1 Peristenus digoneutis Loan is a parasitoid of Lygus plant bugs, which was successfully introduced from Europe into North America in the 1980s for controlling native Lygus populations. Surveys confirmed that P. digoneutis populations have become established throughout eastern North America and that the spread of the parasitoid continues. For unknown reasons, previous releases of P. digoneutis in Western Canada were not successful. 2 A bioclimate (climex ® ; Hearne Scientific Software Pty Ltd, Australia) model for P. digoneutis in North America was developed, based on climate and ecological parameters, and then validated with actual distribution records. The current distribution of P. digoneutis in eastern North America was consistent with the predicted distribution. The model suggests that P. digoneutis will probably continue its spread westwards throughout the U.S.A. along the Great Lakes. 3 The southern distribution of P. digoneutis is expected to be limited by hot summer temperatures, whereas its northern range is limited by the number of Lygus host generations rather than cold stress. 4 Peristenus digoneutis has the potential to occur in the southern parts of the prairie ecozone of western Canada; however, Ecoclimatic Index values in the prairies indicate mainly marginal or unfavourable conditions, which may explain why earlier releases of P. digoneutis in Western Canada failed.
The ability of bumble bees to disseminate conidia of Beauveria bassiana (Balsamo) Vuillemin from hive-mounted dispensers to greenhouse sweet peppers for the control of tarnished plant bug (TPB) and western Xower thrips (WFT) was investigated in greenhouse trials using large screened enclosures. Samples collected from the enclosures (four treatments) on two sampling dates showed that 97, 90, 91, and 42% of the collected bees, Xowers, leaves, and TPB, respectively, showed detectable densities of B. bassiana on the Wrst sampling date. On the second sampling date, 99, 96, 87, and 30% of collected bees, Xowers, leaves, and TPB, respectively, showed detectable densities of the fungus. Mean mortalities of TPB collected from cages treated with B. bassiana were 34 and 45% compared to 9 and 15% in the controls on the Wrst and second sampling dates, respectively. Mean infection rates of WFT were 40 and 34% compared to 3% in the controls on the Wrst and second sampling dates, respectively. These results indicate that bumble bees are an eVective means of vectoring the fungal conidia to the crop. The pollinator vector technology is a novel example of integrating agro-ecosystem processes of pollination and pest management, that reduces the reliance on insecticides and increases crop yields and quality.
Greenhouse cage trials were conducted to determine the optimal concentration of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) (BotaniGard 22WP 1 formulation) as vectored by the bumble bee, Bombus impatiens (Cresson) (Hymenoptera: Apidae) pollinator for control of greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) on greenhouse tomato, tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae) and green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) on greenhouse sweet pepper. Three inoculum concentrations of B. bassiana: low, 9 9 10 9 ; middle, 6.24 9 10 10 ; and high, 2 9 10 11 conidia g -1 of inoculum and two controls (one with bees and heat-inactivated inoculum, and the other which contained only the host plants and pest species) were tested in a completely randomized block design. Beauveria bassiana killed 18, 54 and 56% of the adult T. vaporariorum and 33, 70 and 67% of the adult L. lineolaris, respectively, at the low, middle and high concentrations; but no infection from B. bassiana occurred in each of the control treatments. Internal infection rates after surface sterilization of the pest insects were 11, 34 and 35% for adult T. vaporariorum, 29, 54 and 58% for adult L. lineolaris, 22, 34 and 30% for nymphal M. persicae and 17, 29 and 32% for nymphal T. vaporariorum, respectively, at the low, middle and high concentrations. Significantly more bumble bees died at the high concentration of B. bassiana (42-45%) than at the other concentrations (9-15%) and the controls (5-7%). Spores of B. bassiana were collected throughout the plant canopy with the greatest numbers sampled from the top third of the canopy [ca. 1,200 colony forming units (CFU) per cm -2 ]. The middle concentration was selected as the optimal concentration because it provided the best pest control with the least impact on the bees.
Both honey bees and bumble bees have been shown to be excellent vectors of biological control agents that suppress pests on various crops. Honey bee and bumble bee hives can be fitted with special dispensers that contain inocula of biological control agents (bacteria, fungi and viruses) that are antagonistic to microbial and fungal plant pathogens and to pest insects. The technology has been used successfully against grey mold on soft and tender fruit (strawberries and raspberries), fire blight on pome fruit (pears and apples), and potentially against sclerotinia on oil seeds (canola). Similarly, viral, bacterial, and fungal pathogens of pest insects, such as corn earworm, pollen beetles, banded sunflower moths, and tarnished plant bugs on alfalfa, canola, and sunflower can be delivered to flowers to help protect the crop while improving yields and crop quality through pollination and reduced chemical pesticide load. The development of the technology requires that the biological control agent be effective against the pest, not harm the pollinating vector, and be environmentally acceptable. This new technology is reviewed and its successes noted.
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