Journal of Entomological Society of Iran
Year:2004 | Volume:24 | Issue:1|Papers Count:7

The knowledge of biochemical characteristics of insects haemolymph can be a solution in physiological analysis. To determine the abundance and the range of some biochemical macromolecules in silkworm haemolymph, the amount of glucose, cholesterol, urea and uric acid in fourth and fifth instar larvae were analyzed. The results showed that except for urea as larval age increased, the abundance of these compounds in the larval haemolymph has enhanced. The amount of measured urea in fourth instar larvae were 48.94± 3.05mglml while its occurrence in the fifth instar larvae with over 87% decrease reached to 6.18± 2.4.This is mostly because of the entering of urea to synthesis process of the silkworm shell by silk glands. The amount of glucose, uric acid and cholesterol in the fourth instar larvae were 7.85± 1.03, 1.89± 0.61 and 11.52± 2.03 mg/dl respectively. While the abundance of these compounds were 18.9± 2.4, 3.22± 1.09, 24.65± 2.35 mg on deciliter, respectively for the 6th day of fifth instar larvae.

In order to determine the efficacy of Sunn pest (Euygaster integriceps) parasitoid flies in Ham province during 2000-2001, two wheat or barly fields in Lumar and Eivan regions were selected and sampled weekly following pest infestation. Sampling was carried out in two major heights, Ghalajeh and Ghochali (hibernation and aestivation sites). The collected materials transferred to laboratory and parasitism was determined by dissecting 50 specimens each time. Result showed that average efficacy of flies in Lumar and Eivan cities was 14.8 and 14.4 percent respectively. In two mentioned heights, these values were 7.5-8 percent. Meanwhile number of eggs in ovaries were compared between parasitized and unparasitized females. It was found that the parasitoid flies have significantly reduced the fecundity potential female adults.

Some quality parameters of Trichogramma brassicae Bezd. populations including: fecundity, emergence rate from factitious host, progeny sex ratio, longevity and female wing abnormality were evaluated on eggs of Sitotroga cerealella Olivier at 25±1degrees c, 60 ±5% RH. and 16:8 L:D condition. Biological characteristics of various T. brassicae populations were significantly different and the highest obtained in fecundity and longevity that ranged between 30.41- 71.88 eggs in life span and longevity was 4.34-7.6 days. Progeny sex ratio differed between 52.57- 72.76% of females and rate of emergence varied between 91.25- 96.72%. Female abnormality in all populations was less than 1%. The Ramsar, Vazivar(Noor) and Babol populations had the highest fecundity, longevity and sex ratio respectively. Fecundity, emergence rate and sex ratio of these populations were approximately the same as the Internationa Organization of Biological Control (IOBC) standards but longevity had a clear difference and results disscused in follow.

Several spider mites species have been considered to be major pests of agricultural economic plants in Iran and elswhere. In last four decades, application of phytoseiid mites in biocontrol of spider mites has had steady progress in many parts of the world. Typhlodromips caspiansis Denmark & Oaneshvar with broad host spectrum act as a potential natural enemy of phytophagus mites in Guilan province. Study on biology of this predatory mite was carried out in laboratory condition at 26 ± 1°C, 70-80% relative humidity (RH), photoperiod O/L 10: 14 hours with prey mites (Tetranyehus urtieae, Panonyehus eitri, Oligonyehus hieolor). Experiment was conducted with the excised leaf method in petri dishes under stereo binocolar microscope. The results indicated that, minimum mean of immature stages of female predatory mite completed at 6.3, 7.2 and 7.9 on T. urtieae, 0. hie%r and P. citri respectively. While, maximum daily fecundity recorded as 1.691, 1.367 and I.22l when predatory mite reared on 0. hiea/or, T. urtieae and P. eitri respectively. The minimum duration of predatory mite life span (egg to egg) was 9.4 days when T. urticae was selected as prey mite. This finding with referring to feeding ability of predatory mite on phytophagus mites showed that, due to resembelance of immature stage as well as life history of predatory mite with prey mites in Guilan province, this similarity gives the potential use of T. easpiansis in biological control programs of the above mentioned spider mite species.

