Eight Bacillus thuringiensis strains activated against mosquito larva were compared their characterization. Spherical-shaped parasporal inclusion of B. thuringiensis subsp. tohokuensis CAB167 was observed by phase-contrast microscopy and scanning electron microscopy. LC₅₀ values of B. thuringiensis subsp. tohokuensis CAB167 against Culex pipiens molestus, Culex pipiens pallens, and Aedes aegyti were 173, 190 and 580 ng/㎖, respectively. B. thuringiensis subsp. tohokuensis CAB167 had a parasporal inclusion containing 4 major protein components, for example, 135, 80, 49 and 28-kDa by SDS-PAGE. Otherwise, after trypsin digestion of parasporal inclusion, SDS-PAGE was showed new protease-resistant peptides at 72 and 63-kDa. Activated toxins of isolated CAB167 were different from other reference strains on a serological by immuno-diffusion test.
Bacillus thuringiensis with selected high toxicities against tobacco cutworm, Spodoptera litura were isolated from domestic soils. When being observed under a phase-contrast microscope, the insecticidal crystal proteins were showed a bipyramidal crystal types. New CAB 109 isolate was identified to B. thuringiensis subsp. aizawai in the H serotype. As a results of insecticidal activities between CAB 109 isolate and 3 existing ready-made products against 3rd larva of S. litura, CAB 109 isolate showed 100% mortality with spore concentration (1.3×10⁷ cfu/㎖). It was a very high insecticidal activity compared with a existing ready-made B. t. products. LD₅₀ values of CAB 109 isolate was 9.78×10⁵, 6.87×10⁶ and 1.83×10⁷ cfu/㎖ spore concentration against 2nd, 3rd and 4th larva of S. litura, respectively. Unlike Plutella xyfostella, S. litura was slowly died after application up to 7 days. The weight of S. litura larva applied with CAB 109 isolate were 6-7 times less than controlled group. Even though it didn"t die, it did not grow into next larva. The result observed with scanning electron microscope was that CAB 109 isolate of B. t. aizawai formed a typical bipyramidal crystal protein type. Otherwise, when CAB 109 isolate was examined with SDS-PAGE and with trypsin, there was no difference between CAB 109 strain and ready-made products of B. thuringiensis.
Bioassay of mosquito, Culex pipiens molestus, larva was investigated by several environment-friendly insecticides. These insecticides were Novaluron as chitin synthesis inhibitor, Metho-xyfenozide as ecdysone agonist, Pyriproxyfen as juvenile hormone mimic, and Spiromesifen as lipid biosynthesis inhibitor. The 50% lethal concentration (LC₅₀) of these insecticides were 0.00039, 0.07193, 0.65006 and 0.04839 ppm, respectively. Novaluron has lower concentration than any other insecticide. To determine the treatment time against larval stages, insecticides were applied to different larval stages of C. pipiens molestus. Mortality ratios of mosquito larva treated with Novaluron were 100.0, 84.5, 71.0 and 48.5% on 2, 4, 7 and 10 days after hatching from eggs, respectively. Otherwise, with the other insecticides, mortality ratios were under 80% with 2 days old larva. When exposure periods were tested to 3 or 4 days old larva against 4 insecticides, at least 3 hours were needed to 100% control effect against Novaluron, and over 12 hours with other insecticides.
The multicolored Asian ladybird beetle (Harmonia axyridis) has been commonly used with biological control agents for control of several kinds of aphids in agroecosystems. Also, environment friendly agricultural materials have been commonly applied in crop fields because the government held down pesticide application and environment friendly agricultures are gradually increased with consumer"s desires. The multicolored Asian ladybird beetles may be directly or indirectly under the influence of environment friendly agricultural materials in crop fields. The insecticidal environment friendly agricultural materials (IEFAMs) might be safe against each developmental stage of multicolored Asian ladybird beetle. Fungicidal environment friendly agricultural materials (FEFAMs) had a miner effect to each developmental stage of multicolored Asian ladybird beetle with the exception of FEFAM A. Environment friendly agricultural materials contained useful soil microorganisms (EFAMSMs) C and H might be down the hatching rate of eggs, and EFAMSM A and F had a killing effect to 1st instar of lady beetles. Environment friendly agricultural materials contained plant extracts (EFAMPEs) A and D might be suffered effect a deathblow of egg hatching with lady beetles. Otherwise, there was a miner effect to lady beetles with the rest of tested environment friendly agricultural materials.
