Percentage Of Adult Emergence Research Articles

Individual and synergist activities of monocrotophos with neem based pesticide, Vijayneem against Spodoptera litura Fab.

Evaluation of monocrotophos and Azadirachta indica oil, herein referred to as ‘Vijayneem’, were combined in ratios of 10% (10: 90), 20% (20: 80), 30% (30: 70), 40% (40: 60) and 50% (50: 50) [Monocrotophos: Vijayneem] under laboratory conditions to determine efficacy for properties of pesticidal, repellency, attraction, stimulant of consumption, development and reproduction. Asa biopesticide, Vijayneem oil (LC50 = 10.619%), caused greater mortality in dermal toxicity bioassays (LC50 = 18.045%) over ingestion. The greatest repellent activity was observed in third (Access Proportion Index = −0.25), fourth (API = −0.52) and fifth instar larvae (API = −0.67) in sprays of cotton leaves with monocrotophos. The detoxification enzymes like esterase (0.3, 11.1 μl/min/mg) and lactate dehydrogenase (6.8, 13.8 μl/min/mg) levels increased postingestion of treatments. Insects which ingested treated leaves showed an increase in carbohydrate (27.0, 18.0%), protein (4.7, 7.7%) and lipid (4.0, 10.4%) content. The greatest deformation of larvae, pupae and adults occurred in monocrotophos alone treatments, while the least deformities were recorded for monocrotophos + Vijayneem treatments. The male and female ratio and percentage of adult emergence was high in control than in A. indica oil alone treated S. litura. The greatest fecundity was observed in control (1620/4 female). In conclusion, the synergistic effects of A. indica oil + monocrotophos can be used for use the management of S. litura.

Laboratory Evaluation of the Effect of Insecticides on Non-target Organisms: 1- The Predatory Green Lacewing, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae)

A study purposed to evaluate the acute residual toxicity of six insecticides (different groups); Dursban and Malathion (OP), Chess (Selective feeding broker), Spintor (bioinsecticide), Biogard: (Bacillus thuringiensis) (bacteria), and Biover: (fungus) on immature stages of the predator, Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) was carried out under laboratory conditions. Lethal and sub-lethal effects of the tested insecticides (4 concentrations each) on the development of the eggs (3 ages) and the 2nd instar larvae of the predator were assayed. The eggs were treated using the dipping method, while the larvae were treated using the residual film contact method. LC50, LC90, LC99 and the sub-lethal concentration (LC20) for each insecticide were estimated. Hatchability values, percentages of the treated eggs as well as percentages of larvae were calculated. Pupation and adult emergence percentages were estimated and compared with those of the untreated check to study the residual effect on the treated larvae, using LC20 of each insecticide. The dose-mortality responses of theeggs were compared in terms of differences in slopes and LC50 values. Data showed that the 3-day old eggs were more tolerant to the tested insecticides than the newly ones. The mean mortality percentages of treated larvae were: 100, 100, 55, 50, and 20% for Dursban, Malathion, Biogard, Chess and Spintor, respectively. According to the classification of (IOBC/WPRS), Dursban and Malathion were classified as harmful insecticides, Biogard and Chess as moderately harmful, and Spintor as harmless insecticde. C. carnea larvae showed a relative tolerance to the insecticides tested as they pupated and developed successfully to the adult stage. The highest larval mortality (24%) was recorded for Dursban, while the lowest one (18%) was for Spintor compared with (10%) for the control. Statistical analysis of accumulated larval mortality indicated that there were insignificant differences among the mortality percentages in any of the studied insecticides and also between the treated larvae with each insecticide and the control. Spintor was the most suitable insecticide recommended to be used in IPM programs as it is safe for different stages of C. carnea.

