2nd Larvae Research Articles

New prospective insecticidal agents based on thiazolo[4,5-b]quinoxaline derivatives against cotton leafworm Spodoptera litura (Fabricius): Design, synthesis, toxicological, morphology, histological, and biomedical studies

In this study, a new series of thiazolo[4,5-b]quinoxaline derivatives 3–8 were synthesized by treating 2,3-dichloroquinoxaline with thiosemicarbazone and thiourea derivatives under reflux conditions. The chemical structure of the newly designed derivatives was conducted using spectroscopic techniques. The insecticidal bioassay of the designed derivatives was evaluated against the 2nd and 4th larvae of S. litura after five days as toxicity agents via median lethal concentration (LC50) and the lethal time values (LT50). The results indicated that all the tested compounds had insecticidal effects against both instar larvae of S. litura with variable values. Among them, thiazolo[4,5-b]quinoxaline derivative 3 was the most toxic, with LC50 = 261.88 and 433.68 ppm against 2nd and 4th instar larvae, respectively. Moreover, the thiazolo[4,5-b]quinoxaline derivative 3 required the least time to kill the 50% population (LT50) of 2nd larvae were 20.88, 13.2, and 15.84 hs with 625, 1250, and 2500 ppm, respectively, while for the 4th larval instar were 2.75, 2.08, and 1.76 days with concentrations of 625, 1250, and 2500 ppm, respectively. Larvae's morphological and histological studies for the most active derivative 3 were investigated. According to SEM analysis, the exterior morphology of the cuticle and head capsule was affected. In addition, there were some histological alterations in the cuticle layers and the midgut tissues. Columnar cells began breaking down, and vacuolization occurred in the peritrophic membrane. Moreover, treating 4th S litura larvae hemolymph with compound 3 showed significant changes in biochemical analysis, such as total proteins, GPT, GOT, acetylcholinesterase (AChE), and alkaline phosphatase (AlP). Finally, the toxicity prediction of the most active derivative revealed non-corrosive, non-irritant to the eye, non-respiratory toxicity, non-sensitivity to the skin, non-hepatotoxic, and don't have toxicity on minnow toxicity and T. pyriformis indicating a good toxicity profile for human.

Temperature-dependent Prey Consumption and Functional Response of Episyrphus balteatus De Geer (Diptera: Syrphidae) to Macrosiphum rosae L. (Homoptera: Aphididae) reared on Rosa alba L. under Laboratory Conditions

Laboratory experiments were conducted to determine the prey consumption and functional response of the aphidophagous hoverfly Episyrphus balteatus DeGeer (Diptera: Syrphidae) to different densities of fourth instar rose aphids, Macrosiphum rosae (Homoptera: Aphididae), reared on Rosa alba L. (Rosaceae) at 20 oC, 27 oC and 35 oC. The third instar of E.balteatus consumed a maximum of 51.3±0.53 M. rosae aphids at 27 oC, followed by the third instar with 46.5±0.53 aphid predation at 20 oC. The lowest handling time (Th) was noted for the third instar larvae of E. balteatus (0.407± 0.012) at 27 oC, and the maximum handling time (Th) of (0.662 ± 0.024) was noted for 2nd larvae of E. balteatus at 35 oC. The highest attack rate was noted for 3rd instar larvae (0.201± 0.014) at 27 oC, while the lowest attack rate was noted for second instar at 35 oC. Both instars of Episyrphus balteatus exhibited type II functional response at all three temperatures.

Composition and Diversity of Gut Bacterial Community in Different Life Stages of a Leaf Beetle Gastrolina depressa.

Insect gut bacteria have a significant impact on host biology, which has a favorable or negative impact on insect fitness. The walnut leaf beetle (Gastrolina depressa) is a notorious pest in China, causing severe damage to Juglandaceae trees including Juglans regia and Pterocarya rhoifolia. To date, however, we know surprisingly little about the gut microbiota of G. depressa. This study used a high-throughput sequencing platform to investigate the gut bacterial community of G. depressa throughout its life cycle, including the 1st, 2nd, and 3rd instar larvae, as well as male, female, and pre-pregnant female adults. Our results showed that the diversity of the gut bacterial community in larvae was generally higher than that in adults, and young larvae (1st and 2nd larvae) possessed the most diversified and abundant community. Principal coordinate analysis results showed that the gut microbiota of adults cluster together, which is independent of the 1st and 2nd instar larvae. The main phyla were Proteobacteria and Firmicutes in the microbial community of G. depressa, while the dominant genera were Enterobacter, Rosenbergiella, Erwinia, Pseudomonas, and Lactococcus. The gut bacteria of G. depressa were mostly enriched in metabolic pathways (carbohydrate metabolism and amino acid metabolism) as revealed by functional prediction. This study contributes to a better knowledge of G. depressa's gut microbiota and its potential interactions with the host insect, facilitating the development of a microbial-based pest management strategy.

