Buchner, Rick

Pickel, Carolyn

Stimman, Mike

Zalom, Frank

Undetermined

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4. Chemical ControlEFFICACY AND RESIDUE ANALYSIS OF PYRETHROIDINSECTICIDES ON PEST AND BENEFICIAL SPECIESCarolyn Pickel. Frank Zalom, Mike Stimman, and Rick BuchnerUniversity of California Cooperative Extension142-AGarden HighwayYuba City, CA 95991Although the role of pyrethroids in mite and other pest outbreaks has been documented, itis important to revisit them in relation to California orchards as their use increases. Somegrowers are choosing to use pyrethroids in the dormant season as an alternative to theorgano-phosphate insecticides for control of peach twig borer, aphids, and scale insects.Other growers are understandably applying pyrethroids in-season for other insect pestsinstead ofmore costly treatments. They are known to be effective as dormant sprays, butit is not known if they can be used without causing other problems at that time. Field andlaboratory trials carefully testing these materials have been conducted to establishguidelines for its possible use in pest management programs.Field trials carefully testing these materials were conducted in single tree plots in prunesand almonds and large orchard plots in prunes for the second year in 1996. Treatments inthe single tree plots were applied by handgun to single trees in eight replicatedcompleteblocks. Treatments in the single tree prune plots consisted of96 dormant seasonesfenvalerate (Asana), dormant diazinon, and dormant Asana and diazinon over the 95treatments, untreated control treatments, and in-seasonAsana treatments. The plots inalmonds repeated the Asana treatments with permithrin. The additional 96 esfenvalerateand permethrin treatmentswere added to find effects of repeated pyrethroid applications.Treatments in the large prune plots, 8X8 trees with 3 replicates, were applied by anorchard sprayer. Treatments consisted ofDormant oil as the untreated control, Dormantoil plus Asana,Dormant oil plus Diazinon, and two Bacillus thuringiensis (Bt) with 2gals/acre sprays during bloom, andDormant oil Diazinon plus in-seasonAsana. Monthlymite samples from each tree in the single tree plots and 6 center trees in the large plotswere collected and using a mitebrushing machine to evaluatefor European red mites, twospotted mites, and predator mites. Mite populations were monitored in both the singletree plots and the large plots in May, June, July, and August.Branches were cut from trees in the esfenvalerate, permethrin and control treatments inthe single tree plots periodically during the season, and residue analysis performed on thesamples. The extraction and analysis process involves about 20 separate steps. Results ofthe residue extractions have shown that almost all of the insecticides is in the bark andvery little or none is in the woody portion. A laboratory experiment was conducted on asubsample of the branches to determine effect of residues remaining on prune twigson thewestern orchard predator mites. Twigs were collected from almond and prune treesseveral daysafter the dormant spray application. Predator mites were placed on 2 cm81circular pieces on the twigs collected and evaluated for mortality and egg-laying after 48hours.Results from the almond plot indicated that residues ofboth esfenvalerate (0.047 ng/mm2)and permethrin (cis- =1.153 ng/mm2; trans- = 0.012 ng/mm2) had persisted theentire yearsince the previous dormant season application, and that there remained biological activityon predators during this time. Residues remaining from the one year old dormant sprayand a hullsplit spray applied to the same trees was not significantly different from thatremaining from the one year old dormant spray alone. By comparison, residue analysis ofsmall branches collected less than 1 day following application yielded higher residues ofesfenvalerate (0.265 ng/mm2) and permethrin (cis- = 1.693 ng/mm2; trans- = 1.603ng/mm2). In2 independent bioassays of the small almond twigs collected from thesetreatments, all esfenvalerate and permethrin treatments resulted in significantly higherpredator mite mortality than was observed on the untreated control twigs. The diazinonapplication resulted in some mortality of predator mites (-15%), but this was not as greatas that observed for the various esfenvalerate and permethrin treatments that varied from24% to 38% for esfenvalerate and from 19% to 42% for permethrin. Similarly the numberof eggs per treatment replicate were also significantly affected relative to the untreatedcontrol, and somewhat more by the esfenvalerate treatments than by the permethrintreatments. This effect was also seen in the lab bioassays conducted on prune twigs whereone dormant application ofAsana reduced predators by 40%, a 95 in-season Asanaapplication by 24%, and 95 dormant Asana plus a 95 in-season Asana by 14%, and thethree Asana applications reduced predators by 35%. Not only does the Asana reducepredators but they lay fewer eggs. The three Asana applications treatment hadsignificantly less egg laying than all the other treatments.In these associated laboratory trails, we were able to develop a relationship offield rate ofboth esfenvalerate and permethrin to bark residues, and to relate this to predator mitemortality and oviposition. In this way we are now able to accurately predict the biologicaleffect of a given level of bark residue. We were also able to determine the effect ofpermethrin leaf resides on predator mite mortality and oviposition. In this study we foundsignificantly increased mortality (54%) and decreased oviposition (86%) at the 0.125 labelrate.These results indicate that the pyrethroid insecticides esfenvalerate and permethrin canhave long term negative residual effects on predaceous mites on bark where theyoverwinter and disperse within tree, and short term negative effects from residues onleaves. Growers using pyrethroids with repeated applications will have to watch forincreasingmite populations. As a result some PCAs are recommending lower rates ofpyrethroids.82

Efficacy and residue analysis of pyrethroid insecticides on pest and beneficial species

https://ir.library.oregonstate.edu/downloads/js956p262

Efficacy and residue analysis of pyrethroid insecticides on pest and beneficial species

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