Effects of elevated CO2 and transgenic Bt cotton on plant chemistry, performance, and feeding of an insect herbivore, the cotton bollworm

Effects of elevated atmospheric CO₂ (double‐ambient CO₂) on the growth and metabolism of cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), fed on transgenic Bacillus thuringiensis (Berliner) (Bt) cotton [Cry1A(c)], grown in open‐top chambers, were studied. Two levels of CO₂ (ambient and double‐ambient) and two cotton cultivars (non‐transgenic Simian‐3 and transgenic GK‐12) were deployed in a completely randomized design with four treatment combinations, and the cotton bollworm was reared on each treatment simultaneously. Plants of both cotton cultivars had lower nitrogen and higher total non‐structural carbohydrates (TNC), TNC:Nitrogen ratio, condensed tannin, and gossypol under elevated CO₂. Elevated CO₂ further resulted in a significant decrease in Bt toxin level in GK‐12. The changes in chemical components in the host plants due to increased CO₂ significantly affected the growth parameters of H. armigera. Both transgenic Bt cotton and elevated CO₂ resulted in a reduced body mass, lower fecundity, decreased relative growth rate (RGR), and decreased mean relative growth rate in the bollworms. Larval life‐span was significantly longer for H. armigera fed transgenic Bt cotton. Significantly reduced larval, pupal, and adult moth weights were observed in the bollworms fed elevated CO₂‐grown transgenic Bt cotton compared with those of bollworms reared on non‐transgenic cotton, regardless of the CO₂ level. The efficiency of conversion of ingested food and of digested food of the bollworm were significantly reduced when fed transgenic Bt cotton, but there was no significant CO₂ or CO₂× cotton cultivar interaction. Approximate digestibility of larvae reared on transgenic cotton grown in elevated CO₂ was higher compared to that of larvae fed non‐transgenic cotton grown at ambient CO₂. The damage inflicted by cotton bollworm on cotton, regardless of the presence or absence of insecticidal genes, is predicted to be more serious under elevated CO₂ conditions because of individual compensatory feeding on host plants caused by nitrogen deficiency.     

Effects of elevated CO2 on the foraging behavior of cotton bollworm, Helicoverpa armigera

Effects of elevated CO2 on the foraging behavior of cotton bollworm Helicoverpa arrnigera Hübner reared on milky grains of spring wheat grown in ambient, 550μL/L and 750μL/L CO2 concentration atmospheres in open-top chambers （OTC） were studied. The results indicated that： （i） elevated CO2 significantly affected both the type and amount of food eaten by H.arrnigera reared on milky grains of ambient CO2-grown wheat were significant higher than those for bollworm larvae reared on wheat grains grown in 550 and 750μL/L CO2 atmospheres; （ii） when bollworm larvae were reared on mixed milky grains from different CO2-grown wheat （food-choice condition）, larval duration increased significantly-pupal weight, adult longevity, and fecundity decreased significantly, comparing with those reared on milky grains of ambient CO2-grown wheat, 550μL/L CO2-grown wheat and 750μL/L CO2-grown wheat respectively; （iii） significant decreases in the contents of fructose and gross protein （GP） and significant increases in the contents of glucose, amylose, total saccharides （TSC）, TSC： GP ratio, free amino acids and soluble protein in the wheat grains with CO2 rising; （iv） and selected-foraging amount/food-choice index of cotton bollworm H.armigera were significantly positive correlated with the contents of fructose and GP of wheat grains, but they had significantly negative relationships with the contents of glucose, amylose, TSC and TSC： GP ratio of wheat grains.     

Response of multiple generations of cotton bollworm Helicoverpa armigera Hübner, feeding on spring wheat, to elevated CO2

