فصلنامه تحقیقات آفات گیاهی
سال پنجم شماره 3 (پاییز 1394)

In the present research, we studied the effects of larval starvation on survival rate, incidence of cannibalism and survival time in the larval stage of Mediterranean flour moth, Anagasta kuehniella (Zeller) (Lep.; Pyralidae). Effects of starvation and cannibalism of fifth larval instars were also evaluated on adult's fertility and percentage of female larvae in next generation. All experiments were carried out at 27±2 ºC, 70±5% R.H., and L:D 16:8 h. Feeding of larvae on natural food mixture (wheat flour and bran; 3:1) was considered as the control. According to the results, all individuals of the first and second larval instars, and a high percentage of third, fourth (about 87%) and fifth larval instars (about 73%) died because of starvation but it should be noted that cannibalism behavior increased the survival rate of larvae (about 33-73%) compared to the starvation. Negative effects of starvation were most obvious in first and second larval instars. The mean rate of cannibalism increased significantly on eggs by third, fourth and fifth larval instars and also on larvae by fourth and fifth larval instars. The highest fertility of females was observed in female fifth instars that fed on natural food (the control). Fertility of females that produced from fifth instars that had eggs and larvae cannibalism decreased considerably. Feeding state of fifth instars (natural feeding, starvation, and cannibalism) had no significant effect on the percentage of female fifth instars in the next generation. The results showed that in the case of larval starvation due to transient absence of nutrients, larvae of this species can increase their viability by cannibalizing on larvae of earlier instars or wretched larvae and therefore would increase the opportunities or energy required for penetration into the nutrients.

Storage at low temperature (cold storage) is an appropriate way to extend longevity of natural enemies such as insect parasitoids. The aim of this study was to determine the optimal time of storage of the parasitoid, Habrobracon hebetor (Say) and its factitious host, the flour moth, Anagasta kuehniella (Zeller) at 12 °C. After in vitro rearing of the above insects, the adult female wasp of H. hebetor and also the larvae of host, A. kuehniella were stored in five replicates for one to six weeks at 12°C. After this, effects of storage time on some biological traits such as survival, fecundity and efficiency were evaluated weekly. The results showed that at 12°C, the adult parasitoid wasps could be stored for four weeks. Also at the same temperature, A. kuehniella larvae could be stored for three weeks, but for the parasitoid, they can be stored for four weeks. Thus, short-term storage of H. hebetor adult wasps could be used to hold and store a large number of mass reared parasitoids.

Two-spotted spider mite, Tetranychus urticae Koch, is one of the important pests of cucumber, which can cause severe damage on it. Vermicompost is one of the organic fertilizers, as its addition to the soil can decrease the population of the pest. In this research, effect of four different vermicompost: soil ratios including 0:100 (control), 10:90, 20:80 and 30:70 % was investigated on biological and population growth parameters of T. urticae. The experiments were carried out in Petri dishes in a growth chamber at 25 ± 2 °C, 65 ± 5 % RH and 16 L: 8 D. The duration of developmental stage, was significantly affected by vermicompost ratios. The longest immature period, shortest longevity of females and shortest oviposition period were obtained at 30:70 % ratio. Furthermore, vermicompost ratios significantly affected population growth parameters of the mite. The intrinsic rate of natural increase (rm) of the mite ranged from 0.216 to 0.247 day-1, which its lowest and highest values were at 30:70 % ratio and control plants, respectively. The lowest net reproductive rate (R0) and finite rate of increase (λ) of the mite and the highest value of mean generation time (T) and doubling time (DT) were estimated at 30:70 % ratio. The results of this study showed that 30:70 % ratio had better potential for decreasing the population of the two-spotted spider mite and it can be used in the mite IPM programs.

Aphis gossypii Glover is one of the most important pests in greenhouse and field plants. Considering the importance of human health and the environmental protection, reduction of pesticide use in the pest control program is essential. The experiment was performed with 25 replicates for each concentration of each treatments consisting of plant extract, imidacloprid, control 1 (distilled water, as control for insecticide) and control 2 (water+ Tween+ ethanol, as control for the plant extract). Therefore, in the present study, effects of sublethal concentration (LC30) of ethanolic extract of Eucalyptuscamaldulensisand imidacloprid was tested on the aphids using dipping method. Reproduction and mortality rates of aphids on cucumber leaves were counted in the laboratory conditions. Based on the results obtained in the imidacloprid, plant extract eucalyptus and control 1 and 2, respectively the net reproductive rate (R0), was 4.32 ± 0.14, 14.89 ± 0.57 and (control 1 and 2, respectively was to 55.21 ± 0.11 and 49.50 ± 0.13 female/female, intrinsic rate of increase (rm) was 0.18 ± 0.03, 0.32 ± 0.02 and 0.41 ± 0.005 female/female/day, finite rate of population increase (λ) was 1.20 ± 0.004, 1.39 ± 0.02 and 1.51 ± 0.004 female/female/day, mean generation time (T) was 7.97 ± 0.05, 8.42 ± 0.00 and 9.42 ± 0.00 day, the population doubling time (DT) was 2.38 ± 0.001, 1.84 ± 0.06 and 1.57 ± 0.001 day. This information provides support for E. camaldulensis having a role in aphids control.

A survey was carried out during 2008-2009 to study the fauna of the fruit flies (Diptera: Tephritidae) and their hosts associations in Sistan and Baluchestan Province. Twelve species belonging to seven genera were collected and identified. New species records for Iran fruit flies fauna are marked by an asterisk (*). The list of identified species is:Bactrocerazonata (Saunders, 1842); Bactrocera latifrons (Hendel, 1909); Bactrocera cucurbitae; (Coquillett, 1849); Bactrocera dorsalis (Hendel, 1794); Bactrocera oleae (Rossi, 1790); Dacus ciliatus (Loew, 1862);Acanthiophilus helianthi (Rossi, 1794); Rhagoletis cerasi (Linnaeus, 1758); Ceratitis capitata (Wiedemann, 1824); Anastrepha striata* Schiner, 1868; Carpomyia vesuviana Costa, 1854; Carpomyia pardalina (Bigot, 1891). An identification key for collected fruit flies in Sistan and Baluchestan is provided.

Natural activities such as volcanic eruptions, erosion, springs water and human activities such as exploration, mining, agriculture and fossil fuels forms due accumulation of heavy metals in soil and implicit toxicity to plants, animals and humans. Among heavy metals, Zinc is considered as an essential element. The effect of median concentrations of zinc (25, 50 and 100 mg/ kg diet) was studied on cellular immune of American cotton bollworm. Our results demonstrated significant increase in total hemocytes count (THC) in 50 and 100 mg/kg concentrations of zinc compared to the control. In differential hemocytes count (DHC), prohemocytes were significantly reduced in 100 mg/ kg concentration of zinc but in 50 and 100 mg/ kg concentrations of zinc, oenocytoids increased significantly compared to the control. After latex bead injection, immune response (nodulation) significantly was enhanced in 100 mg/ kg concentration of zinc compared to the control. Understanding, the influence of environmental factors and stresses on immune responses can be effective solutions for pest control.

During a faunal study in the year 2014 on flowers and ornamental plants in Mahallat, Arak city (Markazi Province), several thrips species were collected. Among them, both genus and species of Chaetanaphothrips orchidii (Moulton, 1907) were recorded from Iran for the first time. Specimens were collected on aconite (Ranunculaceae).