FIELD AND LABORATORY STUDIES ON INFESTATION OF IMMATURE MANGO FRUITS BY THE PEACH FRUIT FLY, BACTROCERA ZONARA (SAUNDERS)

the peach fruit fly, Bactrocerazonata, is one of the fruit flies thatattack mango fruits during maturity and ripening stages causing significant damage. This paper iscontribution for evaluation the role of dropped immature fruits as host of B. zonata through sampling dropped mango fruits of different varieties at different stages of maturity in different types of mango cultivations. Also, the study was extended to find an interpretation via laboratory investigation the ability of B. zonata females for egg laying on immature mango fruits after abscission for different periods (5, 10 and 15 days) comparing with freshly harvested fruits correlating with biochemical and physical fruit changes after abscission. The results indicated that the immature fruits that on the tree were free of infestation, while the infestation was observed on that were sampled under the trees. Percentages of infestation during the 1stseason (2014) for the early and mid-ripen season varieties were 7.83 and 9.14%, respectively and during the 2nd season(2015) were 5.18 and5.52%, respectively. The mean no. of obtained pupae/ infested fruit were 7.54 and 12.16 pupae/infested fruit, respectively, and 7.25 and 8.10 pupae / infested fruit, respectively during the second season(2015).The sampled immature fruits of late ripen varieties were free of infestation during the two season. The dropped immature mango fruits were firstly observed to be infested during the 4th week of May and the 1st week of June during the two seasons, respectively. The obtained data revealed that, the immature infestation percentages of early and mid-ripening season varieties were lower in comparison with those sampled during maturity and ripening stages. The laboratory study ensured the preference of B. zonatafemales for egg laying on the fruits that were abscised for 5, 10 and 15 days in percentages of 26.67, 46.67 and 53.33%, respectively, the pupation percentages were 80.85, 87.33 and 89.47%, respectively, adult emergence percentages were 63.16, 65.59 and 72.18%, respectively, while, the durations of total immature stages that reared on the mentioned abscised fruits were, 18.20, 16.98 and 16.79 days, respectively. The fruit phenological changes including increasing of total soluble sugars, total soluble solids(T.S.S), also reduction of fruit juice acidity and fruit firmness factor maybe play an important role in susceptibility of dropped immature mango fruits to the peach fruit fly attacks. Removal of such fruit becomes a necessity for avoiding such risk, also, attention should be paid for following and monitoring the fruit flies status in early times (after fruits setting) instead of later periods during June or July.

The Efficiency of Terpenes Extracts of Eucalyptus Camaldulensis Seed to control Larval Stage of Callosobruchus maculates (Coleoptera:Bruchidae)

The current study has beenconduced to evaluate the effect of extracted crude terpens at the concentrations of 6,8% of seeds of Eucalyptuscamaldulensison the 4th larval instar oftheCallosobruchusmaculates and the percentage of the cowpea seed germination.The Results showed that the terpens extract of the concentration of 8% increases the mortality rate of the fourth larval instar and it reach to 63.3%, and then decrease of to 26.6,20% at concentration of 6%and forcontrol treatment respectively The percentage of adult emergence reduces to 0% at the concentration of 8% compared with control treatment in which it reach to 66.6%. The extraction atbothconcentrations 6,8% does not affect the germination rate

EFFECT OF FOOD STUFFS AND SOME ECOLOGICAL FACTORS ON DIFFERENT BIOLOGICAL ASPECTS OF THE ADULT RED PALM WEEVIL, RHYNCHOPHORUS FERRUGINEUS (OLIVER) (COLEOPTERA: CURCULIONIDAE)

The results obtained showed no significant difference (P>0.05) in weevil male and female longevity as a result of feeding either on palm core, palm leaf base, sugarcane pieces or artificial diet. Also, non-significant differences between weevil male and female longevity under the same ecological, biological and food supply conditions were obtained. Data obtained revealed that there were some differences between pre-oviposition periods recorded in different food stuff treatment, while feeding on pear fruits showed the shortest pre oviposition period (6.64±0.67 days), while feeding on apple, sugarcane and corn stem showed the longest pre-oviposition period (11 days). High significant (P 0.05) in adult emergence percentage except when feeding females on 30% molasses concentration artificial diet, but a significant change in adult emergence percentage that reached (99.33±2.33 %) from (89.12±0.07%) in case of 10% molasses concentration in the artificial diet. The weevil longevity was directly proportional to the photoperiod. Photoperiod had no effect on fecundity. The ratio F/M was 1.5:1 at temperature of 25oc and reached 1:1 at the temperature of 40oC.