Abstract:  The growth, development and consumption of three successive generations of cotton bollworm, Helicoverpa armigera (Hübner), reared on milky grains of spring wheat grown under elevated CO₂ (double-ambient vs. ambient) in open-top chambers (OTCs) were examined. Decreases in protein, total amino acid, water and nitrogen content, and increases in total non-structure carbohydrates (TNCs) and ratio of TNC : nitrogen were found in wheat milky grains grown under elevated CO₂ conditions. Changes in quality of wheat grains affected the growth, development and food utilization of H. armigera . Significantly longer larval lifespan for the third generation and lower pupal weight for all generations were observed in cotton bollworm fed on milky grains of spring wheat grown under elevated CO₂ conditions. Bollworm fecundity was significantly decreased for the second and third generations under elevated CO₂ levels. The consumption, frass per larva and relative consumption rate significantly increased in elevated CO₂ compared with ambient CO₂ conditions. However, the potential population consumption was significant reduced by elevated CO₂ in the second and third generations. The results of this study indicate that elevated CO₂ levels adversely affect grain quality, resulting in consistently increased consumption per larva for a longer period to produce less fecund bollworm through generations, suggesting that net damage of cotton bollworm on wheat will be less under elevated atmospheric CO₂ levels because increased consumption is offset by slower development and reduced fecundity.     

在高CO2浓度下生长的小麦对棉铃虫生长发育和繁殖的影响

通过室内饲养实验研究了在高CO₂浓度（738.8±25.7μL/L）中生长的小麦对棉铃虫 Helicoverpa armigera (Hübner)生长发育,繁殖以及营养效应的影响。结果表明： （1）取食高CO₂浓度大气中生长的麦粒的棉铃虫对食料的取食量和粪便排泄量增加,与对照相比,取食量和粪便排泄量分别增加46.3%（P<0.05）和37.8%;（2）大气CO₂浓度增加影响了麦粒中的营养成分的含量,其中,可溶性蛋白、游离氨基酸、葡萄糖和总糖的含量及碳氮比(C∶N)都显著增加,果糖和粗蛋白的含量都显著降低;（3）大气 CO₂浓度升高所导致的麦粒营养成分的变化影响了棉铃虫幼虫的食物利用效率,与对照组相比,棉铃虫幼虫对食物的毛转化率和净转化率分别降低27.2%和25.4%,对食物的相对取食率则显著提高58.8%（P < 00.1）。据此推测,未来高CO₂浓度的大气环境会降低春小麦的营养价值,从而影响棉铃虫的生长发育,加重其对小麦的危害。     

棉铃虫的谷胱甘肽S—转移酶(GSTs)：杀虫药剂和植物次生性物质的诱导与GSTs对杀虫药剂的代谢

棉铃虫Helicoverpa armigera(Hubner)中肠谷胱甘肽S-转移酶(GSTs)对甲基对硫磷和灭多威的代谢能力明显高于对马来酸二乙酯(DEM)和两个混剂。LD₅剂量的对硫磷和灭多威对棉铃虫3龄幼虫GSTs的活性均没有诱导增加的影响,用LD₅₀的选择剂量仅对硫磷组GSTs活性增加15%。用含0.01%的芸香苷、2-十三烷酮和槲皮素的人工饲料饲养棉铃虫经1～4代后,GSTs活性提高4～18倍。3种植物次生性物质诱导组对灭多威和溴氰菊酯的敏感度均没有明显的变化,而槲皮素组对甲基对硫磷的敏感度则降低近一半,芸香苷和2-十三烷酮组对甲基对硫磷的敏感度略有降低。这种对甲基对硫磷敏感度的变化可能与上述GSTs活性的变化有关。     

单宁酸对棉铃虫谷胱甘肽S转移酶的影响

通过培养基混药法,研究了植物次生物质单宁酸对棉铃虫Helicoverpa armigera（Hübner）谷胱甘肽S-转移酶活性的影响。谷胱甘肽S-转移酶活性随棉铃虫发育期的进程而变化,在卵期最低,5龄、6龄幼虫和成虫期最高。用含0.005%单宁酸的饲料饲喂棉铃虫后,5龄和6龄幼虫的谷胱甘肽S-转移酶活性明显降低,分别为对照的59%和67%。单宁酸低剂量、短时间处理棉铃虫幼虫,可诱导中肠和脂肪体中的谷胱甘肽S-转移酶的活性增加,高剂量或低剂量长时间处理没有诱导增加作用,甚至还有抑制作用。单宁酸连续处理4代,对棉铃虫6龄幼虫中肠谷胱甘肽S 转移酶均有抑制作用,对脂肪体谷胱甘肽S-转移酶活性无明显影响或有抑制作用。单宁酸处理的第4代幼虫对溴氰菊酯的敏感度有增加的趋势,对甲基对硫磷的敏感度没有明显改变。     

Impacts of elevated CO2 on expression of plant defensive compounds in Bt‐transgenic cotton in response to infestation by cotton bollworm

