扶桑绵粉蚧部分生物学特性研究

扶桑绵粉蚧Phenacoccus solenopsisTinsley给我国的棉花产业发展带来了巨大的威胁。针对扶桑绵粉蚧的形态特征、行为习性、发育起点温度和有效积温以及越冬前后脂肪含量的变化等进行了研究,结果表明：扶桑绵粉蚧存在雌雄二型现象,在30℃条件下,卵、若虫（1龄、2龄、3龄）的生长发育均较快,发育历期分别为1.2±0.17,4.5±0.50,2.3±0.26,3.2±0.17 d,产卵前期为8.1±0.06 d;卵的发育起点温度为14.07℃,有效积温为10.12 d.℃,若虫期（1龄、2龄、3龄）的发育起点温度为7.50,14.74,13.65℃;扶桑绵粉蚧越冬前、后脂肪含量存在明显差异,分别为35.86%和4.9%。     

扶桑绵粉蚧部分行为学的初步研究

对扶桑绵粉蚧的成虫及若虫部分行为学特性进行了初步观察。研究发现,1至2龄若虫多聚集在寄主植物的幼嫩部位取食,3龄后开始向老叶及茎部位取食,尤其是多聚集在叶片背面叶脉上取食。雄成虫一生只能行一次交配,雌成虫可多次交配,交配时间约为2 min。雄虫具有趋光性和向上性。     

不同药剂对扶桑绵粉蚧的防治试验

利用4种药剂对检疫害虫扶桑绵粉蚧的防治效果试验表明:2.5%高效氯氰菊酯1 000倍对成虫防效1 d后达70%,5 d后防效达96.16%;对2龄若虫则以80%敌敌畏效果最好,达到100%。     

扶桑绵粉蚧寄主植物种类调查及危害研究

为了查明扶桑绵粉蚧的寄主种类,为防治扶桑绵粉蚧提供技术支持,2011～2012,对长沙地区扶桑绵粉蚧寄主种类及危害情况进行了调查。结果表明：寄主种类共有16科22种,危害程度以茄科和锦葵科最为严重;此外,扶桑绵粉蚧在不同寄主上的种群发生情况和成活率亦不相同。     

棉田外来入侵害虫扶桑绵粉蚧的防治

从扶桑绵粉蚧的形态特性、生物学特点、寄主植物、危害特点4个方面较详细地介绍了一种新入侵棉田的害虫扶桑绵粉蚧,简单概括和介绍了对其危害的关键防治技术。     

扶桑绵粉蚧入侵河南省的风险分析

通过入侵有害生物风险识别,建立有害生物危险性评价体系,采用定性和定量的方法从入侵性、适生性、扩散性、潜在风险性、控制可行性等5个方面对扶桑绵粉蚧入侵河南省的风险性进行了分析,得出其综合风险性R值为2.32,属于高度危险性有害生物.根据分析结果提出了风险管理对策.     

不同密度条件下扶桑绵粉蚧翅形分化初步研究

对不同密度条件下的扶桑绵粉蚧翅型分化进行了初步探讨.研究发现,扶桑绵粉蚧在温度25±1℃,湿度65％～80％,12 h全光照条件下,取食苗期棉花,种群在低密度时雌雄比例为0.31∶0.11,中等密度时雌雄比例为0.26∶0.17,高密度时雌雄比例为0.52∶0.48.由此可见,随着种群密度的增加,产雄的机率也随之增加.     

扶桑绵粉蚧雄虫产生的主要影响因子分析

研究表明,扶桑绵粉蚧雄虫产生的主要影响因子有寄主、环境因子（温度、光照、湿度）和种群密度。扶桑绵粉蚧在65%~70%RH,24 h全光照,温度28±1℃条件下,取食棉花（营养生长期）产雄率最大,雌雄比例为0.62∶0.38;在室温、24h全光照、80%RH条件下,取食棉花（营养生长期）时,种群密度在200头/株产生雄虫的机率最大,雌雄比例为0.585∶0.415。相同条件下,取食冬苋菜（营养生长期）产雄率最大,雌雄比例为0.68∶0.32。     

棉花上扶桑绵粉蚧广州种群生物学特性观察

 观察了以棉花为寄主的扶桑绵粉蚧交配、产卵、取食、趋性等主要生物学特性,新发现了扶桑绵粉蚧广州种群为两性生殖、雌雄虫均可多次交配、部分卵胎生等生物学现象。建立了雌成虫体长与产仔量的关系模型y = 7.9911x^2.7755。研究结果揭示入侵中国的扶桑绵粉蚧具有巨大的繁殖潜能,为进一步开展该虫生物学和防控技术等研究提供了依据。     

