Study of the damage of two-spotted mite Oligonychus spp. on Gliricidia, and characterization of a fungus Rhizopus spp. infecting the mite

Abstract

Mites are severe pests of crops and are difficult to manage when their population is very high supported by the changing environmental conditions. Rising of temperature in the atmosphere may help to increase the population of mites, and therefore, natural mechanisms are needed to be identified to manage such pests and to establish sustainable management tactics. This may minimize unnecessary use of pesticides in the ecosystem. The present qualitative study is carried out to describe the damage of the two spotted mite, Oligonychus sp on the fodder crop, Gliricidia sp. and to characterize the subsequent natural infection of a fungus on this mite. Oligonychus spp with the characteristic two spots on its idiosoma was found damaging on leaves of Gliricidia sp. The chlorophyll in all the leaves of Gliricidia was scrapped out and the leaves looked white/bleached due to severe feeding. The removed exoskeleton of the mite was also found adaxial surface of the leaf. Careful examination of the cadavers of mite at the laboratory revealed an infection of a fungus on Oligonychus sp. fed on Gliricidia leaves. The fungus profusely produced whitish mycelium in PDA. The hyaline, aseptate cottony mycelia produced unique dark sporangiophores and sporangia. Mycosis development was prudent on all stages of the mites and proliferation of mycelium was found on the body of the mites. Subsequent examination in the laboratory confirmed the infectivity of the fungus on the mites. Microscopic examination of aerial growth revealed numerous sporangia-bearing sporangiophores arising directly opposite to the rhizoids. The morphological characteristics of the isolated fungus from the diseased cadavers of Oligonychus sp. mites were used and diagnosed the fungus as Rhizopus sp. This fungal infection on the mite reveals the existence of natural mechanism of control of pests if the ecosystem is undisturbed and suitable environment prevails.