Efficiency of some insecticides in male annihilation technique of peach fruit fly, Bactrocera zonata (Saunders) under Egyptian conditions

The effectiveness of technical products of Naled, Lambada, Fenthion (Lebaycid), Fenitrothion (Sumithion), Malathion and Dimethoate (mixed with methyl eugenol in the ratio of 1:4), in addition to commercial Malathion (57% EC mixed with methyl eugenol in two ratios of 1:2 and 2:3) were evaluated under field conditions as male annihilation technique (lure and kill) of Bactrocera zonata (Saunders) (Diptera: Tiphritidae). Plant fiber blocks saturated with mentioned mixtures were used at four governorates of Egypt (Damietta, Dakahlia, Ismailia and Fayoum) over 12 successive weeks. Efficiency (as lured and killed populations per block per day) of all tested mixtures degraded over time regardless the area. The obtained results revealed that Naled mixture was significantly superior to all other mixtures regard less area or inspection. Naled mixture blocks were relatively effective for up to 8 weeks while others efficiency did not exceed 4 weeks. Commercial Malathion (1:2), technical Malation, Dimethoate were the worth. It was recommended that Naled mixture can be used successfully in B. zonata male annihilation technique and renewed every two months. Lambada, Lebaycid, Sumithion, commercial Malathion (2:3) mixtures could be used with monthly renewal.


Peach
fruit fly (PFF), Bactrocera zonata (Saunders) (Diptera : Tephritidae) is considered one of the most economic important pests for several kinds of fruits in temperate, tropical and subtropical countries (Fletcher, 1987 andYounes et al., 2009).
In Egypt, B. zonata became a serious pest since 90 s of the last century attacking a wide range of fruits that differ in their ripening time stage all over the year (El-Minshawy et al., 1999 andHashem et al., 2007).
Male annihilation technique (MAT) (lure and kill) is a fruit fly control method removes male insects, thus reducing male population.This disturbs the male: female ratio and reduces the insect's chances of mating and females produce very few progeny.As a result, the wild population in the target area declines and the insects are eradicated in the end (Cunningham, 1989 andZaheeruddin, 2007).
The insecticides used in MAT are generally organophosphorus compounds, such as Naled, Malathion, and Dichlorvos (DDVP) (Vargas et. al., 2003).This method is applied as spot treatments by using many dispensers as carriers of methyl eugenol and toxicant (such as cotton cord, neutral gel, plant fibers blocks and felt blocks).The use of lure-andkill stations (i.e.plant fibers and felt blocks impregnated with the methyl eugenol-insecticide mixture) is often preferred (Afia, 2007;Abd El-Kareim et al., 2009 andGhanim, 2009).Male flies are attracted to the blocks, feed from their surfaces and killed (Stonehouse et al., 2002).
In Egypt, there is a necessity for improving the system of "lure and kill" under the local conditions; therefore, the present work concerned to evaluate the efficiency of some insecticides in this technique for B. zonata at different regions of Egypt.

MATERIAL AND METHODS 1. Experimental areas:
The experiments of the present work were conducted during the period from October 2009 till January 2010 in four governorates of Egypt; Damietta (at the north of Egypt), Dakahlia (at the delta region), Ismailia (at the canal region) and Fayoum (at the north of Upper Egypt).The cultivated host plants at these locations were guava, citrus, and mango, respectively.

Field bioassay:
To evaluate the efficiency of tested insecticides against B. zonata males, field bioassay was carried out by using plant fibers blocks (measuring 5x5x1.1 cm).
Blocks were impregnated with the solution of tested insecticide and methyl eugenol according to the mentioned ratios of mixture for about four hours in the laboratory.The impregnated blocks were transferred to the field on plastic bags.The blocks were hanged on the trees by metallic wire on regular distance at height of about two meters in shady and airy place.Blocks were distributed at 50 meters intervals along all of each area study.
In each location, each treatment was replicated seven times and distributed in a completely randomized design.
To collect the dead insects, plastic containers (measuring 20 cm in height and 10 cm in diameter) were fixed under the treated blocks by metallic wire for receiving the dead male flies.The lured and killed B. zonata males in the plastic containers were counted and recorded weekly without renewal the treatments.
Statistical analysis was conducted as Analysis of variance (three ways) for each 4 weeks using Proc ANOVA in SAS (SAS Institute, 1998).

