Recent studies have revealed diverse patterns of cytoplasmic incompatibility (CI) induced by Wolbachia in the two spotted spider mite (Tetranychus urticae Koch). The mechanism of CI consists of two steps: modification (mod) of sperm of infected males and the rescue (resc) of these chromosomes by Wolbachia in the egg, which results in female embryonic mortality (FM), male development (MD) or no CI. Our study reports that Wolbachia infections were highly prevalent infecting all T. urticae populations from various crops in 14 commercial greenhouses in Korea, with two Wolbachia strains expressing distinctive phenotypic effects on hosts. Analyses for wsp gene sequences obtained from collected mite populations revealed all sequences were categorized into two groups (group W1 and W2) discriminated by three diagnostic nucleotides while all Wolbachia strains belonged to the subgroup Ori in Wolbachia supergroup B. Host plants of each mite population were also generally correlated this grouping. Various mating experiments with two mite populations from each group showed that CI patterns and host plants of the mite populations were completely matched with the grouping; no CI (mod(-)resc(+)) for group W1 and mixed pattern of FM and MD (mod(+)resc(+)) for group W2. No distinct changes in fecundity or sex ratio due to Wolbachia infections were observed in four mite populations regardless of Wolbachia grouping. Our study suggests a potential correlation between phenotypic effect of Wolbachia infection and its genetic diversity associated with host plants in Korean mite populations.

Thrips palmi Karny, melon thrips was introduced and first recorded in 1993 in Korea. This species has become a serious pest of vegetable and ornamental crops. The CLIMEX simulation was applied to T. palmi to predict its potential geographic distribution in Korea under the Representative Concentration Pathway (RCP) 8.5 climate change scenario. In the CLIMEX simulation, the ecoclimatic index was calculated, and compared in each simulated year and each simulated location. The map comparisons show good agreements between simulated and present distributions of T. palmi, indicating that the CLIMEX model has promising potential for prediction of future distributions of this species in Korea. In the near future, until the year 2020, all the western and eastern parts of Korea show favorable to marginal suitability for T. palmi populations in the fields. After the year 2040, potential distributions shift from no persistence to favorable for establishment and persistence from coastal to interior regions of the Korean peninsula, except for a north-eastern interior region which is the northernmost part of a high mountainous (Baekdu-Daegan) area in Korea. Based on the simulation results, the geographical distribution of T. palmi will expand over its current weather restrictions in the near future under a severe climate change scenario. Thus, pest management measures and strategies should be re-evaluated in Korea, and should include further studies on interspecific competition and ecosystem changes due to climate changes.

The thalamus has been implicated in fear extinction, yet the role of the thalamic reticular nucleus (TRN) in this process remains unclear. Here, in mice, we show that the rostroventral part of the TRN (TRNrv) is critically involved in the extinction of tone-dependent fear memory. Optogenetic excitation of TRNrv neurons during extinction learning dramatically facilitated, whereas the inhibition disrupted, the fear extinction. Single unit recordings demonstrated that TRNrv neurons selectively respond to conditioned stimuli but not to neutral stimuli. TRNrv neurons suppressed the spiking activity of the medial part of the dorsal midline thalamus (dMTm), and a blockade of this inhibitory pathway disrupted fear extinction. Finally, we found that the suppression of dMTm projections to the central amygdala promotes fear extinction, and TRNrv neurons have direct connections to this pathway. Our results uncover a previously unknown function of the TRN and delineate the neural circuit for thalamic control of fear memory.

The spatial distribution of the count of adult greenhouse whiteflies, Trialeurodes vaporariorum (Westwood), on yellow sticky traps was analyzed using Taylor's power law and spatial autocorrelation statistics in the cherry tomato greenhouses from 1998-1999. Samples were collected weekly using a cylindrically shaped yellow sticky trap placed in a 5 by 8 grid covering 0.10-0.15 ha in each of five cherry tomato greenhouses. Taylor's (1961) power law indicated that counts of T. vaporariorum on traps were aggregated within greenhouses. Spatial autocorrelation analysis showed that trap catches were similar (positively autocorrelated) to a distance of 12.5 m, and then dissimilar (negatively autocorrelated) at >12.5 m. Autocorrelation-lag plots showed a globally significant spatial relation in 34 of 57 sample-weeks according to Bonferroni's approximation. The presence of this spatial relation was not related to the changes of mean density. Trap counts at the second lag distance (12.5-25 m) showed little spatial autocorrelation and tended to be the most spatially independent. A fixed-precision-level sequential sampling plan was developed using the parameters from Taylor's power law. The presence of spatial dependency in data sets degraded the sampling plan's precision relative to performance in data sets lacking significant spatial autocorrelation. Therefore, to obtain an unbiased mean density of T. vaporariorum per greenhouse, sticky traps should be placed at least >12.5 m apart to ensure that they are spatially independent.

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