The tomato potato psyllid (Bactericera cockerelli (Sulc)) probably invaded New Zealand in the summer of 200506 The first authenticated records from May to June 2006 indicated that it was widely distributed in the Auckland area with a further record from Taupo so that no attempt was made to eradicate it By April 2009 records indicated that it had spread throughout much of New Zealand Its spread within New Zealand is likely to be from a combination of natural and human mediated dispersal The psyllid and the liberibacter it transmits will provide a serious challenge to the ongoing development of Integrated Pest Management in greenhouse crops (especially tomato and capsicum) outdoor tomatoes and potatoes The economic impact of this insect and disease in the 4 years it has been in New Zealand has been in millions of dollars in terms of increased management costs crop losses and loss of export markets
Onion thrips from onion (Allium cepa) crops were tested for resistance to four insecticides (deltamethrin, diazinon, dichlorvos, and endosulfan) following reports of failure of insecticides to control onion thrips in the field. Bioassays to determine baseline concentration-mortality responses used thrips from two insecticide susceptible populations. Leaf discs (24 mm diam.) cut from leek (Allium porrum) were dipped in insecticide solutions and placed, when dry, in Petri dishes (50 mm diam.) with ventilated lids. Ten adult female thrips were added, and mortality was recorded after 24 h at 25°C. Five or six concentrations of each insecticide were tested and bioassays were usually repeated 3 times. The lowest concentration, which consistently killed over 90% thrips, was used as a diagnostic concentration to screen thrips populations collected from four onion crops and compared with both susceptible populations using the same bioassay. Each test population was also exposed to leaves dipped in water. One Canterbury and three Auckland populations were resistant to deltamethrin, whereas only the three Auckland populations were resistant to diazinon and dichlorvos. No population was resistant to endosulfan. Concentration-mortality responses were determined for deltamethrin and diazinon. Based on the LC 50 s, one Auckland population was 40 times more resistant to diazinon and the Canterbury population was 550 times more resistant to deltamethrin than susceptible populations. The New Zealand onion industry responded to the initial failure of insecticides by developing and implementing an insecticide resistance management strategy and research to improve onion thrips control.
The BamA protein of Escherichia coli plays a central role in the assembly of -barrel outer membrane proteins (OMPs). The Cterminal domain of BamA folds into an integral outer membrane -barrel, and the N terminus forms a periplasmic polypeptide transport-associated (POTRA) domain for OMP reception and assembly. We show here that BamA misfolding, caused by the deletion of the R44 residue from the ␣2 helix of the POTRA 1 domain (⌬R44), can be overcome by the insertion of alanine 2 residues upstream or downstream from the ⌬R44 site. This highlights the importance of the side chain orientation of the ␣2 helix residues for normal POTRA 1 activity. The ⌬R44-mediated POTRA folding defect and its correction by the insertion of alanine were further demonstrated by using a construct expressing just the soluble POTRA domain. Besides misfolding, the expression of BamA ⌬R44 from a low-copy-number plasmid confers a severe drug hypersensitivity phenotype. A spontaneous drug-resistant revertant of BamA ⌬R44 was found to carry an A18S substitution in the ␣1 helix of POTRA 1. In the BamA ⌬R44, A18S background, OMP biogenesis improved dramatically, and this correlated with improved BamA folding, BamA-SurA interactions, and LptD (lipopolysaccharide transporter) biogenesis. The presence of the A18S substitution in the wild-type BamA protein did not affect the activity of BamA. The discovery of the A18S substitution in the ␣1 helix of the POTRA 1 domain as a suppressor of the folding defect caused by ⌬R44 underscores the importance of the helix 1 and 2 regions in BamA folding.
