JASP 3 -- 1985.pdf - International Herbage Seed Group

36 JOURNAL OF APPLIED SEED PRODUCTION, VOL. 3, 1985CarbofuranResidues of carbofuran or the metabolites were not detectedin alfalfa pollen, nectar or pollen-nectar balls (Table3). Therefore, as with dimethoate, logically the pollinationactivities of the bees should not be impacted. However, thenumber of bee cells constructed on the carbofuran-treatedplots averaged 40% fewer in 1980, and 5% fewer than thecontrol in 1981 (Table 1). Lack of control of detrimentalinsects in mid- to late-season reduced alfalfa flowering.Therefore, the reduced availability of pollen and nectar forthe bees accounts for the reduced number of bee cells. Thepercent cells with cocoons, percent live larvae, and percentpollen-nectar balls compare favorably with the control, withthe exception of percent pollen-nectar balls in 1981. We haveno explanation for the increased pollen-nectar balls in 1981.AldicarbResidues of aldicarb and its metabolites were previouslyreported detected in alfalfa leaves, nectar, and leaf from beecells but not in the pollen-nectar ball (Table 3). Low levels ofaldicarb residues and its metabolites (Table 3) were detectedin samples from plots not treated in 1980 but previouslytreated in 1978 and 1979. High levels of residue were detectedin samples from the leaf from cells from the single plottreated and sampled in 1980.The number of cells constructed in 1980 were I 0% fewerin the aldicarb plot than the control (Table 1). However, thepercent cells with cocoons, percent live larvae and percentpollen-nectar balls generally compares favorably with thecontrol. The one exception is in 1980 when the percent ofcells with cocoons from the untreated aldicarb (treated in1978 and 1979 at 3.36 kg of a.i. ha-I rate) plot produced 64%good cells compared to 74% for the control. Lack of controlof detrimental insects in the nontreated plots resulted infewer alfalfa flowers and thus a diminishing supply of pollenand nectar for the bees. Aldicarb appears to have no adverseeffect on leafcutting bees and their pollination activities at therates used in this study, particular! y when the results of 197 8and 1979 are considered. The aldicarb-treated plots producedthe highest seed yields and had more live bee larvae than thecontrol or the demeton or trichlorfon treated plots in 1978 and1979.Oxydemeton-methylOxydemeton-methyl was applied for the first time in 1981and residues in alfalfa leaves, pollen, nectar, pollen-nectarballs, and leaf from the bee cells are reported (Table 2). Leafsamples for residues of oxydemeton-methyl and its sulfonemetabolite were taken 12 hrs to 14 days after the second spraytreatment and 4 days after the third spray treatment. Residuesranged from a high of 28.9 ppm (12 hrs) to 2.65 ppm (14Table 3. Summary of residues in pollen-nectar (p-n) ball and alfalfa leaf collected by Megachile rotundata from alfalfa seed plotstreated with several insecticides in 1980. (Condensed from George and Rincker, 1982).InsecticideTreatment(kg a.i. ha-l)Sampling interval(Days after application)p-n ballResidue found (ppm)leaf-cellDemeton0.280.42389213892148948926 to 6926 to 6926 to 5426 to 544756600.44 0.020.30 NDI0.27 O.Q70.02 0.050.10 0.020.03 0.060.21 2.970.10 0.0715.675.45 5.770.64 1.080.27 1.140.75 1.240.68 4.48nonenonenonenonenone 0.6 to 10.0none 0.6 to 10.0ND 2.09ND 0.610.12 9.27Trichlorfon1.682.52DimethoateCarbofuranAldicarb0.560.841.121.683.36IBelow lower limit of sensitivity of the method used.