A study on the cannibalism behaviour and predation of the larvae of fall armyworm (Spodoptera frugiperda)

AbstractCannibalism behaviour in the Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is among of liming factor for mass production of the larvae for laboratory experiment. To understand the change of cannibalism, larvae of 1st, 2nd, and 3rd were used to study cannibalism they were put on the 3rd, 4th, and 5th larvae growth stages in a density of 30, 40, 50, 60, and 70. In this study, the results showed that the functional response of the 3rd ‐5th instar larvae to the 2nd larvae and the 4th–5th instar larvae to the 3rd larvae and 5th and 6th instar larvae to the 4th larvae fitted well with the Holling II mode. The maximum predation of the 3rd‐5th instar larvae on the 2nd instar larvae were 27.17, 74.63, and 232.6 respectively, the maximum predation of the 4th–5th instar larvae on the 3rd instar larvae were 76.92 and 11.82 respectively, and the maximum predation of the 5th–6th instar larvae on the 4th instar larvae were 15.83 and 10.40. The predation of the older larvae to the younger larvae increased with the increase of the density of the younger larvae. This research aims at selecting the minimum number of larvae that will be effective and sustainable for laboratory experiments and minimizing the development of cannibalism in S. frugiperda, reduces crowding for larvae management and promoting healthy larvae. This study provides a pavement of managing larvae ensuring massive indoor larvae rearing to reduce the challenge of inadequate larva for the experiment.

Effect of different silica sources on cotton leaf worm population in sugar beet plants, and their influence on sugar beet yield

Field and laboratory experiments were conducted at Taifaa region and Agricultural research station, Kafr El-Sheikh Governorate, during two successive seasons 2019/2020 and 2020/2021. To estimate the efficiency of alternative materials for controlling Spodoptera littoralis, some silica sources were incorporated to the soil such as (straw and husk) and sprayed on the plants, spray such as potassium, magnesium, sodium silicate and Si NPs. Burnt husk added to the soil at the rate of 200 g/m2 gave the highest reduction 50.48, 48.72%, highest root yield 25.16, 24.60 ton/fed, foliage yield 8.99, 8.60 ton/fed, sucrose percentage 16.71, 17.43%, T.S.S%20.40, 20.60%, purity 81.91, 84.61% and white sugar 4.20, 4.29 ton/fed in the two seasons, respectively. Spray of silica NPs at the rate of 4g/L gave the highest reduction 68.46, 77.81%, root yield 26.03, 26.01 ton /fed, foliage yield 8.60, 8.36 ton/fed, sucrose percentage 18.80, 19.00%, TSS% 22.90, 22.60%, Purity 86.46, 84.07% and white sugar 4.89, 4.94 ton/fed in the two seasons, respectively. In the laboratory, the toxic effect of each of silica NPs, potassium silicate, magnesium silicate and sodium silicate for 2nd larvae instar after 96 hr., was and found that Lc50values were 0.079, 0.212,0.239 and 0.261 g/L. While the corresponding values for 4th after 96 hr., were 0.120, 0.218, 0.261 and 0.594 g/L, respectively.

Study of The Effect of Hot Water Extract of Some Plants on The Alfalfa Weevil Hypera Postica (Gyllenhal, 1813) (Coleoptera: Curculionidae)

The research was conducted in the laboratory of insects in the Faculty of Agriculture/the University of Muthanna about studying the effect of Hot water extract of the pomegranate peels, eucalyptus leaves and basil leaves in different stages (egg, larva, pupa and adult) for Alfalfa Weevil Hypera postica. The results showed that the pomegranate peel extract superiority the percentage of mortality in all the stages used in the experiment over the other plant extracts mentioned above, followed by eucalyptus leaf extract and then basil leaf extract, The results showed that the pomegranate peel extract was effective in controlling the larval stage of the insect, especially st and 2nd larvae instars in addition to the adult stage, the highest percentage of mortality in the larval stage of the insect at the first larval age was (60.0, 46.6 and 26.7%) For all extracts respectively at 1.5 mg/ml after 5 days of treatment. In the pupae stage the highest percentage of mortality was (16.7, 10.0 and 03.3%) at the concentration of 1.5 mg/ml For all extracts respectively. while the effectiveness was very weak in controlling of the eggs and pupa of insect and all extracts. where the highest percentage of mortality in the eggs was at 1.5 mg/ml. It was (20.0, 10.0 and 03.3%) respectively after 7 days of treatment. While The highest mortality rate in adult was (53.3, 40.0 and 16.7%) At 1.5mg/ml for all extracts respectively compared with control treatment (00.0%) for all the insect stages. The plant extracts used in the experiment at a concentration of 0.5 mg/ml did not show any effect on the rates of insect death after a day of treatment and for all stages that reaching (00.0%).

