Insecticidal effect of plant extracts on common pistachio psylla,Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Aphalaridae)

The common pistachio psylla, Agonoscena pistaciae (Hemiptera: Aphalaridae) is one of the most detrimental pests to pistachio trees. Nowadays various pesticides are used to control the common pistachio psylla, but extensive pesticide spraying against this pest over a period of several years has overpowered its natural enemies. The plant’s byproducts come as an alternative ecologically more compatible in substitution to the synthetic insecticides. This work aims to evaluate the insecticidal potential of herbal extracts of fruit peels of Citrus sinensis and Citrus reticulata, seeds of C. sinensis and Rubia tinctorum, and leaves of Lawsonia inermis against common pistachio psylla. Five concentration 40, 47, 56, 67 and 80 µl/ml, of these plant extracts were sprayed on the fifth instar nymphs of common pistachio psylla by Potter Spray Tower under laboratory conditions (26?±?2?°C, 60–70% RH and a photoperiod of 16L: 8D h). Results showed significant differences among the treatments of the plant extracts and between the concentrations. The LC₅₀ values of C. sinensis peels, C. reticulata peels, C. sinensis seeds, R. tinctorum seeds and L. inermis leaves were 62.04, 38.84, 43.60, 59.01 and 33.99 µl/ml, respectively. Also, all extracts showed the greatest mortality effect in 80 µl/ml concentration. According to these results, these plant extracts may use as herbal pesticides chemical control programme of common pistachio psylla.     

Abundance and biological parameters of psyllophagous coccinellids in pistachio orchards

The abundance of coccinellids on pistachio trees was monitored at both a cultivated pistachio plantation and a wild pistachio growing area in Rafsanjan, Iran. Eleven ladybird species were identified from planted pistachio trees with Adalia bipunctata (Linnaeus) and Oenopia conglobata contaminata (Menetries) the most abundant ladybirds. At the wild pistachio plantation site, 17 coccinellid species were collected, with Brumus undulatus Weise the most abundant ladybird, followed by A. bipunctata and O. conglobata contaminata. Three species of Coccinellidae were evaluated for their potential for biological control of the common pistachio psylla (CPP), Agonoscena pistaciae Burckhardt and Lauterer. Coccinella undecimpunctata aegyptica (Reiche), Exochomus nigripennis (Erichson) and Hippodamia variegata (Goeze) developed successfully on A. pistaciae nymphs and reproduced successfully. Development and reproduction of these ladybirds were also examined on an alternative prey, the cotton aphid Aphis gossypii Glover, the most abundant aphid species on herbal weeds in pistachio orchards. The highest intrinsic rate of natural increase (r_m value) was observed in C. undecimpunctata aegyptica, 0.22 and 0.23 when it was fed on A. pistaciae and A. gossypii Glover, respectively. In comparison, the lowest r_m values (0.12 and 0.13) were found in E. nigripennis on the CPP and cotton aphid diets, respectively. Exochomus nigripennis consumed the largest number of psyllid nymphs during larval period, while the adults consumed the lowest number of psyllid nymphs daily. Although eight psyllophagous coccinellid species were collected in colonies of the CPP on pistachio trees, they did not regulate psyllid numbers below damaging levels. At present, conservation should assume a central role in biological control strategies for this pest.     

Effects of a juvenile hormone analogue, pyriproxyfen, on the apterous form of soybean aphid (Aphis glycines)

