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Aqueous emulsions of 21 insect growth regulators were tested for juvenile hormone activity against 1st-molt Aonidiella aurantii (Maskell) by spraying emulsions on the scale insects while these fed on lemon fruit. Residues of the 1st 6 available compounds were tested by spraying emulsions of these on lemon fruit and introducing crawlers onto the fruit 10 h later. These same compounds used to develop a method of testing by exposing white cap, 1st molt, 2nd molt, and adult stages of scales to their activity. Of these, mixed stereoisomers of methyl 10, ll-epoxy-7-ethyl-3,4-dimethyl-2,6-tridecadienoate and 6, 7-epoxy-3,7-dimethyl-l-[3,4-(methylenedioxy)phenoxy]-2-nonene were the most active (inhibited adult eclosion and prevented embryogenesis) at concentrations of 0.1 and 1.0%. The latter compound also inhibited adult eclosion of progeny from female treated with these concentrations 5 days after mating and suppressed the production of sex pheromone in virgin females treated in the 2nd molt with concentrations of 0.2 or 0.5%. Males were 16 times more susceptible to the activity of methoprene than females.

Union carbide UC-21149 (2-methyl-2-(methylthio) propionaldehyde O -(methylcarbamoyl) oxime) was applied as a 10% granular formulation to the soil under the canopy of 2-year-old navel orange trees at rates of 1.5, 7.5, and 40.0 g active ingredient per tree. The systemic activity against several major citrus pests was measured by laboratory bioassays and field counts. When young and mature leaves were collected at frequent intervals and test arthropods were permitted to feed on them in the laboratory for 3 days, the citrus red mite, Panonychus citri (McGregor), was the most susceptible, the California red scale, Aonidiella aurantii (Maskell), next, and. the citrus thrips, Scirtothrips citri (Moulton), least. The 2 higher doses effectively controlled field populations of the citrus red mite for 44 weeks, the spirea aphid, Aphis spiraecola Patch, for 29 weeks, and the citrus thrips for 10 weeks. Fruit collected at 100 days posttreatment contained no residues of UC-21149. The sulfoxide residues in the peel and fruit pulp from trees receiving the highest dose were 12.75 and 2.63 ppm, respectively. In the same fruit, the sulfone residues in the peel and pulp amounted to 2.24 and 0.58 ppm, respectively. No evidence of phytotoxicity was seen in any tree. This compound shows considerable promise for controlling the 3 major pests of nonbearing citrus trees.

The noninclusion virus of Panonychus citri (McGregor) distributed in orange trees by spraying distilled aqueous suspensions of triturated diseased mites. A 0,01% concentration produced as high an incidence of disease as a 0.1% concentration, and applications after sundown were not more effective than applications during a sunny day. The application of suspensions of diseased mites buffered at p H 6.0 produced nearly twice the incidence of infection as a comparable unbuffered suspension. Release of infected mites obtained in the field from an area known to harbor an active epizootic into an apparently virus-free grove produced more than twice the incidence of infection as the release of laboratory-reared and infected mites. Epizootics of the disease developed in all experimental groves.

Attempts to eradicate the Mexican fruit fly, Anastrepha ludens (Loew), which was discovered infesting citrus in Texas in 1927 (unpublished reports), were not successful. Suspecting that the pest might be drifting in from its place of origin in Mexico, a commission of entomologists was sent to its native country where investigations could be made. An informal cooperative agreement was therefore made between the Mexican and American governments, and the Mexican Fruit Fly Laboratory (Laboratorio Entomologico) was opened in Mexico City Nov. 22, 1928. It was originally staffed by American entomologists supported by Mexican professionals and subprofessionals. When the laboratory was closed Sept. 30, 1968, much of the equipment was transferred to the Mexican College of Agriculture at Chapingo where the work with the Mexican fruit fly is being continued by entomologists of the Instituto Nacional de Investigaciones Agricolas. Throughout all the 40 years of the life of the laboratory, the informal cooperation between the Mexican Defensa Agricola (now the Sanidad Vegetal) and the Agricultural Research Service of the USDA has been the major factor in the success of the investigations of the Mexican fruit fly and in the containment of the citrus blackfly, Aleurocanthus woglumi Ashby, a dangerout pest present in Mexico but not the United States. The experience has also contributed greatly to mutual international respect and goodwill.

Fifty-one citrus groves in 9 counties were sampled at regular intervals from February 1966 to May 1967 to determine populations of Panonychus citri (McGregor) and the presence of a noninclusion virus to which it is subject. Diseased mites were found on navel and Valencia oranges, lemon, grapefruit, mandarin, and lime. Incidence of the virus was noticeably higher in samples from central California than from other districts. High incidence of the disease was correlated with high density of mites. Invariably, epizootics succeeded large populations. Collecting mites with a vacuum insect net from groves of continuously low population revealed light infections in a large percentage of samples. Diseased mites were found in 82% of the groves sampled by this method and by brushing mites from leaf samples. Data suggested that the virus is in an occult state until conditions are suitable for infection. Three methods of diagnosing infection were used simultaneously, but none of them revealed infection in all populations; thus, better diagnostic criteria are needed.

