Insects2016, 7(3), 42; doi:10.3390/insects7030042 (registering DOI) - published 26 August 2016 Show/Hide Abstract
Abstract: The potential of a dry powder co-formulant, kaolin, to improve the control of storage beetles by the entomopathogenic fungus Beauveria bassiana, isolate IMI389521, was investigated. The response of Oryzaephilus surinamensis adults to the fungus when applied to wheat at 1 × 1010 conidia per kg with and without kaolin at 1.74 g per kg wheat was assessed. Addition of kaolin increased control from 46% to 88% at day 7 and from 81% to 99% at day 14 post-treatment. Following this the dose response of O. surinamensis and Tribolium confusum to both kaolin and the fungus was investigated. Synergistic effects were evident against O. surinamensis at ≥0.96 g of kaolin per kg of wheat when combined with the fungus at all concentrations tested. For T. confusum, adult mortality did not exceed 55%, however, the larvae were extremely susceptible with almost complete suppression of adult emergence at the lowest fungal rate tested even without the addition of kaolin. Finally, the dose response of Sitophilus granarius to the fungus at 15 and 25 °C, with and without kaolin at 1 g per kg of wheat, was examined. Improvements in efficacy were achieved by including kaolin at every fungal rate tested and by increasing the temperature. Kaolin by itself was not effective, only when combined with the fungus was an effect observed, indicating that kaolin was having a synergistic effect on the fungus.
Insects2016, 7(3), 43; doi:10.3390/insects7030043 (registering DOI) - published 26 August 2016 Show/Hide Abstract
Abstract: We conducted a laboratory study to determine the impact of ground-applied termiticides on the above-ground foraging behavior of Coptotermes formosanus. Two concentrations (1 and 10 ppm) each of three termiticides, viz. fipronil, imidacloprid and chlorantraniliprole, were tested. After one month post-treatment (fipronil 10 ppm was run for 12 days only and all other treatments were run for one month), fipronil had the lowest percentage of survival (3%–4%) at both concentrations. Termite survival ranged from 31% to 40% in the case of imidacloprid treatments and 10 ppm chlorantraniliprole. However, 1 ppm chlorantraniliprole did not cause significant mortality compared to the controls. Foraging on the bottom substrate was evident in all replicates for all chemicals initially. However, a portion of the foraging population avoided the ground treatment toxicants after several days of bottom foraging. Only the slower-acting non-repellents created this repellent barrier, causing avoidance behavior that was most likely due to dead termites and fungus buildup on the treated bottom substrate. Fipronil appeared more toxic and faster acting at the concentrations tested, thus limiting this repellent effect. Suggestions by the pest control industry in Louisiana that some non-repellents can create a repellent barrier stranding live termites above ground are supported by this laboratory study.
Abstract: Ambrosia beetles tunnel into the heartwood of trees where they cultivate and feed upon a symbiotic fungus. We assessed the effectiveness of flood stress for making Cercis canadensis L. and Cornus florida L. trees attractive to attack as part of insecticide and fungicide efficacy trials conducted in Ohio and Virginia. Since female ambrosia beetles will not begin ovipositing until their symbiotic fungus is established within the host, we also assessed pre-treatment of trees with permethrin, azoxystrobin, and potassium phosphite on fungal establishment and beetle colonization success. Permethrin reduced attacks on flooded trees, yet no attacks occurred on any of the non-flooded trees. Fewer galleries created within flooded trees pre-treated with permethrin, azoxystrobin, and potassium phosphite contained the purported symbiotic fungus; foundress’ eggs were only detected in flooded but untreated trees. While pre-treatment with permethrin, azoxystrobin, and potassium phosphite can disrupt colonization success, maintaining tree health continues to be the most effective and sustainable management strategy.
Abstract: We found that decayed wood stakes with no termite damage collected from a termite-infested field exhibited a deterrent effect against the termite Reticulitermes speratus, Kolbe, 1885. The effect was observed to be lost or reduced by drying. After identification, it was found that the decayed stakes were infected by brown rot fungus Fibroporia radiculosa (Peck) Parmasto, 1968. In a no-choice feeding test, wood blocks decayed by this fungus under laboratory condition deterred R. speratus feeding and n-hexane extract from the decayed stake and blocks induced termite mortality. These data provided an insight into the interaction between wood-rot fungi and wood-feeding termites.
Abstract: Legal requirements and consumer demands for residue-free products pose a big challenge for pest control in grain stores. One possible alternative to chemical insecticides is biological pest control with the pteromalid wasp Lariophagus distinguendus against the weevils Sitophilus granarius, S. oryzae (Coleoptera: Dryophtoridae), and many other storage pest beetles. The use of this wasp as a biocontrol agent was already suggested in 1919 by Prof. Dr. Hase . Despite many studies on host-finding and behavioral biology, the applied aspect was neglected until 1994. Nowadays the wasps are commercially available and can now even be reared on-site, facilitating their use tremendously. This review highlights the milestones in L. distinguendus research, gives insights in current studies, and ventures a glimpse into the future.
Abstract: An X-ray computed-tomographic examination of nest-gallery development from timbers naturally infested by foraging groups of Incisitermes minor colonies was conducted. This study documents the colonization process of I. minor to new timbers and how the isolated groups maintain their nest-gallery system. The results suggested that development of a nest-gallery within a suitable wood item is not random, but shows selection for softer substrate and other adaptations to the different timber environments. Stigmergic coordinations were expressed in dynamic changes of the nest-gallery system; indicated by fortification behavior in sealing and re-opening a tunnel approaching the outer edge of the timber, and accumulating fecal pellets in particular chambers located beneath the timber surface. The study also examines the caste composition of isolated groups to discover how I. minor sustains colonies with and without primary reproductives.