EFFICACY OF ESSENTIAL OILS OF Thymbra capitata L. AND Mentha pulegium L. COLLECTED IN TUNISIA ON LARVAE OF Galleria mellonella L.

The wax moth is one of the honeybee pests that cause a lot of damage and loss for the beekeepers in Tunisia. The use of insecticides is more and more used although they are known to contaminate wax and honey. This study aims to test the essential oils of two North African common plants Thymbra capitata L. and Mentha pulegium L. efficacy as alternative method by fumigation on instars of Galleria mellonela L. We also determined the duration of the development stages of the great wax moth (GWM) presented in Tunisia. Results showed that under a temperature ranged between 30 and 33°C, the total duration from eggs to adults of GWM lasted 51 days. The fumigant test showed the toxicity of both oils on larvae instars tested. The second larvae instar was more susceptible than the 4th instar. Moreover, M. pulegium was more toxic against the 2nd larvae instar than T. capitata with an LC50 at 48h of 41.82 and 456.27 µl/L air, respectively. The essential oils present a good alternative to the insecticides to control wax moths.

Effectivity of Bacillus thuringiensis from Soil in Freshwater Swamps against Epilachna sp. Larvae

Bacillus thuringiensis is an entomopathogenic bacterium isolated from the soil and has been widely used as an active ingredient in the manufacture of bioinsecticides. The target insects are very specific and depend on the type of protein content. Epilachna sp. are important insect pests because both larvae and adults as plant-eating pests. The research aimed was to investigate the effectivity of B. thuringiensis against the larvae of Epilachna sp.. B. thuringiensis- bio-insecticide was prepared using isolates originally from freshwater swamp soil of South Sumatra (SMR04). Epilachna sp larvae were mass-reared with Solanum torvum leaf feed in the laboratory. The design used was a completely randomized design, with 6 treatments and 5 replications. Treatments were spore concentration contained in the bioinsecticide solution included: 1 x 108, 1 x 107, 1 x 106, 1 x 105 spores/mL, commercial bio-insecticide and without treatment as a control. Each replication used 10 individual of the 2nd larvae. Statistical test results showed larval mortality in B. thuringiensis treatment was significantly different from commercial bio-insecticide treatment. The highest mortality of bio-insecticide treatment occurred at a concentration of 108 spores/ml (40.00 %) and the lowest was at a concentration of 105 spores/mL (18.01 %). The lowest LT50 value of bio-insecticide treatment was at a concentration of 108 spores/mL, namely 79.37 hours. The control of larvae included in the Coleoptera order was still not satisfactory yet, considering the presence of protein content in B. thuringiensis strain SMR04 which did not match the type of protein required.

Effect of Plant Extracts of Withania somnifera (L.) Dunal. on Some Biological Performance of Cotton Leaf Worm (Spodoptera littoralis Boisd.)

Al-Jorany, R.S. and H.I. Al-Khazraji. 2021. Effect of Plant Extracts of Withania somnifera (L.) Dunal. on Some Biological Performance of Cotton Leaf Worm (Spodoptera littoralis Boisd.). Arab Journal of Plant Protection, 39(1): 22-28. This study was conducted to determine the effect of ethanol and hexane extracts of withania somnifera on the larvae of the cotton leaf worm Spodoptera littoralis when the 2nd and 4th larvae instars were fed on food treated with plant extract concentrations of 1.25, 2.5 and 5%. The results showed that the 2 nd instar larvae were the most susceptible than the late ones. The highest mortality rate reached 58.52% for the 2 nd instar larvae and 20.74% for the 4 th ones when 5% ethanol extract concentration was used. The results pointed to prolonged durations of the larval and pupal stages depending on the extract concentration used. The longest period of growth stage was found for the treatment with 5% hexane extract concentration. The fertility rate of adults emerged from treated larvae was decreased. The numbers of eggs laid was 670 eggs/female and the egg hatching rate reached 71% when 5% extract concentration was used to treat 2 nd larvae instars. Keywords: Extracts, Withania somnifera, cotton leaf worm, mortality rate, biological effects.

