Effects of Spirotetramat on Aonidiella aurantii (Homoptera: Diaspididae) and Its Parasitoid, Aphytis melinus (Hymenoptera: Aphelinidae)

Laboratory and field studies were conducted to measure the effects of spirotetramat on life stages of California red scale, Aonidiella aurantii (Maskell), and a primary parasitoid, Aphytis melinus DeBach. Organophosphate-resistant and -susceptible populations responded similarly to spirotetramat, suggesting there is no cross-resistance between these insecticide classes. First and second instar male and female A. aurantii were 10- and 32-fold more susceptible to spirotetramat (LC50 = 0.1-0.2 ppm) compared with early third (LC50 = 1.5 ppm) and late third instar females (LC50 = 5.3 ppm). The LC99 value indicated that late stage third instar females would not be fully controlled by a field rate of spirotetramat; however, spirotetramat would reduce their fecundity by 89%. Field applications of spirotetramat in two water volumes and using two adjuvants (oil and a nonionic spray adjuvant) showed similar reduction in A. aurantii numbers, even though the higher water volume demonstrated more complete coverage. These data suggest that this foliarly applied systemic insecticide can be applied in as little as 2,340 liters/ha of water volume, minimizing application costs, and that the two adjuvants acted similarly. The endoparasitoid, A. melinus, was unaffected by the field rate of spirotetramat when it was applied to the host when the parasitoid was in the egg or larval stage. Adult A. melinus showed 2 wk of moderate reductions in survival when exposed to leaves with field-weathered residues. Spirotetramat is an integrated pest management compatible insecticide, effective in reducing A. aurantii stages and allowing survival of its primary parasitoid A. melinus

Influence of Spray Equipment and Water Volume on Coverage of Citrus and Control of Citricola Scale, Coccus pseudomagnoliarum (Hemiptera: Coccidae) With Mineral Oil

A trial was conducted in a commercial Citrus sinensis L. variety 'Washington' navel orange orchard to compare the coverage and efficacy against citricola scale Coccus pseudomagnoliarum (Kuwana) (Hemiptera: Coccidae) of 45.5 liters/ha of an nC24 agricultural mineral oil treatment applied by two different methods: a conventional air blast sprayer and a rotary atomizer. Three water volumes (2,340, 4,680, and 7,020 liters/ha) were applied with the air blast sprayer to determine the optimal spray volume for that equipment. A single volume (2,340 liters/ha) was applied with the rotary atomizer to compare its effectiveness with that of the air blast sprayer at this same volume. Results demonstrated that all treatments reduced citricola scale densities. Moreover, all treatments conducted with the air blast sprayer provided significantly greater coverage and significantly reduced citricola scale densities compared with the treatment made with the rotary atomizer. Larger water volume applications with the air blast sprayer did not significantly reduce citricola scale densities, although significantly better coverage was attained in the interior of the tree when spraying with 4,680 and 7,020 liters/ha. As a consequence, this study demonstrated that the increased coverage obtained by applying higher water volume with the air blast sprayer was not required for an optimal treatment in August, when the citricola scale population consisted of nymphs inhabiting the outside leaves of the tree

Armored scale insecticide resistance challenges San Joaquin Valley citrus growers

Organophosphate and carbamate insecticides have been used to treat citrus pest problems for more than 40 years. From 1990 to 1998, we documented California red scale and yellow scale resistance to these insecticides. Armored scale resistance is found on an estimated 40% of 163,000 acres of citrus in the San Joaquin Valley. Citrus growers have responded by either increasing their use of natural enemies, especially the parasitoid wasp Aphytis melinus, or by applying newly registered insect growth regulator or neonicotinoid insecticides. While the California red scale problem is, for the moment, greatly reduced, outbreaks of cottony cushion scale are occurring because the new insecticides are highly toxic to the predatory vedalia beetle

Armored scale insecticide resistance challenges San Joaquin Valley citrus growers

Organophosphate and carbamate insecticides have been used to treat citrus pest problems for more than 40 years. From 1990 to 1998, we documented California red scale and yellow scale resistance to these insecticides. Armored scale resistance is found on an estimated 40% of 163,000 acres of citrus in the San Joaquin Valley. Citrus growers have responded by either increasing their use of natural enemies, especially the parasitoid wasp Aphytis melinus, or by applying newly registered insect growth regulator or neonicotinoid insecticides. While the California red scale problem is, for the moment, greatly reduced, outbreaks of cottony cushion scale are occurring because the new insecticides are highly toxic to the predatory vedalia beetle

Diaprepes Root Weevil

Diaprepes root weevil is a serious pest of Florida citrus, sweet potatoes, papayas, and ornamental plants, and it threatens to become established in California as well. This publication gives guidelines for pest identification and control. 23 color photos

Diaprepes Root Weevil

Diaprepes root weevil is a serious pest of Florida citrus, sweet potatoes, papayas, and ornamental plants, and it threatens to become established in California as well. This publication gives guidelines for pest identification and control. 23 color photos