Lindsay Robinson

Attraction of thrips (Thysanoptera: Thripidae and Aeolothripidae) to colored sticky cards in a California avocado orchard

Yellow, white, and blue sticky cards were tested in an avocado orchard for their attractiveness to Scirtothrips perseae, Frankliniella occidentalis and Franklinothrips orizabensis. Clear pieces of plastic coated with adhesive were used as controls to determine rates of random interception of thrips independent of color. Yellow was most attractive to S. perseae and white cards captured mostly F. orizabensis and F. occidentalis. Capture rates on blue cards declined across the course of four trials for S. perseae and F. occidentalis; this trend was not observed for F. orizabensis. Cardinal direction of traps did not significantly effect capture rates of thrips suggesting south westerly prevailing winds did not influence patterns of aerial dispersal. r 2002 Elsevier Science Ltd. All rights reserved.

Biological control of Oligonychus perseae (Acari: Tetranychidae) on avocado: III. Evaluating the efficacy of varying release rates and release frequency of Neoseiulus californicus (Acari: Phytoseiidae)

Abstract Three different release rates and timings of the phytoseiid Neoseiulus californicus (McGregor) were evaluated for Oligonychus perseae Tuttle, Baker, and Abbatiello control on avocado trees in a commercial orchard in southern California, USA. Densities of natural enemies and O. perseae were monitored on trees for 34 weeks that were treated with either one, two, or three releases of 500, 1000, or 2000 N. californicus, or two applications of 5% narrow range (NR) 415 petroleum oil. Predator releases were made when 50% (release one), 75% (release two), or 95% (release three) of sampled leaves were infested with one or more motile O. perseae. Densities of O. perseae on trees treated with N. californicus or petroleum oil were compared to control trees that received no treatments for O. perseae suppression. Release of a minimum of 2000 N. californicus per tree was necessary to significantly reduce O. perseae densities in comparison to control trees. Releasing 1000 N. californicus twice or 2000 N. californicus once provided O. perseae control similar to petroleum oil treatments and to trees treated with cumulative releases totaling more than 2000 predators per tree. This result indicated that releases totaling more than 2000 N. californicus per tree did not substantially improve O. perseae control and the cumulative number of predators released per tree is more important than the number of times N. californicus is released for controlling O. perseae.

Evaluation of neonicotinoid, organophosphate and avermectin trunk injections for the management of avocado thrips in California avocado groves.

BACKGROUND Trunk injections of systemic insecticides were evaluated for the management of avocado thrips. Insecticide residues were quantified in leaves to determine when after treatment, and for how long, toxic concentrations of the insecticides were present. Residues in fruit were quantified to determine whether trunk injection of insecticides might present a greater risk than traditional application methods for contaminating fruit. RESULTS Residues of imidacloprid and dinotefuran were at least tenfold higher in leaves when trees were treated via trunk injection compared with soil application. Dinotefuran uptake was more rapid than imidacloprid, and no residues were detected within fruit. Acephate was also mobilized very rapidly and gave good control of thrips in bioassays; however, residues of acephate and its insecticidal metabolite methamidophos were detected in the fruit for up to 4 weeks after injection. Avermectin uptake was very slow, and it was ineffective against avocado thrips. CONCLUSIONS Trunk injections of acephate and dinotefuran permitted rapid uptake into avocados, and they are strong candidates as control methods for avocado thrips. However, residues of organophosphates in fruit could necessitate increased preharvest intervals. Residues of neonicotinoids were below detection limits in fruit, suggesting that neonicotinoids may be the more suitable control option of the two chemical classes.

The effects of neutral detergents on the crystallization of soluble proteins

Abstract A number of protein and nucleic acid molecules were crystallized in the presence and the absence of the neutral detergent β-octyl glucoside (0.0–1.5%) from polyethylene glycol and ammonium sulfate. Our results, though in great part qualitative, support the contention that the growth of macromolecular crystals is influenced in a positive manner by the presence of detergent. In general, more reproducible and rapid growth was observed with a larger proportion of large individual crystals at the expense of microcrystals. In some instance, the crystal habit or the crystallographic unit cell was altered.

