A single semi‐synthetic diet with improved antimicrobial activity for mass rearing of lepidopteran insect pests of cotton and maize

Abstract

Helicoverpa armigera (Hübner), Earias vittella (Fabricius), Spodoptera litura (Fabricius), Spodoptera exigua (Hübner) (all Lepidoptera: Noctuidae), Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) are the major pests of cotton and maize. Mass‐rearing of these insects under controlled conditions is necessary to obtain the numbers needed to conduct bioassays to screen insecticides, proteins, and other compounds, as tools for insect pest management. We present a diet suitable for rearing the six lepidopteran pests (five cotton and one maize pest). We further show that this diet is on par with or superior to the published diet recipes for each of the insect species, which were studied for three generations. We also discuss the advantages of antimicrobials other than formalin for keeping microbial growth under check. A combination of antimicrobial solution and benomyl provided effective control and suppressed the growth of microbes for a longer period than a formalin‐containing diet. A common diet for six pests provide opportunities for automation of diet preparation in addition to improved throughput and consistency in the process, while eliminating diet‐batch related errors.

The effect of streptomycin on survival, development, and some biochemical aspects of Drosophila melanogaster

“…Streptomycin has been commonly used for improving the nutritional quality of artificial diets to mass rearing of model insects including Corcyra cephalonica (Pyrallidae: Lepidoptera), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), Spodoptera litura (Lepidoptera: Noctuidae), Spodoptera exigua (Lepidoptera: Noctuidae), Rhynocoris marginatus (Hemiptera: Reduviidae) for various purposes at laboratory condition (Sahayaraj and Balasubramanian, 2016;Nair et al 2018;Arun Kumar et al, 2018;Huynh et al 2019). In the case of struggle with microbial contamination in mass rearing of insects, the right proportion of antibiotic agents in artificial diets should be able to prevent microbial contamination but not exert or have less detrimental effects on host insect (Thakur et al 2016;Nair et al 2018;Huynh et al 2019;. Recent studies pointed out that the high concentration of antibiotics increased the mortality rate and prolonged development time of insect through the changing physical and chemical properties of artificial diets (Büyükgüzel and Kalender, 2009;Lin et al, 2015;Aslan et al 2019).…”

“…Several antibiotic agents have been used for mass rearing of model insects in aim to prevent microbial contamination on artificial diets. While insects can able to tolerate applied antibiotic agents in various ways related to dietary concentrations, the right proportion of additional antibiotics on artificial diets should be able to prevent microbial contamination but not exert their negative effects on the insect (Thakur et al, 2016;Nair et al 2018;Huynh et al 2019;. Streptomycin, an aminoglycoside antibiotic, have been used to treat bacterial infections such as tuberculosis, Mycobacterium avium complex, endocarditis, brucellosis, Burkholderia infection by the inhibiting protein synthesis through binding 30S subunit of the ribosome in a broad range of gram-negative bacteria (Kohanski et al, 2010, Holzgrabe et al, 2011Van and Coenye, 2017).…”

“…Antibiotics that are applied to the artificial diet of insects exert their bactericidal effects via the production of reactive oxygen species (ROS) regardless of their molecular action (Büyükgüzel and Kalender 2009;. Because of the maintaining physiological balance between ROS production and antioxidant activity is a key process to the avoiding from destructive impacts of oxidative stress, the enzymatic antioxidant activity of the host provides an essential index for the defining physiological changes of model organisms exposed to antibiotics (Büyükgüzel and Kalender, 2007;Hyršl et al, 2007;Sahayaraj and Balasubramanian, 2016;Huynh et al, 2017;Nair et al, 2018). Insects have also an antioxidant system that protects themselves from the destructive impact of oxidative stress (Güneş and Büyükgüzel, 2017;Aslan et al, 2019;Stanley and Kim, 2020).…”

Insects in production – an introduction

“…Next to beneficial effects, microorganisms can be neutral or detrimental to insect fitness and health. As such, they may be exploited for improving insect rearing, but also form a threat for infections and diseases in insect monocultures (e.g., Nair et al, 2019). In particular, large monocultures increase the risk of pathogenic infections and some devastating outbreaks of diseases in insect mass cultures have been reported (reviewed by Eilenberg et al, 2015).…”

Introduction: host plant choice and feeding ecology of insects

“…Developing such an artificial diet or medium is challenging, and it gets even more challenging when multiple pests are involved. In the last paper of this issue, Nair et al (2019) describe the development of a semi-synthetic diet with enhanced antimicrobial activity that could be used to rear six lepidopteran species from three families (Crambidae, Gelechidae, and Noctuidae). As they point out, development of such a diet could have significant implications for mass rearing, and mass rearing of these insects is critical for numerous screening platforms.…”