The soybean aphid, Aphis glycines Matsamura, is an eastern Asian soybean [Glycine max (L.) Merr.] pest which can reduce soybean yield. We determined the effects of pyriproxyfen, a juvenile hormone analogue, on development, mortality, longevity and fecundity of A. glycines under laboratory conditions. Distance Insect Growth Regulator, containing ∼11.2% pyriproxyfen, was applied at two concentrations, 50 and 150 mg/l, to first and fourth instar nymphs. When first or fourth instar A. glycines were treated with pyriproxyfen, some nymphs became supernumerary‐molted nymphs with 1–3 extra molts or were sterilized. Mortality of treated first instar nymphs was >68% greater than the control group and longevity was reduced by >40%. The higher concentration of pyriproxyfen reduced fecundity of first instar nymphs when they reached adulthood by ∼79%. Pyriproxyfen similarly affected fourth instar nymphs. Mortality of treated fourth instar nymphs was ≥15% greater than the control group and longevity was reduced by >24%. Both concentrations of pyriproxyfen lowered the fecundity of fourth instar nymphs by >27%. Pyriproxyfen also had other sublethal effects on fourth instar nymphs which became apparent when they molted to adulthood. In a few instances they developed wing pads and many produced dead, deformed or abnormal neonates that lacked appendages.     

Seasonal biology and abundance of Psyllaephagus pistaciae,a biocontrol agent of the common pistachio psylla Agonoscena pistaciae

The solitary endoparasitoid Psyllaephagus pistaciae Ferrière (Hymenoptera: Encyrtidae), is the most widely distributed biological control agent of the common pistachio psyllid, Agonoscena pistaciae Burckhardt and Lauterer (Hemiptera: Psylloidea), in Iran. The pupation and overwintering sites of diapausing parasitoids and the psyllid were studied for 2 years using emergence traps in pistachio orchards in Rafsanjan, Iran. The psyllid mummies containing the overwintering parasitoid adhered to pistachio leaves and were carried on these leaves away from the tree when they latter senesced. The present results verified that plant litter which included dried grasses and old pistachio leaves tended to support a greater population of adult winter-form psyllid and psyllid mummies during the winter through early spring than other options examined. Adult parasitoids appeared in the field in early April, about 30 days after the emergence of adult psyllids, but almost at the same time as the hatching of the first generation psyllid nymphs in early April. Rates of parasitism of CPP were generally low throughout most of the year, ranging from 1 to 5%, but rose in late autumn to about 11%. Results suggest that the density of P. pistaciae is not great enough to keep pace with the psyllid populations in these orchards. They explain why growers consider it necessary to apply pesticides for this pest. However, this parasitoid undoubtedly does play an important role in the natural control of A. pistaciae late in the growing season, particularly in non-sprayed orchards. Conservation of these natural enemies should be one of the objectives in the development of sustainable pest management programs.     

Toxicity of diflubenzuron, pyriproxyfen, imidacloprid and diafenthiuron to the predatory bugOrius laevigatus (Het.: Anthocoridae)

The susceptibility of the predatory bugOrius laevigatus (Fieber) to the insect growth regulators diflubenzuron, pyriproxyfen, the nitroguanidine insecticide imidacloprid and the thiourea compound diafenthiuron was investigated in the laboratory. Fifth-instar nymphs were exposed to formulated materials of each compound and adults were exposed to formulated materials of diafenthiuron and imidacloprid. In each case, exposure via ingestion and residual contact was tested. Pyriproxyfen was harmless toO. laevigatus nymphs by both ways of exposure. The respective LC₅₀-values of diflubenzuron via ingestion and residual contact were 229.9 and 391.1 mg a.i./l. Diafenthiuron did not cause significant mortality to fifth-instar nymphs and adults via ingestion but was toxic by residual contact with LC₅₀-values of 329.4 mg a.i./l and 125.9 mg a.i./l for nymphs and adults respectively. Imidacloprid proved to be the most toxic compound with LC₅₀-values of 1.1 and 0.04 mg a.i./l for nymphs and 2.1 and 0.3 mg a.i./l for adults, via ingestion and residual contact, respectively. The results suggest that use of pyriproxyfen in an integrated pest management programme will not cause any problems but that imidacloprid, and to a lesser extent, also diflubenzuron and diafenthiuron could be harmful to the predator.     

