Scale insects infesting guava trees and control measure of Pulvinaria psidii ( Hemiptera : Coccidae ) by using the alternative insecticides

Nine scale insect species (Hemiptera: Coccoidea) belongs to four families were collected during updated survey at Qaliobiya Governorate for two successive years. A key with photographs and illustrations are introduced; the seasonal fluctuation and the population density of all stages of the most serious soft scale insect, Pulvinaria psidii Maskell (Hemiptera: Coccidae) were studied in relation to five main weather factors. Three predators, Rodalia cardinalis Mulsant, Chilocorus bipustulatus L. (Coleoptera: Coccinellidae) and Amblyserius swiriskii (Athias-Henriot) (Acari: Phytoseiidae) were collected associated with P. psidii and their effect with the other meteorological factors are analyzed statistically using partial regression method to decide their contemporary effect. The half monthly variation was calculated and the number of generations of this soft scale per year were estimated throughout the two successive years of investigation to indicate the high infestation of this pest to reach 327 insect/ leaf at 1 may, the lowest population density were during winter season. The efficacy of the alternative pesticides (Biological insecticides, mineral oils, IGRs) and organophosphorus insecticides for controlling this serious pest different stages during summer and winter field sprayings were applied to insure that: the summer spray was more effective than the winter spray, the mineral oils and soap gave high efficacy after two weeks of spraying and still increasing till the end of the experiment, without observed phytotoxicity; IGRs and biological insecticides started to give good efficacy after one month of spraying and also still to increase till the end, in addition to their safety effect, opposite to the synthetic insecticides that gave a very good efficacy at the beginning of the experiment and decreased gradually. Finely the application time is very important; the organophosphorus compounds must be replaced by these other friendly alternatives; rearing and releasing these predators must be used in this pest control management.


INTRODUCTION
Scale insect ( Hemiptera: Coccoidea) styles branched up to three times in the sheath to reach the phloem (intracellular or intercellular), likely come into contact with the secondary metabolites in vacuoles; leaves are first penetrated, in high temperature, the crawlers move to the aerial portions, settled on buds, causing dangerous loss (annual loss by pink hibiscus mealybug only in Grenado Island was 3.5 million dollars before establishing the biological control), especially through their toxic saliva, secondary infection and associated insects (Newberg et al. 1983 andBaker et al., 2009).Most scales are sensitive to the meteorological changes, agriculture activities and host preferable, so updated survey was required after the previous survey of El Minshawy et al. (1974) in Alexandria.The identification of scale insects must be accompanied with figures and illustrations to decrease confusion (Hamon andWilliam, 1984 andBakr et al. 2010).Extensive ecological study to the pest and their natural enemies is the first step toward the progress of the integrated pest control management (Hassan and Radwan, 2008).
Present control procedures are mainly through insecticides, in some instances some formula of mineral oils are employed, besides the releasing of few predators and parasites with rarely safe procedures (Abd-Rabou, 2003).So this work explains the efficacy of the alternative insecticides (biological insecticides, IGRs, mineral oils), comparing with the efficacy of chemical insecticides, during summer and winter field evaluations to the most serious soft scale attacking seven economic crops (Abd El-Razak, 2000;Helmy et al., 2001 andHariss et al., 2006).
The aim of the present work is to study the survey of scale insects infested guava trees and the control measure of P. psidii in Egypt.

MATERIALS AND METHODES
I. Ecological studies:-1.Survey of scale insects infesting guava trees at Qaliobiya Governorate: Three orchards of guava trees (Psidium guajava) at (El-Khanka, Shebeen El-Qanater and Benha) were chosen for collecting its scale insects.The collection was carried out monthly for two successive years from August 2005 to July 2007 in each area.Ten infested guava leaves were collected and examined through the binocular microscope and the microscopic slides for detailed characters.Identification of insects was done by using different keys as: (Ezzat, 1958;Ezzat and Husein, 1967;Hamon andWilliams, 1984 andMiller et al.,(2006).The main climatic factors: maximum temperature (Max.Temp.),minimum temperature (Min.Temp.),relative humidity (R.H. %), rain fall and wind speed were recorded at Qaliobiya governorate with the aid of Meteorological Agency.

