Plant diseases caused by, or associated with, phytoplasmas occur in hundreds of commercial and native plants, causing minor to extensive damage. Insect vectors, primarily leafhoppers, planthoppers, and psyllids, have been identified for relatively few phytoplasma diseases, limiting the capacity of managers to make informed decisions to protect crops and endangered indigenous plants. In the past two decades our knowledge of insect vector-phytoplasma interactions has increased dramatically, allowing researchers to make more accurate predictions about the nature and epidemiology of phytoplasma diseases. These better-characterized systems also may provide clues to the identity of insect vectors of other phytoplasma-associated diseases. We review the literature addressing the ecology of insect vectors, phytoplasma-insect ecological and molecular interactions, vector movement and dispersal, and possible management strategies with an emphasis on research from the past 20 years.

The production of crops under protected conditions is increasing worldwide. Owing to growing consumer demands for healthy and green produce, and intensifying pesticide resistance, non-chemical solutions--foremost among which is biological control--are being sought. The authors review recent advances related to the application of predatory mites for the control of greenhouse pests, and discuss interactions among acarine biocontrol agents (ABAs) and the effects of crop plants and new technologies on ABAs, such as artificial lighting, elevated carbon dioxide levels and genetically modified organisms. This is followed by a discussion of the problems associated with the search for and use of new ABAs, including management, the benefits of modelling and avenues of future research.

No abstract

This review discusses the economically important pest mites (Acari) of greenhouses, aspects of their biology, and the acarine predators that attack them as well as various insect pests. Greenhouse factors affect pest mites as well as their natural enemy populations and their interactions. Conversely, pest mites affect greenhouse management in terms of the chemical and biological methods required to control their populations. Structure affects heating, cooling, and light, which can be manipulated with suitable screens. Crops often select for pests and their mite enemies. Both groups may be affected in greenhouses by adding pollen and by a CO(2)-enriched atmosphere. These factors impact pest mite populations, the damage they cause, and the methods used to control them. The possibility of incipient evolution occurring in greenhouses, along with the benefits and consequences for pest control, is discussed.

Sweet pepper is now grown, in tropical and subtropical areas, under the integrated pest management (IPM) tactic of 'physical barrier', whereas it was once grown primarily in open fields. This management tactic, when properly employed, has the advantage of eliminating many of the larger open-field pests, and has resulted in greatly increased pepper yields. However, certain other pest populations are exacerbated by this IPM tactic. This paper reviews the primary pests and current control tactics in sweet pepper.

Comparative bioassays of two chloronicotinyl insecticides, acetamiprid and imidacloprid, against the whitefly Bemisia tabaci (Gennadius), using foliar and systemic applications, were conducted under laboratory conditions and in field trials. Under controlled conditions, the ovicidal activity of foliar applications of acetamiprid on cotton seedlings was much higher than that of imidacloprid. According to LC50 and LC90 values, acetamiprid was 10- and 18-fold more potent than imidacloprid. Both compounds were effective when applied to soil against whitefly adults; however, the potency of imidacloprid was somewhat higher than that of acetamiprid 2, 7 and 14 days after application; resulting (with the concentration of 25 ml a.i./l) in adult mortality of 90, 93, and 96% and 76, 84, and 76% respectively. In an experimental cotton field, the efficacy of foliar applications of 60 g a.i./ha acetamiprid and 210 g a.i./ha imidacloprid was compared. Field residual activity of acetamiprid to whitefly adults lasted for approximately ten days, compared with three days for imidacloprid.

Hyalesthes obsoletus Signoret (Homoptera: Cixiidae) is a polyphagous planthopper that transmits stolbur phytoplasma (a causative agent of "yellows" disease) to various weeds, members of the Solanaceae, and wine grapes (Vitis vinifera L.) in Europe and the Middle East. Planthoppers were collected by hand vacuuming eight native plant species. Vitex agnus-castus L., a shrub in the Verbenaceae, hosted the largest number of H. obsoletus, although Olea europaea L. also served as a host for adults. Using a Y-olfactometer, we compared the planthoppers relative preference for V. agnus-castus, Convolvulus arvensis, and V. vinifera. V. agnus-castus was more attractive to both male and female H. obsoletus than the other plants. H. obsoletus antennal response was stronger to volatiles collected from V. agnuscastus than from Cabernet Sauvignon variety of V. vinifera. To determine if V. agnus-castus would serve as a reservoir for the pathogen, H. obsoletus were collected from leaf and stem samples of native V. agnus-castus, and were tested by polymerase chain reaction (PCR) for the presence of phytoplasma DNA. While 14% and 25% (2003 and 2004, respectively) of the insects tested positive for phytoplasma DNA, none of the plant samples tested positive. To determine if V. agnus-castus could serve as a host plant for the development of the planthopper, we placed emergence cages beneath field shrubs and enclosed wild-caught H. obsoletus in a cage with a potted young shrub. We found adult H. obsoletus in the emergence cases and planthopper nymphs in the soil of the potted plant. We concluded that V. agnus-castus is attractive to H. obsoletus, which seems to be refractory to phytoplasma infections and warrants further testing as a trap plant near vineyards.

No abstract