Intraguild Predation between Chrysoperla carnea (Neuroptera: Chrysopidae) and Hippodamia variegata (Coleoptera: Coccinellidae) at Various Extraguild Prey Densities and Arena Complexities.

Intraguild predation (IGP) is a ubiquitous, important and common interaction that occurs in aphidophagous guilds. The effects of extraguild prey (EGP, i.e., aphids) density, predator life stage combinations and duration of the interaction on the level, asymmetry and direction of intraguild predation between lacewing Chrysoperla carnea and ladybird Hippodamia variegata were examined in simple laboratory arena and more complex microcosm environment. Three initial densities of 50, 150 and 400 Aphis fabae third instar nymphs and a control without aphids were provided to six combinations of predator life stages (2nd and 3rd larval instars of lacewing and 3rd and 4th instars and adult females of ladybird). The remaining aphid density and occurrence of IGP were checked after 24, 48 and 72 h. The IGP intensity (IGP level, IL) was similar in the simple arena (reaching 0.6 between larvae in absence of EGP and 0.3 between lacewing larvae and ladybird females) and microcosm environment (0.3 without EGP). In both environments, increasing EGP density lowered IL according to negative exponential relationship. IGP was asymmetric (general average asymmetry was 0.82 in simple arena and 0.93 in microcosm, the difference was not significant) and mostly in favour of larvae of C. carnea, except in the combination of 2nd larvae of C. carnea with the 4th larvae and adults of H. variegata. The direction of IGP, but not other characteristics, partially changed during the duration of the experiment. The incidence of IGP interactions among aphid predators under real conditions and its consequences on aphid biological control are discussed.

Effects of Co-60 radiation on the activities of three main antioxidant enzymes in Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Co-60 radiation has been broadly used for pest management because it results in male sterility and a lack of emergence of unparasitized hosts due to oxidative damage. Insect life is significantly affected by abiotic stress factors, including Co-60 radiation. In the present study, we determined the influence of Co-60 radiation on an important pest in southern China, the oriental fruit fly Bactrocera dorsalis (Diptera: Tephritidae). We exposed 30-h-old B. dorsalis eggs to Co-60 radiation at doses of (0, 5, 10, 15, 20, 25, 30, 35, and 40 Gy) and determined the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). CAT and POX activity significantly increased in B. dorsalis in the 1st larvae instar after high-intensity radiation doses (25–40 Gy) and played an important role in the antioxidant response to intensive radiation. The activity of POX in B. dorsalis at the 2nd larval instar sharply decreased after different doses of radiation, except for 10 and 40 Gy. Our results demonstrated that Co-60 radiation affected the activity of antioxidant enzymes and disturbed the physiology of B. dorsalis, especially at early stages (the 1st, 2nd larvae instar). These three antioxidant defense enzymes cooperatively play an important role in protecting B. dorsalis from oxidative damage.

Rearing of Mallada basalis (Neuroptera: Chrysopidae) on modified artificial diets.

Mallada basalis (Walker) has the potential to be a valuable biological control agent because of its predatory abilities, strong reproductive capacity, and broad prey range. This study aimed to improve on a previously used artificial diet for M. basalis, to achieve a longer oviposition period and greater survival rate and fecundity. We analyzed the development, survival, longevity, and reproduction of M. basalis (F1 and F2 generations) fed two artificial diets (AD1 and AD2). Both diets contained chicken egg yolk, beer yeast powder, honey, trehalose, seawater spirulina, and potassium sorbate. AD1 also contained sucrose and vitamin C. The duration of F1 1st larvae, F1 2nd larvae, F1 pupae, F2 egg, and F2 2nd larvae reared on AD1 were significantly shorter than those reared on AD2. F1 adult longevity and F2 oviposition period for AD1 (45.40 d and 31.00 d) were significantly longer than for AD2 (30.74 d and 20.80 d). All the following were significantly greater for AD1 compared with AD2: F1 female proportion, F1 daily oviposition, F1 female oviposition, F2 daily oviposition, F2 female oviposition, F1 emergence rate, F2 pupation rate, and F3 egg hatching rate. Moreover, for M. basalis fed AD2, the duration of F2 2nd and 3rd larvae (9.00 d and 8.64 d) were significantly longer than for F1 (4.70 d and 4.92 d). The F1 oviposition period (31.57 d) was significantly longer than F2 (20.80 d). The F2 female oviposition (189.20 egg/female) was significantly less than F1 (307.14 egg/female). We found that the oviposition period and female longevity of F1 reared on AD1 was longer than that reared on the artificial diet in a previous study. The daily oviposition and female oviposition of F1 from AD1 was larger, while the F2 egg hatching rate was greater compared with that from the previous diet. However, the offspring of M. basalis fed AD2 were less thrifty. We found diet AD1 supported development and reproduction better than AD2 and the diets in our previous study. These findings may contribute to the mass rearing of this economically important predatory green lacewing.

