Induction of 2-cyanoethyl-isoxazolin-5-one as an antifeedant against the tobacco cutworm (Spodoptera litura) by jasmonic acid in sweet pea leaf.

Although sweet pea (Lathyrus odoratus) beans contain toxic ß-aminopropionitrile, the plant itself is readily attacked by insects and is, therefore, protected through the use of pesticides. Consequently, the induction of L. odoratus resistance to insect attack via exogenous treatment is promising for pest control development. Screening of inducible elicitor effects showed that treatment of sweet pea foliage with jasmonic acid (JA) can induce antifeeding-based resistance to tobacco cutworm (Spodoptera litura) larvae. Spectroscopic analysis identified 2-cyanoethyl-isoxazolin-5-one (2-CEIX) as the antifeedant with a half-maximal effective concentration of 33.6 µmol/g fr. wt., i.e., exogenous JA treatment induced antifeeding activity due to the accumulation of 2-CEIX. Moreover, 2-CEIX-induced mortality of S. litura larvae was evaluated by a dipping test and the half-maximal lethal dose was determined to be 5.9 mg/mL. Therefore, 2-CEIX was concluded to be a suitable induced resistance target for elicitors or a lead compound for insecticide development.

Effect of food thickener and jelly wafer on the pharmacokinetics of levofloxacin orally disintegrating tablets.

This study was designed to determine the effects of a food thickener and deglutition aid jelly for oral administration, jelly wafer, on the pharmacokinetics of levofloxacin orally disintegrating tablets. With an increase in immersion time, the disintegration time of levofloxacin orally disintegrating tablets immersed in food thickener was prolonged, whereas that of the tablets immersed in jelly wafer was shortened. The dissolution behavior of non-immersed levofloxacin orally disintegrating tablets was not similar to that of tablets immersed in food thickener, but was similar to that of tablets immersed in jelly wafer. The time to reach the maximum systemic levofloxacin concentration was the same for non-immersed orally disintegrating tablets and tablets immersed in food thickener and jelly wafer. Moreover, there was no significant difference in the maximum concentration after administration between non-immersed orally disintegrating tablets and tablets immersed in food thickener or jelly wafer. These findings suggest that drugs with a high bioavailability, such as levofloxacin, enter the systemic circulation even when administered with a food thickener or jelly wafer.

Lethal male combats in Schizotetranychus brevisetosus (Acari: Tetranychidae) on blue Japanese oak (Quercus glauca).

Male spider mites (Acari: Tetranychidae) guard preimaginal quiescent females to reserve paternity. In a few species of Stigmaeopsis that make densely woven silky nests on the surface of host plants, mature males attack and even kill rivals to gain their rights to inseminate young females in the nest. Here we report that the adult males of Schizotetranychus brevisetosus (Acari: Tetranychidae), whose web nest construction behavior evolved independently from Stigmaeopsis spp., also exhibit highly aggressive behavior towards one another. Combat mortality was measured in an experimental design where two males in the treatment group were forced to live in a nest made by adult females on a leaf arena, while one male in the control group was allowed to live in a nest on another arena. We found that the 5-day mortality of males in the treatment group (56 and 37 % in two replicates) was significantly higher than in the control group (9 and 12 %) and that lethal combats frequently arose in the treatment group. However, we found no consistent trend for the length of the first legs, which is known to affect the outcome of battle in Tetranychus urticae and Stigmaeopsis miscanthi. This might be due to a relatively small number of measurable specimens, and the effects of body size should be explored in future studies.

Reproductive isolation between Stigmaeopsis celarius and its sibling species sympatrically inhabiting bamboo (Pleioblastus spp.) plants.

Stigmaeopsis celarius Banks (hereafter Sc) is a spider mite living and feeding on the leaves of various bamboo species such as Moso bamboo [Phyllostachys edulis (=P. pubescens)] and Pleioblastus spp. (Poaceae). A previous phylogenetic study revealed a cryptic, phylogenetic sister species to Sc (hereafter Ss). Although its life type appears to be similar to that of Sc, individuals of Ss make much smaller nests compared with Sc, and the nests have been found mostly on Nezasa bamboo (Pleioblastus argenteostriatus). To investigate whether Sc and Ss are reproductively isolated, we explored their populations in southwestern Japan, and crossed them to examine mating behaviors and fertilization success. Field surveys revealed that the nests of these two species occur on the same leaves and, thus, the individuals of these species may make frequent contact. Reciprocal crosses suggested that the two species are reproductively isolated. Though Sc males have tried to mate with Ss females, copulation seldom occurred because of their long opisthosoma (hind body), which prevented the insertion of the aedeagus into the genitalia of Ss females. In contrast, most Ss males ignored Sc females, and eggs were not fertilized even in the few cases where copulation appeared to occur. These results suggest that strong selection pressure is imposed on body length to prevent interspecific hybridization in the contact area of these species.

