No abstract

Several hundred disinfection byproducts (DBPs) in drinking water have been identified, and are known to have potentially adverse health effects. There are toxicological data gaps for most DBPs, and the predictive method may provide an effective way to address this. The development of an in-silico model of toxicology endpoints of DBPs is rarely studied. The main aim of the present study is to develop predictive quantitative structure–activity relationship (QSAR) models for the reactive toxicities of 50 DBPs in the five bioassays of X-Microtox, GSH+, GSH−, DNA+ and DNA−. All-subset regression was used to select the optimal descriptors, and multiple linear-regression models were built. The developed QSAR models for five endpoints satisfied the internal and external validation criteria: coefficient of determination (R2) > 0.7, explained variance in leave-one-out prediction (Q2LOO) and in leave-many-out prediction (Q2LMO) > 0.6, variance explained in external prediction (Q2F1, Q2F2, and Q2F3) > 0.7, and concordance correlation coefficient (CCC) > 0.85. The application domains and the meaning of the selective descriptors for the QSAR models were discussed. The obtained QSAR models can be used in predicting the toxicities of the 50 DBPs.

No abstract

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a destructive pest on tomato, has invaded most Afro-Eurasian countries. Recently invaded by the pest, most tomato crops in greenhouses and open fields in Tajikistan are currently suffering major damage. While failure in management using chemical insecticide has been frequently observed, alternative options such as biological control is urgently needed. In this study, we evaluated the effectiveness of the common green lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) against T. absoluta. In controlled laboratory conditions, C. carnea showed high predation rate on both T. absoluta eggs (i.e., 36 ± 2 eggs within 24 h and 72 ± 4 eggs within 48 h) and larvae, especially it can attack the larvae both inside and outside the leaf galleries (i.e., an average of 22% of the larvae was killed inside, and an average of 35% was killed outside). In a cage exclusion experiment, T. absoluta showed relatively low larval density in the cages with pre-fruiting release of C. carnea, whereas the larval density was four to six times higher in the “no release” cages. In the “post-fruiting release” cages, the pest population that had already built up during the pre-fruiting stage eventually crashed. In an open-field experiment, the tomato crops in control plots were fully destroyed, whereas low levels of larvae density and damage were observed in the biocontrol plots. Moreover, the field release of C. carnea resulted in significantly higher tomato yield than those without release, despite no differences between the “pre-fruiting release” and “post-fruiting release” treatments. We conclude that the local commercial biocontrol agent C. carnea could be promising for the management of T. absoluta in Tajikistan. It is also one of the first reports showing the management of T. absoluta using a lacewing species. The effectiveness should be validated by further field trials in larger area of commercial crops and various locations.