The expression analysis of cysteine proteinase-like protein in wild-type and nm2 mutant silkworm (Lepidoptera: Bombyx mori)

The mutant of non-molting in the 2nd instar (nm2) is a recently discovered mutant of Bombyx mori. The mutant cannot molt and exuviate and died successively in premolting of 2nd instar. In this study, two dimensional gel electrophoresis (2-DE) was performed to screen the differential expression of epidermis proteins in pre-molting larvae of 2nd instar between the wild-type and nm2 mutant. Interestingly, a cysteine proteinase-like (BmCP-like) protein in nm2 was significantly higher than that of the wild-type. The transcription profiles of BmCP-like gene were investigated by quantitative real-time PCR (qRT-PCR), and the result revealed that BmCP-like mRNA was remarkably higher in nm2 than that of the wild-type. The transcription level of BmCP-like was high in the epidermis while low in the midgut and hemocytes, and fluctuate with development, while the highest in the newly molted larvae of 3rd and lowest in the pre-molting of the 1st and 2nd instar. The body of injected BmCP-like RNAi of 2nd larvae formed a dark spots around the injection place. These results suggested the BmCP-like gene play a key role in the degradation of the cuticle and epidermis layer during molting of 1st and 2nd instar silkworm. Furthermore, the ORF of BmCP-like gene in nm2 was the same to the wild-type. These studies give us a hint that BmCP-like gene maybe not the major gene responsible for nm2, but BmCP-like gene might participate in the immune systems of silkworm, and the upregulation of BmCP-like transcription in the nm2 mutant might be induced by the disadvantages that limit the growth and development of silkworm in order to survive.

Influence of Two Insect Growth Regulators on Chitinase Activity

Toxicity of two insect growth regulators (IGRs) (lufenuron and hexaflumuron) against two larval instars of cotton leafworm Spodoptera littoralis, laboratory and field strains were determined. Chitinase activity in the two strains also was investigated. Results revealed that, 2nd instar larvae were more sensitive than 4th instar larvae to both insecticides. The sensitivity of chitinase activity was measured by I50 values. The I50 values of lufenuron were 0.31, and 0.64 µM for lab and field strains of S. littoralis 2nd larvae respectively, while I50 values were 0.44, and 0.75 µM for lab and field strains of S. littoralis 4th larvae respectively. The hexaflumuron were 0.57, and 0.76 µM for lab and field strains of S. littoralis 2nd larvae respectively, the I50 values were 0.65, and 0.81µM for lab and field strains of S. littoralis 4th larvae respectively. Also, chitinase enzyme kinetic parameters, as Michaelies-Menten Kinetics (Km and Vmax) values and the inhibition constant (Ki) were determined. The obtained data proved that lufenuron and hexaflumuron compounds are competitive inhibitors of chitinase activity. Results indicated that, the IGRs have shown high potentiality against larvae of S. littoralis, so, these IGRs may be recommended for S. littoralis larvae control, it could be concluded that the use of IGRs instead of conventional hazardous insecticides; may avoid increasing selection pressure of S. littoralis populations to conventional insecticides, hazard effects on human health, environmental components and natural enemies, IGRs may play an important role in future insect pest management programs.