Pulvinaria psidii
The selected locality was (about 3 Feddans) at Shebein El-kanater at Qaliobiya Governorate to study the seasonal fluctuation of P.psidii on guava orchard, throughout the two studied seasons (from 1 st April 2005 to mid March 2007).The selected orchards for present investigation don't receive any chemical control at least for two years before this study; also through the duration of the present study but received agricultural practices only.In each of three aforementioned localities, five trees were selected with the same age, height, size, vigor and size of canopy, as well as homogenous in their insect infestation.Successive fortnight samples of 30 leaves (10 leaves X 3 replicates) were picked out from the trees.Alive individuals on the leaves, insect stages, (pre-adult, adult females, gravid females and ovisacs in case of P. psidii) were calculated through the two successive years.The half monthly variation (H.M.V.) was calculated by (Bodenhimer, 1951).Number of generations of P. psidii per year was estimated from the changes in the half monthly nymphal stage number throughout the two successive years of investigation.The seasonal fluctuation in the population density of the studied pest in relation to five main weather factors [day maximum temperature (D.Max.T.), day minimum temperature (D.Min.T.), daily mean relation humidity (D.M.R.H.), rainfall and wind speed] was carried out; the partial regression (p.reg.) method termed "C" multipliers according to Sendecor and Cochran (1989) were estimated.
The natural enemies (predators) were collected, the identification by using the different keys, the diagnosis and illustrations were added.

II. Toxicological studies:
1. Field evaluation of the tested treatments on Pulvinaria psidii infesting guava trees: For controlling P. psidii on guava trees at Sheibeen El-kanater Qaliobiya governorate, two experiments were carried out in July (2005) andFebruary (2006) in case of summer and winter spraying of the tested alternative pesticides (Biofar, mineral oils) and organophosphorus insecticides.Fifteen trees divided into three rows for each replicate whereas, each treatment had three replicates (45 trees/ treatment) in addition to fifteen trees as control for each experiment divided also into three replicates, then sprayed with the tested treatments by means of 6 horse-power motor sprayer, with 600 liters tank.Samples of 10 infested leaves were collected from each replicates after spraying in all directions and level of the tree (10 leaves X 3 replicates) 30 leaves per treatment and before spraying as a pre-treatment count.Data of the pre-treatment, control and post-treatment samples were recorded for the alive stages (per-adult nymphal stage, adult female and gravid female stages) to calculate reduction percentage in population.The total number of all stages was used as index to the population density of the insect over particular period of time.Four posttreatment counts were taken at 2, 4, 6 and 8 weeks after spraying.Statistical analysis: Percentage of reduction in each stage and population was estimated according to Henderson and Tilton equation, (1955).The percentage of reduction for all treatments was subjected to a simple analysis of variance by the aid of a computing and model design in an IBM compatible computer to show the efficiency of the tested insecticides and their residual effect of tested compounds against the pest different stages; (ovisacs stage, nymphs, adult female, gravid female stages and total population).The "F" values were calculated and the least against insect population and different stages significant difference (L.S.D) between treatments were considered when."F" value was significant Also, L.S.D between the residual effects of the post treatment counts were studied.1) showed that, Benha was the lowest infested area but the highest infested one is Shebeen EL-Qanater.The most serious pests on guava trees were P. psidii then C. cirripediformis, A. nerii and L.ulmi .The other species still represented with low density.2. Key to guava scales at Qaliobiya Governorate 1-The scale is elongated, triangular, strongly tapered toward the exuvial end, light brown to grey, most found on trunk, may appeared banded.Microscopically, adult yellowish, head rounded, eye not developed into a spur sharply pointed laterally pygidium with median lobes, with a pair of gland spine between them, without clubshaped basal scleroses and with many similar dorsal macroductes (Figs 3 and  4) -With soft scale, without cyst, not like spherical ball, with 2-5 pairs of simple eyes………………………………………………….…………………………………5 5-Thin and flat, yellowish-green in color, triangular with blunt pointed front tip; mesothoracic and metathoracic coxae different in shape than prothoacic coxae, with thin tibia and very short tarsi (Fig. 9)…………….………Kilifiaacuminate (Signoret) -Oval or globular, with different color, meso and metathoracis coxae similar in shape to from prothoracic coxea, with normal tibia and tarsi………….……….…….……...6 6-Yellowish brown, with transparent area and brown spots with variable dorsal setae; spine -shape, cylindrical, capitate and clavate; with many preoperculer pores and four apical satae at anal plate ……….…………...…....………..Coccus hespridium L.

