Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2013
Publication Date: 9/1/2014
Citation: Portilla, M., Snodgrass, G.L., Luttrell, R.G. 2014. A novel bioassay to evaluate the potential of Beauveria bassiana strain NI8 and the insect growth regulator novaluron against Lygus lineolaris on a non-autoclaved solid artificial diet. Journal of Insect Science. 14:1-13. Available online: http://www.insectscience.org/14.114.
Interpretive Summary: A non-autoclaved solid diet was used to evaluate the entomopathogenic fungus Beauveria bassiana strain NI8 and the growth regulator novaluron (Diamond ®) for control of the tarnished plant bug (TPB) Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae). The diet was composed of toasted wheat germ, ground lima bean meal, soy flour, yolk chicken eggs, inhibitor and agar. It was prepared in one step by blending the ingredients in heated boiling water. The diet was used to bioassay TPB from the second instar to the adult stage. Fourth instar (97.5 ± SE 0.02), fifth instar (95.0 ± SE 0.03) and adults (95 ± SE 0.03) of TPB were more susceptible (infection %) than second (52.5 ± SE 0.07) and third instar (85.0 ± SE 0.05) to B. bassiana; while, second instar (100), third instar (100) and forth instar (97.5 ± SE 0.02) had higher mortality than fifth instar (92.5 ± SE 0.04) after ten days of novaluron exposure. No effects on longevity (days) were observed in adults (21.57 ± SE 0.9) treated with novaluron when compared with the control (20.47 ± SE 1.2), but longevity was significantly different when compared with adults exposed to B. bassiana (5.2 ± SE 0.2). Adults of TPB were maintained for over a month without changing the diet. The non-autoclaved diet is semi-liquid before it cools which facilitate the mechanics of diet packaging similar to food packaging or lepidopteran diet preparation. The solid artificial diet for Lygus bugs provides improved research capacity for studying the ecology and susceptibility of the insects to a number of different control agents include beneficial organisms, insect pathogens and insecticidal toxins being developed for transgenic technologies.
Technical Abstract: The entomopathogenic fungus Beauveria bassiana and the insect growth regulator novaluron are potential candidates for the control of Lygus lineolaris. Efforts are being made for their use in the Mississippi Delta. B. bassiana and novaluron highly affected TPB survival when they were applied directly to the insects in our test. Both products could be considered to have good potential to control TPB; however, even under laboratory conditions the low susceptibility of early nymphs to B. bassiana and lack of effect of novaluron on adults reduces the effectiveness for TPB control.