Chris Peterson

Plant growth regulatory effect and insecticidal activity of the extracts of the Tree of Heaven ( Ailanthus altissima L.)

BackgroundThere is an urgent need to explore and utilize naturally occurring products for combating harmful agricultural and public health pests. Secondary metabolites in the leaves of the Tree of Heaven, Ailanthus altissima L. have been reported to be herbicidal and insecticidal. The mode of action, however, of the active compounds in A. altissima are not understood. In this paper, we report the chemical characteristics of the herbicidal and insecticidal components in this tree, and will discuss the effect of light on the bioactivity of the active components.ResultsExtracts from the fresh leaves of A. altissima showed a strong plant germination/growth inhibitory effect in laboratory bioassays against alfalfa (Medicago sativa). The effect was dose-dependent. The growth inhibitory components were in the methylene chloride soluble fraction of the extract. The effect was greater in the light than in the dark. Other fractions had plant growth enhancing effect at lower concentrations. The extract was slightly insecticidal against yellow fever mosquito larvae (Aedes aegypti).ConclusionsThe extract or its semi-purified fractions of A. altissima were strong plant growth inhibitors, therefore good candidates as potential environmentally safe and effective agricultural pest management agents. The finding that light affects the activity will be useful in the application of such natural products.

Glucosinolate breakdown products as insect fumigants and their effect on carbon dioxide emission of insects.

BackgroundGlucosinolate breakdown products are volatile, therefore good candidates for insect fumigants. However, although they are insecticidal, the mode of action of such natural products is not clear. We studied the insecticidal effect of these compounds as fumigants, and monitored the production of carbon dioxide by the insects as a probe to the understanding of their mode of action.ResultsThe fumigation 24-h LC50 against the house fly (Musca domestica L.) of allyl thiocyanate, allyl isothiocyanate, allyl cyanide, and l-cyano-2-hydroxy-3-butene was 0.1, 0.13, 3.66, and 6.2 μg cm-3, respectively; they were 0.55, 1.57, 2.8, and > 19.60 μg cm-3, respectively, against the lesser grain borer (Rhyzopertha dominica Fabricius). The fumigation toxicity of some of the glucosinolate products was very close to or better than that of the commercial insect fumigants such as chloropicrin (LC50: 0.08 and 1.3 μg cm-3 against M. domestica and R. dominica, respectively) and dichlorovos (LC50: < 0.02 and 0.29 μg cm-3 against M. domestica and R. dominica, respectively) in our laboratory tests. Significantly increased CO2 expiration was found in insects exposed to the vapor of allyl isothiocyanate, allyl thiocyanate and allyl isocyanate. Allyl isothiocyanate was also found to increase the CO2 expiration of the American cockroach (Periplaneta americana L.).ConclusionsGlucosinolate breakdown products have potential as biodegradable and safe insect fumigants. They may act on the insect respiratory system in their mode of action.

Historical Review of Termite Activity at Forest Service Termiticide Test Sites from 1971 to 2004

Abstract The U.S. Forest Service has a long history of providing termiticide efficacy data used for product registration and labeling. Four primary test sites (Arizona and Florida, Mississippi, and South Carolina [hereafter southeast]) have been used for this purpose. Various parameters of termite attack at water-only control plots were examined in this study to assess the relative pressures of termites at each site. Termiticide studies installed between 1971 and 2001 by using ground board (GB) and concrete slab (CS) test methods were included. GB control plots were attacked 85% of the time in the southeast, about twice the rate observed in Arizona (43%). CS plots were attacked 59–70% of the time in the southeast, significantly higher than in Arizona (43%). Termites were slower to initiate attack at control plots in Arizona compared with the southeast, and they were up to twice as slow at GB controls. Once initial attack began, GB plots were reattacked at higher percentages in the southeast (89–90%) than in Arizona (67%). Reattack at CS plots ranged from 65% in Arizona and South Carolina to 76% in Mississippi. Termites caused less damage to wooden blocks in control plots in Arizona than the southeast. Attack rates at controls generally declined during the 1990s, but these rates have rebounded since 2000, except at CS plots in Arizona and South Carolina. Statistical analysis of attacks at plots treated with chlorpyrifos, cypermethrin, fenvalerate, and permethrin also was undertaken. Time to initial termite attack (failure) of the organophosphate chlorpyrifos was generally shorter in Arizona than in the southeast, whereas time to initial attack in plots treated with one of three pyrethroids (cypermethrin, fenvalerate, and permethrin) was generally longer in Arizona.

Varying termiticide application rate and volume affect initial soil penetration

ABSTRACT n The initial soil penetration of Premise 75 and Termidor SC, containing imidacloprid and fipronil, respectively, were tested in laboratory columns of five different soils, Three combinations of application concentration and volume were used: double the recommended active ingredient concentration at one half the recommended volume (DR), the full concentration and volume (FR), and one half the concentration and twice the volume (HR), In all three cases, the same total amount of active ingredient (0.01 g of imidacloprid for Premise and 0.012 g of fipronil for Termidor) was applied to the same soil surface area (45.36 cm2), Regardless of soil or application method, the concentration of active ingredient was highest in the top 1 cm of soil. Within each soil, the concentration in the top 1 cm was highest in the DR treatment and lowest in the HR treatment. At each depth below 1 cm, active ingredient concentration was highest in the HR treatment and lowest in the DR treatment. The DR treatment therefore results in a thinner barrier of higher initial concentration in the top 1 cm, whereas the HR treatment results in a thicker barrier but of lower initial concentration in the top 1 cm.