Seasonal fluctuation of ovisacs:
The results in the Tables (2 and 3) and Fig. (18) showed that, the P. psidii ovisacs had a regular occurrence all over the year, except during the end of each year (from 1 st January till 1 st April) where the number was very low.Also, there were three peaks of egg sacs per year after that the number was decreased.The highest peak were at mid June and mid September (19, 18 ovisacs/leaf) respectively.

Seasonal fluctuation of Nymphs:
The obtained data as shown in the same tables, Fig.
(19) indicated that: the nymphal stage had three peaks per year, the highest one was in1 st May with 320 nymphs / leaf and decreased from mid January till mid March.

Seasonal fluctuation of adult females:
AS presented in the same Tables (1 and 2) and  Fig . (20) gave the same picture, the highest peak was at 1 st September (40 adult females /leaf), there were three depression periods the deepest one at mid March (1 adult females /leaf).

Seasonal fluctuation of the gravid females:
From the fortnightly obtained data, the graved females had vacillating elevation but it revealed three tips which climbs during 1 st October and mid November to 7 Gravid females / leaf as shown in table ( 2 and 3 22), where the prevalence curve indicated that there were three annual peaks per year.The highest occurrence achieved at 1 st May with (327, 283 insect / leaf)during the two years; on the other hand, there were depression periods occurred per year, the deepest one was during January, February and in the early March reached (3 insects / leaf).3.6.The rate of half monthly variation (H.M. V.): Data given in the same Tables (2and 3) and Fig.( 23) indicated that the highest maximum monthly variation was at 1 st December (3.06).The minimum monthly variation was recorded at mid November (0.26).

3.7.Number and duration of the annual generations:
As presented in Tables (2, 3 and 4) recorded that there were three annual generations; The 1 st generation with highest density, the third was the longest with high representation at the beginning, then clearly depression from mid December till mid March; with minor differences in some generation's time.5) showed a positive highly significant correlation where(r) value was (0.521).3.8.2.Effect of the night minimum temperature (N.Mn.T.).Statistical analysis of (N.Mx.T.) on the same table indicated a highly significant positive simple correlation where (r.) value was (0.485).The partial regression showed positive slightly significant relation with (P.reg.) 0.450 during the two years.3.8.3.Effect of the daily mean relative humidity (D.M.R.H.):The simple correlation was negative slightly significant relation with (r.) value was -0.367.However the partial regression showed positive slightly significant relations during the two year of study with (P.reg.)values (0.164).3.8.4.Effect of rain fall.Statistical analysis of rain fall showed that, the simple correlation indicated no relation in the two years.The partial regression showed a positive slightly significant relation during the two years of study with (P.reg.)value equal (0.933).3.8.5.Effect of wind speed.Statistical analysis of data in this table showed slightly significant positive simple correlation relation (r.= 0.045) and also positive slightly significant relation where (P.reg.) value (0.588) during the two years of study.3.8.6.The combined effect of the five studied factors.The combined effect of the abiotic five main factors on P. psidii total population revealed slightly significant effect where F value equal ( 2.068 ) during the two years .Analysis of variance clearly indicated that the low effect of the explained variance (E.V) which recoded (36.50) during the two successive years of study as shown in the Table (5).3.9.Biotic factor (the natural enemies associated with Pulvinaria psidii: 3.9.1.Rodalia cardinalis Mulsant (Fig. 15) (Coleoptera: Coccinellidae) Oval, convex pubescent ladybird, ground color reddish with black markings, with small size, 2.5-5.5 mm in length, its antenna is short,8-segmented, basal segment enlarged.The eyes are faceted& hairy; the apical segment of the maxillary palpi is securiform.Pronotum broadest subbasally, with curved margins, anterior angels are broadly rounded; elytra broader than pronotum at base, punctuation dense, elytral marking of variable size and shape, elytral epipleura is broad, without foveae; the suture between meso and metasternum is narrow; prosternum very short, prosternal process prominent between procoxae.Tibiae somewhat flattened and expanded near basal third, capable of receiving tarsi when legs retracted, tarsi trimerous and the abdomen has six visible sternites.3.9.2.Chilocorus bipustulatus L. (Fig. 16) (Coleoptera: Coccinellidae), can be distinguished from other scale predator by its very convex body, shiny colored, head reddish-brown, deeply inserted; the pronotum covering a posterior portion of eyes, clypeus with marginal ridge, elevated at its middle and depressed on both sides; epistoma dilated, concealing the base of antennae and subdividing the eyes; antenna 8-segmented, clavate, the terminal joint tapering; labrum dark brown& hairy; mandible with two teeth only.Pronotum reddish-brown, meso& metathorax dark brown; elytra reddish-brown and shining, with three red spots on each elytron, the two inner spots united; the outer side of the tibia at the basal third with tooth-like extension, claws toothed.Abdominal segments are five visible in female & six in male.3.9.3.Amblyserius swiriskii (Athias-Henriot) (Acari :Phytoseiidae) (Fig. 17) It can be distinguished from other related species by its body which is compressed dorsally, brownish in color, with dorsal shield large.