Many kinds of environment friendly agricultural materials were used for the insect pest control and the control of plant diseases, furthermore they support the growth of crops in the greenhouses and the kindly environment friendly farming. Phytoseiulus persimilis might be used for control of two-spotted mites with environment friendly agricultural materials at the same time. For testing the toxicity of environment friendly agricultural materials against to P. persimilis, 61 environment friendly agricultural materials were selected by material contents and using methods. When environment friendly agricultural materials were directly sprayed on P. persimilis, IEFAM C, FEFAM A, EFAMSM A, D, EFAMPE A, EFAMCh B, EFAMME A, and EFAMMo C killed over 90%. However, there was no effects to FEFAM C, D, EFAMSM C, EFAML A, EFAMME C, E, H, J, EFAMMo G and I against P. persimilis. P. persimilis adults were not survived in vial for 48 hours after sprayed and dried with the environment friendly agricultural materials, for examples, EFAMSM I, EFAMME A, EFAMMo A, C, and I. Otherwise, EFAMCh C and EFAMMo B were no effects to P. persimilis. Some environment friendly agricultural materials are of different qualities, and consequently test of their toxity have to necessary.
Bacillus thuringiensis strains were isolated from the domestic soil and a strain was selected that had a new host range and high toxicity against agriculture insect pest. The 142 samples of soil were sampled from the mountains, paddy fields and patches, in Daejon, Chungnam, Chungbuk and Jeonbuk and used for the investigation. Sixteen B. t strains were isolated from 12 samples among collected samples. There were 11 strains that showed toxical activity on Plutella xylostella (Lepidoptera: Yponomeutidae), 7 strains on Spodoptera litura (Lepidoptera: Noctuidae), 5 strains on Arcte coerulea (Lepidoptera: Noctuidae), 5 strains on Culex pipiens pallens (Diptera: Culicidae) among the 16 isolated B. t strains. But there were not any strains that showed activity against Hyphanria cunea (Lepidoptera: Arctiidae) and Sitophilus oryzae (Coleoptera: Rhynchophoridae). And also some of B. thuringiensis strains showed insecticidal activity with 2, 3 or 4 kinds of insects. But there were also 3 strains that did not show any activities to the 6 insects which were used in the experiment. When examined with a phase-contrast microscope, the insecticidal crystal protein produced from 16 selected strains had 13 bipyramidal and 3 spherical shapes. The insecticidal bioactivity of the S. litura showed 100% mortality when there were 1.3×10⁷ (cfu/㎖) of CAB109 isolates.
For the biological control of the greenhouse whitefly, aphids, American leaf-miners, Encarsia formosa, Aphidius colemani, Diglyphus isaea, and Dacnusa sibirica were used as biological control factors. Otherwise, many kinds of environment friendly agricultural materials were also used in the kindly environment friendly fanning. For testing the toxicity of environment friendly agricultural materials against to insect parasitoids as biological control factors, 61 environment friendly agricultural materials were selected by using methods and periods with insect parasitoids in the greenhouses. Environment friendly agricultural materials were sprayed to mummies and adults of E. formosa and A. colemani, and adults of Diglyphus isaea and Dacnusa sibirica in laboratory condition. Emergence rates were checked during 12 days after spray to mummies of E. formosa and A. colemani, and survival rates were at 24 and 48 hours after viral test for adult parasitoids, with 10% sugar solution. Emergence rates of E. formosa mummies were inhibited by sprayed the fungicidal environment friendly agricultural material (FEFAM) E and the environment friendly agricultural materials contained molybdenum (EFAMMo) G as 0.4 and 2.7%, respectively. E. formosa adults were not survived in vial for 48hours after sprayed and dried with the environment friendly agricultural materials contained plant extract (EFAMPE) J and the EFAMMo C. The environment friendly agricultural materials contained microelements (EFAMMEs) B and EFAMPE H, environment friendly agricultural materials contained useful soil microorganisms (EFAMSMs) H, FEFAM A and FEFAM D were recorded low survival rates of E. formosa adults with 6.7, 13.3, 13.3, 20.0 and 20.0, respectively. In case of the spraying environment friendly agricultural materials to mummies of A. colemani there were low emergence rate from mummies to adults as around 20s % with water spraying as control. A. colemani adults were not survived in vial with EFAMMo C. EFAMPE J, EFAMPE F, EFAMPE H, EFAMSM H were recorded low survival rates under 20% as 6.7, 13.3, 13.3 and 13.3, respectively. D. isaea and D. sibirica adults were not survived in vial with EFAMPE J. EFAMMo C was 53.3% of survival rates in 48 hours vial tests. D. isaea and D. sibirica were not affected by environment friendly agricultural materials compared with E. formosa and A. colemani.