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English :
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Ecological studies on boll worms and effect of some new methods in their control
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Arabic :
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دراسات بيئيه علي ديدان اللوز وتأثير بعض الطرق الحديثه في مكافحنها
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| Abstract |
The present study aims to investigate the effect of ecological factors (biotic and abiotic) on the pdiapaused pink bollworm (PBW), PectinoPhora gossypiella (Saunders) larvae, the biological and histological effects of the bioinsecticide (Xentari) against the spiny bollworm (SPW), Earias insulana (Boisd.) larvae; and evaluation of certain control programs against cotton
bollwoi-ms . The obtained results revealed the following:
1- Studies on the dipaused larvae of the pink bollworm (Pectinophora
gossypiella) seasons :
1.1- The excluded dipaused larvae from cotton seeds during the rest period of 1994/95 and 1995/96:
The excluded P. gossypiella resting larvae from cotton seeds were
classified to dead larvae (266 & 108) and alive larvae (140 & 169) during tile rest period of both years 1994 - 95 and 1995- 96, respectively.
Follow-up the excluded alive larvae obtained from the cotton seeds . during 95 & 96 years revealed that some of these larvae reached to the adult stage (78.57 % & 55.03 %, respectively), while 21.43 % & 44.97 % of them died either as larvae or pupae. However, at the end of the ls/ and 2nd rest periods only 27.10 % and 33.57 % of the larvae completed their uietamorph.. osis and reached the adult stagpe.
It was found that the death of PBW during diapause was due to either normal or due to bacterial and/or viral infection as well as to the effect of the parasitoids Pyemotes herfsi and P. robarator.
1.2- Spring emergence of P. gossypiella in both years of 1995 and 1996 : Emergence of PBW adults took place from March until May and the peak of emergence occurred during April.
1.3- Forecasting of timing of PBW spring emergence on the basis-of degreedays (dd's) or accumulated heat units (A.H.U.) during 1994-95 and 1995-96 seasons :
Adult emergence started in 9th and 5th of March and nearly completed, However, in 14th and 26th of May for lst and 2nd season, respectively. However, present study indicated that PBW spring emergence was initialized when about average of 433.5 dd's were accumulated. Also, It was found that lItc low rate of heat units accumulation worked as a mortality factor on the pink bollworm; so it was concluded that A.H.U. is an important factor for timing and determining size of pink bollworm spring emergence (Ist generation).
ll- The biological effects of the biainsecticide (Xentari) against the spiny bollworm neonate larvae :
Six concentrations of Xentari (1.25, 0.63, 0.31, 0.16, 0.08 and 0.04) g/l. at rate of 2.5 ml/50 gm of diet were tested against neonate larvae of E. inscrlana. The mortality percentages were 87.5, 80.0, 65.0, 37.5, 15.0 and 12.5%, respectively after two days of feeding on contaminated diet.
The LC50 and LC90 values of Xentari against E. insulana neonate larvae were 0.29 g/1 and 1.30 g/1, respectively with upper and lower confidence limits of (0.29 & 0.18 g/1) and (1.96 & 0.88g/1).
Xentari displayed latent effects during the subsequent stages . The obtained effects were :1) death the different larval instars due to feeding the E. insulana neonate larvae for 2 days on contaminated artificial diet.contained the LC50 of Xentari; the percentage of surviving subsequent larvae was 31.9%, 2) increase in larval and pupal diirations and 3) decrease the longivity of the adult and the number of deposited eggs/female comparing with the untreated check.
lll- Histopathological effects of Xentari on the spiny boilworm larvae: Feeding the 4th instar larvae of E. insulana on Xentari - contaminated dict, using the highest concentration( 1.25 g / 1 ) at the rat of Sml / 100g diet, for 24 hrs caused many pathological effects in the mid-gut of the treated larvae. These effects, as shown in cross sections of the mid-gut, were separation of the -epithelial cells from the basement membrane as well as elongation, vaculization and breakdown of the larval epithelium mid-gut. Also, Xentari caused disorganization and disintegration of pretrophic membrane.
IV- Evaluation of certain control. programs against cotton boliworms:
Three control programs were evaluated against the cotton bollworms (P. gossypiella, E. insulana and their complex) during 1994 cotton season. Another three control programs were tested during 1995 cotton season. During 1996 cotton season, the previous six control programs were reevaluated.
The tested control programs during 1994 season were program "A", (a sequence of 4 sprays with the bio- insecticide Dipel-2X at the, rate of 400 gm/fed; program "B" a sequence of 3 sprays with the mixture of Dipel- 2X at 400 g/fed. with chemical insecticides at the half recommended rate and in the
recommended sequence; and program "C", recommended. sequence and rate of chemical insecticides, Dursban EC 45%, Cutabron EC 50% and Bulldock EC 15%.
During 1995 cotton season, the tested control programs were : program sequence sprays with the bio-insecticide Xentari at 500 g/fed; program "E", a sequence of sprays with the mixtures of Xentari (500 g/fed.) + chemical insecticide at half of the recommended rates; and program "F" (a sequence of sprays with chemical insecticides (Cyanophos EC 50%, Cutabron EC 50% and Bulldock EC 15%) at the recommended rates and sequence).
During 1996 cotton season, the efficacy of the programs A, B, C, D, E and F was evaluated against the bollworms PBW & SBW and their complex Bws.
The cotton plants received the lst spray in July 24th, August 2nd and 7th during 1994, 1995 and 1996 seasons, respectively. Spraying of each program was performed when the correlation between small larvae (1st instar) and all counted larvae in infested bolls was significant,
The conclusions of this set of experiments were :
1- Program "C" (Dursban, Cutabron and Bulldock) was the most effective program against PBW, SBW and their complex BWS.
2- The tested control programs were more effective against PBW than SBW especially program "D" (Xentari alone).
3- The efficiency of program "D" (Xentari alone) against PBW larvae was higher than that of program "F" (Cyanophos, Cutabron and Bulldock). while program "F" was most effective against SBW and BWS.
4- Program "B" (mixture of Dipel-2X + chemical insecticides) revealed higher potential protective efficacy against bollworms than the two bioinsecticides, Dipel-2X and Xentari when used alone
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| Publication year |
1998
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| Availability location |
معهد بحوث وقاية النباتات - ش نادى الصيد - الدقى - الجيزة
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| Availability number |
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| Organization Name |
Plant Protection Research Institute (PPRI)
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| Country |
Egypt
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| Author(s) from ARC |
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| Agris Categories |
Pests of plantsProtection of plants - General aspects
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AGROVOC
TERMS |
Control methods.
Cottonseed.
Earias insulana.
Ecology.
Larvae.
Pectinophora gossypiella.
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| Publication Type |
PhD Thesis
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