 days, the amounts of toxic and non-toxic ¹⁴C-labelled compounds in the aphids, their honeydew and the untreated foliage were determined. There were no significant differences between the amounts in leaves at the same level on the plant when infested and aphid-free plants were compared, but the aphids and their honey-dew contained two and 23 times as much of the toxic and non-toxic ¹⁴C-compounds, respectively, found in the host leaflets. Following translocation to aphids on leaves above or below treated leaflets, the aphid colonies again contained more labelled compounds than the host-plant leaves. The movement of non-toxic compounds into the roots was reduced when the aphid colonies were situated on foliage between the site of treatment and the roots. More of the toxic and the non-toxic fractions were translocated downwards from the third to the second leaf than in the reverse direction.     

Harmonious interaction of kaolin and two insect predator species in plant protection

Lacewings and lady beetles represent two important groups of natural enemies for pest control. Kaolin is used in various crop ecosystems to reduce abiotic plant stressors and pest colonization. Compatible methods aimed at reducing abiotic and biotic plant stressors are desired in crop management systems. Therefore, this work evaluated the development and survival of Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) and Eriopis connexa (Germar) (Coleoptera: Coccinellidae) larvae of different ages treated with kaolin at three different concentrations (ca. 60, 80, and 100 g/L) and prey consumption when treated with kaolin at a field rate of 60 g/L. The prey used were the whitefly Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) and the aphid Lipaphis erysimi (Kalt.) (Hemiptera: Aphididae). Survival rates and development durations for E. connexa larvae topically treated with kaolin at different ages were similar to those for untreated larvae. However, larvae of C. externa reduced survival and delayed development when treated with kaolin concentrations greater than the recommended field rate. Otherwise, kaolin treatments did not affect prey consumption by larvae and adults of both predator species.