Effect of different compounds on Icerya seychellarum ( Hemiptera : Monophlebi-dae ) and Rodalia cardinalis ( Coleoptera : Coccinellidae ) on mango leaves under laboratory conditions

The relative toxicity of different compounds against the seychellarum mealybug, Icerya seychellarum (Westwood) (Hemiptera: Monophlebidae) and the vedalia beetle, Rodalia cardinalis (Mulsant) (Coleoptera: Coccinellidae) were studied on mango leaves under laboratory conditions. The obtained data indicated that different compounds (Biofly, NeemAzal and Super Mesrona oil) gave medium effects on nymphs, and adult females of I. seychellarum and immature and mature stages of their predator R.cardinalis, compared with Malathion which gave highly effects on the mealybug and its predator using direct exposure technique.


INTRODUCTION
The mealybug, Icerya seychellarum (Westwood) (Hemiptera: Margarodidae) infests different parts (leaves, branches and fruits) of mango trees (Mangifera indica L.).The female lays a large number of eggs (600-800 eggs/female) in an ovisac made of wax secreted from wax gland lays on the lower side of I. seychellarum.The mealybug is usually found in clusters on branches and leaves; it also feeds on the sap sucked from the host plant tissues.As this sap contains only a very low concentration of protein, the insect sucks a great amount of sap from which it obtains the amount of protein sufficient for its growth and egg development.The high number of insects, attacking leaves, branches and fruits of the tree results in a great loss of sap, thus leading to defoliation, dryness and reduction of the tree vitality.In addition, the mealybugs secrete honeydew, which offers a suitable medium for the growth of fungus (Dreistadt et al., 1994).The vedalia beetle, Rodalia cardinalis (Mulsant) (Coleoptera : Coccinellidae) was introduced to Egypt from Los Angeles during (1890-1892) and in 1922, Willcocks made another attempt to introduce the beetle into Egypt from California.That introduction was succeeded and this beneficial beetle became established and common all over the country (Kamal, 1951).
The present work aimed to study the relative toxicity of different compounds against the seychellarum mealybug, Icerya seychellarum and the vedalia beetle, R. cardinalis on mango leaves under laboratory conditions.

Relative toxicity of different compounds against the seychellarum mealybug, I. seychellarum and their predator the vedalia beetle, R. cardinalis:
The experimental insects of the seychellarum mealybug, I. seychellarum used in the present investigation were the, nymphs, and adult females, also, the experimen-tal predator of the predator the vedalia beetle, R. cardinalis used in the present investigation were the, immature and mature stages.The infested mango leaves were collected from the field and kept in polyethylene bags and transferred to the laboratory few hours before treatment.The laboratory experiments were carried as mentioned above.The method of direct exposure was used throughout the present investigation.Five concentrations of each compound were used; five leaves infested with mealybugs and their predators were dipped in each concentration for five seconds.Leaves were divided into four replicates.Also, five leaves were dipped on clean water and used as untreated check (control).The leaves were transferred to clean wide plastic dishes which then covered with muslin cloth held in position by rubber bands.They were maintained at laboratory temperature about 25±1°C and 65±1% relative humidity in polyethylene bags according to (Zidan et al., 1982).After 24 hours, the dead nymphs, and adult females were counted.2. The following materials were tested: a. Biofly, an entomopathogenic fungi (3X 10 7 c.f.u./1ml), containing the fungus Beauveria bassiana.b.NeemAzal, a botanical extract containing 1% Azadirachtin A (10 g/liter) from the neem tree, Azadirachta indica (Meliaceae).c.Super Mesrona oil 95% EC, a local mineral oil, containing 95% paraffinic oil w/w and 5% inert ingredients, unsulfonated residue content reached 92%.d.Malathion 57% EC, a chemical insecticide of the common name Malathion and the chemical name, O, O-dimethyl-S-(1,2-dicarbethoxyethyl) dithio phosphate.

Statistical analysis:
In laboratory tests, the mortality percentages were calculated and corrected for natural mortalities by Abbott's formula (1925).The corrected percent mortalities were statistically computed according Finney (1971) and plotted on probit analysis paper.The tested compounds were compared for their efficiency on the mealybugs according to their LC 50 , LC 90 and slopes of the toxicity lines .

RESULTS AND DISCUSSION
1. Relative toxicity of different compounds against the seychellarum mealybug, Icerya seychellarum and their predator the vedalia beetle, R. cardinalis on mango leaves under laboratory conditions: Results showed that the potency of different compounds (Biofly, NeemAzal and Super Mesrona oil) compared with Malathion against the nymphs, and adult females of the seychellarum mealybug, I. seychellarum and immature and mature stages of their predator the vedalia beetle, R. cardinalis using direct exposure technique.
(1) indicated that Biofly gave medium effects on the nymphal and adult stages of I. seychellarum (LC 50 and LC 90 0.6705, 3.5216 against nymphal stages and 0.8165, 4.1417 against adult females, respectively).On the base of the slope of line is useful to know the homogeneity of different stages (nymphs, adult females) of mealybug population and the different stages (mature, immature stages) of predator population, which collected from the field to different compounds.When the population of mealybug or predator is similar in homogeneity or the degree of resistant meaning that the slope is big or increase in regression.Data in Table (1) and Fig.
(1) showed that the slope of all stages, (nymphs and adult females) of I. sey-chellarum population is big (1.7792,1.8173) this meaning that the insect population is homogeneity in response to Biofly.
(1) indicated that Biofly gave medium effects on the immature and mature stages of R. cardinalis (LC 50 and LC 90 0.7782, 5.0516 against immature stages and 0.841, 6.0646 against immature stages, respectively).Data in Table (1) and Fig. (1) showed that the slope of all stages, (immature and mature stages) of R. cardinalis were (1.5777, 1.4937) this meaning that the insect population is homogeneity in response to Biofly.