In January 2006 a grower reported failure to control whitefly on greenhouse capsicums in Karaka South Auckland despite high release rates of the biological control agent Encarsia formosa The whitefly was identified morphologically as Bemisia tabaci and capsicum represents a new host record for this species in New Zealand Bemisia tabaci is polyphagous and 24 biotypes are currently recognised worldwide Biotypes B and Q have attracted international attention in the past two decades because of their rapid global spread They are morphologically indistinguishable DNA sequence analyses of samples collected in a survey in 2006 from capsicums and poinsettias revealed the presence of B tabaci biotype Q in New Zealand In a subsequent survey commissioned by Biosecurity New Zealand 12 sites were visited between 27 June and 30 August 2006 Bemisia tabaci was only detected at one site but on multiple hosts Sequences were identical to biotype Q sequences detected during the preliminary survey and to B tabaci biotype Q samples from overseas
A series of experiments was conducted to develop a bioassay for determining the susceptibility of Allium plants to adult female onion thrips. Onion thrips (Thrips tabaci (Thysanoptera: Thripidae)) are the main insect pest on onions in New Zealand. This research aimed to develop better methods for determining the susceptibility of Allium species leaves and onion bulbs to onion thrips. Discs, 10mm diam., cut from leek (Allium porrum) and onion (Allium cepa) leaves or onion bulbs, were put singly into small plastic Petri dishes with 1-day-old adult female thrips, and kept at 25 o C in 16 hlight: 8h dark. After 3 days the discs were stained in acid fuchsin and the eggs counted using a stereo microscope with transmitted light. Adult thrips survived equally well on leek leaves and onion bulb scale, but laid more eggs per day on onion leaves than on leek leaves and least on onion bulbs. Thrips laid fewer eggs per day when there was more than one thrips per dish. Changing discs daily or leaving them for 3 days had no effect on the numbers of eggs laid by thrips each day. Four cultivars of onions were grown with 50, 100, 150, and 200 kg nitrogen (N) fertiliser per ha. The susceptibility of bulbs to onion thrips feeding and damage from the highest and lowest N treatments was compared. Analysis of the proportion of discs with more than one egg showed that cultivar 'Kiwigold' (early brown) was more susceptible than 'Meteor' (early red), and 'M&R Regular' (main crop brown) was more susceptible than 'Red Star' (main crop red) to onion thrips. The proportion of discs with more than three eggs was higher for brown onions in the high N treatment than in the low N treatment, suggesting that brown onions from the high N treatment were more susceptible. After 5 months in storage, red onions were softer and had more sprouts than brown onions, and their innermost skins and the outermost scales had more thrips damage. This apparent increase in susceptibility of red onions may be related to changes in the physiology of the outer scale as it shrinks to become a skin. The bioassays confirmed that both genetic (cultivar) and agronomic (N fertiliser) factors affect the susceptibility of onion bulbs to onion thrips.
Lettuce aphid Nasonovia ribisnigri Mosely (Hemiptera Aphidoidae) was first detected in New Zealand on lettuce (Lactuca sativa) in Christchurch in March 2002 Lettuce growers immediately found the new pest difficult to control using insecticides Failure of insecticides to provide adequate control could have been due to inadequate spray coverage because lettuce aphid prefers to feed in the interior of the lettuce or to insecticide resistance which has been recorded in lettuce aphid in Europe To determine the efficacy of topically applied insecticides on lettuce aphid in New Zealand 12 pesticides were applied at recommended field rates with a Potter tower to apterous lettuce aphids on lettuce discs imbedded in agar Only acephate (806) and methomyl (907) failed to give complete mortality after 48 hours at 18C The concentrationmortality relationships for acephate methomyl and pirimicarb were estimated and compared with data from Europe
Onion thrips (Thrips tabaci) is the main insect pest on New Zealand onions (Allium cepa). Insecticide applications are triggered by thrips numbers exceeding action thresholds. A new crop monitoring protocol that involves sampling a minimum of 100 plants (up to 4 ha) or 25 plants/ ha, was tested in 10 young or mature onion crops. Two people independently sampled each crop by zigzagging up and down groups of onion beds defined by pairs of sprayer wheel tracks and selecting a plant at random at predetermined intervals along the crop beds. The number of thrips adults and larvae per plant was recorded. A strong relationship was found between total numbers of thrips and the percentage of plants infested. If the onion industry raised its spray action threshold from 0.1 thrips/plant to 2 or 3 thrips/plant (c. 50% plants infested), it could adopt presence-absence sampling that would be faster than counting all thrips. The time to monitor a crop was affected by field size, and only increased slightly with higher levels of infestation. The new H08042; guidelines could also be used for monitoring disease and weeds.
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