Histopathology Caused by the Entomopathogenic Fungi,Beauveria bassianaandMetarhizium anisopliae, in the Adult Planthopper,Peregrinus maidis, a Maize Virus Vector

Abstract

The planthopper Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae) is an important vector of maize viruses in tropical and subtropical areas. Planthoppers are biologically controlled with several species of entomopathogenic fungi that have been isolated from these insect pests of rice in Asia. Beauveria bassiana (Balsamo-Crivelli) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) appear to be the most useful against planthoppers because of their ease of mass production, storage, virulence, and application. In the present study, adults of P. maidis infected with B. bassiana and M. anisopliae were observed under light and scanning electron microscopy to characterize morphologically the process of infection and the development of these fungi, prior to and after the death of the host. The hydrophobic conidia of both fungal species were able to attach to all body regions, with a preference for surfaces containing hairs. Few germinated conidia were observed on the insect's body surface at 24, 48, and 72 hr post-inoculation. On the cuticular surface of P. maidis treated with B. bassiana and M. anisopliae, bacillus-like bacteria were observed. These microorganisms could be interacting with fungal conidia, playing a role of antibiosis that will not allow the fungal pathogens to germinate and penetrate. In the colonization events observed in this study, the formation and multiplication of hyphal bodies by both fungal species inside the host's body was noted. The host's whole body was invaded by hyphae between five and six days post-inoculation, and body fat was the most affected tissue.

Infection of silkworm larvae by the entomopathogenic fungus Metarhizium anisopliae

“…On the sixth dpi the larvae began to die and on the seventh dpi all the larvae were dead. These dark spots corroborated previous studies (ALVES, 1998;TOLEDO et al, 2010) and confirmed what is known about the integument of insects being the main route of entomopathogenic fungal entry, including M. anisopliae; the dark spots were the result of fungal germination and penetration in the cuticle through the action of extracellular enzymes and mechanical pressure exerted by hyphae.…”

“…This was related to the availability of nutrients in tissues because, as pointed out by TOLEDO et al(2010), nutrient limitation leads to the formation of hyphae with a smaller diameter. Fatty tissue is another preferential target.…”

“…Figure 1F shows that we detected the presence of M. anisopliae hyphae and blastospores in the lumen of the tracheal system. Tracheae are responsible for aeration and; therefore, form channels of oxygen transport which, in this case, can act as an important distribution system of the pathogen since the spiracles are also sites of pathogen penetration (TOLEDO et al, 2010). Furthermore, SCHRANK & VAINSTEIN (2010) state that the blastospores facilitate dispersal of the fungus, thereby causing generalized infection.…”

Histological changes in the larvae of the domestic mosquito Culex pipiens treated with the entomopathogenic fungus Beauveria bassiana

“…In the colonization events observed by Toledo et al (2010) in the planthopper Peregrinus maidis (Hemiptera: Delphacidae) traited by B. bassiana and Metarhizium anisopliae, the formation and multiplication of hyphal bodies by both fungal species inside the host's body was noted. The host's whole body was invaded by hyphae between five and six days post-inoculation, and body fat was the most affected tissue.…”

Bioesai bioinsektisida Beauveria bassiana dari Sumatera Selatan terhadap kutu putih pepaya, Paracoccus marginatus Williams & Granara De Willink (Hemiptera: Pseudococcidae)

“…Serangga uji yang diaplikasikan bioinsektisida menghasilkan LT 50 sebesar 3-4 hari. Toledo et al (2010) mendapat kecenderungan yang sama karena cendawan butuh waktu untuk berkecambah, mulai dari perkecambahan konidia membutuhkan 24-48 jam, setelah 72 jam tabung kecambah sudah dapat ditemukan pada kutikula integumen serangga inang tersebut.…”