Location: Southern Insect Management Research Unit
Title: A novel bioassay to evaluate Beauveria bassiana strain NI8 and the insect growth regulator, novaluron, against Lygus lineolaris on a non-autoclaved solid artificial diet Authors
Submitted to: National Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 11, 2012
Publication Date: N/A
Interpretive Summary: A new method to evaluate the potential of Beauveria bassiana strain NI8 and the growth regulator novaluron (Diamond ®) for tarnished plant bug (TPB), Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae) control was developed using a non-autoclaved solid diet. Diet ingredients include toasted wheat germ, ground lima bean meal, soy flour, yolk chicken eggs, inhibitor and agar. The diet was prepared in one step by blending the ingredients in heated boiled water, and it was suitable for bioassays of TPB from second instar to adult that required continuous observation over a period of several weeks. 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) nymphs had higher growth inhibition (mortality %) than fifth instars (92.5 ± SE 0.04) after ten days of exposure to novaluron. No effects in longevity (days) were observed in adults (21.57 ± SE 0.9) treated with novaluron when compared with control insects exposed to water alone (20.47 ± SE 1.2), but both had highly significant greater longevity than 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 insect to a number of different control agents include beneficial organisms, insect pathogens, and insecticidal toxins being developed for transgenic technologies.
Technical Abstract: Detailed life-tables studies or more quantitative estimates of the impact of control agents on TPB life history require a bioassay option to study the impact of prolonged exposure for weeks following contact with the control agent. This is difficult with plant tissue that must be routinely replaced over the period of the study. Our study with TPB that determined the impact of B. bassiana and novaluron on adults and nymphs was the first bioassay that evaluated control agents against L. lineolaris on solid artificial diet throughout its life cycle.