Pest Management Science

doi: 10.1002/ps.2780170501pmid: N/A

Bettarini, Franco; Massardo, Pietro; Piccardi, Paolo; Caprioli, Vincenzo

doi: 10.1002/ps.2780170502pmid: N/A

A new class of compounds derived from hydroquinone ethers showed high and predominantly ovicidal activity against the two‐spotted spider mite, Tetranychus urticae Koch. The sequence of compounds synthesised and the factors which appeared to have contributed most to the discovery of these promising acaricides are presented.

Wells, David; Grayson, B. Terence; Langner, Eric

doi: 10.1002/ps.2780170503pmid: N/A

The vapour pressures of the separate isomers of permethrin have been determined over a range of temperatures by two laboratories using different versions of the gas saturation method. A statistical analysis of the sets of data from the two laboratories shows no significant differences for the cis isomers but a small difference in the 20°C extrapolated values for the trans isomer exists. However, this difference is discounted as arising from experimental error and the mean values of the estimated vapour pressures at 20°C are given as 2.5 μPa (cis) and 1.5 μPa (trans).

Abbott, Henry A.

doi: 10.1002/ps.2780170504pmid: N/A

The addition of 20% molasses to water did not reduce the rate of evaporation of water from spray droplets. The 20% molasses droplets evaporated at the same rate as water droplets until ca 20% of their volume was left. When sprayed under field conditions at 30% relative humdity (r.h.) the volume median diameter (v.m.d.) of the 20% molasses spray (132 μm) was larger than the v.m.d. of the water spray (116 μm) and more droplets smaller than 19 μm were captured on magnesium oxide slides than with the water spray. The addition of molasses improved the impaction efficiency of droplets by increasing their density, and increased the minimum size to which a given droplet could evaporate.

Sawicki, Roman M.; Farnham, Andrew W.; Denholm, Ian; Church, Valerie J.

doi: 10.1002/ps.2780170505pmid: N/A

An intensifier (factor 161) identified on the second autosome in a pyrethroid‐resistant strain of houseflies (Musca domestica L.) was isolated and introduced into a strain with super‐kdr. Unlike E0.39, which on its own also confers very weak (< × 3) resistance to pyrethroids, factor 161 very strongly intensified super‐kdr resistance to pyrethroids. Together, factor 161 and super‐kdr conferred immunity to deltamethrin in female houseflies (LD50 > 20 μg fly−1) but produced much less intensification of resistance to WL 48281, the (1R)cis (αS) isomer of cypermethrin, which differs from deltamethrin only in having chlorine instead of bromine substituents in the acid side‐chain. Intensification was strongly decreased by piperonyl butoxide and propyl prop‐2‐ynylphenylphosphonate (NIA) but was unaffected by S,S,S‐tributyl phosphorotrithioate (DEF). This synergism suggests involvement of oxidative rather than esteratic metabolism in the intensification of super‐kdr by factor 161.

Kulshrestha, Gita; Mukerjee, Sunil Kumar

doi: 10.1002/ps.2780170506pmid: N/A

The photochemical degradation of the herbicide isoproturon in aqueous and non‐aqueous solutions and in soils has been investigated. Four new photometabolites were formed in non‐aqueous solution and three in soil. These were characterised by spectroscopic methods and identified by comparison with authentic synthetic samples such as 3‐(4‐isopropylphenyl)‐1‐methylurea; 3‐(4‐isopropylphenyl)urea; 4,4′‐diisopropylazobenzene and 4,4′‐diisopropylazoxybenzene. The pathway of formation of these photo products is depicted.

Walker, Alastair L.; Wood, Roger J.

doi: 10.1002/ps.2780170507pmid: N/A

The variation in tolerance to diflubenzuron [1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl)urea] was examined in fourth instar larvae of seven strains of Aedes aegypti, some of which were resistant to DDT and permethrin. The difference between the least and the most tolerant to diflubenzuron was approximately two‐fold. There was no correlation with resistance to the other insecticides. A DDT‐resistant strain (T8) was selected 10 times (during 12 generations) with diflubenzuron. The LC50 to diflubenzuron had increased 3.3 times by the S8 generation but there was no further increase in later generations despite further selection. Associated with this increase, a marked decrease in resistance to DDT was observed but no change in permethrin tolerance. A genetically enriched strain (Hotchpotch) was synthesised from 35 strains of different geographic origin and crossed to the selected T8 strain before subsequent generations were selected five times with diflubenzuron. This procedure resulted in an 8 to 12‐fold increase in the LC50 value over that for unselected T8, accompanied by a decrease in the slope of the log dose against probit mortality line.

Le Patourel, Geoffrey N. J.; Salama, Mohamed A.

doi: 10.1002/ps.2780170508pmid: N/A

The uptake, accumulation, metabolism and excretion of gamma‐HCH (the gamma isomer of 1,2,3,4,5,6‐hexachlorocyclohexane) by a highly gamma‐HCH‐resistant strain of Sitophilus granarius was studied. It was found that the resistant strain was able to excrete a large proportion of a topically‐applied dose of gamma‐HCH in its frass pellets; under comparable conditions a susceptible strain accumulated a high body load of gamma‐HCH. Neither strain metabolised gamma‐HCH to any significant extent over a 48‐h period after dosing.

Jacobsen, Niels; Pedersen, Lars‐Erik K.

doi: 10.1002/ps.2780170509pmid: N/A

A series of 2‐(1‐alkenyl)‐3‐hydroxy‐1,4‐naphthoquinones has been prepared and their toxicities assessed against Musca domestica. By comparison with analogous compounds having saturated 2‐alkyl substituents, or unsaturated substituents with an unconjugated double bond (e.g. lapachol), it was demonstrated that the α‐unsaturation of the substituent is responsible for a significant increase in the toxicity. The effect of the compounds against several other insect species and Tetranychus urticae follows completely different patterns.

Ishizaki, Hiroshi; Kobayashi, Issei; Kunoh, Hitoshi

doi: 10.1002/ps.2780170510pmid: N/A

The effects of IBP (S‐benzyl O,O‐diisopropyl phosphorothioate) on tips of single hyphae of Pyricularia oryzae were investigated by interference contrast microscopy. Labelling hyphae with calcofluor white followed by IBP treatment revealed that elongation of apices of almost all hyphae at the colony margin was inhibited after treatment for 4 h. Successive observations on single hyphae of an IBP‐sensitive isolate indicated that apical cells stopped elongating approximately 10 min after the onset of treatment with 2 μg IBP ml−l. Small vacuoles appeared after 50 min; later they increased in number and size, and coalesced, finally producing a chain‐like arrangement of vacuoles in the cytoplasm. When hyphae were treated with 10 μg IBP ml−1, cessation of elongation and vacuolation occurred earlier than when treated with 2 μg ml−1. Apical cells of hyphae of an IBP‐tolerant isolate appeared unaltered even when treated with 10 μg ml−1. These results indicate that a major effect of IBP is to inhibit specifically the growth of apical cells of the IBP‐sensitive isolate.