新入侵害虫扶桑绵粉蚧严重危害棉花

 试验观察了扶桑绵粉蚧(Phenacoccus solenopsis Tinsley)不同虫口密度对苗期棉花的危害情况,结果显示,棉花受其危害后出现叶片卷曲/畸形、叶片枯萎、顶心枯死、植株生长停滞、植株死亡等症状。受害后植株出现各种症状比率显著较高,以虫量达每株200～400头及以上危害较为严重。     

Effect of temperature on development,survival and reproduction of the mealybug,Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) on cotton

The effect of temperature on life cycle of the solenopsis mealybug, Phenacoccus solenopsis Tinsley, on cotton (Gossypium hirsutum L.) was assessed under laboratory conditions at ten constant temperatures (18–40 °C). The development duration of female and male nymphal instars linearly decreased with the increase in temperature from 18 to 32 °C. Cumulative developmental time of females ranged from 43.9 d (18 °C) to 15.0 d (32 °C). Survival of crawlers to adulthood was lowest (<53%) at 20 and 36 °C and highest (80%) at 32 °C. The solenopsis mealybug exhibited obligate sexual ovoviviparous reproduction and the pre-oviposition period in mated females showed a significant decreasing trend between 20 °C (23.0 d) and 30 °C (9.5 d). The oviposition period of 10.2–11.5 d at ≥25 °C was nearly half the duration than at 20 °C and the highest fecundity (245 eggs + crawlers) was observed at 30 °C. Longevity of mated females was significantly prolonged at 20 °C (46.0 d) compared to 30 °C (21.4 d). Proportion of females was highest (97.5%) at 25 °C. Males required higher degree-days (363.6) for their cumulative development compared to females (317.5). Lower temperature thresholds estimated from the linear model for cumulative female and male development were 11.7 and 10.1 °C, respectively. The estimated optimum temperature thresholds for nymphal instars (32–33.4 °C) from β type distribution function were closer to the observed maximum developmental rate compared to Lactin-2 model. The population trend index using survival, fecundity, and sex ratio of P. solenopsis with an initial population of 100 crawlers in the Morris-Watt life table model indicated a potential population increase of 170.3 and 97.6 times at 30 and 35 °C, respectively, in the next generation. The usefulness of the information on the temperature-dependent life cycle of P. solenopsis in understanding its field abundance and distribution on cotton and implications for management is discussed.     

Selection of bifenthrin resistance in cotton mealybug Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae): Cross-resistance,realized heritability and possible resistance mechanism

Cotton mealybug Phenacoccus solenopsis Tinsley is an important pest of cotton in Pakistan, and its management is difficult due to the development of insecticide resistance. This research was conducted to characterize the bifenthrin resistance in populations of P. solenopsis and different parameters such as cross-resistance, realized heritability and possible resistance mechanisms were studied to improve the management of this important pest. A field-collected population was selected with bifenthrin in the laboratory for 14 generations and developed a resistance of 178-fold. The realized heritability of bifenthrin resistance was 0.54 in the selected population. The toxicity of bifenthrin was synergized by the addition of either piperonylbutoxide (PBO) or S,S,S tributylphosphorotrithioate (DEF) which suggests a general metabolic resistance due to possible involvement of mono-oxygenases or esterases. However, the resistant population did not develop a significant cross-resistance to either buprofezin, chlorpyrifos or lambda-cyhalothrin. These data suggest that alternative insecticide-based management programs can be developed for this pest in the short-term, but resistance management strategies which can reduce the sole reliance on insecticides are still needed.     

Genetic analysis,realized heritability and synergistic suppression of indoxacarb resistance in Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae)

Cotton mealybug Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae) has caused huge crop and economic losses in different countries of the world including Pakistan. Considering P. solenopsis as a key cotton pest, research was conducted to understand genetics, realized heritability and preliminary mechanism of indoxacarb resistance. As a result of selection with indoxacarb, P. solenopsis developed a 2223.13-fold resistance after five generations. Indoxacarb resistance was autosomal in nature, and the degree of dominance for F₁ and F₁′ was 0.60 and 0.62, respectively, indicating the incomplete dominance of indoxacarb resistance. A monogenic model of inheritance also showed the involvement of multiple loci in indoxacarb resistance in P. solenopsis. Realized heritability for indoxacarb resistance was markedly high (h² = 1.13) in P. solenopsis suggesting how quickly resistance can develop as a result of selection. Synergism tests with piperonylbutoxide (PBO) and S,S,S-tributylphosphorotrithioate (DEF) also suggested that indoxacarb resistance in P. solenopsis was metabolism-based due to possible involvement of both mono-oxygenases and esterases. Hence, it was concluded that indoxacarb resistance in P. solenopsis was autosomal, incompletely dominant, polygenic and metabolism-based. These findings will be helpful in the management of P. solenopsis.     

