Phenyltin compounds inhibit digestive enzymes of Tribolium confusum larvae     

Isaac Ishaaya  John E. Casida 《Pesticide biochemistry and physiology》1975,5(4):350-358

The potency of dietary phenyltin compounds in inhibiting the growth of first and fourth instar Tribolium confusum L. larvae and the gut proteolytic activity of fourth instar larvae decreases in the order of triphenyltin chloride (Ph₃SnCl) ? diphenyltin dichloride (Ph₂SnCl₂) ? phenyltin trichloride or tetraphenyltin. The growth retardation, which prolongs the larval stage without affecting pupation or emergence, may result from an antifeeding effect involving gut protease inhibition by Ph₃Sn⁺ and Ph₂Sn²⁺. Gut amylase and invertase activities are less sensitive than the protease activity to in vivo inhibition. Under in vitro conditions, relatively high concentrations of Ph₃SnCl and Ph₂SnCl₂ are required for inhibition, the order of enzyme sensitivity is protease > amylase > invertase, and Ph₂SnCl₂ is more potent than Ph₃SnCl. Proteins such as casein, albumin and hemoglobin, but not carbohydrates such as starch and sucrose bind Ph₃Sn⁺ so it is inaccessible for inhibition of digestive enzymes. The level of Ph₃Sn⁺ inhibiting gut protease in vivo is far below that necessary for in vitro inhibition of this enzyme activity. It is speculated that the in vivo inhibitory effects of Ph₃Sn⁺ and Ph₂Sn²⁺ on digestive enzymes may result from binding to the enzyme protein, its zymogen or to other proteins involved in production of the digestive enzymes.  相似文献   

Effect of pyriproxyfen on developing stages and embryogenesis of California red scale (CRS), Aonidiella aurantii     

Eliahu M  Blumberg D  Horowitz AR  Ishaaya I 《Pest management science》2007,63(8):743-746

During the past decade, the insect growth regulator pyriproxyfen has been the most used insecticide for controlling the California red scale (CRS), Aonidiella aurantii (Maskell), an important pest in citrus groves worldwide. The aim of the present research was to develop bioassays for determining the effect of pyriproxyfen on developing stages and embryogenesis of CRS that can serve as baselines for monitoring resistance. Pyriproxyfen was very effective against first- and second-instar nymphs of a susceptible strain of CRS; 0.1 and 0.2 mg AI L(-1), resulting in 80 and 100% mortality of first-instar nymphs, and in 62.5 and 91.7% mortality of second-instar nymphs respectively. According to probit analysis, the LC(50) and LC(90) values of pyriproxyfen for first-instar nymphs were 0.03 and 0.15 mg AI L(-1), and for second-instar nymphs they were 0.05 and 0.25 mg AI L(-1) respectively. Pyriproxyfen was quite effective on first-instar nymphs of a CRS field strain originating from a citrus grove where two successive applications of the compound had been applied. Mortality rates were 86 and 100% at concentrations of 0.2 and 0.4 mg AI L(-1) respectively. Pyriproxyfen suppressed embryogenesis when CRS females were treated with pyriproxyfen. Young CRS females treated with 1.0 and 5.0 mg AI L(-1) pyriproxyfen produced 6.6 N(1)/F and 2.4 N(1)/F as compared with 10.9 N(1)/F in untreated control.  相似文献   

Toxicity and growth-suppression exerted by diafenthiuron in the sweetpotato whitefly,Bemisia tabaci     