Biological activity of Hyposidra talaca nucleopolyhedrovirus against all instar stages of a destructive tea pest Hyposidra talaca (Lepidoptera: Geometridae) in India

Hyposidra talaca (Walker) (Lepidoptera: Geometridae) is the most harmful pest of northeastern tea hub of India that devastates the tea production by feasting on the tea leaves. Hyposidra talaca nucleopolyhedrovirus (HytaNPV) is a natural enemy of the aforesaid pest, as it poses great obstruction in the multiplication of the pest by causing significant larval mortality. The study was undertaken to screen the virus activity against first to fifth instar H. talaca larvae. Early instar stages are found more susceptible than the late stages as they tend to reflect highest LC₅₀ value for fifth instar as 4.3 × 10⁷ POB/ml and lowest LC₅₀ value for first instar as 7 × 10⁴ POB/ml within seven days of inoculation. LT₅₀ values vary between 2.47 and 8.45 days for neonates to fifth instar. The high record of virulence of HytaNPV indicates its bright prospect as a useful microbial biopesticide.     

Susceptibility of the predatory stinkbug <Emphasis Type="Italic">Picromerus bidens</Emphasis> to selected insecticides

The Palaearctic stinkbug Picromerus bidens L. (Heteroptera: Pentatomidae) has been considered as a potential biocontrol agent of several defoliator pests in various agricultural and forest ecosystems. It may therefore be a valuable alternative for the Nearctic pentatomid Podisus maculiventris (Say) (Heteroptera: Pentatomidae), the augmentative use of which has largely been abandoned in Europe given its possible environmental impact as an exotic polyphagous predator. However, no study has yet documented the impact of insecticides on P. bidens, which is essential to evaluate the possible combination of this predatory pentatomid with current insecticide applications in integrated pest management (IPM) programmes. This study reports on laboratory experiments investigating the susceptibility of P. bidens to five insecticides with different modes of action: the pyrethroid deltamethrin, the diacylhydrazine methoxyfenozide, the juvenile hormone mimic pyriproxyfen, the spinosyn spinosad, and the neonicotinoid imidacloprid, all of which are used to control defoliator pests. Fourth-instar nymphs and female adults of the predator were exposed to formulated materials of the insecticides by residual contact. Methoxyfenozide and spinosad did not cause significant mortality to 4th instars and female adults of P. bidens. In contrast, deltamethrin and imidacloprid were harmful to nymphs and adults of the predator, with LC₅₀ values ranging between 1.5 and 9.9 mg a.i./l. Pyriproxyfen was toxic to 4th instars with an LC₅₀ value of 13.9 mg a.i./l but did not affect female adults. Reproduction and longevity of P. bidens were not adversely affected when the predator was exposed to field concentrations of spinosad, methoxyfenozide, or pyriproxyfen, or sublethal concentrations (around LC₁₀) of deltamethrin and imidacloprid. The results from residual contact experiments suggest that methoxyfenozide, spinosad, and to a lesser extent, pyriproxyfen may be compatible with P. bidens in an IPM programme. Further experiments assessing food chain toxicity of these compounds should offer a more complete picture of their selectivity.     

Chemical composition and larvicidal activity of leaf essential oil from Clausena dentata (Willd) M. Roam. (Rutaceae) against the chikungunya vector,Aedes aegypti Linn. (Diptera: Culicidae)

Larvicidal activity of essential oil and isolated compounds from Clausena dentata leaves were tested against early fourth instar Aedes aegypti larvae. GC–MS analysis of essential oil revealed the presence of fourteen compounds of which the major compounds were sabinene (21.27%), biofloratriene (19.61%), borneol (18.34%) and β-bisabolol (17.68%). The essential oil of C. dentata exhibited significant larvicidal activity, with 24 h LC₅₀ and LC₉₀ values of 140.2 and 341.6 mg/l, respectively. Larvicidal activities of the four major compounds of essential oil were also tested. The LC₅₀ values of sabinene, biofloratriene, borneol and β-bisabolol were 27.3, 47.4, 43.5 and 33.2 mg/l, respectively. Results of this study show that the leaf essential oil of C. dentata and its four major compounds may be a potent source of natural larvicides.     

