Efficacy of Natural Compounds on The Pear Psylla, Cacopsylla pyricola (Hemiptera: Psyllidae), The Olive Scale Insect, Parlatoria oleae (Hemiptera: Diaspididae) and Their Natural Enemies in Pear Orchards in Egypt

The journal of Toxicology and pest control is one of the series issued twice by the Egyptian Academic Journal of Biological Sciences, and is devoted to publication of original papers related to the interaction between insects and their environment. The goal of the journal is to advance the scientific understanding of mechanisms of toxicity. Emphasis will be placed on toxic effects observed at relevant exposures, which have direct impact on safety evaluation and risk assessment. The journal therefore welcomes papers on biology ranging from molecular and cell biology, biochemistry and physiology to ecology and environment, also systematics, microbiology, toxicology, hydrobiology, radiobiology and biotechnology. www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.

Nymphs and adults of the pear psyllid are phloem feeders.Honeydew, produced by nymphs, drips or runs onto fruit, causing dark russet blotches or streaks.This results in downgrading of fresh and sometimes process in fruit in large numbers, pear psylla can stunt and defoliate trees and cause fruit drop.A carry-over effect may reduce fruit set the following year.These symptoms, called psylla shock, are caused by toxic saliva injected into the tree by feeding nymphs.
When psylla are controlled to prevent fruit russet, psylla shock does not occur.Pear psylla also transmits a mycoplasma disease organism through its saliva.The disease damages sieve tubes in the phloem, which prevents synthesized nutrients moving down the tree and results in root starvation.Diseased trees may either decline slowly or collapse suddenly and then die ( Hodgson &Mustafa, 1984 andSolomon et al., 1989).
Pear psylla's status as a major pest of pears is based on its damage potential and its ability to develop resistance to insecticides.The control of population numbers of pear psylla implies reducing stand instability (pear plantings) by combined methods: reduced insecticide application, use of specific insecticidespsyllocides, monitoring population of natural predators and creating conditions favouring their development and maintainance, introduction of less susceptible and 146 resistant pear cultivars and optimal pruning and other cultural measures (Injac, 1992 andStamenkovic &Milenkovic, 1992).
The olive scale, Parlatoria oleae (Colvee) (Hemiptera: Diaspididae) infested different host plants especially economic crops , apple, plum, olive, pear and peach trees in Egypt (El-Minshawy et al.,1974).It is a serious pest on fruit and nut trees, on ornamental shade trees, shrubs and on ground covers, on forest trees, in greenhouses and on indoor plantings.Polyphagous pest that is introduced to new geographic areas is usually of higher economic importance.The main injury caused by this insect is the ingestion of plant sap.Its damage is manifested in reducing the number of healthy plant.Severely infested plants grow poorly and may drop leaves prematurely and suffer dieback of twigs and branches (Miller and Kosztarab, 1979).
Abdel-Megeed et al. (1992) evaluated the efficiency of conventional insecticids for the control of P. oleae.While Mohamed (2002) tested nonconventional insecticides in controlling P. oleae.
The aim of this work is to study the effect of different natural control compounds on the pear psylla, the olive scale and their natural enemies on pear trees in Ismailia and Gharbia Governorates.Governorates, Egypt, using pear infested by the pear psylla and the olive scale, respectively.Four experiments were conducted during May and October (2013) and repeated in the second season May and October (2014), respectively.In each treatment, 10 trees (replicates) were sprayed with one of the tested compounds or water (control).The compounds were applied using a knapsack sprayer (20 liters).The sample consists of 60 leaves, which were randomly collected.The pear psylla, the olive scale insect and their natural enemies (parasitoid and predator) were counted just before spraying and 1, 2 and 3 weeks after spraying.Samples were kept in fine perforated paper bags and transferred to the laboratory for careful examination; populations of the two pests and their natural enemies were counted by the aid of a stereomicroscope.Each leaf with petiole was stored in glass emergence tube and monitored daily for parasitoid emergence and counted the predators.

Statistical Analysis:
In four experiments, the percent reduction of infestation was calculated according to the equation of (Henderson and Tilton , 1955).The data was subjected to analysis of variance (ANOVA) and the means were compared by LSD test at 0.05 level, using SAS program (SAS Institute, 1988).