II. Toxicological studies:
Field evaluation of the tested treatments on P. psidii infesting guava trees was conducted.Two experiments were conducted in one district, Shebeen El-Kanater at Qaliobiya Governorate.1.The summer field evaluation of the tested treatments on Pulvinaria psidii : 1.1.The first post treatment count after two weeks from spraying: Statistically analysis of variance of data presented in Table ( 6) and histogramatically illustrated in Figs ( 24 and 25) Revealed, that the efficiency of treatment showed that, Sumithion was the highly effective one (83.7%),followed by actellic (81.8),KZ oil (79.7%),Misrona oil (77.8),Apploud (61.9%)Biofar (57.2%) then Admiral (53.1%) with significant difference between the efficacy of the tested treatments on P. psidii total population.On the other hand, the two tested organophosphorous insecticides and the two types of oils had insignificant differences between one of them with the other where L.S.D. was 2.68.Concerning the susceptibility of P. psidii different stages to the tested treatments, analysis of data clearly showed the highly affect of the pre-adult (nymphs) followed by the ovisacs with percentage reduction (93.9 and 74.2), respectively, then adult females gave good percentage reduction (73.4).
It showed 41.4% reduction.There was significant difference between different stages each other except adult females and ovisac stages.L.S.D was 14.64.1.2.The second post treatment count after 4 weeks from spraying: Statistically analysis of data presented in Table ( 6) and histogramatically illustrated in Fig. ( 25) clearly showed a highly significant difference between the bio-residual efficacies of the tested treatments on P. psidii against population response.Where " L.S.D. value was 0.97.The average percentages of reduction were superior in case of Apploud (88.5%) which had significant difference with the other treatments, followed by KZ oil (86.2%),Misrona oil (85.8%) and Sumithion (85.7%) which had insignificant difference between them.Then actellic (80.3),Admiral (78.4%) and Biofar (70.3%) which had significant differences between them.Statistical analysis of data presented in table, 6, Figs 24&25 clearly indicated that, there were significant differences between the efficacies of the tested treatments on P. psidii different stages L.S.D. value was 10.37.The average reduction in nymphs, adult females, gravid females and ovisac stages were 96.3, 83.9, 52.9 and 86.2, respectively.However, there was a significant difference between the response of the gravid female and the response of all other stages (nymphs, adult females and ovisacs stages).1.3.The 3 rd post treatment count after 6 weeks from spraying: Statistical analysis of data presented in Table ( 6) and histogramatically illustrated in Fig. ( 25) clearly indicated significant differences between the bio-residual efficacies of the tested treatments on P. psidii against population response, L.S.D. value was 0.96.The highest percentage of reduction was recorded by Misrona oil (87.2%) and Apploud (86.9%) with insignificant