Cosmopolites sordidus (Germar) susceptibility to indigenous Cameroonian Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) isolates

Abstract

Management of the banana root borer (BRB), Cosmopolites sordidus (Germar; Coleoptera: Curculionidae), remains a challenge in banana and plantain production worldwide. Synthetic pesticides remain the most widely used solution while mycoinsecticides are increasingly being recommended. In this study, we selected indigenous isolates of Beauveria bassiana and Metarhizium anisopliae collected from plantain fields in Cameroon, and tested them in the laboratory for their viability, pathogenicity and virulence against all C. sordidus life stages. Of 13 isolates initially screened for spore germination and pathogenicity to adult weevils in conidial suspension of 3.2 × 108 conidia/ml, eight isolates with high to moderate germination and highest weevil mortality were selected for dose–response bioassays with four concentrations per isolate: 3.2 × 102, 3.2 × 104, 3.2 × 106 and 3.2 × 108 conidia/ml. The virulent isolates from adult bioassays were tested with eggs, larva and pupae in conidial suspension of 3.2 × 108 conidia/ml. Isolates performance depended on insect life stage with significantly high pathogenicity and virulence against larval, pupa and adult stages. The Beauveria isolate BIITAC6.2.2 caused the highest mortality rates followed by MIITAC1.1.5. Lethal times and lethal concentrations were relatively low for the three M. anisopliae isolates and three B. bassiana isolates which were the best isolates in almost all insect life stages. Apart from being effective in multiple life stages, these isolates were transmitted horizontally from one stage to another when eggs and pupae were treated. The implication of these findings for integrated management of the BRB, and potential biopesticides development and commercialization are discussed.

Biological control in ornamental plants: from basic to applied knowledge

“…Beauveria bassiana infects at least ten species of thrips (Butt and Brownbridge, 1997). Cryptic insects like F. occidentalis that live in flowers do not die immediately after infection, creating the opportunity for further horizontal transmission of the inoculum to different developmental stages (Membang et al, 2020). This horizontal transmission contributes to high combined mortality and mycosis that varies among the isolated ones.…”

Integration of Entomopathogenic Fungi into IPM Programs: Studies Involving Weevils (Coleoptera: Curculionoidea) Affecting Horticultural Crops

“…cf. foveatus [ 92 ], Anthonomus signatus [ 93 ], Cosmopolites sordidus [ 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 ], Cylas formicarius [ 103 , 104 ], C. puncticollis [ 105 ], Heilipus lauri [ 106 ], Hypothenemus hampei [ 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 ], Kuschelorhynchus macadamiae [ 119 ], Odoiporus longicollis [ 120 , 121 , 122 ], Pantorhytes plutus [ 65 ], Pityophthorus juglandis [ 123 ], Rhynchophorus ferrugineus [ 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 ,…”

“…foveatus [ 92 ], C. sordidus [ 145 ], H. hampei [ 111 ] and H. lauri [ 106 ], whilst the opposite result was found with R. ferrugineus [ 126 , 147 , 148 ]. Other studies showed that M. anisopliae and B. bassiana were equally effective in killing C. sordidus [ 95 , 97 , 102 ], C. puncticollis [ 105 ], K. macadamiae [ 119 ], P. juglandis [ 123 ] and R. ferrugineus [ 129 , 134 , 143 ]. The majority of highly virulent isolates and/or the highest conidial concentrations tested in each study resulted in moderate (60–80%) to high levels (>80%) of mortality in the target weevils, except for C. sordidus [ 98 , 100 ], H. hampei [ 115 ] and X. affinis [ 76 ] where only a low level of mortality was obtained.…”

Evaluation of the Entomopathogenic Potential of Beauveria bassiana, Metarhizium anisopliae and Isaria fumosorosea for Management of Cosmopolites sordidus Germar (Coleoptera: Curculionidae)

“…However, the increase in the global ban on most of the synthetic pesticides coupled with the high cost of the pesticides leaves banana farmers with few alternative management options. The possibility of using entomopathogenic fungi (EPF) in the management of BW has been studied in vitro [22][23][24][25] and in the field [26,27].…”