RESULTS
The obtained results are summarized in Tables (1 to 4) as mean values of weekly collected male flies per block per day for different tested mixtures at the four tested sites.

Effect of time on the efficiency:
As shown in Tables (1 to 4), all of the tested methyl eugenol-insecticides mixtures exhibited their highest efficiency (as lure and kill) over the first 3 to 5 weeks.After that, this efficiency degraded as time progressed regardless site or mixture.
Efficiency of some insecticides in male annihilation technique of peach fruit fly, B. zonata 15

Effect of different tested mixture:
Statistical analysis of obtained data are presented in Table 5.
The obtained results revealed that Naled mixture was significantly superior to all other mixtures regardless of site or inspection.Naled mixture blocks were effective for up to 8 weeks while others efficiency did not exceed 4 weeks.Lured and killed males per block per day for Naled mixture blocks were 19.68 and 6.30 for the first and second 4 weeks, respectively regardless of site.These values were higher than those obtained by all other mixtures other the first 4 weeks (Table 5).At the last 4 weeks it was still significantly higher than all others.Commercial Malathion (1:2), technical Malathion, Dimethoate mixtures were the worth (Table 5).

Effect of site:
The presented results over different governorates revealed significant differences on lured and killed PFF males per block per day.Over the first 4 weeks, Damietta was the highest site followed by Dakahlia, Ismailia and Fayoum, respectively.Over the 5 to 8 weeks, Damietta was significantly higher than other sites.Over the last 4 weeks differences were not significant between all sites (Table5).(Chambers et al., 1974 andSanderson, 2009).EPPO (2002) reported that the insecticides used in MAT for B. zonata are generally organophosphorus compounds such as Malathion or Naled.Vargas et al. (2003) reported that Naled is one of the most effective insecticides against B. dorsalis and B. cucurbutae in Hawaii.
The present study revealed that Lambada, Lebaycid, Sumithion, commercial Malathion (2:3) had the second rank of efficiency against B. zonata males.Afia (2007) reported that Malathion and Lebaycid had a moderate effect on B. zonata males (in comparison with DDVP).In Mauritius, Seewooruthun et al. (1997) reported that use of plywood blocks impregnated with methyl eugenol and Malathion 57% (with a ratio of 6:1) gave positive results in controlling of B. dorsalis.
On the other hand, Dimethoate had the lowest effect on B. zonata males.Afia (2007) mentioned that Dimethoate was one of the least effective insecticides on B. zonata.
In Hawaii, bucket traps with cotton dispensers containing methyl eugenol and either Naled, Malathion, or DDVP proved effective against B. dorsalis or B. cucurbitae for 20 weeks without replacement of the lure or toxicant.The efficiency of blocks reduced by 50% after 8 weeks (Vargas et al., 2003).In Nauru, methyl eugenol or cue-lure and the insecticide Fipronil were used in MAT of Bactrocera species and the blocking campaigns and repeated every eight weeks (Allwood et al., 2002).
It is recommended that Naled mix is the most effective against B. zonata males especially during the first two months of hanging.So, it can be used in MAT of B. zonata and renewed every two months.Lambada, Lebaycid, Sumithion, commercial Malathion (2:3), respectively, could be used in MAT of B. zonata with monthly renewal.

Table ( 1
): Mean lured and killed male flies per block per day over time at Damietta using different methyl eugenol-insecticides mixtures.

Table ( 2
): Mean lured and killed male flies per block per day over time at Dakahlia using different methyl eugenol-insecticides mixtures.
Table(3): Mean lured and killed male flies per block per day over time at Ismailia using different methyl eugenol-insecticides mixtures.

Table ( 4
): Mean lured and killed male flies per block per day over time at Fayoum using different methyl eugenol-insecticides mixtures.

Table ( 5
): Statistical analysis of obtained results.