• 1 The allocation of defensive compounds of transgenic Bt (cv. GK‐12) and nontransgenic cotton (cv. Simian‐3) grown in elevated CO₂ in response to infestation by cotton bollworm Helicoverpa armigera (Hübner) was studied in closed‐dynamics CO₂ chambers.
• 2 A significant reduction in foliar nitrogen content and Bt toxin protein occurred when transgenic Bt cotton grew under elevated CO₂. A significantly higher carbon/nitrogen ratio as well as condensed tannin and gossypol contents was observed for transgenic Bt (cv. GK‐12) and nontransgenic cotton in elevated CO₂, in partial support of the carbon nutrient balance hypothesis as a result of limiting nitrogen and excess carbon in cotton plants in response to elevated CO₂.
• 3 The CO₂ level and infestation time significantly affected the foliar nitrogen, condensed tannin, gossypol and Bt toxin protein contents of cotton plants after feeding by H. armigera. The interaction between CO₂ levels × cotton variety had a significant effect on foliar nitrogen content after injury by H. armigera.

     

How does atmospheric elevated CO2 affect crop pests and their natural enemies? Case histories from China

Abstract Global atmospheric CO₂ concentrations have risen rapidly since the Industrial Revolution and are considered as a primary factor in climate change. The effects of elevated CO₂ on herbivore insects were found to be primarily through the CO₂‐induced changes occurring in their host plants, which then possibly affect the intensity and frequency of pest outbreaks on crops. This paper reviews several ongoing research models using primary pests of crops (cotton bollworm, whitefly, aphids) and their natural enemies (ladybeetles, parasitoids) in China to examine insect responses to elevated CO₂. It is generally indicated that elevated CO₂ prolonged the development of cotton bollworm, Helicoverpa armigera, a chewing insect, by decreasing the foliar nitrogen of host plants. In contrast, the phloem‐sucking aphid and whitefly insects had species‐specific responses to elevated CO₂ because of complex interactions that occur in the phloem sieve elements of plants. Some aphid species, such as cotton aphid, Aphis gossypii and wheat aphid, Sitobion avenae, were considered to represent the only feeding guild to respond positively to elevated CO₂ conditions. Although whitefly, Bemisia tabaci, a major vector of Tomato yellow leaf curl virus, had neutral response to elevated CO₂, the plants became less vulnerable to the virus infection under elevated CO₂. The predator and parasitoid response to elevated CO₂ were frequently idiosyncratic. These documents from Chinese scientists suggested that elevated CO₂ initially affects the crop plant and then cascades to a higher trophic level through the food chain to encompass herbivores (pests), their natural enemies, pathogens and underground nematodes, which disrupt the natural balance observed previously in agricultural ecosystems.     

BIOCHEMICAL ASPECTS OF INSECTICIDE RESISTANCE IN COTTON BOLLWORM FROM HANDAN OF HEBEI PROVINCE*

Abstract The cotton bollworms, Helicoverpa armigera Hübner, collected from Handan of Hebei Province, have evolved high resistance to pyrethroid, organophosphate and carbamate insecticides, The sensitivity of acetylcholinesterase (AChEs) to paraoxon and methomyl varied with the development stages of the cotton bollworm. After the treatments with LD₅ and LD₅₀ of parathion and methomyl to the cotton bollworms, the affinity of AChE to acetylthiocholine (ATCh) and acetyl-β-bmethyl-thio choline (MeTCh) increased significantly except the treatment of parathion using LD₅₀ dosage while the sensitivity of AChEs to paraoxon significantly decreased. The sensitivity of AChEs to methomyl strongly increased in the treatment of parathion using LD₅₀ dosages while strongly decreased in other treatments. The affinity of carboxylesterase to β-naphthyl acetate (β-NA) was higher in groups of treatment with insecticides than in group of control. The glutathione-s-transferase (GST) activity significantly decreased in the induced groups using LD₅ dosages, while increased in the selection groups using LD₅₀ dosages. The effects of parathion and methomyl on the phosphatases of cotton bollworm were related to the dosages of application and the time after treatment and the effect on the alkaline phosphatase was stronger than on acid phosphatase.     