Fourteen systemic insecticides were tested against female Panonychus citri (McGregor) by applying 0.4 g active ingredient to the soil around potted nonbearing seedling orange plants. When mites were confined at intervals to detached leaves placed in Tashiro leaf cages, disulfoton, phorate, aldicarb, and schradan consistently caused mortality greater than 80% for 68, 45, 28, and 28 weeks, respectively. However, disulfoton and phorate did not reach their maximum effectiveness until the 4th week posttreatment. The other insecticides ranged from nontoxic to highly toxic for 9-24 weeks. Seven of the insecticides caused phytotoxicity, and yellow spotting was severe when aldicarb and dimethoate were used. Propoxur caused burning of leaf edges and dry spotting.

Panonychus citri (McGregor) infesting potted citrus plants in 2 greenhouses were suppressed or controlled when the surface of the foliage was sprayed with a mist of viral inoculum (0.05 or 1.0% infected mites with a non inclusion virus triturated and suspended in distilled water buffered at p H 6.0). At Chula Vista on the coast where the summer was cool, the citrus red mite was effectively controlled; at the inland station in Riverside where temperatures were much higher, the populations of adult citrus red mites were materially suppressed hut not economically controlled, though repeated applications were made in an effort to perpetuate the infection. Since summer temperatures in both greenhouses were favorable to the mite, the higher temperatures were obviously less favorable to the virus.

About 7,700,000 marked (sprayed with colored lacquer) and sterilized (with tepa) adult Mexican fruit flies, Anastrepha ludens (Loew), were released between 1963 and 1965 in several areas of Texas and Mexico for study of dispersion and migration, One fly was recovered 12 months after release. Maximum migrations were 11 miles in Morelos, 23 miles in northwestern Baja California, and 12 miles from Tijuana, Baja California. into California. (Air currents are believed to have aided migrations. However, dispersal of 3-5 miles was normal.) Estimates of native fly population of 1 per square mile in Texas and 29 per square mile in Tijuana were derived by comparing the numbers of native flies captured with the number of sterile flies recaptured.

Experiments conducted during 1962 and 1963 in a 10-acre mango grove in Morelos, Mexico, involved the release of Mexican fruit flies, Anastrepha ludens (Loew), chemosterilized by dipping the puparia in a 5% aqueous solution of tepa. By releasing the flies in sufficient numbers to overwhelm the natural population present in the mango grove during development of the principal crop, protection of most of the crop was effected.

Endrin, isodrin, dieldrin, heptachlor, and aldrin were the most promising of 27 wettable-power or emulsifiable insecticides screened in the laboratory as soil toxicants against the Mexican fruit fly ( Anastrepha ludens (Loew)). Granulated aldrin appeared to have higher initial toxicity than similar formulations of endrin, dieldrin, or heptachlor in laboratory tests, but the latter were more effective after 294 days. Endrin emulsifiable and wettable-powder formulations were still highly toxic 1,134 days after application to small field plots during the dry season but less effective when the applications were made during the rainy season. A dieldrin emulsifiable formulation at the rate of 12.1 pounds per acre was the best treatment 1,037 days after application in a second series of field tests. However, 5 pounds in either emulsifiable or granulated formulations was not an adequate dosage. Heptachlor gave good initial kill in all tests but its efficiency declined rapidly within 6 months. The toxicants appeared to be more effective on loamy sand than on sandy loam but the amount of spray per acre did not affect performance.

When white, yellow, blue, red, green, and black sticky traps were used to capture Scirtothrips citri (Moulton) on navel orange trees at Riverside, California, the white traps captured the significantly greater numbers. Also, activity was significantly greater on the southeast quadrant of the tree, and a significantly greater number was found 2.7 m aboveground. Other species of Thysanoptera captured included Frankliniella occidentalis (Pergande), F. minuta (Moulton), Thrips tabaci Lindeman, Scolothrips pallidus (Beach), Bregmatothrips sonorensis Stannard, and Isoneurothrips australis Bagnall.

Visual inspection of citrus groves to detect infestations of the California red scale. Aonidiella auranti (Maskell), is not entirely reliable. because very light infestations may escape detection. Therefore, we made spot tests to determine the presence of male scales with a virgin-female sticky-card trap developed earlier (Rice and Moreno 1969) for field studies.

Three formulations of 10% aldicarb (as a coke powder, as a granular coke, and as granular corncob grits) were applied, at doses that were 1/4 and 1/2 the manufacturers’ recommended rate, to soil around potted sweet orange seedlings in the greenhouse and under 1-year-old navel oranges in the field, respectively, to suppress Panonychus citri (McGregor). The biossays with the greenhouse seedlings did not show statistically significant difference in mortality of mites for the 3 formulations, and all caused better than 82% mortality for 16 weeks. In the field where the populations of mites were small, the mean suppression by all 3 formulations was 95% for 52 weeks.