Parasitoids associated with the common pistachio psylla, Agonoscena pistaciae, in Iran

The parasitoids associated with the common pistachio psylla, Agonoscena pistaciae Burckhardt and Lauterer, were investigated at three pistachio plantations in Rafsanjan, Iran. Of the 6504 wasps emerging from mummified psyllids, 46% were the primary parasitoid Psyllaephagus pistaciae Ferrière, and the remaining 54% represented six species of hymenopterous hyperparasitoids, including Chartocerus kurdjumovi (Nikol’skaja), Marietta picta (André), Pachyneuron aphidis (Bouché), Pachyneuron muscarum (Linnaeus), Psyllaphycus diaphorinae (Hayat), and Syrphophagus aphidivorus (Mayr). Lysiphlebus fabarum Marshall, the parasitoid of Aphis gossypii Glover and Aphis craccivora Koch present on weeds, was found to be an alternative host for three major hyperparasitoids of A. pistaciae. The most abundant hyperparasitoid was S. aphidivorus, appearing during the growing season in all trial locations on psyllids and aphids in pistachio orchards. The weed-infesting aphids, along with their primary parasitoid, can act as a reservoir of A. pistaciae secondary parasitoids. Therefore, parasitized aphids allow populations of secondary parasitoids to increase and consequently to apply higher pressure on P. pistaciae. We detected that two primary parasitoid species, including P. pistaciae and L. fabarum, attacking different species of hosts interact indirectly through shared secondary parasitism. It is suggested that the community structure of A. pistaciae may be influenced by apparent competition, although more work is needed to provide firm evidence.     

Effects of pyriproxyfen on some physiological aspects of the pistachio fruit hull borer,Arimania comaroffi Ragonot,pupae

The pistachio fruit hull borer, Arimania comaroffi (Lepidoptera: Pyralidae) is one of the minor pests of pistachio orchards. This pest passes the winter as pupae in silken cocoons in soil beside pistachio trees. In this study, effects of insect growth regulator pyriproxyfen were investigated on some physiological aspects of the pest by measuring glycogen, total sugar, lipid, protein, low-molecular-weight carbohydrates (trehalose and glucose) and polyols (sorbitol and myo-inositol) contents of the pupal body. Last larval instar was treated with 1?μl of the pesticide, and the effects on pupae were measured after one week. Glycogen content in treatment with 3.11?mg/g fresh body weight was significantly different from control with 8.51?mg/g fresh body weight, but no significant differences in protein and lipid contents (p?>?0.05) were observed. Glucose content in treated pupae with 1.50?mg/g fresh body weight was significantly different from control with 2.99?mg/g fresh body weight. Trehalose and sorbitol contents in treated pupae with 0.52 and 0.04?mg/g fresh body weight, respectively, were significantly lower than control with 2.07 and 1.5?mg/g fresh body weight, while there were no significant differences in glucose and myo-inositol contents between treated and control pupae.     

Effects of a juvenile hormone analog, pyriproxyfen, on the apterous form of Lipaphis erysimi

Effects of a juvenile hormone analog, pyriproxyfen, on various developmental stadia of the apterous form of the turnip aphid, Lipaphis erysimi (Kaltenbach), were bioassayed at three concentrations (50, 100, and 150 mg [AI]/l) in the laboratory. Supernumerary-molted nymphs with 1-3 extra molts were found when the first three nymphal instars were treated, and all these nymphs died prematurely. In contrast, all treated fourth instar nymphs molted normally to adults. The longevity of all pyriproxyfen-treated L. erysimi nymphs and adults and the fecundity of treated adults were reduced by 50%. Higher concentrations of pyriproxyfen (100 and 150 mg [AI]/l) caused sterility in adults from treated fourth instars; whereas the lowest concentration (50 mg [AI]/l) did not cause any adult sterility. A majority of adults from treated fourth instars and treated adults produced normal nymphs, and some adults produced dead nymphs with normal appendages or dead and deformed nymphs without any appendages. Normal nymphs produced by the adults from treated adults or treated at fourth instars developed more slowly from first instar to adult than the water-treated nymphs, and all adults in the new generation apparently reproduced normally. The potential role of pyriproxyfen in a vegetable aphid IPM program was discussed.     

