Feeding responses of Helicoverpa armigera and H. assulta to Solanaceae plants were investigated. Among the five plant diets (eggplant leaf, eggplant fruit, tomato leaf, tomato fruit, and tobacco ...leaf) and artificial diet (Insecta LF) tested, H. armigera had the highest preference for eggplant fruit, whereas H. assulta had equal preference for eggplant fruit, insecta LF and tobacco leaf. We also investigated the feeding responses of both species to methyl alcohol extracts of Solanaceae plants. H. armigera had equal preference for the methanol extracts of eggplant fruit, eggplant leaf, tomato fruit and tobacco leaf, whereas H. assulta preferred that of tobacco leaf. These results suggest that the feeding stimulants that exist in Solanaceae plants for H. armigera and H. assulta are slightly different.
The Rice Stem Borer, Chilo suppressalis (WALKER), is a serious pest of rice plants in Asia. In Japan, host plants of are mainly rice plants (Oryza sativa) and the water-oat (Zizania latifolia). Our ...previous study indicated significant differences in insecticide susceptibility and esterase isozyme patterns between the rice-feeding and water-oat-feeding strains. In the present study, the mating time of the two strains was investigated in the laboratory. The mating time was significantly different. The peak of mating time of the rice-feeder was 5h earlier than that of the water-oat-feeder, suggesting that the two strains are reproductively isolated.
Effects of insecticides on the biodiversity in paddy fields were investigated in Tohoku district. Test paddy field (10a) was divided into four areas, i.e., (A) control area; (B) imidacloprid applied ...area; (C) imidacloprid and cycloprothrin applied area; (D) imidacloprid, cycroprothrin, and ethofenprox applied are Imidacloprid, cycloprothrin and ethofenprox were applied on 26 May, 25 June and 29 July in 1998, respectively. Population density of aquatic organisms and natural enemies decreased by the insecticide applications. Particularly, that of C and D areas was affected significantly. On the contrary, the density of pests was siginificantly decreased even in B area. The results suggested that single insecticide application such as imidacloprid is preferable for protecting the biodiversity (natural enemies and aquatic organisms) in paddy fields. if we are forced to control pests by insecticides.
The insecticide susceptibility of the Fall Webworm, Hyphantria cunea and its parasitoid fly, Exorista japonica, was studied. Larvae of H. cunea were hardly susceptible to organophosphorus ...insecticides, such as fenitrothion (LD50=>100μg/larva) and isoxathion (LD50=54μg/larva). However, adults of H. cunea were quite susceptible to fenitrothion (LD50=1.4μg/male and 2.2μg/female). Adults of E. japonica emerging from pupa of H. cunea were very susceptible to fenitrothion (LD50=0.082μg/adult). The results suggest that a judicious choice of insecticide is necessary to control H. cunea, if E. japonica is used as a biological control agent, too.
Distribution of glutathione S-tansferases (GST) activity in insect tissues was studied using 1-chloro-2, 4-dinitrobenzene (CDNB), 2, 4-dinitrophenyl benzenesulfonate (DNPES), 1, ...2-dichloro-4-nitrobenzene (DTNB) and fenitrothion (0, 0-dimethyl 0-3-methyl-4-nitrophenyl phosphorothioate) as substrates. The highest GST activity was found in the Malpighian tubes. CDNB and DNPBS conjugation activities in the American cockroach, Periplaneta americana (Orthoptera: Blattidae), were distributed mainly in Malpighian tubes, fat body, guts nerve cord and testis, while blood and muscle had low activity. Similar results were obtained in the common cutworm, Spodoptera litura (Lepidoptera, Noctuidae) and the rice stem borer, Chilo suppressalis (Lepidoptera: Pyralidae). As for DCNB conjugation activity, each insect showed different distribution patterns among tissues from that of CDNB and DNPBS. Fenitrothion conjugation activity of the American cockroach and the common cutworm was also the highest in Malpighian tubes. Fenitrothion was degradaded mainly by 0-alkyl conjugation.
The rice grasshopper, Oxya yezoensis, shows a three color polymorphism: red, green and brown. To examine the factors regulating adult color polymorphism, crosses between the three color morphs were ...carried out. It was shown that color polymorphism in Oxya yezoensis is partly controlled by genetic factors.
Protein kinase C (PKC)-related cDNA clones encode an 84 kd protein, nPKC. nPKC contains a cysteine-rich repeat sequence homologous to that seen in conventional PKCs (alpha, beta I, beta II, and ...gamma), which make up a family of 77-78 kd proteins with closely related sequences. nPKC, when expressed in COS cells, confers increased high-affinity phorbol ester receptor activity to intact cells. Antibodies raised against nPKC identified a 90 kd protein in rabbit brain extract as well as in extracts from COS cells transfected with the cDNA construct. nPKC shows protein kinase activity that is regulated by phospholipid, diacylglycerol, and phorbol ester but is independent of Ca2+. The structural and enzymological characteristics of nPKC clearly distinguish it from conventional PKCs, which until now have been the only substances believed to mediate the various effects of diacylglycerol and phorbol esters. These results suggest an additional signaling pathway involving nPKC.
We investigated the LD50 values and acetylcholinesterase (AChE) sensitivity to carbamate insecticides in the rice leaf beetle, Oulema oryzae Kuwayama. Resistant populations showed high levels of ...resistance to PHC (>28, 000×), BPMC (135×to 151×) and benfuracarb (21×to 29×). The median inhibition concentration (I50) of carbamates to AChE in resistant populations was clearly greater than in susceptible populations. The acetylcholinesterase insensitivity ratio (IR) values ranged from 634×(benfuracarb) to>20, 000×(PHC and BPMC). Therefore, insensitivity to AChE is an important mechanism in carbamate resistance in the rice leaf beetle.
PDF
