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Entomopathogenic nematodes (EPN) have good application prospects for the control of the black cutworm, Agrotis ipsilon. In the present study, the effects of isolate, exposure rate, temperature and larval stage on EPN infectivity to A. ipsilon were evaluated. Results of in vitro tests showed that Steinernema carpocapsae Mex and Heterorhabditis indica LN2 were the most virulent and promising species, causing 80.0 and 83.3% mortality, respectively, to the third instar larvae at 25°C and 72 h after infection. Mortality of A. ipsilon caused by the nematodes was significantly affected by EPN exposure rate, temperature and the larval stage. Both S. carpocapsae and H. indica caused greater mortality to the third instar of A. ipsilon at 25°C than at 15, 20 and 30°C. Both EPN isolates also caused higher mortality to the second instar than to the third and fourth instar larvae of A. ipsilon. The field trials of EPN for the control of A. ipsilon also showed that S. carpocapsae Mex and H. indica LN2 reduced the damage caused by A. ipsilon and increased the cabbage yield when compared with the control. Both EPN isolates showed better control effects than cyfluthrin and Bacillus thuringiensis, indicating that these two EPN isolates could be used for sustainable control of A. ipsilon in vegetable fields in China. [ABSTRACT FROM AUTHOR]

The Nipa palm hispid, Octodonta nipae (Maulik) is an important invasive pest of palm trees particularly in Southern China. How this beetle interacts with invading pathogens via its immune system remains to be dissected. Steinernema carpocapsae is a pathogenic nematode that attacks a number of insects of economic importance. The present study systematically investigates the cellular immune responses of O. nipae against S. carpocapsae infection using combined immunological, biochemical and transcriptomics approaches. Our data reveal that S. carpocapsae efficiently resists being encapsulated and melanized within the host's hemolymph and most of the nematodes were observed moving freely in the hemolymph even at 24 h post incubation. Consistently, isolated cuticles from the parasite also withstand encapsulation by the O. nipae hemocytes at all-time points. However, significant encapsulation and melanization of the isolated cuticles were recorded following heat treatment of the cuticles. The host's phenoloxidase activity was found to be slightly suppressed due to S. carpocapsae infection. Furthermore, the expression levels of some antimicrobial peptide (AMP) genes were significantly up-regulated in the S. carpocapsae-challenged O. nipae. Taken together, our data suggest that S. carpocapsae modulates and surpasses the O. nipae immune responses and hence can serve as an excellent biological control agent of the pest., (Copyright © 2018 Elsevier Ltd. All rights reserved.)