BIOCHEMICAL EFFECTS OF SOME INSECT GROWTH REGULATORS ON FIELD STRAINS OF THE COTTON LEAFWORM, Spodoptera littoralis

Different strains of cotton leafworm, Spodoptera littoralis larvae were collected from heavily sprayed fields or recently cultivated fields in different areas in Alexandria, and El-Boheira, proviance governorate. Chitinase activity was determined in laboratory susceptible strain of cotton leafworm and compared with enzyme activity for other collected strains which cleared that highest level of chitinase activity was found in Alexandria strains. The sensitivity of chitinase activity to chlorfluazuron and teflubenzuron was measured by I50 values, values of I50 in the case of chlorfluazuron were 0.23, 0.34, 0.41, 0.60, and 0.69 µM for lab strain; Borg El-Arab; West of Nobaria; Abou El-Matamir, and Edko strains of Spodoptera 2nd larvae respectively, while I50 values were 0.31, 0.40, 0.46, 0.66, and 0.74 µM for lab strain and four field strains of Spodoptera 4th larvae respectively, similarly, the teflubenzuron were 0.40, 0.50, 0.57, 0.74, and 0.82 µM for lab strain and four field strains of Spodoptera 2nd larvae respectively, the I50 values were 0.47, 0.59, 0.65, 0.88, and 0.93 µM for lab strain and four field strains of Spodoptera 4th larvae respectively. Also, the inhibition constant (Ki) values were determined, the obtained data proved that compounds competitive inhibition of chitinase activity. The significant high mortality percentages were observed at all tested concentrations with chlorfluazuron than teflubenzuron and the result clearly showed that the 2nd instar larvae were more sensitive to the compounds tested, compared to those of the 4th instar, so when IGRs used for S. littoralis larvae control, dosage and timing of application should be carefully considered. The results of the present study may add some forward steps to use IGRs as alternative to conventional insecticides especially against this insect, so, the IGRs can be involved in important steps necessary for successful IPM programs applied against S. littoralis.

Toxicity and persistence of <em>Boscia senegalensis</em> Lam. (Ex Poir.) (Capparaceae) leaves on <em>Callosobruchus maculatus</em> Fab. (Coleoptera:Bruchidae)

In this study, we examined the toxicity and persistence of ground fresh leaves of B. senegalensis on the development of Callosobruchus maculatus, major insect pest of cowpea (V. unguiculata) in the sahelian area. The effect of the product has been evaluated over the three developmental stages (egg, larvae and adult) of C. maculatus. At high concentration (4 g/l of ground leaves), 100 % of adults were killed within 24 h of exposure to the leaf extract, and the development of newly laid eggs and neonate larvae was also inhibited. However, the ground leaves of B. senegalensis have a variable efficacy against the bruchid instars larva. The 2nd larvae stage (L2) of C. maculatus developing inside the seeds have proved to be highly susceptible while the 4th larval stage was relatively tolerant. The study of the toxicity persistence of the leaves of B. senegalensis showed that whatever its concentration, the efficacy of crushed leaves of B. senegalensis decreased with the storage time. At a concentration of 20 g/l, the effect of B. seneglensis can persist up to 7 days.Keywords: Biopesticides, Bruchids, cowpea, pest control, Niger

꽃노랑총채벌레 목화진딧물, 점박이응애에 대한 애꽃노린재(Orius sauteri)의 포식반응

애꽃노린재의 먹이로 꽃노랑총채벌레를 주었을 경우, 애꽃노린재 암 수 약충의 온도별 일일포식량은 17, 22, 27, <TEX>$32^{\circ}C$</TEX>에서 전체 약충기간(암/수) 동안 각각 4.2/3.9, 11.4/9.5, 14.3/10.8, 14.7/12.5 마리였고 <TEX>$27^{\circ}C$</TEX>에서 먹이종류별 일일포식량은 먹이로 꽃노랑총채벌레, 목화진딧물 및 점박이응애를 공급하였을 경우 전체 약충기간(암/수) 동안 각각 14.3/10.8, 7.5/7.2, 45.9/38.8마리를 포식하였다. 애꽃노린재 암컷 성충은 <TEX>$27^{\circ}C$</TEX>에서 산란전기간에 42.8마리, 산란기간에 63.2마리를 포식하였다. 애꽃노린재는 꽃노랑총채벌레의 밀도 증가에 띠라 포식량은 점차 증가하였으나 증가율은 차차 감소하는 Holling의 기능반응곡선 제II형(포화형)과 유사한 포식반응을 나타냈고 애꽃노린재 암컷 성충의 탐색율이 5령 약충에 비해 높고 탐색시간도 짧았다. 애꽃노린재의 5령 약충과 암컷 성충은 꽃노랑총채벌레 2령 유충을 가장 선호하였다. Daily predation of female/male O. sauteri during nymphal development were 4.2/3.9, 11.4/9.5, 14.3/10.8, and 14.7/12.5 at 17,22,27, and <TEX>$32^{\circ}C$</TEX>, respectively, and consumed 14.3/10.8 thrips, 7.5/7.2 aphids, 45.9/38.8 mites at <TEX>$27^{\circ}C$</TEX>, respectively. Adult females ate 42.8 thrips daily during preoviposition period and 63.2 thrips during oviposition period at <TEX>$27^{\circ}C$</TEX>. Predation by O. sauteri on F. occidentalis increased as the density of F. occidentalis increased. However, the rate of increase gradually lessened, resembling a Holling's type II functional response. The attack rate of adult female is higher than that of the 5th nymph. Adult female and 5th nymph of O. sauteri appeared to prefer 2nd larva of F. occidentalis.

