Summary1. Herbivore attack induces plants to mobilize chemical defences, including the release of volatiles that attract natural enemies of the herbivore. This commonly involves the jasmonic acid (JA) pathway. However, phloem-feeding whiteflies specifically trigger salicylic acid (SA)-signalling, thereby suppressing JA-based defences and enhancing host plant suitability. 2. Here, we show with Arabidopsis thaliana plants that the whitefly parasitoid Encarsia formosa outsmarts this apparent host plant manipulation by exploiting the SA-triggered emission of b-myrcene. Assays with various Arabidopsis mutants and phytohormone and gene-expression analyses reveal that the whiteflies induce the accumulation of endogenous SA, thereby enhancing the expression of SA-regulated genes, one of which encodes ocimene/myrcene synthase, which resulted in the recruitment of parasitoids under greenhouse conditions. Performance assays confirmed that whiteflies directly benefit from suppressing JA-based defences. 3. Taken together, we conclude that by activating SA-signalling whitefly feeding suppresses direct, JA-based defences, but that parasitoids can adapt to this by exploiting specific, SA-induced volatile emissions for host location. 4. Our work further confirms that herbivory contributes to selective pressure governing the evolution of inducible volatile signals as indirect plant defences.

The striped flea beetle, Phyllotreta striolata (F.) (Coleoptera: Chrysomelidae), is an economically important pest on crucifer vegetables worldwide. Twenty isolates of entomopathogenic nematodes (EPNs) (Rhabditida: Steinernematidae and Heterorhabditidae) were evaluated against soil-dwelling stages of the flea beetle in the laboratory. The corrected mortalities and reproduction rates at a concentration of 36 infective juveniles (IJs) cm -2 surface area of sand against third instars of the pest greatly differed among the tested isolates, ranging from 6.7% to 100%. When tested over a range of temperatures from 15°C to 35°C, 25°C was found to be the optimal temperature for four selected nematode isolates (Steinernema carpocapsae All, Steinernema pakistanense 94-1, Heterorhabditis indica LN2 and H. indica 212-2) to infect the third instar and reproduce in the cadavers. S. pakistanense 94-1 and H. indica 212-2 showed markedly greater heat-tolerance compared to S. carpocapsae All and H. indica LN2. Corrected mortalities and reproduction rates increased as the concentration of IJs increased from 4 to 36 IJs cm -2 . The LC 50 values of S. carpocapsae All, S. pakistanense 94-1, H. indica LN2 and 212-2 were 17.1, 15.5, 6.5 and 5.9 IJs cm -2 , respectively. The third instars larvae and pupae of P. striolata were more susceptible to the four nematode isolates than the first and second instars. Higher pathogenicity and greater heat tolerance and reproduction potential makes H. indica 212-2 the most promising candidate for the biological control of P. striolata under the field conditions of South China.

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We measured developmental time and survival rate of the immature stages as well as longevity and fecundity of the adult stage of sweetpotato whitefly, the B biotype of Bemisia tabaci, on seven marginal host plant species (defined as species on which the B biotype occurred occasionally in the field). Although causing little damage in the field, B. tabaci can exploit all of the marginal plant species as hosts. Solanum tuberosum, Lablab purpureus and Helianthus annuus can be regarded as preferred hosts compared to the other four. Our results revealed that most mortality occurs in the younger nymph stages of B. tabaci on the host plant species. Oviposition preference was not correlated with feeding preference. The shortest developmental time of B. tabaci was found on L. purpureus and H. annuus, and the highest survivorship and fecundity were observed on S. tuberosum and L. purpureus, respectively. The discrepancies are indicative of different strategies by B. tabaci in adjusting to novel host plants. Our findings provide a valuable basis for understanding the field population dynamics of B. tabaci, biotype B.

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Flexspline frictional degradation causes failure of harmonic drives. This study focused on the improvement of the flexspline tribological properties. Flexspline material 40Cr was modified with a robust polydimethylsiloxane (PDMS) coating. Etched and chemically modified films were utilized to enhance the organic PDMS coating–substrate link strength. Comparing modified and unmodified 40Cr, the surface friction coefficient decreased by 82.2%. Moreover, the modified 40Cr exhibited excellent load-bearing properties. The effects of speed and lubricant–coating interaction on the tribological properties were verified. This study provides an essential theoretical basis for improving the tribological performance of harmonic drives via soft coating modification.