Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2014
Publication Date: 7/1/2014
Citation: Lawrence, S.D., Farrar, R.R., Blackburn, M.B. 2014. Arabidopsis genotypes resistant and susceptible to diamondback moth (Lepidoptera: Putellidea): No net effects on insect growth. Journal of Entomological Science. 49(3):285-289.
Interpretive Summary: The diamondback moth (DBM) is a voracious pest of cole crops, which include broccoli, cabbage and cauliflower, to name a few. Globally over $1.0 billion in estimated annual management costs are spent on DBM control. Recently, several lines of plants that are resistant and susceptible to DBM have been described in the model cole crop Arabidopsis thaliana. The authors measured the amount of leaf remaining after DBM feeding and determined that four times more leaves were consumed of the susceptible plants compared to the resistant ones. We found that visually measuring the amount of leaf eaten was not an accurate measure of the amount ingested by the insect. We measured several other parameters for judging plant resistance to feeding and concluded that there was no effect of the different lines to DBM. This work will be useful for other scientists trying to understand what makes a cole crop resistant to this insect pest.
Technical Abstract: Plutella xylostella (L.), diamondback moth (DBM) is a destructive pest of the Brassicaceae including Arabidopsis thaliana (L.) Heynhold. Ecotypes of Arabidopsis vary in the amounts of leaf area consumed when fed on by DBM, which has been used as a measure of resistance to DBM. Recombinant inbred lines (RILs) were examined by Collins et al. (2010 Plos One 5(4):e10103) and these lines varied in their resistance to DBM as measured by leaf area consumed. In order to further assess these results, the resistant and susceptible RILs were subjected to infestation with third instar DBM larvae for 48hr and several parameters of insect feeding were measured. A strong negative correlation was found between the relative consumption rates (RCR) and efficiency of conversion of ingested material (ECI). For example, while larvae feeding on RIL 162 and 57 consumed the greatest amount of leaf material, the larvae feeding on these varieties had the lowest ECI, which characterizes larval digestive efficiency. As a consequence there was not a significant difference between the lines for larval relative growth rates (RGR). While in the original analysis RIL 162 was judged as susceptible and RIL 57 as resistant (Collins et al. 2010), results of these bioassays show no difference in larval weight following feeding with these Arabidopsis lines. Clearly larvae can compensate for lower quality food by eating more, with no apparent deleterious effect on the larvae. Leaf area consumed alone may not be an ideal parameter for determining insect resistance.