담배거세미나방과 파밤나방에 활성이 있는 Bacillus thuringiensis subsp. aizawai CAB109 균주의 특성

국내에서 분리된 Bacillus thuringiensis subsp. aizawai CAB109균주가 난방제 해충으로 알려진 담배거세미나방과 파밤나방에 동시에 높은 독성을 보이는 것으로 나타났다. B.t. CAB109 균주의 활성을 평가하기 위해 혈청형이 aizawai이면서 미생물농약으로 시판중인 TB-WP제품 및 SC제품과의 살충활성을 비교한 결과, B.t. CAB109균주, TB-WP제품, SC제품은 담배거세미나방 2령충에 대한 반수치사농도(<TEX>$LC_{50}$</TEX>)가 각각 <TEX>$1.3{\times}10^5cfu/ml$</TEX>, <TEX>$2.3{\times}10^6cfu/ml$</TEX>, <TEX>$5.2{\times}10^5cfu/ml$</TEX>으로 나타났고 파밤나방 2령충에 대한 반수치사농도는 <TEX>$1.8{\times}10^4cfu/ml$</TEX>, <TEX>$1.3{\times}10^6cfu/ml$</TEX>, <TEX>$1.5{\times}10^6cfu/ml$</TEX>으로 나타나 두 종 해충 모두에서 B.t. CAB109 균주가 독성이 더 높은 것을 볼 수 있었다. B.t. CAB109균주가 이미 알려져 있는 aizawai와 비교해 차이가 나는 새로운 유전자를 소유하는지 확인하기 위해 Plasmid DNA를 추출하여 전기영동 한 결과 B.t. subsp. aizawai HD-133과 다른 패턴을 보이는 것을 확인 할 수 있었고 Cry1-Cry5의 primer를 사용하여 PCR을 진행한 결과 B.t. subsp. aizawai CAB109균주는 Cry1Aa, 1Ab, 1C, 1D를 B.t. subsp. aizawai HD-133은 Cry1Aa, 1Ab를 가지고 있음을 확인 할 수 있었다. Bacillus thuringiensis subsp. aizawai CAB109 isolated in Korea is known active against Spodoptera sp.. Especially, B. thuringiensis aizawai CAB109 isolates showed 100% mortality against Spodoptera litura and Spodoptera exigua. To screen highly active B. thuringiensis, the pathogenicity of B. thuringiensis CAB109 was compared with that of commercialized B. thuringiensis products. <TEX>$LC_{50}$</TEX> values of CAB109, product TB-WP and product SC strains of B. thuringiensis were <TEX>$1.3{\times}10^5$</TEX>, <TEX>$2.3{\times}10^6$</TEX> and <TEX>$5.2{\times}10^5\;cfu/ml$</TEX> against the 2nd larva of S. litura and <TEX>$1.8{\times}10^4$</TEX>, <TEX>$1.3{\times}10^6$</TEX> and <TEX>$1.5{\times}10^6\;cfu/ml$</TEX> against the 2nd larva S. exigua, respectively. To determine new gene's existence and absence, the plasmid DNA was extracted, and compared to that of B.t. aizawai HD-133. Both B. thuringiensis were not like plasmid DNA pattern. PCR technique was used to predict both plasmid DNA's cry gene. PCR products analysis showed that B.t. CAB109 harbor Cry1Aa, Cry1Ab, Cry1C and Cry1D and B.t. HD-133 has Cry1Aa and Cry1Ab, respectively.

