High-Throughput Feeding Bioassay for Lepidoptera Larvae

AbstractFinding plant cultivars that are resistant or tolerant against lepidopteran pests, takes time, effort and is costly. We present here a high throughput leaf-disk consumption assay system, to screen plants for resistance or chemicals for their deterrence. A webcam capturing images at regular intervals can follow the feeding activities of 150 larvae placed into individual cages. We developed a computer program running under an open source image analysis program to analyze and measure the surface of each leaf disk over time. We further developed new statistical procedures to analyze the time course of the feeding activities of the larvae and to compare them between treatments. As a test case, we compared how European corn borer larvae respond to a commercial antifeedant containing azadirachtin, and to quinine, which is a bitter alkaloid for many organisms. As expected, increasing doses of azadirachtin reduced and delayed feeding. However, quinine was poorly effective at the range of concentrations tested (10–5 M to 10–2 M). The model cage, the camera holder, the plugins, and the R scripts are freely available, and can be modified according to the users’ needs.

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A semi-automated design for high-throughput Lepidoptera larvae feeding bioassays

10.1101/2020.08.02.232256 ◽

2020 ◽

Author(s):

Inoussa Sanane ◽

Judith Legrand ◽

Christine Dillmann ◽

Frederic Marion-Poll

Keyword(s):

High Throughput ◽

European Corn Borer ◽

Large Scale ◽

Time Course ◽

3D Models ◽

R Package ◽

Leaf Disk ◽

Source Image ◽

Corn Borer ◽

Feeding Activities

Lepidopteran pests cause considerable damage to all crops over the world. As larvae are directly responsible for these damages, many research efforts are devoted to find plant cultivars which are resistant against them. However, such studies take time, efforts and are costly, especially when one wants to not only find resistance traits but also evaluate their heritability. We present here a high throughput approach to screen plants for resistance or chemicals for their deterrence, using a leaf-disk consumption assay, which is both suitable for large scale tests and economically affordable. To monitor larvae feeding on leaf disks placed over a layer of agar, we designed 3D models of 50 cages arrays. One webcam can sample simultaneously 3 of such arrays at a rate of 1 image/min, and follow individual feeding activities in each cage as the movements of 150 larvae. The resulting image stacks are first processed with a custom program running under an open-source image analysis package (Icy) to measure the surface of each leaf disk over time. We further developed statistical procedures running under the R package, to analyze the time course of the feeding activities of the larvae and to compare them between treatments. As a test case, we compared how European corn borer larvae respond to quinine, considered as a bitter alkaloid for many organisms, and to Neemazal containing azadirachtin, which is a common antifeedant against pest insects. We found that increasing doses of azadirachtin reduce and delay feeding. However, contrary to our expectation, quinine was found poorly effective at the range of concentrations tested. The 3D printed model of the cage, of the camera holder, the plugins running under Icy, and the R procedures are freely available, and can be modified according to the particular needs of the users.

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Four Species of Noctuid Moths Degrade Sex Pheromone by a Common Antennal Metabolic Pathway

Journal of Entomological Science ◽

10.18474/0749-8004-31.4.404 ◽

1996 ◽

Vol 31 (4) ◽

pp. 404-413 ◽

Cited By ~ 7

Author(s):

Jerome A . Klun ◽

William J. E. Potts ◽

James E. Oliver

Keyword(s):

Sex Pheromone ◽

Trichoplusia Ni ◽

European Corn Borer ◽

Time Course ◽

Fall Armyworm ◽

Cabbage Looper ◽

Beet Armyworm ◽

Corn Borer ◽

Black Cutworm

Z-9-tetradecenyl acetate (Z-9-14:OAc) is a component in the female sex pheromones of the cabbage looper, Trichoplusia ni (Hübner), beet armyworm, Spodoptera exigua (Hübner), fall armyworm, Spodoptera frugiperda (J. E. Smith), and black cutworm, Agrotis ipsilon (Hufnagel). We compared the in vivo catabolism of Z-9-14:OAc in time course fashion after the tritiated compound was applied topically to the antennae of males in the four species. Catabolism of tritiated European corn borer, Ostrinia nubilalis (Hübner), sex pheromone (Z-11-14:OAc) was monitored concomitantly so direct comparisons could be made between the male borer and the noctuid males. Results showed that catabolism of pheromone in all four noctuid moths proceeded along the same hydrolysis-alcohol oxidation pathway as has been observed in the European corn borer male. Catabolism was mathematically modeled with first-order differential equations as a four-compartment degradative system in which tritiated pheromonal acetate was sequentially converted to tetradecenol, tetradecenoic acid and water. The modeling revealed subtle differences in catabolism from one species to another and that most species exhibited a finite capacity to catabolize the pheromone.

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