Raul T. Villanueva

Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida.

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731 ml/ha + FC 435-66 petroleum oil at 46.8 l/ha, pyridaben 75 WP at 469 g/ha, ethion 4 EC at 7.01 l/ha + FC 435-66 petroleum oil at 46.8 l/ha, propargite 6.55 EC at 3.51 l/ha, chlorfenapyr 2 SC at 1.46 l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8 l/ha, sulphur 80 DF at 16.81 kg/ha, dicofol 4 EC at 7.01 l/ha, fenbutatin oxide 50 WP at 2.24 kg/ha, benomyl 50 WP at 2.24 kg/ha, benomyl 50 WP at 1.68 kg/ha + ferbam 76 GF at 5.60 kg/ha, ferbam 76 GF at 11.21 kg/ha, neem oil 90 EC at 46.8 l/ha, and copper hydroxide DF (40% metallic copper) at 4.48 kg metallic copper/ha + FC 435-66 petroleum oil at 46.8 l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48 kg metallic copper/ha + FC 435-66 petroleum oil at 46.8 l/ha, fenbuconazole 2 F at 280 ml/ha + FC 435-66 petroleum oil at 46.8 l/ha, FC 435-66 petroleum oil applied alone at 46.8 l/ha or 23.4 l/ha, and diflubenzuron 25 WP at 1.40 kg/ha. Pesticides that were non-toxic included: fenbuconazole 2 F at 585 ml/ha, malathion 57 EC at 5.85 l/ha, FC 435-66 petroleum oil at 46.8 l/ha, carbaryl 80 S at 3.36 kg/ha, chlorpyrifos 4 EC at 4.68 l/ha, and formetanate 92 SP at 1.12 kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.

Acaricidal Properties of Spinosad Against Tetranychus urticae and Panonychus ulmi (Acari: Tetranychidae)

Laboratory bioassays were conducted to characterize the activity of the insecticide spinosad against the twospotted spider mite, Tetranychus urticae Koch, and European red mite, Panonychus ulmi (Koch) (Acari: Tetranychidae). T. urticae females and larvae were individually placed on bean, Phaseolus vulgaris L. (Fabaceae), leaf disks treated with four rates of spinosad (25, 55, 121, and 266 ppm) and a water control. Significantly fewer T. urticae completed development on any spinosad rates (<15%) compared with the control (>85%), whereas spinosad exhibited no significant effects on P. ulmi development; 72.5 and 83.1% of P. ulmi completed development on apple (Malus pumila P. Mill, Rosaceae) leaf disks treated with 75 ppm spinosad and the control, respectively. T. urticae adult females placed on spinosad-treated disks had significantly higher mortality and lower oviposition rates compared with the water control; no significant mortality effects were observed until 3 d after placing adults on leaf disks. In choice tests where half of a bean leaf was treated with 55 ppm spinosad transversally or longitudinally, T. urticae females were repelled by spinosad and largely oviposited and fed on nonspinosad treated areas. Spinosad did not affect the behavior of P. ulmi females. When T. urticae females were released on potted bean plants (two-leaf stage) in which leaves received spinosad sprays on the adaxial or abaxial leaf surfaces, or complete spinosad coverage on one or two of the leaves, mite population increase lagged significantly behind those released on control plants. These results indicate that spinosad has significant acaricidal effects against T. urticae but not P. ulmi.

Development of Iphiseiodes quadripilis (Banks) (Acari: Phytoseiidae) on pollen or mite diets and predation on Aculops pelekassi (Keifer) (Acari: Eriophyidae) in the laboratory.

Abstract Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28° ± 1°C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 ± 0.47 and 3.5 ± 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.

Larval Cryptothelea gloverii (Lepidoptera: Psychidae), an arthropod predator and herbivore on Florida citrus.

The orange bagworm (OBW), Cryptothelea gloverii (Packard) (Lepidoptera: Psychidae) was previously reported feeding on citrus fruit and foliage and preying upon the camphor scale Pseudaonidia duplex (Cockerell) (Homoptera: Coccidae). In this study using laboratory assays, OBW preyed upon citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae) and consumed eggs and adults of both P. oleivora and Panonychus citri (McGregor) (Acari: Tetranychidae), two important pest mites on Florida citrus. OBW was also observed to feed on the purple scale, Lepidosaphes beckii (Newman) (Homoptera: Diaspididae) and on a fungus (Penicillium sp.). OBW fed on orange and grapefruit leaves by starting from the border and eating part of the leaf, by chewing holes, or consuming the outer epithelium of either the axial or abaxial surface of the leaf without penetrating through the leaf. OBW was observed in orange orchards in association with fruit extensively russeted by P. oleivora feeding. Laboratory assays revealed that OBW larvae preferred to feed on oranges infested with P. oleivora rather than on clean fruits that were free of mite feeding damage. Feeding damage to citrus fruit by OBW larvae results in one to several holes being eaten into the rind or albedo, without damage to the fruit sacs.