Effects of temperature and nonionizing ultraviolet radiation treatments of eggs of five host insects on production of Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) for biological control applications

Trichogramma species are used worldwide as biological control agents. A particularly important application is mass-rearing and release for management of field-crop and warehouse insect pests. Eggs of commonly available hosts, Spodoptera litura, Corcyra cephalonica, Plutella xylostella and Helicoverpa armigera, were exposed to different temperature and nonionizing ultraviolet (UV) radiation treatments to consider whether particular combinations of treatments positively affected T. chilonis development. The treatments had different effects on three measures of parasitoid production: the rate of parasitization, adult emergence, and adult viability. At constant temperature (24, 28, 32°C), the mean percentage of egg parasitization was greatest on treatments of S. litura eggs. However, the mean percentage of adult emergence was significantly greater from C. cephalonica eggs at 28°C than from eggs in other treatments. The mean percentage of adult viability was found to be 83.9% from C. cephalonica eggs at 28°C. Ultraviolet radiation treatments (3, 6, or 9min at 254nm) significantly increased the mean percentage parasitization over that of the non-UV treatments. Also, the mean percentage of adult parasitoid emergence and viability were greater from C. cephalonica eggs exposed to non-ionizing UV radiation than from eggs of other hosts in all other treatments. This information can be used by managers of mass-rearing programs to increase the effectiveness of T. chilonis production for biological control of pest insects.

Effect of fertilized, unfertilized, and UV‐irradiated hosts on parasitism and suitability for Trichogramma parasitoids

AbstractTrichogramma spp. (Hymenoptera: Trichogrammatidae) parasitoids have been commonly used as biological control agents in insect pest management. Host quality is believed to influence parasitism, host preference, and suitability for parasitoids. To date, limited studies have compared the parasitism of Trichogramma parasitoids on fertilized, unfertilized, and sterilized host eggs. Hence, we studied the performance of three Trichogramma egg parasitoids, Trichogramma japonicum Ashmead, Trichogramma chilonis Ishii, and Trichogramma leucaniae Pang & Chen, on fertilized, unfertilized, and ultraviolet (UV)‐irradiated fertilized (UVF) eggs of rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae). In a no‐choice test, T. japonicum and T. leucaniae parasitized significantly more fertilized or UVF than unfertilized hosts, and T. chilonis parasitized significantly more UVF than either fertilized or unfertilized hosts. In a choice test, all three Trichogramma parasitoids parasitized UVF hosts the most, and unfertilized hosts the least. There were similar percentages of adult emergence and female progeny among fertilized, unfertilized, and UVF hosts for all three Trichogramma parasitoids, except that T. japonicum had significantly lower adult emergence on fertilized hosts. We also found that all three Trichogramma parasitoids developed slower on unfertilized hosts. Regardless of host treatments, T. leucaniae had the longest developmental time and T. chilonis had the shortest. We conclude that Trichogramma parasitoids prefer parasitizing UVF eggs of C. cephalonica without negative effects on their emergence and sex allocation.

Effect of Beauveria bassiana and Metarhizium anisoplae on some biological aspect of Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae)

This experiment were carried out to study the effect of treatment of newly hatched (neonate) larvae and pupae of the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) with different entomopathogenic fungi; Biover (Beauveria bassiana) and Bioranza (Metarhizium anisoplae) was investigated under laboratory conditions of 27 ± 1o C and 65 % ± 10 % R.H. The results show that P. Gossypiella was susceptible to both fungi. LC50 values obtained were1.42 and 0.98 glfor P. Gossypiella larvae treated with different concentrations of B.bassiana and M.anisopilae, respectively. The biological aspects of P. gossypiella were affected when treating the newly hatched larvae with the LC50's of both fungi. Results generally revealed changes in the different biological aspects (larval duration, pupation percentage, pupal duration and the percentage of adult emergence). Determine the effect of B. bassiana and M. anisopliae on the prey consumption rate of Oriusa lbidipennis to pink bollworm eggs.

Effects of halolactones with strong feeding-deterrent activity on the growth and development of larvae of the lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae).