difference between them.On the other hand, there were significant differences between them and the following.Treatments where KZ oil (82.5%),Sumithion (78.6%) and Actellic (78%) followed by Admiral (76.7%) and Biofar (74.8%) with significant difference between these treatments and the preceding them.Also data which presented in the above mentioned table and  25) showed significant differences between the bio-residual efficacies of the tested chemical treatments on P. psidii against population response, L.S.D. value was 1.96.The average reduction was the highest in case of Masrona oil (88.3%), followed by KZ oil (83.4%),Apploud (80.8%),Biofar (75.6%),Actellic (75.5%),Sumithion (72.6%) then Admiral (69.1%) with significant differences between them.In contrast, Actellic and Biofar with insignificant differences between them.Statistical analysis of the obtained data indicated that there was significant difference between the efficacies of the tested treatments on P. psidii different stages; L.S.D. was 12.02.Per-adult, recorded (95.6%), followed by ovisacs stage (76.1%),gravid female stage (73.9%) then adult stage with (66%) 2. Winter field evaluation of the tested treatments on Pulvinaria psidii : The toxic efficacy of the tested treatments (Albolium oil 2%, Diver oil 2%, Misrona oil 2% KZ oil 1.5% and Apploud 0.5%) against Pulvinaria psidii scale insect infesting guava trees at Shebeen El Kanater, Qaliobiya governorate were presented in Table ( 7) and illustrated in Figs ( 26 and 27) as follows:   27) revealed significant differences between the bio-residual efficacies of the tested treatments on P. psidii population response, L.S.D. was 3.3.Percentage of reduction in general mean of insect population as indication of efficiency of the tested treatments was high after using Misrona oil (77.68%), followed by KZ oil (68.9%) and Albolium oil (66.58%), then Diver oil (60%) and Apploud with (51.5%), with a significant differences between the treatments each other except the second and third treatments Good response of P. psidii different stages to the tested treatments.Pre-adult, adult females, gravid females and ovisacs (74.16, 77.28, 60.02 and 48.3%) respectively, with insignificant difference between the first two stages (pre-adult and adult).On the other hand, there was significant difference between the first two stages and the other stages, where L.S.D.was 8.79.occurrence was during spring season, then autumn season, whereas the Min.Temp, Max.Temp, were suitable, R.H% was slightly high, no rain fall and slightly wind speed.But the lowest density was during winter season due to unsuitable climatic factors (Aly and Nada, 1993).There were great differences in the time from the previous seasonal fluctuation, in 1974 the greatest occurrence were during summer (July) and winter (November), this may be due to the changes in climatic factors or the high occurrence of their effective predators (R. cardinalis, C. bipustulatus and A. swiriskii).Hassan and Radwan (2008) recorded the highest population density of R. cardinalis during July and August).