Elevated ozone induces jasmonic acid defense of tomato plants and reduces midgut proteinase activity in Helicoverpa armigera

As a consequence of membrane lipid peroxidation, foliar defense compounds are changed by elevated ozone (O₃), which in turn affects the palatability and performance of insect herbivores. The induced defense of two tomato [Solanum esculentum L. (Solanaceae)] genotypes, namely jasmonic acid (JA) pathway‐deficient mutant spr2 and its wild‐type control, was studied in response to cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), as well as the digestive adaptation of these insects under elevated O₃ in open‐top field chambers. Our data indicated that elevated O₃ increased foliar JA and salicylic acid (SA) levels simultaneously and up‐regulated proteinase inhibitors (PIs) and lipoxidase activities in wild‐type plants, regardless of H. armigera infestation. In contrast, only the O₃+H. armigera treatment increased free SA levels in spr2 plants, but did not affect JA level or PI activities. Additionally, the lower activity of midgut digestive enzymes, including active alkaline trypsin‐like enzyme and chymotrypsin‐like enzyme, was observed in the midgut of cotton bollworms after they consumed wild‐type plants treated for 2 h with elevated O₃. With temporary increases at 8 h, all four digestive enzymes of interest in the insect midgut dropped when they were fed with wild‐type plants under elevated O₃ treatment. Increases in atmospheric O₃ are thought to increase JA signaling and consequently reduce the activities of midgut digestive enzymes in H. armigera, therefore enhancing plant resistance against insect herbivores.     

Impacts of elevated CO2 on Bemisia tabaci infesting Bt cotton and its parasitoid Encarsia formosa

Atmospheric carbon dioxide concentration is expected to rise in the coming decades. Rising atmospheric CO₂ levels may alter plant‐insect‐parasitoid associations due to the indirect effects of CO₂ enrichment on phytochemicals important for herbivore and parasitoid nutrition. Tritrophic effects of elevated CO₂ on Bt cotton (GK‐12) and non‐transgenic (Simian‐3, or S3) cotton [Gossypium hirsutum L. (Malvaceae)], Bemisia tabaci (Gennadius) biotype B (Hemiptera: Aleyrodidae), and its parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), were examined in open‐top chambers. Significantly, longer egg‐adult developmental duration and higher mortality of nymphs were observed under elevated CO₂ concentrations on both cotton cultivars during three successive generations. However, no significant differences were found in adult longevity, offspring sex ratio, and the number of eggs laid per female adult of B. tabaci fed on transgenic (GK‐12) or non‐transgenic cotton (S3) grown under elevated CO₂. Abundance of B. tabaci adults increased from 10 to 120 per plant and then decreased to 40 per plant through the growing season, but no significant differences in density occurred between CO₂ treatments and between cultivar treatments. Similarly, no significant differences were found in the developmental duration, parasitization rate, and adult emergence rate of E. formosa after parasitizing B. tabaci for three successive generations. Our results showed that the effects of transgenic Bt cotton did not significantly affect the development, survivorship, life span, or fecundity of B. tabaci and its parasitoids. Moreover, interactions between B. tabaci and E. formosa were not significantly affected by elevated CO₂. These results suggest that the biological control of B. tabaci by E. formosa would not be influenced by transgenic Bt cotton and/or elevated CO₂, indicating that the current risk management strategy regarding B. tabaci outbreaks and biocontrol by E. formosa will remain effective if the atmospheric CO₂ level continues to rise.     

Effects of climate change and crop planting structure on the abundance of cotton bollworm,Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

The interactions between plants and insects play an important role in ecosystems. Climate change and cropping patterns can affect herbivorous pest insect dynamics. Understanding the reasons for population fluctuations can help improve integrated pest management strategies. Here, a 25‐year dataset on climate, cropping planting structure, and the population dynamics of cotton bollworms (Helicoverpa armigera) from Bachu County, south Xinjiang, China, was analyzed to assess the effects of changes in climate and crop planting structure on the population dynamics of H. armigera. The three generations of H. armigera showed increasing trends in population size with climate warming, especially in the third generation. The relative abundances of the first and second generations decreased, but that of the third generation increased. Rising temperature and precipitation produced different impacts on the development of different generations. The population numbers of H. armigera increased with the increase in the non‐Bacillus thuringiensis (Bt) cotton‐planted area. Asynchrony of abrupt changes existed among climate change, crop flowering dates, and the phenology of H. armigera moths. The asynchronous responses in crop flowering dates and phenology of H. armigera to climate warming would expand in the future. The primary factors affecting the first, second, and third generations of moths were T_mean in June, the last appearance date of the second generation of moths, and the duration of the third generation of moths, respectively. To reduce the harm to crops caused by H. armigera, Bt cotton should be widely planted.     