The effects of dietary applied of β-damascone and its synthetic derivatives γ- and δ-halolactones, which show strong antifeedant activity, on the growth and development of larvae of the lesser mealworm, Alphitobius diaperinus Panzer (Coleoptera: Tenebrionidae), were studied. Bioassays were performed in a dose-dependent manner. In the bioassays, oat flakes treated with 1.0, 0.5, and 0.1 % (w/v) acetone solutions of the tested compound or acetone alone as control were served as food. The experiments were conducted using 2-week-old larvae with an average body weight of 4.35–4.88 mg. High correlations between antifeedant activity and larvicidal and growth-inhibitory effects were observed. Larvae reared on diets containing the compounds (at a concentration of 1 %) with high deterrent activity were characterized by a prolonged period of development, lower body weight gain, and strong tendency for cannibalism as a result of starvation. The control larvae ended their development after 24 days with a mean body weight of 22.9 mg. At the same developmental time, the mean body weights of larvae treated with the δ-halolactones γ-chloro- and γ-bromo-δ-lactone were only 60.3 % and 43.2 % of that of the control larvae. The larval periods for larvae on the diets containing γ-chloro- and γ-bromo-δ-lactone were 33 and 41 days, respectively. The larval developmental time and body weight gain were not significantly influenced by lower doses of the compounds, with the exception of γ-bromo-δ-lactone. This compound, when applied at a concentration of 0.5 %, significantly prolonged larval development as compared to the control larvae, and caused high mortality of larvae and pupae. The adult emergence percentage was 37.51 % when this treatment was applied, as compared to 90.0 % in the control. Thus, β-damascone derivatives with a lactone ring exhibit both dose-dependent behavioral effects and post-ingestion toxicity against A. diaperinus larvae, and may have the potential to control this pest.

Biological and histopathological effects of cyromazine on the laevae of Culex pipiens (Diptera Culicidae).

Laboratory studies were carried out to investigate the efficacy of the chitin synthesis inhibitor (cyromazine) against all larval stages of Culex pipiens. The compound was tested its efficacy on larval mortality, larval duration, pupation, pupal duration and adult emergence. Also, the histological effects of cyromazine on the midgut, the integument, the fatbodies and the muscles of 4th larval instar treated as 1st larval instar were studied. The tested compound increased the larval mortality, decreased the percent pupation and adult emergence and prolonged the pupal duration. Also, this compound elicited histological effects on the midgut, the integument, the fat bodies and the muscles of 4th larval instar of C. pipiens treated as 1st larval instar with 0.01 and 0.1 ppm.

Parasitism and Optimization of Hyposoter didymator (Hymenoptera: Ichneumonidae) Rearing on Spodoptera littoralis and Helicoverpa armigera (Lepidoptera: Noctuidae).

This study was carried out to improve the rearing methods of endoparasite Hyposoter didymator (Thunberg) for biological control release. The growth and the development of H. didymator on the first, second, and third instars of Spodoptera littoralis (Boisduval) and Helicoverpa armigera (Hübner) under laboratory conditions were investigated. Results indicated that S. littoralis was a suitable host for the rearing of H. didymator . The development time of the parasite on the second instar of both hosts was almost the same (∼17 d). The age of the female parasite affected the percentage of adult emergence, pupal mortality, and females in the offspring reared on S. littoralis host. The best copulation period of H. didymator females and males was 36 h that resulted in 51.8% of females in the offspring. The male to female ratio during copulation period, as well as the presence of males after copulation, and the number of host larvae for each parasite female had no effect on parasitism. Results suggested that S. littoralis second instar is a suitable host for mass rearing of H. didymator parasite, which may improve the use of H. didymator as a biocontrol agent.

Effects of tea saponin on growth and development, nutritional indicators, and hormone titers in diamondback moths feeding on different host plant species

The diamondback moth (DBM) is an important worldwide pest. This insect has been studied for several decades; however, its control remains problematic. Numerous chemical insecticides have become ineffective and chemical residues constitute an important problem. In the present study, we determined the mortality of 3rd instar DBM larvae feeding on three different host plant species and exposed to various concentrations of tea saponin (TS). In addition, we evaluated growth and development parameters, nutritional indicators, and juvenile hormone (JH) and molting hormone (MH) titers in 2nd instar larvae exposed to LC20 and LC50 doses of TS. We found that treatment of DBM larvae with LC20 and LC50 doses of TS led to lower growth rates, decreased feed consumption, reduced frass production, lower pupal weights, reduced percentage pupation, slower adult emergence percentages, and diminished fecundity, but prolonged durations of the larval and pupal periods. The efficiency of conversion of ingested and digested food increased, but the approximate digestibility did not differ significantly between treatments and controls. JH and MH titers were higher after TS treatment; these increases varied according to the host species and TS concentration. Our results indicate that TS represents a potential new alternative insecticide based on its natural origin, low cost, and minimum environmental impact.