I. Ishaaya  Zmira Mendelson  A. R. Horowitz 《Phytoparasitica》1993,21(3):199-204

Diafenthiuron (CGA 106 ’630), a thiourea, was sprayed prior to a 48-h infestation by adult females of the sweetpotato whiteflyBemisia tabaci Gennadius, on cotton seedlings under greenhouse conditions; it subsequently suppressed strongly progeny formation of the whitefly, resulting in approximately 50% progeny formation relative to control at 5 mg a.i./l. When the different development stages were separately sprayed directly, the larval stage was the most susceptible, resulting in 50% and 90% mortality of 2nd instars at concentrations of 6.5 and 49.2 mg a.i./l, whereas the LC50 values of adults and pupae were 23 and 45 mg a.i./l, respectively. A mild (30–35%) reduction of egg hatch was obtained at a range of 5–125 mg a.i./l. Thus the potency of diafenthiuron against various stages was in the order larvae > adults > pupae > eggs. Diafenthiuron exhibited a low vapor phase toxicity and had no translaminar effect when tested on first instars ofB. tabaci. The high potency of diafenthiuron against whiteflies described herein, against aphids and mites, as stated in the literature, and against some lepidopterous pests, render this compound an important insect control agent for pests of cotton and other crops.  相似文献   

Abstracts of Papers Presented at the 6th Meeting on Whiteflies in Field Crops and Vegetables     

C. Shoham  G. Forer  U. Mor  J. Kern  S. Cohen  I. Harpaz  Rachel Ben-Joseph  Y. Antignus  H. Czosnek  S. Cohen  R. Ber  Rachel Ben-Joseph  N. Navot  D. Zamir  Venezia Melamed-Madjar  J. Hameiri  M. Chen  I. Ishaaya  Zmira Mendelson  M. J. Berlinger  R. Dahan  Sara Mordechi  I. M. Seligman 《Phytoparasitica》1987,15(3):259-265

  相似文献   

Dietary triorganotins affect lymphatic tissues and blood composition of mice     

Isaac Ishaaya  Judith L. Engel  John E. Casida 《Pesticide biochemistry and physiology》1976,6(3):270-279

Ph₃SnCl, Ph₃SnAc (Brestan), Cy₃SnOH (Plictran), and (Bu₃Sn)₂O (TBTO) markedly reduce the weight of the spleen and the gain in body weight of young mice feeding for 7 days on diets containing 260 μequiv organotin/kg diet. With mature mice feeding for 4 days on diets containing 780 μequiv organotin/kg, these compounds result in a loss in spleen weight and body weight and an alteration in the blood composition (reduction in lymphocytes and total leucocytes and an increase in erythrocytes, hemoglobin level, and hematocrit value). Four other organotins, [(PhCMe₂CH₂)₃Sn]₂O (Vendex), PhSnCl₂, Ph₂SnCl₂, and Ph₄Sn, are much less toxic based on these parameters. Poisoning by these dietary triorganotins was not related to cerebral edema or alterations in adrenal epinephrine level, liver nonprotein -SH groups, or the activity of digestive enzymes (intestine and stomach proteases and intestine amylase and invertase). The most sensitive indices of triorganotin toxicity appear to be those associated with changes in the lymphatic tissues and blood composition.  相似文献   

Pyrethroid synergism by esterase inhibition in Spodoptera littoralis (Boisduval) larvae     

Isaac Ishaaya  K.R.Simon Ascher  John E. Casida 《Crop Protection》1983,2(3):335-343

The susceptibility of cotton leafworm, Spodoptera littoralis (Boisduval) larvae to poisoning by trans-permethrin and cis-cypermethrin was increased when these pyrethroids were applied topically after the larvae had ingested profenofos, monocrotophos or azinphos-methyl for 24 h. An ingested dose of 4 nmol profenofos per larva gave a synergism factor of about threefold for both trans-permethrin and cis-cypermethrin. These pyrethroids were not synergized by oxidase inhibitors such as piperonyl butoxide, SV-1 and MPP ingested at 80 nmol/larva. Esterase preparations of larval gut hydrolysed trans-permethrin two to three times more rapidly than cis-permethrin, deltamethrin, trans- or cis-cypermethrin. Integument esterase(s) are less active but show a similar preference for trans-permethrin. The gut esterase(s) hydrolysing trans-permethrin are more sensitive in vitro and in vivo to inhibition by profenofos than by azinphos-methyl or monocrotophos. The susceptibility of S. littoralis larvae to pyrethroids appears to be limited by pyrethroid esterases in the gut. Organophosphorous compounds inhibiting these detoxifying enzymes serve as synergists.  相似文献   

