Seasonal Occurrence of Key Arthropod Pests and Associated Natural Enemies in Alabama Satsuma Citrus

Abstract

Six Alabama Satsuma mandarin orchards (four conventionally sprayed and two unsprayed) were surveyed during 2005 and 2006 to determine the population dynamics of arthropod pests and their natural enemies. Twenty-eight arthropod pest species were encountered; the major foliage pests were citrus whitefly, Dialeurodes citri (Ashmead); purple scale, Lepidosaphes beckii (Newman); Glover scale, L. gloveri (Packard); and citrus red mite, Panonychus citri (McGregor). Two distinct population peaks were recorded for citrus whitefly at most locations. The most important direct sources of citrus whitefly mortality were parasitism by Encarsia lahorensis (Howard) and infection by the pathogenic fungus, Aschersonia aleyrodis Webber. In general, all stages of both scale insects (purple scale and Glover scale) were present in the orchards year-round, indicative of overlapping generations; however, the highest densities were recorded during the early season. Citrus whitefly, purple scale, and Glover scale were more abundant on leaves collected from the interior of the tree canopy than in the exterior canopy. Citrus red mite densities were highest in the spring, with populations declining at the start of the summer, and were more abundant in the exterior canopy than in the interior canopy. The most important natural enemies of citrus red mite were predatory mites belonging to several families, of which Typhlodromalus peregrinus Muma (Phytoseiidae) was the predominant species. Major differences were recorded in the relative abundance of different arthropod pest species in the orchards: citrus whitefly, purple scale, and Glover scale predominated in the unsprayed orchards, whereas citrus red mite infestations were more severe in the sprayed orchards. The results are discussed in relation to the possible effect of orchard management practices on abundance of the major pests.

Field Evaluation of Predacious Mites (Acari: Phytoseiidae) for Biological Control of Citrus Red Mite,Panonychus citri(Trombidiformes: Tetranychidae)

“…Two parasitoids were reared from citrus leafminer: Ageniaspis citricola Logvinovskaya (Hymenoptera: Encyrtidae), an endo-parasitoid, and Cirrospilus ingenuus Gahan (Hymenoptera: Eulophidae), an ecto-parasitoid. Widespread epizootic infection by the fungal pathogen, Aschersonia aleyrodis Webber was also recorded on citrus whitefly at most of the locations (Fadamiro et al, 2007).…”

“…The minor (secondary) pests include citrus mealybug (Planoccocus citri Risso), black citrus aphid Toxoptera aurantii Fonscolombe), flower thrips (Frankliniella bispinosa Morgan), green stink bug (Acrosternum hilare Say), and red imported fire ant (Solenopsis invicta Buren). Occasional pests (encountered only sporadically) include broad mite (Polyphagotarsonemus latus Banks), brown soft scale (Coccus hesperidium L.), chaff scale (Parlatoria pergandii Comstock), Florida red scale (Chrysomphalus aonidium L.), and orthopteran pests such as eastern lubber grasshopper (Romalea microptera Beauvois) and American grasshopper (Schistocera Americana Drury) (Fadamiro et al, 2007; Table 1). …”

“…Several species of natural enemies were encountered in Alabama Satsuma orchards including predators, parasitoids, and fungal pathogens (Fadamiro et al, 2007). The most common predators observed in the survey were predatory spiders, green lacewing (Chrysoperla spp.…”

“…CREM is a major pest of Satsuma mandarin in Alabama occurring on both leaf surfaces in moderate to high densities at the majority of the orchards sampled during 2005 and 2006 (Fadamiro et al, 2007). These mites feed on foliage (primarily on mature leaves) when present in low numbers.…”

“…Seasonal occurrence of CREM: CREM can overwinter as eggs or motiles in southern Alabama (Fadamiro et al, 2007). It prefers low relative humidity and moderate temperatures.…”