| Abstract |
PART I- The Looper Worm Gymnoscelis pumilata
A) Biological studies :
1- Rearing at 25 ±1ºC and 70 ±5 R.H. on corn cars, corn silk, faba bean, onion flowers, leaves of' young maize plants (1.5 month old) and leaves of tomato plants (one month old) revealed that tomato and maize are not suitable hosts. The larvae died within 1-2 days on tomato leaves and within 1-10 days on maize leaves with incomplete development. .
2- The average durations of the developmental stages oil corn ears, corn silk, faba bean and onion flowers were respectively as Follows:
- The egg incubation period averaged 3.06 ± 0.04, 3.64 ± 0.07, 3.17 ± 0.06 and 3.33 ± 0.07 days, with 96, 90, 90 and 92% hatch.
- The larval period averaged 10.94 ± 0.20, 10.15 ± 0.19, 10.97 ± 0.13 and 11.98 ± 0.13 days.
- The pre-pupal period averaged 1.3 ± 0.05, 1.38 ± 0.08, 1.31 ± 0.07 and 11.1 ± 0.05, days.
- The pupal period averaged 8.38 ± 0.15, 8.69 ± 0.18, 8.53± 0.15 and 7.82 ± 0.10 days and the pupal weight averaged 0.016, 0.413, 0.014 Oand 0.011mg.
- the total period for immatures development averaged 23.40 ± 0.27, 23.95 ± 0.29, 23.93 ± 0.23 and 24.22 ± 0.20 days.
- The adults longevity averaged 8.35 ± 0.74, 10.05 ± ¬0.66, 11.00 ± 1.78 and 2.4 ± 0.13 days for males and 17.3 ± 0.92, 15.65 ± 1.17, 10.35 ± 0.80 and 3.2 ± 0.26 days for females.
- The pre oviposition period averaged 3.7 ± 0.36, 4.3 ± ¬0.36, 2.95 ± 0.38 and 2.00 ± 0.19 days.
- The oviposition period averaged 12.15 ± 0.79, 10.3 ± 0.95, 6.35 ± 0.69 and 1.45 ± 0.11 days.
- The post-ovilosilion period averaged 1.45 ± 0.11, 1.3 ± 0. 11, 1.25± 0.10 and 1.00 ± 0.0 days
- The number of eggs her female averaged 102.50 ± 11.20, 86.35 ± 14.44, 73.8 ± 10.71 and 22.95 ± 1.34.
3- Considering the developmental period, number of eggs per female, pupal weight , and % egg hatch, corn ears was the most favorable nost followed by corn silk, faba bean and the least was onion flowers.
B) Ecological studies :
1- Population studies in two successive seasons, 1993/94-1994/95 on faba bean; (Giza 402) at Fayoun1 revealed the following:
a-In the first season, the infestation began soon alter seedling emergence and continued until the end of the season. The insect had 4 brood peaks (as eggs or larvae). First peak in December (2.6 eggs or 1.5 larvae/10 plants). the second in January (2.5 eggs or 3.8 larvae/10 plants). the third in February (3.3 eggs or larvae/10 plants). The fourth in March (18.3 eggs or 14.5 larvae/10 plants). the simple correlation revealed insignificant negative effect of weather factors (max, min, mean temp. and R.H.%) on Population as eggs or larvae
b- In the second season, the leaks of eggs or larval brood were not that defined because temperature was relatively low (max. 18.42 °C, min 5.25 °C with 57. 12%R.H.). The correlation for eggs was insignificant positive for temp. and insignificant negative for R.H. The correlation for larvae was significant positive with tempratures and significant negative for R.H.
2- In general, the lowest % infestation was at the begining of the season in late November, while the highest was al the end of the season in March. Infestation of intact flowers began in late December with low density and became intense in March. The lowest infestation in drop flowers was in the 1st week of January and the highest was in the 3 rd week of Feburary. The infestation of pods was dependant on the weather factors, and increased at high temperature and R.H.
PART II- Studies on The Leaf Miner
LlrlDi1iZa lrlfOlll
A) Biological studies
l- Reared on faba bean at 15, 20, 2 5 and 30 ºC and 75 ± 5% RH., the durations of different stages were respectively as follows:
- The egg incubation period averaged 5.44 ± 0.10, 4.48 ± 0.10, 3.04± 0.12 and 2.64 ± 0.98 days.
- The larval period averaged 8.88 ± 0.26, 5.92 ± 0.13, 3.96 ± 0.12 and 9.96 ± 0.12 days.
- The pupal period averaged 20.64 ± 0.26, 12.40 ± 0.13, 8.96 ± 0.15 and 7.88 ± 0. 12 with hupal mortality % of 58, 39, 21 and 45%.
- The total period of immatyres development averaged 34.96 ± 0.50, 22.80 ± 0.29, 15.96 ± 0.37 and 13.48 ± 0.13 days.
- The adults longevity averaged 13.6 ± 0.87, 8.4 ± 0.50, 6.00 ± 0.21 and 4.90 ± 0.23 days for females and 11.60 ± 0.54, 8.30 ± 0.49, 5.20 ± 0.25 and 3.90 ± 0.23 days for males.
- The pre-oviposition period averaged 4.90 ± 0.32, 2.90 -F¬0.41, 1.30 ± 0.12 and 1.20 ± 0.13 days.
- The oviposition period averaged 7.70 -t- 0.63, 4.50 -t¬0.34, 3.70 ± 0.26 and 2.70 ± 0.21 days.
The post-oviposilion period was short since all flies died within one day after termination of egg laying at all temperatures tested.
-The number of eggs/female averaged 93.60 ± 12.6 1, 126.50 ± 14.34, 199 ± 18.23 and 180.10 ± 3 1.99 days, with daily oviposition rate eggs/female/day of' 13.45, 28.10, 53.78 and 66.60.
B) Field observations throughout two successive seasons 1993/94-1994/95
1- The infestation began on seedlings, three weeks, after planting. The minimum infestation density was 0.30 - 0.33 mine/plant at the beginning of each season. The maximum densities were 499.5- 804.5 al the end of the seasons. The lowest rate of infestation at the beginning of the two seasons was 21 and 12% and the highest rate reached 100% at the end of December or late February.
2 - Population of mines containing larvae during 1 st season revelaed three peaks of larval brood. The first was weak from December 2nd week to January 3rd week. The second peak was of medium intensity, from January 3rd week to February I st week. The third was strong from February 1 st week to March 3rd week.
3 - Population in the 2nd season also showed three peaks of larval brood. A weak one from December 1 st week to January1 st week. The second was also weak, from January l st week to February l st week. The third was strong, from February 1 st week to March 4th week.
4 - The maximum temperature negatively but insignificantly affected L. tirifolii population in 1993/94 season. However a significant and positive effect occurred in 1994/95 season. The partial regression was significant and positive for both season.
5 – The minimum temperature had a negative but insignificantly effect in 1993/94. The effect was significant and positive in 1994/95. The partial regression was significant and negative in the 1 st season but positive in the 2nd season.
6 – The mean temperature effect on population was insignificant and negative in 1993/94, but significantly positive in 1994/95.
7 - The effect of RH. was significant and negative in correlation with larval popualtion in the two seasons. Also the partial regression showed significant negative relation. ,
8 - The combined effect of temperature (max. and min.) and R.H.% was significant in both seasons.
9- Infestation distribution along the faba bean plant showed that the middle leaves harbored the highest number of mines containing active larvae. The upper leaves harbored the least. The infestation in upper, middle and lower leaves was significantly different in 1993/94 season. However, in the following season the difference was insignificant.
|