Alfalfa is an important forage crops, which has a major role in providing food for livestocks. Alfalfa weevil destroyes the first cut of the crop every year. Various control tactics of alfalfa weevil were applied including chemical control (spraying, Ekamet 1.5 lit./ha. and Gramaxon, 4 lit./ha.), physical control (five gun), cultural control (clear cutting early) and integrated control (simultaneous use of the above in spring and fall). Spring method had better results compared to the falls and use of fire flame and early cutting was the best among spring control methods. In flame use and early cutting treatments, the percentage of the intact leaves were 95 and 97 percent respectively. Therefore cultural control could be recommended for all fields as it contained moside-effects but fire with the flame gun can be applied in large fields with two year crop.

Woolly poplar aphid, Phloeomyzus passeriniii Sign., is considered to be a major insect pest of poplar trees in Iran. This aphid causes serious injury to poplar trees in Hamadan province. In this study, stable population parameters of woolly poplar aphid P. passerinii were evaluated in growth chamber on twelve poplar clones of four species namely, Populus alba (p.a), Populus nigra, Populus del/oides and Populus x euramericana. A poplar cut from each clone was infested with a single newly born aphid, and the reproductive processes were recorded in a controlled condition 21± 1 Celsius, 60-70% RH, and photoperiod of 16:8 (L: D). Subsequently, the experiment was carried out with 18 replications and the aphid fecundity and death rate was recorded until the end of lifespan. Thereafter, stable population parameters were calculated on each clone. The aphids could not reproduce on a number of clones including, P. alba 58/57, P. deltoides 72/51 and P. euramericana 214, showing the immune response in these clones. Intrinsic rate of increase (rm) (0.38) and net reproductive rate (Ro) (62.72 nymph per female) on p.n 56/72 was higher than remaining clones. The rm on p.n 47/13, p.n 56/32, p.n 74/1 and p.n 75/2 were about 0.26-0.34, and the varied within 23.67- 41.00, which these clones were semi susceptible. However, rm and R0 on the resistant clone (p.d missoriensis) was 0.03 and 1.39. Other stable population parameters of the aphid such as gross reproductive rate, mean generation time, doubling time, intrinsic death rate, intrinsic birth rate and finite rate of increase were also calculated on different clones.

Alder leaf beetle, Galerucella lineola is considered to be an important pest of alder; Alnus subcordata in Golestan province. Adults and larval instars of the pest feed on leaves of tl1e host trees. In the period 1998-2000, biological characteristics of the pest including, life cycle, larval instars, rate of egg deposition, generation, sex ratio and population dynamics were studied in two alder forest localities (Kord- Kouy and Jafar-Abad). Over wintering adults emerge in late March on hosts opening buds and foliage. Mating begin in about a week. Mating period lasts about a montl1 and a single female is capable to mate several males. The sex-ratio was 1: 1 for 400 adults. Oviposition starts in early April and cluster of eggs are laid on lower side of host leaves. Each cluster include 4 to 30 eggs with an average of 21.5± 7. Total egg number for each female varid from 78 to 538. There are 3 larval instars. Under field conditions, first larvae emerge in second week of May, 12 to 16 days following egg laying. The first larval molt occurs in 5-6 days following hatching. Second and tl1ird larval instars occures 5.5-7 and 7-10 days later respectively. Late third instars leave the fliage of host trees, descend the trunk and pupate at or near tl1ebase of the tree, 5-10 cm beneatl1 tl1e soil surface. First pupae were collected in late June. Pupal duration lasts 7 to 9 days. Adults emerge in early July to mid-August. Insect has one generation annually. Adult and larvae are foliage feeder, solely on alders and we did not observe other trees or shrubs as insect hosts in Golestan forests.