A temperature-based phenology model for predicting development,survival and population growth potential of the mealybug,Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

The temperature-dependent population growth potential of Phenacoccus solenopsis Tinsley, a highly polyphagous and invasive mealybug species, was studied on sprouted potatoes under laboratory conditions at six constant temperatures (15–40 °C). Several non-linear equations were fitted to the obtained data to model temperature-dependent population growth and species life history. The established equations for each life age/stage of the species were compiled to obtain an overall temperature-dependent phenology model. The life table parameters of P. solenopsis were estimated using stochastic simulation centred on a rate summation and cohort up-dating approach. The theoretical lower development threshold temperatures estimated using linear regressions applied to mean development rates were 11.2, 8.9, 9.8 and 12.7 °C, and the thermal constants for development were 93.7, 129.8, 97.1 and 100.0 degree days (DD) for nymph 1, nymph 2, nymph 3 and male pupa stages, respectively. The developed phenology model predicted temperatures between 25 and 35 °C as the favourable range for P. solenopsis development, survival and reproduction. P. solenopsis population attained a maximum net reproductive rate (107–108 females/female/generation) and total fecundity (216.6–226.5 individuals/female/generation) at temperatures between 25 and 30 °C. Mean length of generations decreased from 75.6 days at 15 °C to 21 days at 40 °C. The maximum finite rate of increase (1.12–1.16 females/female/day) and shortest doubling time (4.3–6.1 days) were also observed at temperatures between 25 and 35 °C. The simulation of phenology model at fluctuating temperatures indicated that P. solenopsis populations might potentially increase with a finite rate of 1.06 females/female/day with an average generation time of 58.7 days and a doubling time of 12.1 days. The obtained life table parameters were reasonably similar when compared with literature data. The present model can be simulated spatially for estimating the pest risk and undertaking agro-ecoregion specific pest management strategies.     

Evaluation of a virus-insecticide combination for cotton pest control in Togo

A low dose of cypermethrin combined with Mamestra brassicae virus was applied weekly against the bollworms Helicoverpa armigera (Hübner) and Diparopsis watersi (Rothschild) in smallholder cotton plots in northern Togo in 1989 and 1990. The timing of treatments was based on action thresholds. One or two additional sprays of Bacillus thuringiensis were applied to control Syllepte derogata F., or dimethoate to control aphids. No significant yield differences were observed between the plots treated with the pyrethroid-virus combination and the control plots, treated with the recommended insecticide schedule. However, the latter had a significantly higher percentage of healthy bolls. The virus applied was not reisolated from insects collected in the field.     

寄主龄期对松粉蚧抑虱跳小蜂寄生和发育的影响

通过限制选择和自由选择试验,研究松粉蚧抑虱跳小蜂(Acerophagus coccois Smith)在扶桑绵粉蚧(Phenacoccus solenopsis Tinsley)的1~3龄若虫与雌成虫体上的寄生及其子代生长发育情况。结果表明:在限制选择和自由选择的2种试验中,松粉蚧抑虱跳小蜂均可寄生扶桑绵粉蚧的1~3龄若虫和雌成虫,其中对2龄若虫的寄生率最高,分别是41.20%和45.00%;对粉蚧雌成虫的寄生率最低,但每头僵蚧平均羽化出蜂数最多,分别为9.42头和7.00头,子代雌蜂比例也最大;子代雌蜂在粉蚧1龄若虫体内发育的历期最长,为14.62 d;在粉蚧雌成虫上发育的历期最短,为13.97 d;在粉蚧1龄若虫体内发育的子代蜂的个体最小,在粉蚧雌成虫上发育的子代蜂个体最大。因此,利用松粉蚧抑虱跳小蜂防治扶桑绵粉蚧,应以粉蚧2龄若虫为防治对象,以粉蚧雌成虫为繁殖寄主。