Effect of Super Mesrona oil:
Data in Table (3) and Fig.
(3) indicated that NeemAzal gave medium effects on the nymphal and adult stages of I. seychellarum (LC 50 and LC 90 11.2451, 35.1153 against nymphal stages and 8.9765, 32.82 against adult females, respectively).Also, results in Table (3) and Fig. (3) showed that the slope of all stages, (nymphs and adult females) of I. seychellarum population (2.5915, 2.2763) this meaning that the insect population is homogeneity in response to Super Mesrona oil.Also, results Table (3) and Fig. (3) indicated that Biofly gave medium effects on the immature and mature stages of R. cardinalis (LC 50 and LC 90 9.5705, 42.0769 against immature stages and 10.0483, 49.812 against immature stages, respectively).Data in Table (3) and Fig. (3) showed that the slope of all stages, (immature and mature stages) of R. cardinalis population (1.9928, 1.8434) this meaning that the insect population is homogeneity in response to Super Mesrona oil.The obtained data are harmony with those obtained by Mangoud (1994) who stated that profenophos is the most potent insecticide as compared to (diazinon, fenitrothion, formthion, malathion, primiphos-methyl and prothiophos) against all stages, (nymphs, non-ovipositing and ovipositing females) of the seychellarum mealybug, Icerya seychellarum using direct exposure technique.Also, Mangoud et al. (2007), found Super Misrona oil is come in the first category.Biovar come in the second category, while Bio-Ranza gave the least effect.On the other hand the OP insecticide (Sumithion) gave highly effect against all stages of the seychellarum mealybug, Icerya seychellarum on Washingtonian leaves under laboratory conditions.

Fig. 1 :
Fig. 1: Toxicity lines of Biofly, Beauveria bassiana against the different stages of the seychellarum mealybug, Icerya seychellarum and its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leaf-dipping technique under laboratory conditions.1.1 Effect of NeemAzal, A. indica : Data in Table (2) and Fig. (2) indicated that NeemAzal gave medium effects on the nymphal and adult stages of I. seychellarum (LC 50 and LC 90 0.8994, 6.0852 against nymphal stages and 0.8915, 11.9979 against adult females, respectively).Also, results in Table (2) and Fig. (2) showed that the slope of all stages, (nymphs and adult females) of I. seychellarum population (1.5435, 1.1352) this meaning that the insect

Fig. 2 :
Fig. 2: Toxicity lines of NeemAzal, Azadirachta indica against the different stages of the seychellarum mealybug, Icerya seychellarum and its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leaf-dipping technique under laboratory conditions.

Fig. 4 :
Fig. 4: Toxicity lines of Malathion against the different stages of the seychellarum mealybug, Icerya seychellarum and its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leaf-dipping technique under laboratory conditions.

Table 1 :
LC values of Biofly, Beauveria bassiana against the different stages of the seychellarum meaand its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leaf-dipping technique under laboratory conditions.
5435, 1.1352)this meaning that the insect in response to NeemAzal.Also, results Table(2) and Fig.(2) indicated that Biofly gave medium effects on the immature and mature stages of R. cardinalis (LC 50 and LC 90 0.959, 6.9537 against immature stages and 0.841, 6.0646 against immature stages, respectively).Data in Table(2) and Fig.(2) showed that the slope of all stages, (immature and mature stages) of R. cardinalispopulation  (1.5426, 1.4896)this meaning that the insect population is homogeneity in response to NeemAzal.

Table 2 :
LC values of NeemAzal, Azadirachta indica against the different stages of the seychellarum mealybug, Icerya seychellarum and its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leaf-dipping technique under laboratory conditions.

Table 3 :
LC values of Super Mesrona oil against the different stages of the seychellarum mealybug, Icerya seychellarum and its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leaf-dipping technique under laboratory conditions.Toxicity lines of Super Mesrona oil against the different stages of the seychellarum mealybug, Icerya seychellarum and its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leaf-dipping technique under laboratory conditions. 1.

3 Effect of Malathion:Data in
Table (4) andFig.(4)indicatedthat Malathion gave highly effects on the nymphal and adult stages of I. seychellarum (LC 50 and LC 90 0.2496, 1.4244 against nymphal stages and 0.1528, 1.4601 against adult females, respectively).Also, results in Table (4) and Fig. (4) showed that the slope of all stages, and 0.1528, 1.4601 against immature stages, respectively).Data in Table (4) and Fig. (4) showed that the slope of all stages, (immature and mature stages) of R. cardinalis population (2.0948, 2.0948) this meaning that the insect population is homogeneity in response to Malathion.
(nymphs and adult females) of I. seychellarum population were (1.6942, 1.3075) this meaning that the insect population is homogeneity in response to Malathion.Also, results Table (4) and Fig. (4) indicated that Malathion gave highly effects on the immature and mature stages of R. cardinalis (LC 50 and LC 90 0.3032, 1.2405 against immature stages

Table 4 :
LC values of Malathion against the different stages of the seychellarum mealybug, Icerya seychellarum and its predator, the Vidalia beetle, Rodalia cardinalis on mango leaves using leafdipping technique under laboratory conditions.