Relationship between body colour, feeding, and reproductive arrest under short-day development in Tetranychus pueraricola (Acari: Tetranychidae).

In Tetranychus spider mites (Acari: Tetranychidae), diapausing females have a conspicuous orange body colour, which is used as an indicator of diapause induction in many laboratory studies. However, to which extent body colour reflects reproductive activity is scarcely investigated. In this study, we investigated the relationship between body colour, reproductive arrest, and food intake in the inbred strain of T. pueraricola individually reared at 20 °C with a 10:14 h light: dark photoperiod. Our results showed that (1) body colour is a good indicator of reproductive arrest 11 days after adult emergence but does not completely reflect reproductive status at an earlier age; (2) even orange females intermittently feed, and the arrest of feeding comes after the change in body colour; and (3) reproducing females have a higher risk of death than non-reproducing females. These results suggest that measurement of diapause incidence by body colour alone may miss the variation in reproductive status in early adult life.

Host suitability of house fly, Musca domestica (Diptera: Muscidae), pupae killed by high or low temperature treatment for a parastoid, Spalangia endius (Hymenoptera: Pteromalidae).

The objective of this study was to establish a high quality progeny production system for the house fly parasitoid, Spalangia endius (Hymenoptera: Pteromalidae), by stockpiling hosts. We performed two host killing methods before host storage: (i) heat-killed by 30 min exposure to 50°C or (ii) freeze-killed by 10 min exposure to -80°C. The average number of parasitoids that emerged from nonstored house fly pupae after heat- or freeze-killing was not significantly different from live pupae. When house fly pupae stored at -20°C after heat-killing were supplied to S. endius, progeny production was significantly less than live pupae. Moreover, productivity became very low when house fly pupae refrigerated at 3°C after heat- or freeze-killing were supplied to S. endius. On the other hand, when house fly pupae stored at -80°C for 1 year after heat-killing were supplied to S. endius, the average number of parasitoids that emerged was not significantly different from live pupae. The average number of parasitoids that emerged from freeze-killed hosts kept for more than 8 weeks at -80°C was significantly fewer than live pupae. Thus, this study clarified that a higher-quality host can be maintained not only by simply storing at -80°C but also by adding heat treatment before storage.

Analysis of genetic variation and phylogeny of the predatory bug, Pilophorus typicus, in Japan using mitochondrial gene sequences.

Pilophorus typicus (Distant) (Heteroptera: Miridae) is a predatory bug occurring in East, Southeast, and South Asia. Because the active stages of P. typicus prey on various agricultural pest insects and mites, this species is a candidate insect as an indigenous natural enemy for use in biological control programs. However, the mass releasing of introduced natural enemies into agricultural fields may incur the risk of affecting the genetic integrity of species through hybridization with a local population. To clarify the genetic characteristics of the Japanese populations of P. typicus two portions of the mitochondrial DNA, the cytochrome oxidase subunit I (COI) (534 bp) and the cytochrome B (cytB) (217 bp) genes, were sequenced for 64 individuals collected from 55 localities in a wide range of Japan. Totals of 18 and 10 haplotypes were identified for the COI and cytB sequences, respectively (25 haplotypes over regions). Phylogenetic analysis using the maximum likelihood method revealed the existence of two genetically distinct groups in P. typicus in Japan. These groups were distributed in different geographic ranges: one occurred mainly from the Pacific coastal areas of the Kii Peninsula, the Shikoku Island, and the Ryukyu Islands; whereas the other occurred from the northern Kyushu district to the Kanto and Hokuriku districts of mainland Japan. However, both haplotypes were found in a single locality of the southern coast of the Shikoku Island. COI phylogeny incorporating other Pilophorus species revealed that these groups were only recently differentiated. Therefore, use of a certain population of P. typicus across its distribution range should be done with caution because genetic hybridization may occur.

Specific accumulation of gamma- and delta-tocotrienols in tumor and their antitumor effect in vivo.

In contrast to extensive studies on tocopherols, very little is understood about tocotrienols (T3). We evaluated the antitumor activities of gamma-T3 and delta-T3 in murine hepatoma MH134 cells in vitro and in vivo. We found that delta-T3 inhibited the growth of MH134 cells more strongly than gamma-T3 by inducing apoptosis. In C3H/HeN mice implanted with MH134, it was found that gamma-T3 and delta-T3 feeding significantly delayed tumor growth. On the other hand, both T3 had no significant effect on body weight, normal-tissue weight and immunoglobulin levels. Intriguingly, we found that T3 was detected in tumor, but not in normal tissues. These results, to our knowledge, are the first demonstration of specific accumulation of gamma-T3 and delta-T3 in tumors and suggest that T3 accumulation is critical for the antitumor activities of T3.