Sublethal effects of essential oil of Cinnamomum zeylanicum Blume on life expectancy (ex) and age-specific fertility (mx) of two-spotted spider mite,Tetranychus urticae Koch (Acari: Tetranychidae)

Two-spotted spider mite, Tetranychus urticae Koch, is one of the most important pests of agricultural products that have a global distribution. Now, the control is dependent on the use of chemical pesticides. The effects of the sublethal concentrations (LC₁₀ and LC₂₅) of the essential oil of Cinnamomum zeylanicum were evaluated on some parameters of the life table of the pest, at the constant temperature of 30?°C, relative humidity of 40?±?5% and photoperiod of 16L: 8D. Our results showed that the essential oil of cinnamon is effective on female adult stage. Lethal concentration at which 50% mortality (LC₅₀) for the essential oils is from C. zeylanicum on female adult mite was 23.39?μl/L air. Sublethal concentrations of the essential oil of C. zeylanicum also impair the natural biology of the mite. Concentrations of sublethal of essential oil decreased age-specific fertility (m_x) of T. urticae compared with the control. Sublethal concentrations (LC₁₀ and LC₂₅) have reduced the life expectancy (e_x) in egg stage. Sublethal effects of the essential oil of C. zeylanicum and its impact on T. urticae management are discussed.     

Toxicity of diflubenzuron and pyriproxyfen to the predatory bugPodisus maculiventris

The susceptibility of the predatory pentatomidPodisus maculiventris (Say) to the insect growth regulators (IGRs) diflubenzuron and pyriproxyfen was investigated in the laboratory. Fifth-instar nymphs were exposed to formulated materials of each compound via direct contact, residual contact and ingestion. Diflubenzuron was harmless toP. maculiventris by direct and residual contact, but was highly toxic when ingested via drinking water. Pyriproxyfen caused severe deformities at ecdysis whatever the method of exposure. Exposure of fifth instars to sublethal concentrations (around LC₁₀) of both compounds had no adverse effects on reproduction of emerging adults. The data suggest that the use of these IGRs in the integrated management of insect pests should be evaluated with caution.     

Evaluations of larvicidal activity of medicinal plant extracts to Aedes aegypti （Diptera： Culicidae） and other effects on a non target fish

A preliminary study was conducted to investigate the effects of the extracts of 112 medicinal plant species, collected from the southern part of Thailand, on Aedes aegypti. Studies on larvicidal properties of plant extracts against the fourth instar larvae revealed that extracts of 14 species showed evidence of larvicidal activity. Eight out of the 14 plant species showed 100% mosquito larvae mortality. The LC50 values were less than 100μg/mL （4.1μg/ mL-89.4μg/mL）. Six plant species were comparatively more effective against the fourth instar larvae at very low concentrations. These extracts demonstrated no or very low toxicity to guppy fish （Poecilia reticulata）, which was selected to represent most common non-target organism found in habitats ofAe. aegypti, at concentrations active to mosquito larvae. Three medicinal plants with promising larvicidal activity, having LC50 and LC50 values being 4.1 and 16.4 μg/mL for Mammea siamensis, 20.2 and 34.7 μg/mL forAnethum graveolens and 67.4 and 110.3μg/mL forAnnona muricata, respectively, were used to study the impact of the extracts on the life cycle ofAe. aegypti. These plants affected pupal and adult mortality and also affected the reproductive potential of surviving adults by reducing the number of eggs laid and the percentage of egg hatchability. When each larval stage was treated with successive extracts at the LC50 value, the first instar larvae were found to be very susceptible to A. muricata and the second instar larvae were found to be susceptible to A. graveolens, while the third and fourth instar larvae were found to be susceptible to M. siamensis. These extracts delayed larval development and inhibited adult emergence and had no adverse effects on P. reticulata at LC50 and LC50 values, except for the M. siamensis extract at its LC50 value.     

