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BACKGROUND Colorado potato beetle ( CPB) has become the biggest enemy of cultivated potato worldwide. One of the most effective sources of resistance to CPB is Solanum chacoense, an accession with a high leptine glycoalkaloid content. The aim of our study was to assay the repellence and toxicity of S. chacoense, its somatic hybrids ( SHs) and their backcross progenies ( BC1) with potato for CPB adults and larvae. Transgenic S. chacoense, deficient in DNA mismatch repair ( MMR), was also used to produce SHs, in order to increase homeologous recombination and hence introgression of wild-species DNA into the potato gene pool. RESULTS Wild-type SH was highly resistant to CPB. Resistance to CPB of BC1 progenies showed a 1:3 inheritance pattern. MMR-deficient SHs performed better in the resistance analysis. Most MMR-deficient SHs had a similar toxicity as S. chacoense and an intensely repellent effect on CPB adults. Resistance of SHs and BC1 clones may be attributed to leptine biosynthesis, which was confirmed using a RAPD marker. CONCLUSION This is the first report of SHs and their progenies exhibiting both antibiosis and antixenosis against CPB. Resistant SHs are an important step forward in combating this voracious pest of potato. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

1. Maternal and offspring diet effects on life-history traits of the bird cherry-oat aphid Rhopalosiphum padi were tested on three wheat varieties. Using nine reciprocal combinations of wheat varieties, the effects of previous experience (maternal diet effect) on the aphid's response to resistant and susceptible varieties (offspring diet effect) were tested. Batis was susceptible, and Xiaoyan22 and Ww2730 were both resistant, but with different mechanisms. 2. Aphids produced the most alatae in the treatments with the most resistant maternal diet variety Xiaoyan22. The fecundity ( F) and intrinsic rate of increase ( rm) of these alatae were at their greatest in the most resistant offspring diet variety, but these traits were not influenced in the apterae. 3. There were significant interactions in the alatae production and apterae life-history traits, such as rm, development time, weight gain, and mean relative growth rate, between the maternal and offspring diet varieties. The interactions in apterae responses between varieties, some of which were reciprocal, indicated phenotypic plasticity in these parthenogenetic aphids. 4. Rhopalosiphum padi produced more alatae on the most resistant variety; the alatae would disperse and were more fecund. The growth responses of the apterae showed phenotypic plasticity to the different combinations of maternal and offspring diet varieties. The phenotypic plasticity would allow R. padi to better utilise the variable environments represented by the small wheat plots of different varieties in China. [ABSTRACT FROM AUTHOR]

1 Previous feeding by herbivores may influence the performance of other herbivores by altering the morphological and physiological properties of the shared host. 2 The present study aimed to examine the fitness of the apterous aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae) when fed spring wheat that was previously attacked by the leafhopper Psammotettix alienus Dahlbom (Hemiptera: Cicadellidae), with an evaluation of the differences in aphid weight (WD), development time (D), mean relative growth rate (MRGR), daily production of nymphs (MDNP) and intrinsic rate of population increase (rm) under controlled greenhouse conditions. 3 For the S. avenae reared on the two spring wheat cultivars that were previously infested with P. alienus, the WD and the MRGR decreased significantly. The S. avenae reared on the previously infested cv. Leguan had significantly prolonged D values and a lowered rm, whereas these parameters did not differ significantly when S. avenae was reared on the cv. Bobwhite. 4 Overall, the fitness of the aphid S. avenae was adversely affected when reared on the two spring wheat cultivars that were previously infested with P. alienus. [ABSTRACT FROM AUTHOR]

Eight isolates from different potato growing regions in Vietnam were characterized. All were highly pathogenic in some potato cultivars, but did not overcome the extreme resistance of Solanum stoloniferum and Solanum demissum. RT-PCR analysis revealed that all of these isolates are recombinants. Sequence data for 4 isolates were obtained, and their reaction in potato cultivars harbouring specific N genes was determined. Different phylogenetic analyses of viral sequences confirmed previous results that the recombinant isolates evolved from different parental sequences. One of the Vietnamese isolates investigated had a specific structure. The need for a clear classification of PVYNWi isolates is discussed. [ABSTRACT FROM AUTHOR]

Life tables of brown and green color morphs of the English grain aphid, Sitobion avenae (Fabricius) reared on barley under laboratory conditions at 20 ± 1°C, 65% ± 5% relative humidity and a photoperiod of 16 : 8 h (L : D) were compared. The plants were either: (i) infected with the Barley yellow dwarf virus (BYDV); (ii) not infected with virus but previously infested with aphids; or (iii) healthy barley plants, which were not previously infested with aphids. Generally, both color morphs of S. avenae performed significantly better when fed on BYDV-infected plants than on plants that were virus free but had either not been or had been previously infested with aphids. Furthermore, when fed on BYDV-infected plants, green S. avenae developed significantly faster and had a significantly shorter reproductive period than the brown color morph. There were no significant differences in this respect between the two color morphs of S. avenae when they were reared on virus-free plants that either had been or not been previously infested with aphids. These results indicate that barley infected with BYDV is a more favorable host plant than uninfected barley for both the color morphs of S. avenae tested, particularly the green color morph. [ABSTRACT FROM AUTHOR]