Mites Inhibiting Guava Trees and Their Dynamics in Relation to Weather Factors and Plant Phenology

Abstract

Surveying mites associated with guava trees (Psidium guajava L.) at Qalyoubia governrate, Egypt indicated the occurrence of main five ones (i.e. the eriophyid, Tegolophus guavae (Boczek), the tenuipalpid, Brevipalpus phoenicis (Ceijskes), the tetranychid, Tetranychus urticae Koch, the phytoseiid, Amblyseius swirskii A.-H. and the stigmaeid, Agistemus exsertus (Gonzalez)). Other six species were present in low numbers. The population dynamics of the main ones in relation to weather factors and guava plant phenology were discussed. Populations of T. urticae peaked in mid-Jun, and Oct. as 183.56 and 172.94 motile stages/leaf, respectively. B. phoenicis was observed at high population level in Jun. and Jul. on fruits and leaves, respectively. T. urticae population peaked in Jun. T. guavae preferred the east side of the tree. Significant relation occurred between mite's populations and temperature increases; while the relation with relative humidity was not significant. The dynamics of the phytophagous mites' population densities (as second trophic level) seemed to follow the plant phenology (specially the leaves). That of the predacious mites seemed to follow their prey dynamics with lag of time. T. guavae population was more significant on upper tree level than middle followed by lower one. Younger leaves and lower surface were preferred to this mite than older ones and upper surface.