Impact of High Dose of Gamma Radiation on Field Collected <i>Aedes aegypti</i>

Mosquitoes that transmit pathogens to humans received much attention during last few decades. Aedes aegypti causes certain diseases like dengue, yellow fever andchikungunya. There are no effective vaccines and drugs available for those diseases. The control of Aedes aegypti is the only effective way for prophylyxis from this disease. Radiation has played an important role in insect pest management. To determine the radio sensitivity, an experiment was conducted to understand the effect of γ - radiation at higher doses on immature stages of Aedes aegypti. One day old pupae were irradiated with variable doses between 100Gy to 1000Gy to study the pupal viability, adult emergence and development of malformation if any. The dose response curve between the pupal viability and dose was determined and there was a marked difference in radiation sensitivity . It was observed that the pupal viability decreased with increase in radiation dose in dose dependent manner. Pupal viability of about 99.2%, 61.4%, 42.5%, 13.4%, 7.5%, 6.7% and 3.9% was found after exposure to gamma radiation at 100Gy, 250Gy, 400Gy, 550Gy, 700Gy, 850Gy and 1000Gy respectively. Similarly, adult emergence was also drastically affected by radiation exposure. The percent adult emergence from irradiated pupae were about 99.2%, 61.3%, 42.4%, 13.4%, 7.2%, 6.4%, and 3.0% at 100Gy, 250Gy, 400Gy, 550Gy, 700Gy, 850Gy and 1000Gy respectively. Morphological deformities on both pupae and adult of Aedes aegypti were noticed after irradiation indicates the somatic damage of pupae and adults. It was observed that head, thorax and part of the abdomen with fore wings were released but the rest of the body still attached to the puparia. Similarly, few malformed adults with curled legs, crumpled wings and with curved abdomen were obtained due to the effects of high dose of gamma radiation at 400Gy and above.

The Efficiency of Terpenes Extracts of Eucalyptus Camaldulensis Seed to control Larval Stage of Callosobruchus maculates (Coleoptera:Bruchidae)

The current study has beenconduced to evaluate the effect of extracted crude terpens at the concentrations of 6,8% of seeds of Eucalyptuscamaldulensison the 4th larval instar oftheCallosobruchusmaculates and the percentage of the cowpea seed germination.The Results showed that the terpens extract of the concentration of 8% increases the mortality rate of the fourth larval instar and it reach to 63.3%, and then decrease of to 26.6,20% at concentration of 6%and forcontrol treatment respectively The percentage of adult emergence reduces to 0% at the concentration of 8% compared with control treatment in which it reach to 66.6%. The extraction atbothconcentrations 6,8% does not affect the germination rate

Biological Studies of Earias insulana (Boisd.) Field Strains at Different Constant Temperature Degrees

