Pathogenic differences of the entomopathogenic fungus Isaria cateniannulata to the spider mite Tetranychus urticae (Trombidiformes: Tetranychidae) and its predator Euseius nicholsi (Mesostigmata: Phytoseiidae)

Abstract

Isaria cateniannulata and Euseius nicholsi are two important biological control agents currently being used in many areas of China to control a variety of pests. In order to determine the possibility of a concomitant application with the two agents in a biocontrol program involving the two-spotted spider mite, Tetranychus urticae, we quantified the pathogenicity of a strain of I. cateniannulata (08XS-1) against females of both T. urticae and E. nicholsi. We observed the infection process using scanning electron microscopy and fluorescence microscopy to distinguish differences in fungal performance. The female mites were infected by I. cateniannulata at 2 × 107 conidia/ml. The mortality of T. urticae was 100% when treated with submerged conidia and 92% when treated with aerial conidia (spray), and that of E. nicholsi was 4.2 and 6.7%, correspondingly. Following infection with aerial or submerged conidia, mated E. nicholsi females displayed no significant differences between treatments and control, indicating the fungus had no obvious effect on their vitality and fertility. This demonstrates that I. cateniannulata is safe to E. nicholsi when used to control T. urticae. The two types of propagules of I. cateniannulata are readily produced by common culture, and the submerged conidia, because of their substantially higher mortality, are preferable to the aerial conidia. Our results indicate that I. cateniannulata and E. nicholsi are viable candidates to be concomitantly applied in the biocontrol programs of T. urticae.

The Colonization and Effect of Isaria cateinannulata on Buckwheat Sprouts

“…Cui et al found that higher concentrations and longer residue times of B. bassiana on maize leaves could result in significant impacts on physical indexes such as plant height, leaf length, and leaf width of maize [ 55 ]. Zhang et al found that I. cateniannulat attached to the surfaces of vegetable leaves could continuously provide protection against Tetranychus urticae for over 10 days [ 15 ]. Wakil et al found that the integrated application of endophytic colonized B. bassiana and B. thuringiensis might be an effective approach against H. armigera [ 68 ]; Qayyum et al found that the endophytic colonization of B. bassiana had an effective strategy to control H. armigera in tomatoes [ 69 ].…”

“…Submerged conidia were then prepared in suspension, with conidia concentrations being measured via hemocytometer and adjusted to 2 × 10 6 conidia/mL using sterile water. The viability of the submerged conidia was confirmed to be >90% on PD at >90% relative humidity [ 15 , 16 , 17 , 18 ].…”

“…A working solution was freshly prepared for each experiment by adding 35 μL of FDA liquid to 4 mL of deionized water. Samples were maintained on ice, protected from light [ 15 ] and were stored at 4 °C for up to 6 months protected from light [ 25 ].…”

“…Isaria cateniannulata (Liang) Sanmson & Hywel-Jones (Hypocreales: Clavicipitaceae), also known as Paecilomyces cateniannulatus or Cordyceps cateniannulata [ 12 , 13 , 14 ], is an important pathogenic fungus of insects that has been utilized for the biocontrol of agricultural and forestry pests [ 15 , 16 , 17 , 18 , 19 , 20 , 21 ]. Recently, some scholars have found that it can promote the growth of buckwheat, tomato, tobacco, and so on [ 22 , 23 , 24 , 25 ], but the method of to colonizing plants and promoting plant growth has not been explored yet.…”

Isolation and Identification of The Fungal Pathogen Aspergillus aflatoxiformans Strain and Its Role in Controlling The Two-Spotted Spider Mite Tetranychus urticae (Koch) عزل وتعريف المسبب المرضي Aspergillus aflatoxiformans ودوره في مکافحة أکاروس العنکبوت الأحمر ذي البقعتين Tetranychus urticae (Koch)

“…Moreover, Zhang et al 2018 observed that the entomopathogenic fungus Isaria cateniannulata caused high mortality to T. urticae (100%) using dipping method while it recorded 92% in spraying method and didn't cause any effect on its predator E. nicholsi females, or any apparent effect on their fertility and vitality. Therefore, I. cateniannulata is safe to E. nicholsi when applied in the biocontrol programs of T. urticae.…”