II-Toxicological Studies:
Control of the most serious scale pest infesting guava trees: Evaluation of certain treatments on P. psidii during summer and winter season.1-Summer evaluation: The present study showed that P. psidii different stages were affected by various types of treatments, (Masrona oil, KZ oil Apploud, Admiral, Biofar, Actellic, Sumithion) during the four post treatment counts; two, four, six and eight weeks after summer spray.The most affected stages were the pre-adult and ovisac stages, followed by the other stages during the experiment period, ensured the results of Helmy et al. (1992).Organophosphorus was more effective than the other groups after two weeks from summer spraying, then their effect was slightly decreased, in agree with Kwaiz (1999).Profenofos was the most effective compound, followed by Diazinon.Mayonnaise oil and miscible oil gave high reduction after two weeks gradually till the end of the experiment.IGRS reduction still to increase and gave high effect after one month (4 weeks) and also still increase till the end of the experiment.

2-The winter evaluation:
The obtained results demonstrated that P. psidii different stages were affected by different types of the tested chemicals during post treatment counts; (two, four, six and eight weeks) after winter spray.The sprayed chemical divided to three groups' mayonnaise oils, miscible oils and I.G.R.During this experiment the most affect stages were pre-adult and adult stage but all stage nearly had the same affect.Miscible oils (Kz oil) had the most efficacy one, followed by mayonnaise oils; Misrona, Alboluim and Diver give good efficacy after two weeks, their effect increase gradually to give very good efficacy at the end of experiment I.G.R. and Applaud started to give good efficacy after 4 weeks (one month) and increase gradually after that to give very good efficacy till the end of experiment.The application time is very important, the summer spray was more effective than the winter spray (it is a lighter version, block insect spiracles, suffocating them).the organophosphorus compounds used only at high infestation where no fruits; mineral oils, I.G.Rs and the biological insecticides demonstrated successful performance against this soft scale insect populations, their effect begins at least two weeks later, extended up to 8 months after treatment in addition to their safety effect and also maintain the natural balance.(Helmy et al. 2001;El-Sobky, 2006;Hariss et al. 2006 andEl-Sahn, 2007).Finally, for increasing crop production of this popular fruit, agriculture precautions (Baker, 2009) must be applied; The organophosphorus compounds must be replaced ( due to its high systemic toxicity ) by these other friendly alternatives during pest control management, the right time must be considered; the success occurred in the last century through releasing R. cardinalis for controlling mealy bugs (Tawfik, 1993) can be repeated during Jun (Hendawy, 1999 andEl Serafi et al. 2004).
) and Fig. (21).On contrary the minimum graved females occurred at many times, the lowest and longest depression of gravid females occurred during the 1st December till mid March with 1-2 insect /leaf during winter season.3.5.Seasonal fluctuation of total population: Total population of P. psidii different stages; (ovisacs, eggs -nymphs, adult and gravid females) / leaf during 2005-2006 was shown in Tables (2 and 3) and illustrated in Fig. ( Pulvinaria psidii total population.3.8.1.Effect of daily maximum temperature (D.Mx.T.).Statistical analysis of (D.Mx.T.) data in Table (

Fig. ( 2
Fig. (2): The relative abundance of the all collected scale insects on guava trees from the three studied areas.
Figure showed significant differences between the efficacy of the tested treatments on P. psidii different stages, L.S.D. value was 11.47.Nymphal stage recorded the highest percentage of reduction (95.6), followed by ovisacs, adult and gravid females stages.The percentage of reduction (86.2, 73 and 67.7) respectively.1.4.The 4 th post treatment count after 8 weeks) from spraying: Statistically analysis of data presented in Table (6) and histogramatically illustrated in Fig. (

Fig. 24 :
Fig.24: Average reduction percent of Pulvinaria psidii different stages in summer spraying

Table 1 :
The collected scale insects on guava trees at Qaluobiya Governorate

Table 2 :
Seasonal abundance of Pulvinaria psidii and total population on guava tree; the half monthly variations in relation to climatic factors from 1st April 2005 till mid March 2006.

Table 3 :
Seasonal abundance of Pulvinaria psidii stages and the total population on guava tree; the half monthly variation in relation to climatic factors from 1st April 2006 till mid March 2007.

Table 4 :
Number and duration of Pulvinaria psidii generations under field conditions during 2005-2007 on guava trees at Qaliobiya Governorate.

Table 5 :
Simple correlation and partial regression of six abiotic and biotic factors with their significant level and percentage of explained variance on the population density of Pulvinaria psidii population at Qaliobiya governorate during the two studied years. E.

Table 6 :
Percentage of reduction in Pulvinaria psidii different stages induced by application insecticidal agent on guava trees at Qaliobiya governorate in summer.

Table 7 :
Percentage of reduction in Pulvinaria psidii different stages induced by application insecticidal agent on guava trees at Qaliobiya Governorate in winter.
2.1.Reduction percent after2 weeks from winter spraying: Analysis of variance of data presented in Table (7) and illustrated in Fig.(