Earia insulana (Boisd.) (Lepidoptera: Noctuidae) larvae and/or pupae (cocoons) were collected from five different cotton varieties (Giza 45, Giza 86, Giza 87, Giza 88, and Giza 92) have been grown in Sakha, Kafr El-Sheikh-Governorate at the end of cotton season 2014. Some biological aspects of these populations were investigated under laboratory conditions at three constant temperatures (25, 27 and 30˚C). The present results concluded that, the tested temperatures had main effect on stages durations, survival, adult emergence percentages, sex ratio, and fecundity of field SBW strain. Regardless the variety of cotton general trend of results indicated that, the highest, moderate and lowest percentage of emerged moths were recorded at 25oC, 30oC and 27oC, respectively. In addition, sex ratio were almost 1:1 but tend to females at 25oC while in reverse to male at 30oC. At 27oC sex ratio was 2♀: 1♂. Moreover, the fecundity of developed female from tested varieties recorded its highest values at 25oC and sharply decreased at 27oC. While, at 30oC, the emerged female lost its fecundity except females of Giza 45 deposited 169.0 eggs / female. Furthermore, the tested temperature may be reliable for one developed stage of spiny bollworm and not reliable for another of same population. Also, cotton variety had highly significant effect on the studied biological aspects on its pest SBW, as well as, the interaction between cotton variety and temperature. Regardless temperature, duration of larval stage was 29 & 25.0 days on cotton varieties Giza 45 and Giza 87 at 25oC, respectively. Although, the respective duration of generation in both cases acquire 50 days and 39.1 days, the reproductive capacity of SBW of Giza 45 equal ten times of that when fed on Giza 87. In addition, the larval mortality was higher in population of Giza 87. Depending on the aforementioned conclusion, cotton variety Giza 45 is more susceptible to SBW infestation. The authors arranged the susceptibility of tested cotton varieties to SBW infestation in descending order as follow: Giza 45, Giza 88, Giza 87, Giza 92 and Giza 86. These composite relations need to further vision to study the insect ecology, biology, physiology and economic damage. However, the use of less susceptible cultivars can be considered as a part of IPM control program.

Inter-regional mating compatibility among Bactrocera dorsalis populations in Thailand (Diptera,Tephritidae).

Mating compatibility among recently colonized (wildish) populations of Bactrocera dorsalis (Hendel) from different geographic origins in Thailand was assessed through inter-regional mating tests. Outdoor octagonal nylon screen field cages containing single potted mango trees (Mangifera indica L.) were used. Sexual compatibility was determined using the index of sexual isolation (ISI), the male relative performance index (MRPI), and the female relative performance index (FRPI). The ISI values indicated that the northern population of Bactrocera dorsalis from Chiang Mai province was sexually compatible with the southern population of Bactrocera dorsalis (previously Bactrocera papayae) from Nakhon Si Thammarat province. The MRPI values showed that the northern males had a slightly higher tendency to mate than southern males, while the FRPI data reflected that females of both origins participated equally in matings. In all combinations there were no differences between homotypic and heterotypic couples in mating latency. Southern males tended to mate first with southern females, followed by northern males mating with northern females, while the latest matings involved heterotypic couples, in particular northern males mating with southern females. Overall, more couples were collected from higher parts of the field cage and the upper tree canopy, while there were no differences between the origins of flies in terms of elevation of couples within the cage. Laboratory assessments of fecundity showed no differences in the average number of eggs resulting from inter-regional crosses. Development of immature stages was also equal in the two hybrid crosses, with no differences found in the number of pupae produced, percentage pupal recovery, and percent adult emergence. The practical implication of this study is that colony of Bactrocera dorsalis derived from any northern or southern region of Thailand can potentially be used in sterile insect technique programs against this pest.

INFLUENCE OF LARVAL FOOD ON NUMBER OF SPERMATOPHORES, FECUNDITY AND SOME BIOCHEMICAL PARAMETERS OF THE SPINY BOLLWORM, Earias insulana (BOISD.)

Experiments were carried out to study the effect of larval food types (cotton bolls, okra pods and artificial diet) on number of spermatophores, fecundity and total soluble protein, lipid and carbohydrate contents of the spiny bollworm, Earias insulana (Boisd.). The obtained results showed that the larvae reared on artificial diet gave the highest weight, while, those collected from cotton bolls gave the lowest weight. The lowest pupal mortality percentage and the highest adult emergence percentages, number of eggs/female and hatchability percentages recorded for the larvae obtained from artificial diet followed by those collected from okra pods and cotton bolls. Pupal duration, pre & post- oviposition periods and male longevity were differed insignificantly as affected by feeding larvae on okra pods, cotton bolls and artificial diet. The newly emerged female moths from larvae collected from cotton bolls were recorded the lowest mean number of the eggs/ovariol and spermatophores, while, those emergence from larvae obtained from artificial diet was recorded the highest one. The highest value of total soluble protein, lipid and carbohydrate contents were recorded in larvae obtained from artificial diet followed by those collected from okra pods and cotton bolls.