Efficacy of some medicinal plant extracts and essential oils against Colorado potato beetle,Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae)

The Colorado potato beetle (CPB), Leptinotarsa decemlineata Say is one of the most important defoliator pests of potato in the world and it often causes extremely large potato yield losses. Potatoes are the preferred hosts for the pest, but it may feed and reproduce on a number of other plants in the Solanaceae family. Public concern related to pesticides and their residues in and on the foods had prompted a rise of consumer interest in organically produced foods. There have been growing efforts to detect and introduce suitable plant compounds that they have insecticidal properties. However, discovering of plant extracts for possible use in control of this pest requires more studying about plant extracts and compounds. Since resistance of CPB to common chemical insecticides is well documented and potato is one of the most prominent nutritious food products for many people in many countries, we examined the effect of essential oils (EOs) of European pennyroyal, lavander, mint, oregano and savory and methanolic extracts of fumitory, licorice and oregano on the pest. These plants were selected because they have medicinal properties and they are safe to human and environment. Adult CPBs were exposed to mentioned plant extracts and essential oils. LC₅₀ values for EOs of lavander and European pennyroyal were 4154 and 3561 ppm, respectively. The results demonstrated that essential oil of European pennyroyal (Mentha longifolia) would be suitable compound to control the pest, but essential oil of mint (Mentha spicata) was not effective against the pest. Also it is notable that at all treatments, the amount of adult feeding was very low.     

不同药剂对欧洲甘蓝粉虱2种表型的毒力及田间药效

[目的] 欧洲甘蓝粉虱B型和L型是近年来新入侵我国的粉虱类害虫。探究当前欧洲甘蓝粉虱2种表型对不同杀虫剂的敏感性水平，能为合理选择高效杀虫剂进行科学防治提供依据。[方法] 采用浸叶法和喷雾法，对油麦菜上的欧洲甘蓝粉虱进行室内毒力测定和田间药效试验。[结果] 室内毒力测定结果表明：阿维菌素原药对B型和L型成虫毒力均最高，LC₅₀分别为0.57、3.54 mg·L^-1；甲维盐对B型和L型若虫毒力最高，LC₅₀分别为0.65、2.29 mg·L^-1。田间药效试验结果表明：5%阿维菌素EW对B型成虫和L型若虫防效最好，分别为65.77%和94.86%；22%氟啶虫胺腈SC对L型成虫的防治效果最好，防效为92.07%；60%啶虫脒WP对B型若虫的防效最好，为95.65%。[结论] 推荐在田间交替使用5%阿维菌素EW、22%氟啶虫胺腈SC和60%啶虫脒WP防治欧洲甘蓝粉虱B型和L型，同时应加强抗药性监测。     

Host discrimination by the endoparasitoid Psyllaephagus pistaciae (Hymenoptera: Encyrtidae): A case of time-dependent ability

Host-discrimination behavior by the koinobiont parasitoid, Psyllaephagus pistaciae Ferrière (Hymenoptera: Encyrtidae), the major biocontrol agent of the common pistachio psylla, Agonoscena pistaciae Burckhardt & Lauterer (Hemiptera: Psyllidae), in Iran, was investigated in the laboratory. The results demonstrated that P. pistaciae quickly detected and avoided freshly parasitized hosts, either after antennating or by probing with their ovipositor. However, this discriminatory ability declined with time, probably influenced by both external and internal markers left by the previous ovipositing female. The results also confirmed that female P. pistaciae responded to changes in host quality associated with the parasitoid's larval development 4 days after the initial parasitization, clearly indicating that the second female could detect the presence of the larvae and adjust her host-selection decision. In addition, psyllid nymphs treated topically with a solution of Dufour's gland were rejected by the parasitoid, showing that Dufour's gland secretion had a significant effect as a host marking chemical. The current study also showed that superparasitism increased the host-mortality and that the rate of encapsulation decreased, suggesting that, when two eggs are laid in the same psyllid nymph, only one parasitoid develops to an adult.     