Evaluation of diets for the development and reproduction of Franklinothrips orizabensis (Thysanoptera: Aeolothripidae)

The suitability of ten diets for the development and reproduction of Franklinothrips orizabensis Johansen, the key natural enemy of Scirtothrips perseae Nakahara, a pest of California grown avocados, was determined in the laboratory. The experimental diets evaluated were: (i) irradiated Ephestia kuehniella Zeller eggs; (ii) irradiated E. kuehniella eggs and avocado pollen; (iii) Tetranychus pacificus McGregor eggs; (iv) T. pacificus eggs and avocado pollen; (v) irradiated E. kuehniella eggs and T. pacificus eggs; (vi) irradiated E. kuehniella eggs, T. pacificus eggs and avocado pollen; (vii) Scirtothrips perseae; (viii) Heliothrips haemorrhoidalis (Bouchè); (ix) avocado pollen; and (x) a young avocado leaf. Franklinothrips orizabensis larvae were unable to develop to adulthood on diets 9 and 10. The remaining eight diets supported complete development of F. orizabensis, but only diets 1, 2, 5, 6, 7 and 8 produced fecund females. On diet 5, F. orizabensis exhibited high larval to adult survivorship (90%), mated females exhibited highest daily and lifetime fecundity, and the progeny of mated females were female biased (53%). Analysis of jackknife estimates of net reproduction (Ro), intrinsic rate of increase (rm), and finite rate of increase (lambda) were all significantly greater for F. orizabensis reared on irradiated E. kuehniella eggs and T. pacificus eggs (i.e. diet 5) than corresponding values for other diets on which female F. orizabensis were able to complete development and reproduce. Incorporation of avocado pollen into diets had an adverse effect on demographic statistics for F. orizabensis, and low quality diets resulted in male biased sex ratios for this predator.

Identification of the sex pheromone of the invasive scale Acutaspis albopicta (Hemiptera: Diaspididae), arriving in California on shipments of avocados from Mexico.

ABSTRACT As a result of relaxation of importation restrictions ordered by the Animal and Plant Health Inspection Service of the U.S. Department of Agriculture, shipments of fresh avocados from Mexico began entering California year-round in 2007, despite the fact that these shipments were heavily infested with a number of exotic and potentially invasive armored scale species that are not thought to be present in California. Here, we report the identification of the sex pheromone of one of these species, Acutaspis albopicta (Cockerell), from a quarantine colony of these insects initiated from specimens collected from commercial shipments of Mexican avocados. The compound was identified as [(1S,3S)-2,2-dimethyl-3-(prop-1-en-2-yl)cyclobutyl)]methyl (R)-2-methylbutanoate, and was similar in structure to the pheromones of several other scale and mealybug species. In laboratory bioassays, the pheromone was highly attractive to male scales in microgram doses. The pheromone will provide a very sensitive and selective tool for detection of the scale to try and prevent its permanent establishment in California.

Developmental Biology of an Exotic Scale, Acutaspis albopicta (Hemiptera: Diaspididae)

ABSTRACT Acutaspis albopicta (Cockerell) is one of seven exotic scale species detected on shipments of ‘Hass’ avocados entering California from Mexico. Here, we present the results of experiments to elucidate basic life history parameters of this species. The scale only reproduces sexually with unmated females producing no offspring. Unmated females survived up to 14 wk after settling on host fruits, whereas males survived for up to 62 h, with the majority dying within 46 h after emergence. Females laid a mean of 52.0 ± 2.8 eggs (range, 5–171 eggs). Lower humidity (50%) was detrimental to the survival of male scales compared with high humidity (75%), especially during the pupal stage. The optimal temperature for development of both sexes was 25°C. At this temperature, females developed from first instars to adults in ≈28 d, whereas males emerged from their pupal cases after ≈37 d. The adjusted lower developmental thresholds for females and males were 13.2 and 13.4°C, respectively. The upper developmental threshold for both females and males was ≈32°C. Total development from first instar to adult female was 329 degree days and to emerged male, 433 degree days.