Effect of Fungus, Trichoderma harzianumas Probiotic on the Growth, Cocoon Parameters, Silk Characters and Resistance of Silkworms (Bombyx mori) Challenged by Muscardine Disease-Causing Metarhizium

Abstract

INTRODUCTION

Sericulture is one of the promising agricultural industries in the Philippines. However, silk production in the country has dropped in the past decades due to muscardine diseases brought by Metarhizium anisopliae and Bauveria bassiana. This motivated the researcher to determine the effect of Trichoderma harzianum as probiotic on the larva length and weight, pupa weight, cocoon weight, shell weight, and ratio, silk weight, tensile strength and resistance of silkworms (Bombyx mori) challenged by the two fungi.

METHODS

Thirty 3rd instar silkworms were divided into five groups and fed with mulberry leaves treated with varying concentrations (30g, 50g, 70g/, 90g/100mL) of T. harzianum solution and compared with the untreated group. The different parameters were measured at the end of the 1st and the 2nd week of treatment. Another 30 T.harzianum-treated silkworms and 30 untreated silkworms were exposed to M. anisopliae or B. bassiana. The percent of infection was measured.

RESULTS

DMRT at 0.05α revealed that the varying concentrations of T. harzianum increased the weight length, silk weight, and tensile strength as compared to the untreated group. However, the only 90g/100mL of T. harzianum solution increased the pupa weight, cocoon weight, shell weight and shell ratio of the silkworms. The silkworms treated with T. harzianum also obtained 0% and 30% of the infection after exposure to M. anisopliae and B. bassiana as compared to 100% of the untreated group.

DISCUSSIONS

This result might be attributed to the probiotic activity of the T. harzianum which played a significant role in food digestion, which, in turn, influenced the growth and resistance of the silkworm and enabled the silkworm to have a better survival rate under the field condition. Probiotics are microbial food supplements beneficially affecting its host by improving the microbial balance and enhancing the rapid cellular, tissue growth, and development. Probiotics are involved in the digestive utilization of feeds and detoxification of metabolite, as well as the stimulation of the non-specific immune system. Probiotics also have the ability to suppress the growth of pathogens. T. harzianum produce the enzyme used for digesting food and retarding the growth of M. anisopliae and B. bassiana. This study could be a breakthrough in the field of agriculture as it offers a novel probiotic other than the Lactobacilli to enhance the growth of the silkworms, improve the quality of the silk produced and serve as a natural fungicide since commercial fungicides were found to cause colon, breast cancer, and leukemia.