Charring does not affect wood infestation by subterranean termites

Fire is an important part of forest ecosystems, as is the insect fauna. Changes in wood brought about by fire may alter the ability of termites to use the wood, interrupting the decay cycle of woody debris. The ability of termites to find, infest, and feed upon wood after it had been charred was evaluated in the laboratory and field. Eastern subterranean termites, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), fed on char from burned wood had significantly reduced numbers of protozoa compared to termites fed on pine shavings, but significantly more than starved termites. The ability of termites to find and infest wood was not affected by surface charring. In a laboratory choice test, there were no significant differences in the onset of feeding by termites between charred and non‐charred wood boards. Likewise in the field, no differences were observed in the time to initial attack by termites on charred and non‐charred wood boards or bolts. Because termites will likely survive fires of low to moderate intensity, in most cases, there should be no disruption of the termite contribution to forest nutrient and carbon cycles.

Effect of vegetation on the longevity, mobility and activity of fipronil applied at the termiticidal rate in laboratory soil columns†

BACKGROUNDnTermiticides are applied at concentrations much higher than those used in agricultural settings. The longevity of fipronil has not yet been examined at the rates used for termite control, nor has the compounds movement in the soil been addressed.nnnRESULTSnFipronil was detected in the eluates of treated soil cones, increasing initially and then decreasing to a steady concentration of about 1 microg mL(-1). In larger PVC pipe plots, fipronil in the top treated soil depth (0-7.5 cm) dissipated more rapidly (half-life of 11-13 months) than in treated soil at the next treated depth (7.5-15 cm; half-life of 20-29 months). The presence of vegetation had no significant effect on the mobility, longevity or movement into untreated depths. Treated soil remained toxic to termites throughout the duration of the study. Fipronil moved into the 15-22.5 cm soil depth in sufficient concentration to cause 100% mortality to eastern subterranean termites in 3 day bioassays.nnnCONCLUSIONnFipronil remains in treated soil at levels toxic to termites for at least 30 months. Movement of the active ingredient was observed in sufficient amounts to kill termites in non-treated soil directly below the treated soil.

Longevity of a mixture of acetamiprid and bifenthrin (TransportTM) at the termiticidal application rate

BACKGROUNDnThe 30 month longevity, mobility and insecticidal activity of a combination of acetamiprid and bifenthrin currently marketed in the United States for the prevention of termite infestation in buildings was investigated in greenhouse and laboratory studies.nnnRESULTSnAcetamiprid dissipated to below the limit of detection within 7 months of application, while bifenthrin remained in the soil at levels sufficient to kill termites for the duration of the study. Acetamiprid was detected in decreasing amounts in eluates of treated soil from months 1 to 4, while no bifenthrin was detected in eluates at any time. The treated soil remained toxic to termites for the 30 month duration of the study. Two indices of synergy between technical-grade acetamiprid and bifenthrin demonstrated that it is unlikely that there would be any synergism between the two active ingredients in the field. The presence of vegetation did not have a significant effect on the longevity of bifenthrin, except at intermediate times, where residues in the treated soil were higher in vegetated plots, depending on depth and time.nnnCONCLUSIONSnAcetamiprid has a short residual time in soil, and this formulations effectiveness beyond about 7 months against subterranean termites is due to the bifenthrin content.

Bifenthrin longevity at the termiticidal application rate

BACKGROUNDnThe longevity, mobility and insecticidal activity of bifenthrin at the termiticidal application rate for perimeter treatment were investigated in packed-soil columns in the laboratory and greenhouse.nnnRESULTSnBifenthrin was not detected in the eluates of packed-soil cones over a period of 6 months. In larger pipe plots incorporating bifenthrin into the top 15 cm of the soil, the compound degraded in a biphasic fashion. Within the treated soil, the effect of vegetation on the amount of bifenthrin remaining in the soil depended on soil depth and time, and soil half-lives were longer in non-vegetated soil. Bifenthrin residues were higher in the top 7.5 cm of soil and declined over time. Movement of bifenthrin into the top untreated soil depth was observed, but much less was observed in lower depths. The soil remained toxic to termites in 3 day and 7 day forced exposure bioassays for the 30 month duration of the study.nnnCONCLUSIONSnConcentrations of bifenthrin will remain in the soil at levels sufficient to kill termites for more than 30 months.

Subterranean Termite Control Examinations on Current and Former Experimental Forests and Ranges

For more than 70 years, the USDA Forest Service’s Termite Team has engaged in research to extend the life of wood in service by studying chemical (and a few nonchemical) subterranean termite control products. These efficacy data are produced in distinct field trials on experimental forests across the USA, and are used by industry cooperators to register their products with the Environmental Protection Agency. Experimental forests and ranges allow long-term undisturbed efficacy examinations of termiticides in preventing subterranean termite attack on wood. This chapter provides historical information on the development of these efficacy studies over the years and the places where these data are collected.

Mobility, longevity and activity of chlorfenapyr in soils treated at a termiticidal rate.

BACKGROUNDnThe mobility, longevity and termiticidal activity of chlorfenapyr applied to soils at the termiticidal labeled rate was evaluated for 30 months after treatment (MAT) in a greenhouse study.nnnRESULTSnThere was little dissipation of chlorfenapyr in soil treated at the labeled rate for perimeter treatments for the prevention and control of termite infestations. Chlorfenapyr was detected in soil immediately below the initially treated soil in the packed soil columns. This was likely due to settling of soil. The treated soil remained toxic to subterranean termites in 3 and 7 day bioassays over the duration of the study. The treated soil displayed slow-acting properties regarding toxicity to termites. Trace amounts of chlorfenapyr were detected in the eluates of packed soil cones.nnnCONCLUSIONnThe commercial formulation of chlorfenapyr used in this study (21.45% concentrate diluted to 0.125% prior to application) killed 100% of the tested subterranean termites for at least 30 months.