TWO SPECIES OF CECIDOMYIIDAE PREDACIOUS ON CITRUS RUST MITE, PHYLLOCOPTRUTA OLEIVORA, ON FLORIDA CITRUS

Abstract Larvae of two undescribed species of Cecidomyiidae (Diptera) were found preying upon Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae) on Florida citrus. Identifications to genus were made from adults reared in the laboratory. The two species had distinctive larval coloration. One larval type was completely yellow and was identified as Feltiella n. sp., while the second larval type had an orange color with a transverse white band close to the mouthparts. The latter cecidomyiid was identified as belonging to a genus near Lestodiplosis in the broad sense. Feltiella n. sp. (n = 17) and the species near the genus Lestodiplosis (n = 12) consumed 33.8 ± 4.6 (mean ± SEM) and 43.0 ± 6.4 citrus rust mite eggs; 14.2 ± 1.4 and 15.0 ± 2.0 citrus rust mite nymphs, and 3.0 ± 0.4 and 5.6 ± 0.9 citrus rust mite adults/10 min., respectively. There were no significant differences (P > 0.05) in the consumption rates of either predator on any rust mite life stage. These data indicate that Feltiella n. sp. and the species near the genus Lestodiplosis are both efficient predators of P. oleivora eggs, larvae, and nymphs.

Amblyseius filcae Denmark and Villanueva, n. sp. (Acari: Phytoseiidae) found on Viburnum in Florida: description, life cycle and feeding studies.

Abstract Amblyseius filcae Denmark and Villanueva, n. sp. was found on Viburnum odoratissimum Ker Gawl. var. awabuki (K. Koch) Zabel (Caprifoliaceae) in Florida. The adult female can be identified by its rosy coloration, and, on permanent slides, by its tubular-fundibular spermathecal calyx 15 μm long and nodular atrium. Developmental times on pollen of crocea iceplant (Malephora crocea Jacquin) (Alzoaceae) were 60.6 ± 1.3, 32.2 ± 1.3, 41.3 ± 1.0, 29.6 ± 1.6, 54.7 ± 1.4, 218.7 ± 3.3 h for eggs, larvae, protonymphs, deutonymphs, preoviposition time and total female developmental time (up to first oviposition), respectively. Amblyseius filcae showed a weak or no predatory performance on Phyllocoptruta oleivora (Ashmead) and adult female Brevipalpus phoenicis (Geijkes) during predator-prey laboratory bioassays, but B. phoenicis egg predation was observed.

Impact of new pesticide chemistry on acarine communities in apple orchards

Changes in the acarine community of several apple orchards due to adoption of new arthropod pest control practices were examined over a 4-year period in western North Carolina, USA. At each of nine study sites, a reduced-risk integrated pest management (IPM) program was compared to a conventional IPM plot. In addition to pheromone-based mating disruption, reduced-risk plots also included one or more of the following new insecticides: the nicotinoids imidacloprid, thiamethoxam, acetamiprid, and thiacloprid; the oxadiazine indoxacarb; the biological insecticide spinosad; and the insect growth regulators methoxyfenozide, novaluron, and pyriproxyfen. Conventional plots were treated with broad-spectrum organophosphate, carbamate, and pyrethroid insecticides. The most common phytophagous mite was Panonychus ulmi, and the most prevalent predators were the phytoseiid Neoseiulus fallacis (>99%) and the stigmaeid Agistemus fleschneri. Results showed that phytophagous mite outbreaks did not occur in the reduced-risk plots, and acaricides were applied 15 and 7 times in the conventional and reduced risk treatments, respectively, throughout the four-year study. Phytoseiid and stigmaeid predatory mites were more abundant in reduced-risk vs. conventional plots. High numbers of the mite-eating thrips, Scolothrips sexmaculatus, were noticed in one orchard in 2004 and they were more abundant in reduced-risk vs. conventional plots. In addition, crop protectant aluminum silicate clay (Surround® WP) negatively affected phytoseiid mites compared to a control involving a water spray.