Tannic acid와 Bacillus thuringiensis subsp. kurstaki KB100균주의 혼합처리에 의한 파밤나방 살충활성의 상승효과

Bacillus thuringiensis subsp. kurstaki KB100 isolated from the domestic soil have the most effective activity against the beet armyworm, Spodoptera exigua larva. The tannic acid as protease inhibitor might be increased the efficacy of sublethal concentrations of B. thuringiensis. The tannic acid was identified as a protease inhibitor that could increased the efficacy of sublethal concentrations of B. thuringiensis. Mixture of B. thuringiensis and tannic acid was investigated the mortality of S. exigua larva in the laboratory and field. When B. thuringiensis treated to 2nd larva of S. exigua, mortality was shown 54.4%. However, mixtures of B. thuringiensis with 4 and 40 mM tannic acid were increased mortalities to 2nd larva of S. exigua as 64.0 and 95.5%, respectively. Also, synergy effect of mixture of B. thuringiensis and 40 mM tannic acid was increased the mortality of S. exigua 3rd larva to 93.3%, even though 60.0% mortality with only B. thuringiensis treatment. On the other hand, the mortality of mixture with B. thuringiensis and 80 mM tannic acid was 53.3% lower than B. thuringiensis single treatment. In the welsh onion field, the accumulated mortalities of 3 times replicated with mixture of B. thuringiensis and 40 mM tannic acid were 83.9, 89.4 and 66.8% compare with 61.8, 80.4 and 47.3% as only B. thuringiensis treatment, respectively.

국내 토양으로 분리된 Bacillus thuriniensis subsp. kurstaki CAB133균주의 생물학적 특성

국내의 난방제 해충에 선택적으로 생물활성을 나타내는 균주를 선발하기 위하여 작물재배 지역의 토양으로부터 채취한 115개의 토양샘플 중 46개의 Bacillus thuringiensis 균주를 분리하였다. 이러한 B. thuringiensis균주를 사용하여 난방제 농업해충에 생물활성을 검정한 결과 배추좀나방(Plutella xylostella)에 CAB119을 포함한 35균주, 파밤나방(Spodoptera litura)에는 CAB128, CAB141균주가, 담배거세미나방(Spodoptera exigua)은 CAB133과 CAB159균주가 효과를 나타냈으며 CAB162균주는 3종류의 모든 해충에 높은 활성을 보였다. 분리된 B. thuringiensis CAB133 균주는 H serotype에 의한 혈청학적 동정과 SDS-PAGE를 통한 독소 단백질 패턴에서 B. thuringiensis subsp. kurstaki (3abc)로 동정되었다. 담배거세미나방 2령 유충에 대한 활성검정의 결과 B. thuringiensis subsp. kurstaki (3abc) CAB133, CAB162의 두 균주에 대한 <TEX>$LD_{50}$</TEX> 값은 각각 0.089, <TEX>$3.144{\mu}g/ml$</TEX>로 높은 활성을 나타났다. 담배거세미나방의 령기에 따른 생물실험에서 CAB133 균주 <TEX>$1.5{\times}10^6(cfu/ml)$</TEX>에서 1령의 경우 3일, 2령은 5일에 100%의 사충율을 보였다. 담배거세미나방의 경우 B. thuringiensis를 섭식 후 먹기를 중단하여 성장이 멈추면서 <TEX>$5{\times}7$</TEX>일 후에 사망하였다. 그러므로 B. thuringiensis의 결정성독소단백질<TEX>$(1.267{\mu}g/ml)$</TEX>를 섭식하고 성장하지 못하는 담배거세미나방 유충의 무게는 대조군보다 5일후 약 30배정도 차이로 나타나서 사망하였다. To screen highly active Bacillus thuringiensis isolates against Spodoptera litura (Lepidoptera, Noctuidae), 46 B. thuringiensis was isolated from 115 samples obtained from several crop soils. Especially, B. thuringiensis subsp. kurstaki CAB133 and CAB162 isolates showed 100% mortality against S. litura. <TEX>$LD_{50}$</TEX> values of CAB 133, CAB162 and HD-1 strains of B. thuringiensis subsp. kurstaki were 0.089, 3.144 and <TEX>$0.513{\mu}g/ml$</TEX> against 2nd larva of S. litura, respectively. The weight of 3rd larva of S. litura which were fed crystal inclusion protein <TEX>$(1.267{\mu}g/ml)$</TEX> with B. thuringiensis subsp. kurstaki CAB133 was about 30 times lass than control group. CAB133 and CAB 162 strains of B. thuringiensis subsp. kurstaki which were taken a highly toxity against S. litura were analyzed by SDS-PAGE, and estimated the molecular weight of the Cry proteins. Their serological identification by H serotypes were showed B. thuringiensis subsp. kurstaki (3abc) type.