Transgenic Cotton-Fed Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Affects the Parasitoid Encarsia desantisi Viggiani (Hymenoptera: Aphelinidae) Development.

Cotton cultivars expressing Cry proteins are widely used to control lepidopteran pests. The effects of transgenic plants containing insecticidal Cry proteins on non-target species must be comprehended for a better and rational use of this technology for pest management. We investigated the influence of the Bt cotton cultivars NuOPAL and FM 975 on biological parameters of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), a non-target pest of Bt cotton cultivars and on its parasitoid Encarsia desantisi Viggiani (Hymenoptera: Aphelinidae). The experiments were conducted in a climatized room, and the non-transgenic near isolines were used for rearing whiteflies as control hosts. The effects of the Bt cotton cultivars on the period of embryonic and larval development and the percentage of adult emergence of B. tabaci were assessed. The period required for embryonic, larval, and pupal development and the percentage of emergence and longevity of E. desantisi females were determined using Bt cotton-fed and non-Bt cotton-fed B. tabaci as hosts. Both Bt cotton cultivars resulted in a decrease of approximately 20% of adult emergence of B. tabaci. Differently, an increase of approximately 10% of adult emergence of E. desantisi was observed for parasitoids that used hosts fed with both Bt cotton cultivars. However, female parasitoid longevity decreased when their hosts were fed on Bt cotton cultivars. Our data suggest that the use of Bt cotton cultivars in association with the biological control agent E. desantisi could be functional for the management of B. tabaci in Bt cotton crops.

BIOLOGICAL AND HISTOLOGICAL EFFECTS OF METARHIZIUMANISOPLIAE ON THE COTTON LEAFWORM, SPODOPTERA LITTORALIS (BOISD.) (LEPIDOPTERA: NOCTUIDAE)

Toxicological, biological and histological effects of the isolated entomopathogenic fungus Metarhizium anisopliae from the red palm weevil adult on the newly molted 2nd and 4th instar larvae of the Egyptian cotton leaf worm, Spodoptera littoralis (Boisd.), were investigated under laboratory conditions at 27o ± 2o and 60% ± 5% R.H. Results revealed a decrease in the mean larval, pupal, and adult durations for the 2nd and 4th instar larvae surviving treatment with the LC50 of 2.8x108 and 2.8x109 spore/ml for the two tested instar larvae, respectively. Treatment also caused a reduction in the pupation and adult emergence percentage. There was also a great reduction in the mean number of eggs/female and the mean number of hatched eggs; The histological changes in the mid gut tissues in 6th instar surviving treatment with LC50 of M. anisopliae as newly ecdysed 3rd instar larvae was investigated. Sections in mid gut of untreated S. littoralis showed linning with columnar cells surrounded by cross longitudinal muscles fiber, the epithelial cells linning mid gut with its brush border and goblet cells. While, in mid gut of treated S. littoralis some epithelial cells which linning mid gut have lost their brush border, others were completely destructed.

Sub-lethal effects of Vip3A toxin on survival, development and fecundity of Heliothis virescens and Plutella xylostella.

The assessment of sub-lethal effects is important to interpret the overall insecticide efficacy in controlling insect pest populations. In addition to the lethal effect, sub-lethal effects may also occur in exposed insects. Vegetative insecticidal proteins (Vips) have shown a broad spectrum of insecticidal activity against many insect pest species. In this study the sub-lethal effects of the Bacillus thuringiensis vegetative insecticidal toxin Vip3A on the development and reproduction of Heliothis virescens F. and Plutella xylostella L. were evaluated in the laboratory. The results indicated that the sub-lethal concentration of Vip3A increased the duration of the larval and pupal stages as compared with the control treatment for both species. The percent pupation and percent adult emergence were significantly lower for Vip3A-treated insects. The proportion of pairs that produced eggs and the longevity of adults were not significantly different between treatments. H. virescens and P. xylostella treated with Vip3A showed an 11 and 17% decrease in their intrinsic rate of increase (rm) respectively compared with untreated insects. The results from this study will be helpful to develop the strategy to incorporate Vip 3A containing crops in an integrated pest management programme.