Flufenerim, a novel insecticide acting on diverse insect pests: biological mode of action and biochemical aspects   总被引：1，自引：0，他引：1  

Ghanim M  Lebedev G  Kontsedalov S  Ishaaya I 《Journal of agricultural and food chemistry》2011,59(7):2839-2844

A new chemical compound was tested for its insecticidal activity against several major insect pests. The compound, called "flufenerim", has a core pyrimidine structure and an unknown mode of action and showed potent activity against the sweet potato whitefly Bemisia tabaci (Gennadius), the green peach aphid Myzus persicae (Sulzer), and the African cotton leafworm Spodoptera littoralis (Boisduval); however, it did not show any activity against two thrips species: western flower thrips Frankliniella occidentalis (Pergande) and tobacco thrips Thrips tabaci (Lindeman). The compound was relatively potent against the three tested pests and caused mortality rates that reached up to 100% at concentrations under 10 mg of active ingredient (ai) L(-1). The action of the compound was very fast, and mortality was observed within 48 h after exposure of the insects to treated leaves. A unique characteristic of this compound is its very short residual activity, which approximates to 4 days after application under laboratory conditions and to 2 days under outdoor conditions for both B. tabaci and S. littoralis. Although this new compound's mode of action is yet unknown, its rapid and potent action against sap-sucking pests suggests that it acts on a very important target site in the insect body and possibly could be applied very close to harvesting.  相似文献   

Status of pesticide resistance in arthropod pests in Israel     

A. R. Horowitz  Phyllis G. Weintraub  I. Ishaaya 《Phytoparasitica》1998,26(3):231-240

A complex of events and factors, pertinent to a specific insect and insecticide, governs the development of resistance to insecticides. In Israel, resistance to conventional and novel insecticides occurred in insect pests such asBemisia tabaci andSpodoptera littoralis (that damage agricultural crops),Tribolium castaneum and other flour beetles (that contaminate stored products), andPediculus humanus spp., house flies and mosquitoes (that threaten public health). In the mid-1980s an insecticide resistance management (IRM) strategy was established for all cotton grown in Israel and is being adjusted on a yearly basis as needed. At present, insect pest management and IRM strategies are being developed and implemented area-wide for three regions in Israel: Bet She’an Valley, western Galilee, and western Negev. There are several research groups now working in Israel on various aspects of resistance including occurrence, mechanisms, and management practices. This paper offers a tentative review of the status of insecticide and acaricide resistance in pests in Israel.  相似文献   

The effect of BAY SIR 8514 onspodoptera littoralis (Boisduval) eggs and larvae     

K. R. S. Ascher  Nadia E. Eemny  Miriam Eliyahu  I. Ishaaya 《Phytoparasitica》1979,7(3):177-184

The chitin biosynthesis inhibitor diflubenzuron and its analog BAY SIR 8514 are equitoxic for eggs ofSpodoptera littoralis. BAY SIR 8514 residues on alfalfa fed toSpodoptera larvae were more toxic than diflubenzuron residues, whereas BAY SIR 8514 topically applied to these larvae was consistently twice as toxic as diflubenzuron, according to different criteria.  相似文献   

A synthetic diet for the spirea aphid,Aphis citricola van der Goot     

I. Neubauer  B. Raccah  I. Ishaaya  N. Aharonson 《Phytoparasitica》1980,8(1):19-25

Two generations of the spirea aphid were reared successfully on a diet previously used for the green peach aphid, when the sucrose concentration was increased to 24%. Better survival, larviposition and weight gain were obtained when the concentration of five amino acids was also increased. The pea aphid diet was also tested and found unsuitable for this aphid. Synthetic-diet-reared aphids reached a final body weight four times less than that of aphids reared on orange leaves, while their fecundity was about one-third of that recorded for the plant-fed aphids. The possible use of this diet for toxicological and physiological studies is discussed.  相似文献