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The Influences of Temperature on the Small Brown Planthopper, Laodelphax Striatellus

Author: ZhangAiMin
Tutor: LiuXiangDong
School: Nanjing Agricultural College
Course: Agricultural Entomology and Pest Control
Keywords: Small brown planthopper Temperature Population dynamics Growth and development Multiplication Fluctuating asymmetry
CLC: S433
Type: Master's thesis
Year: 2009
Downloads: 39
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Abstract

Striatellus is one of the major pests harmful to rice in rice base nymphs and adults sucking harm, at the same time, the adults lay their eggs in the rice plant tissue to cause harm. Striatellus also spread a variety of viral diseases, resulting in reduced production of diseases prevalent rice. Recent years SBPH outbreak frequency increase. This paper combined the field population survey and indoor temperature stress small brown planthopper populations and to explore the role of the temperature factor in the development of small brown planthopper populations to clarify the small brown planthopper populations outbreak ecological mechanisms and their prediction provide the basis. The study made the following main results: survey the the 2007-2008 Nanjing area small brown planthopper the annual population structure of natural populations and the number of changes, combined with the average temperature of insects the relationship between the amount of change with temperature. The results show that, during the 2008 wintering population of the January low temperature for the whole year a certain extent, the generation of developmental progress is slower than occurred less than 2007. Inhibited the growth and development of the population to the high temperatures in July and August, the formation of a full year of summering trough. Summering and wintering process instar nymphs and adults have to exist, but the 3-5 senior citizens nymphs. Nymphs and adults have a strong cold tolerance, supercooling points in different indoor temperatures below -22 ℃. Similarly, field from November to next March Insect supercooling point also below -22 ℃, and there was no significant difference in each time period. The determination of the 2008 generation adult (F0) and their offspring (F1F2) growth and fecundity under 24 ℃. The results show that, compared with 24 ℃ indoor insects, in addition to the F1 generation development fast, short adult longevity and fecundity (56.19 / ♀), there was no inter-field Insect of F0 and F2 and Indoor Insect significant difference. The small brown planthopper populations through generation feeding experience to adapt to the new environment. In order to clarify the impact of temperature on the outbreak of the small brown planthopper population biology and population, the system studied 18-33 ℃ constant temperature of small brown planthopper populations survival, growth and development, wing dimorphism and reproductive characteristics. The results show that, in the range of 18-27 ℃, developmental duration of instars, adult longevity, spawning early and spawning period shortened with increasing temperature; 30 and 33 ° C significantly inhibited the growth and development of the nymphs, its developmental duration were extended by about 16d and 22d, but had no effect on the egg stage. The 21-27 ℃ lower L. striatellus nymphs survival rate is higher, in the range of 81-88%; 30 ℃ and 33 ℃, the survival rate is very low, only about 5%. Temperature affect the small brown planthopper population sex ratio and fin-type, 18 ℃ male ,21-30 ℃ than female ratio close to 1:1; 18 ℃ and 21 ℃, long-winged males and brachypterous type no significant difference in the ratio of 24 ℃ and 27 ℃, long-winged type was significantly more than the short-winged type. Females mainly to short-fin type, but the long-winged individuals under 24 ℃ and 27 ℃. 18-27 ℃ SBPH fecundity increase with increasing temperature trend, but the adult longevity at 30 ℃ extremely short, there is no egg to produce. Strong proliferative capacity of 18-27 ℃ small brown planthopper populations, the population trend index between 30-46, outbreak disaster. The study also of each instar nymphs in striatellus developmental threshold temperature and effective temperature, which will benefit striatellus forecast period. To explore the impact of low winter temperature environment of small brown planthopper populations, according to the Nanjing area winter minimum temperature set -6 ~ 2 ℃ low temperature environment, 1-7d different duration of the 3-4 age small brown planthopper nymphs low temperature stress. The results show that the duration of growth with low temperature stress, striatellus coma and mortality upward trend, but the the 3d slow rise, stress 7d when the mortality rate was only 41%. Measured the low temperature of the half of the small brown planthopper populations fans time 1.22d, the time semilethal 20.49d. The low temperature to inhibit the growth and development of the nymphs, low temperature stress at different times after the 3-4 instar nymph to adult duration will be extended to 4-9d. Low temperature growth duration of adult life and little effect, but significant increase in the short-fin type proportion. Sustained 2d low temperature stress can increase the amount of adult spawning and spawning adult developmental out after low temperature stress were higher than under conditions of constant temperature, stress 2d up to 405 / ♀. -6 ~ 2 ℃ low temperature continuing role the old nymphae after 1-7d, can stimulate the adult breeding to improve fecundity. 33 ℃ high temperature continued to stress the different time, and then transferred to 27 ° C optimal temperature kept high temperature stress of small brown planthopper populations. The results show that: the adult eggs produced under high temperature stress, regardless of the future continue to be subject to high temperature stress, develop to the adult survival rate is only about 4.5%, and the average age of death of the individual in the third instar. However, development to age 2 survival in the egg and nymph continue to stress more than 80% is still within the 30d, but the development to the fourth instar nymphs dropped below 50%. The adult stage high temperature stress at different times, the egg to the developmental duration of the fourth instar nymphs significantly extend the optimum temperature of 27 ℃. 3rd instar 4th instar nymphs from 33 ° C high temperature stress at different times, stress 1-3d emergence rate of nymphs and adult life than optimal temperature significantly improve or growth, but stress the 5-15d after fitness plague be fairly or decline. High temperature stress causes small brown planthopper adult deformity with abnormal increase the proportion of treatment time. High temperatures continued to stress from the third instar nymphs 1-2d, can significantly increase the amount of adult spawning, but for more than 5d was a dramatic decline in adult fecundity. The temperature on the development of striatellus stability. The high temperature of 30 ° C and 33 ℃ significant than the optimal temperature of 24 ℃ short small brown planthopper the 4th instar If body length. Measuring 12 symmetrical features 8 at various temperatures show the FA, and at 24, 30 and 33 ° C temperature away from long HSL and hind foot-tarsus 3-4 instar nymphs hind long TCTL3 FA, first and then decreased with increasing temperature, while the former hind tibia length TIL1, midfoot shin the section long TIL2 and foot legs long section FL2 the FA with increasing temperature lower. Hind-tarsus length TCTL3 FA nymphal development was a significant negative correlation.

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