Energy allocation changes in overwintering adults of the common pistachio Psylla, Agonoscena pistaciae Burckhardt & Lauterer (Hemiptera: Psyllidae).

The common pistachio psylla, Agonoscena pistaciae Burckhardt & Lauterer (Hemiptera: Psyllidae), is known as the key pest of pistachio orchards in Iran. This pest passes the winter as adults. In this study, energy allocation changes in relation to ambient temperature were investigated in field-collected adults by measuring total body sugar, trehalose, glucose, sorbitol, myoinositol, glycogen, lipid, and protein contents. Glycogen content decreased with decrease in ambient temperature. The decrease in glycogen content was proportional to the increase in total body sugar, trehalose, myoinositol, and sorbitol contents. In January, with mean ambient temperature of 5.4°C, glycogen content was at the lowest level, whereas total body sugar, trehalose, glucose, and sorbitol were at the highest level. Total body sugar, trehalose, myoinositol, and sorbitol contents increased as temperature decreased from 22.7°C in October to 5.4°C in January. In conclusion, low molecular weight carbohydrates and polyols may play a role in winter survival and adaptation to cold of the common pistachio psylla by providing the required cryoprotection. Also, overwintering adults of the common pistachio psylla may store energy in the form of lipid for later utilization during the overwintering.

Effects of temperature on predation by the stinkbugs Picromerus bidens and Podisus maculiventris (Heteroptera: Pentatomidae) on noctuid caterpillars.

Environmental risks associated with the use of non-indigenous organisms for augmentative biological control have received growing attention. In Europe, the native pentatomid predator Picromerus bidens (Linnaeus) has been considered a potential alternative to the North American pentatomid Podisus maculiventris (Say) for the control of lepidopteran, coleopteran and hymenopteran defoliator pests. In the current study, prey consumption and developmental duration of the predatory stages of P. bidens and P. maculiventris were investigated at three temperatures (18, 23 and 27 degrees C) in the laboratory using caterpillars of Spodoptera littoralis as prey. Development time from second to fifth instar was longer for P. bidens than for P. maculiventris, taking on average 17-44 and 14-32 days, respectively, at the different temperatures. Total nymphal consumption of fourth instar S. littoralis caterpillars indicated a greater voracity of P. bidens as compared with P. maculiventris at both the low and high temperatures tested (18 and 27 degrees C). At 23 degrees C, however, the predation rate of P. maculiventris nymphs exceeded that of P. bidens nymphs. Effect of temperature on the functional response of P. bidens to densities of fourth instar Spodoptera exigua was assessed on potted green bean plants. Female adults of P. bidens exhibited a type II functional response at 18 and 23 degrees C but a type III response at 27 degrees C. Searching efficiency was not affected by temperature but handling time decreased from 4.2 to 1.4 h as temperature increased from 18 to 23 degrees C. However, the predator spent twice as much time handling prey at 27 degrees C (2.9 h) than at 23 degrees C. This study indicates high predation rates of P. bidens at a wide range of temperatures and suggests that the species may be a valuable asset for the biological control of defoliating caterpillars, provided that obstacles to its mass production can be overcome.

Detection by RAPD-PCR of polymorphism in populations of Bemisia tabaci (Genn.) collected on four host plants from Iran.

The sweetpotato whitefly, Bernisia tabaci (Genn.) (Hom: Aleyrodidae) is a major pest of field crops, vegetables and ornamentals in Iran. In this study, the infested leaves of cucumber (Cucurnis sativus L.) zucchini (Cucurbita pepo L.) eggplant (Solanum melongena L.) and cotton (Gossypium hirsutum L.) with whitefly nymphs and pupae were collected from Iran, and were transferred to the laboratory. The newly emerged males and females of each population were released separately into a large cage set on cotton plants. Experiments were carried out in a growth chamber on cotton, (Varamin 76 variety) at 24+/-20C, 55+/-3% RH and 16:8 h (L:D) photoperiod. The adults of every collected population after emergency were reared in the large cages (40x50x70) containing pots of cotton plants. In this study five decamer primers were used in the amplification reactions. All the primers produced polymorphisms. Totally, 71 RAPD markers were found. The amplified DNA fragments were 200 to 3000 bp. The Jaccards and Nies similarity coefficient and Euclidian distances were used to generate a dendrogram based on unweighted pair-group method with arithmetic averages (UPGMA). The clusters based on RAPD markers correlate fairly well with classification scheme based on biological traits. This study suggested that RAPD can be useful technique to study DNA polymorphism in Bemisia tabaci.

Comparative study of the five biological parameters of cotton whitefly Bemisia tabaci and silverleaf whitefly B. argentifolii bellows and perring reared on cotton under laboratory condition.

The five biological parameters of sweetpotato whitefly, Bemisia tabaci (Genn.) and silverleaf whitefly Bemisia argentifolii Bellows and Perring (Hom: Aleyrodidae) as an important pest of cotton were compared on cotton in laboratory condition. The infested leaves containing nymphs and pupae were collected from cotton fields in Iran. Experiments were conducted in a growth chamber under 24+/-2 degrees C, 55+/-3% RH and 16:8 (L:D) photoperiod on cotton, Gossypium hirsutum L. The newly emerged populations of each species were released in to a large cage set on cotton plants, separately. In this investigation, total fecundity, oviposition period, adult's longevity, sex ratios and daily fertility rates of 50 mated females were calculated for each whitefly used 50 mated females for each treatment. The treatments included two whitefly species and one host plant i.e. Gossypium hirsutum L. (Varamin 76 variety). Emergence of adults and crawlers and percentages of females emerged from 100-200 eggs at four replications were also calculated. The results revealed that total fecundity, oviposition period, and developmental time for B. tabaci reared on gossipium were 65.25, 4.56, and 23.18, respectively and for B. argentifolii reared on gossipium were 97.06, 5.42, and 23.75, respectively. The results revealed that there are significant differences between parameter of total fecundity at 1%. Probability level and sex ratios at 5% probability level. No significant difference was found between oviposition period, developmental time and maximum adult's longevity at 5% probability level.

Identification and introduction of some Iran pollinator bees of Colletidae, Halictidae, and Megachilidae (Hym: Apoidea).

Insufficient pollination results in less yield and low quality of crops. Many vegetables depend on the cross pollination to produce valuable seeds or fruits. Most flowering plants, fruit and seed formation are highly dependent on the activity of pollinator bees and in some crop such as alfalfa no seeds will form in the absence of bees. The most important crops of Iran from stone fruits (peach, almond, plum, cherry and apricot), pome fruits (apple, pear and quince), alfalfa, clover, sunflower, etc. are collected. These plants are attractive for pollinator bees as source of nectar as well as pollen. Hence to identify and introduce bees of Iran, a study was conducted for three years. Pollinator bees were collected from all flowering plant varieties in the bloom season (from the beginning of spring till end of summer) by using insect net. Collected bees were placed in small plastic jar and details of host, place, date and time of collection were recorded. After preservation and drying, identification of samples was carried out by using identification keys and also by comparison with reference samples.