Effect of Ferula assafoetida essential oil on some biological and behavioral traits of Trichogramma embryophagum and T. evanescens

Fumigant toxicity of the essential oil of Ferula assafoetida L. (Umbelliferae), a potent botanical insecticide against carob moth, was investigated under laboratory conditions on the fitness of two carob moth egg parasitoids, Trichogramma embryophagum (Hartig) and T. evanescens Westwood (Hymenoptera: Trichogrammatidae). The fertility life table parameters were assessed for both species at two different treatments, essential oil and ethanol as control. Although these two species were not affected similarly by the essential oil, exposure to 877 ppm (LC₀₁) in both species significantly reduced the longevity and fecundity of females, as well as the survival, developmental time, wing normality and sex ratio of their progeny. Effects of the essential oil on reproductive behavior of Trichogramma species were also investigated. Under oil treatment, despite that mate searching time increased, the percentage of mating occurrence, the duration of copulation, and sex ratio of F1 progeny declined. Given the negative effects of F. assafoetida essential oil on the two tested wasps, complementary studies are needed to develop the best management strategy for using the oil as environmentally friendly compound in combination with Trichogramma wasps against herbivorous insects.     

Effect of diethyl maleate on the toxicity of essential oil from Citrus reticulata fruit peels to Tribolium castaneum Herbst under laboratory conditions

Certain compounds of plants, essential oils, with insecticidal properties have been considered as alternatives to chemical pesticides for pest control in recent years. In this study, the synergistic effect of diethyl maleate (DEM) on the toxicity of Citrus reticulata Blanco (Rutaceae) peel essential oil against a stored-product insect pest, i.e. red flour beetle, Tribolium castaneum Herbst (Tenebrionidae) adults was studied. DEM [one part], combined with acetone [two parts], was applied on T. castaneum adults. Five concentrations of essential oil from C. reticulata were tested. Three replicates and 30 adult insects/replicate/each concentration were used. LC₅₀ values after 24 and 48?h of exposure were 33.8 and 28.2?μl/l air, respectively. Combination of the essential oil from C. reticulata with the synergist DEM after 24 and 48?h of exposure decreased the corresponding LC₅₀ values to 18.1 and 12.2?μl/l air, respectively. These results revealed that DEM can considerably improve the potency of essential oil from C. reticulata and maybe applied successfully in the stored-product pest control programmes.     

Effects of the IGRs compounds,lufenuron and fenoxycarb on Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae)

In this research work, the susceptibility of egg and four larval instars of Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae) to Insect Growth Regulators (IGRs) compounds (lufenuron 25% EC and fenoxycarb 25% WP) was determined. Different larval instar groups were separated by measuring the head capsule width and were used in all bioassays. The data were analysed with log-probit transformation using the SPSS software. The LC₅₀ for egg was determined by dipping egg masses in different concentration of either compound for 10 s, and LC₅₀ values for each group of larvae was estimated by using treated potato plants. The LC₅₀ values of lufenuron on egg, first, second and third instars of larvae were 682.65, 40.58, 47.83 and 261.38 ppm, respectively, and for fenoxycarb, these were estimated as 897.50, 35.60, 57.91 and 355.23 ppm, respectively. The LD₅₀ values of lufenuron and fenoxycarb on second instar larvae were 139.56 and 228.42 ppm, respectively.