RESULTS AND DISCUSSION
The efficacy of natural compounds on pear psylla, Cacopsylla pyricola and its predator, Orius laevigatus:

In the first season (2013):
In the first season, the average of pre-treatments count of C. pyricola nymphs and its predator, Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) were 48.3-55 and 15-23/leaf (Table 1).2). Results of statistical analysis (F value and L.S.D.) (Table 2) showed that seven treatments had significant effect on populations.4).Results of statistical analysis (F value and L.S.D.) (Table 4) showed that seven treatments had significant effect on populations.
In the present work, Malathion gave high efficiency against nymphs of C. pyricola and its predator, O. laevigatus.While results of (Krysan, 1990) had a contradicting effect.Results indicated that organophosphorous insecticide (Basudin), was not efficient enough on pear psylla.The results of Erler (2004a, b, c) suggested that the botanical insecticides Aksebio2 (a natural botanical product) could used in psylla control instead of synthetic insecticides and may serve as an IPM component in pear orchards .But here the botanical extracts Azadrachtin gave moderate toxic effect against population nymphs of and its predator, O. laevigatus.

The efficacy of natural compounds on olive scale, Parlatoria oleae and its parasitoid, Aphytis lingnanensis:
In the first season, 2013: In the first season, the average prespraying counts of P. oleae population and its parasitiod, Aphytis lingnanensis Compere (Hymenoptera: Aphelinidae) were 54-61 and 19-26/leaf (Table 5).Results in Table ( 6) indicated that in the first year, the four compounds (Jojoba oil, P. fumosoroseus, Azadrachtin and V. lecanii) gave moderate toxic effect against population of P. oleae and its parasitiod, A. lingnanensis and percent reduction ranged between 57.7-66.8% and 54.5-65.9%,respectively.6).Results of statistical analysis (F value and L.S.D.) (Table 6) showed that seven treatments had significant effect on populations.

In the second season, 2014:
In the second season, the average pre-spraying counts population of P. oleae and its parasitiod, A. lingnanensis were 55-61.5 and 18-27.2/leaf(Table 7).Results in Table (8) indicated that in the first year, the four compounds (Jojoba oil, P. fumosoroseus, Azadrachtin and V. lecanii) gave moderate toxic effect against population of P. oleae and its parasitiod, A. lingnanensis and percent reduction ranged between 60.0-66.3% and 56.9-62.4%,respectively.8).Results of statistical analysis (F value and L.S.D.) (Table 8) showed that seven treatments had significant effect on populations.
The obtained results here observed that Mineral oil and Malathion gave high efficacy against P. oleae population and its parasitiod, A. lingnanensis.These results agreed with the results of Abdel-Megeed et al. (1992), they indicated that Sumithion and Sumi oil at the recommended rate, proved to be most effective, followed by KZ oil.Also, in the present work, the natural compound, Jojoba oil gave moderate toxic effect, while Mineral oil and Malathion gave high efficacy against P. oleae population and its parasitoid A. lingnanensis.These results agreed with the findings of Mohamed (2002), who tested Sumithion 50% (fenitrothion) (organophosphorus compounds), Super Masrona (mineral oil 94% EC), Jojoba extract (Nat. 1) and Jojoba oil (Acarol) on P. oleae.The results of the conducted experiment revealed that oil alone or mixed with other materials held superior category all over the time .
It could concluded that treatment with Jojoba oil, P. fumosoroseus, Azadrachtin and V. lecanii gave moderate effect of the pear psylla and the olive scale and their parasitoid and predato , when comparing with Mineral oil, Sulphur and Malathion.This conclusion will be help in integrated pest management program of the two pests infested pear in Gharbia and Ismailia, Governorates.

Table 1 :
Average numbers of the pear psylid, Cacopsylla pyricola and its predator, Orius laevigatus after treatment with different compounds on olive trees during the first season(2013)

Table 2 :
Reduction percentage of different compounds on the pear psylid, Cacopsylla pyricola and its predator, Orius laevigatus on olive trees during the first season (2013).

Table 3 :
Average numbers of the pear psylid, Cacopsylla pyricola and its predator, Orius laevigatus after treatment with different compounds on olive trees during the second season (2014).

Table 4 :
Reduction percentage of different compounds on the pear psylid , Cacopsylla pyricola and its predator, Orius laevigatus on olive trees during the second season (2014).

Table 5 :
Average numbers of the armored scale insect, Parlatoria oleae and its parasitoid, Aphytis lingnanensis after treatment with different compounds on olive trees during the first season (2013).

Table 6 :
Reduction percentage of different compounds on the armored scale insect, Parlatoria oleae and its parasitoid, Aphytis lingnanensis on olive trees during the first season (2013).

Table 7 :
Average numbers of the armored scale insect, Parlatoria oleae and its parasitoid, Aphytis lingnanensis after treatment with different compounds on olive during the second season (2014).

Table 8 :
Reduction percentage of different compounds on the armored scale insect, Parlatoria oleae and its parasitoid, Aphytis lingnanensis on olive trees during the second season (2014).