SUBSTRATE SPECIFICITY AND DEVELOPMENTAL CHANGES OF ACETYLCHOLINESTERASE IN COTTON BOLLWORM*

Abstract The substrate specificity and developmental changes of acetylcholinesterase (AChE) of cotton bollworm, Helicoverpa armigera Hübner, were investigated during 1991 to 1994. The insects were collected from Handan suburbs of Hebei Province and Guan County of Shandong Province. The results show that the specific activity and Michaelis constants (k_m) of AChE toward acetylthiocholine (ATCH) and acetyl-β-methyl-thiocholine (MeTCh) regularly varied with the developmental stage of cotton bollworm. The two peaks of the specific activity were observed respectively in the third instar and sixth instar of larvae. The specific activity of AChE in pupae was the lowest and that in heads of four-days moth was the highest in various developmental stages of cotton bollworms. The tendency of K_m and maximum velocity (V_max) was identical with the change of specific activity in the AChEs of cotton bollworm. The activation energy (Ea) of AChE toward MeTCh in pupae and adults was 3. 9–4. 3 times as much as that of, larvae in cotton bollworms from Handan of Hebei Province. It suggests that the spending energies of AChE for hydrolysing substrate are different in larva, pupa and adult. The optimum conditions of AChE reaction with ATCh in larvae were 50–100 mg of tissue weights for the amount of enzyme, 10–20 minutes for the reaction time, 35°C for the reaction temperature and 8. 0 for the reaction pH value.     

Effects of elevated CO2 on life‐history traits of three successive generations of Frankliniella occidentalis and F. intonsa on kidney bean,Phaseolus vulgaris

The objective of this study was to determine how elevated CO₂ impacts on life‐history traits and life table parameters in three successive generations of invasive species Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and its related native species, Frankliniella intonsa (Pergande), fed with kidney bean leaves grown in ambient CO₂. The oviposition period, sex ratio, net reproductive rate (R₀), intrinsic rate of increase (r_m), and finite rate of increase (λ) of F. occidentalis increased in elevated CO₂, and larval duration, survival rate, mean generation time (T), and population doubling time (DT) decreased. For F. intonsa, larval duration, survival rate, oviposition period, longevity of female adults, R₀, r_m, and λ decreased in elevated CO₂, whereas sex ratio, T, and DT increased. These results indicated that the effects of elevated CO₂ would be beneficial to F. occidentalis, whereas it would be detrimental to F. intonsa. However, the effects of elevated CO₂ on F. occidentalis and F. intonsa differed over generations. In elevated CO₂, larval duration, survival rate, oviposition period, sex ratio, r_m, and λ of F. occidentalis increased linearly through successive generations, whereas T and DT decreased linearly, which suggested that the effects of elevated CO₂ on F. occidentalis would be slowly accentuated over time. For F. intonsa, larval duration, survival rate, oviposition period, r_m, and λ decreased linearly over generations, whereas sex ratio, T, and DT increased linearly. This indicated that the effects of elevated CO₂ on F. intonsa would slowly accentuate over time. We conclude that F. occidentalis would be more adapted to elevated CO₂ than F. intonsa.     

Elevated CO2 lessens predation of Chrysopa sinica on Aphis gossypii

Most studies on the effects of elevated atmospheric CO₂ on organisms have focused on the performance of plants or herbivores. Few reports have examined the impact on the ability of predators at the third trophic level. In this experiment, we made use of open‐top chambers to quantify the effects of elevated CO₂ on growth, development, and predatory ability of two successive generations of Chinese lacewing, Chrysopa sinica (Tjeder) (Neuroptera: Chrysopidae), feeding on cotton aphids, Aphis gossypii (Glover) (Hemiptera: Aphididae), which were reared on cotton, Gossypium hirsutum L. (Malvaceae), grown under elevated CO₂ (double ambient vs. ambient). Higher atmospheric CO₂ concentrations reduced the duration of larval development and the survival rate of pupae, and caused decreased weight in adult female C. sinica, but had no significant effects on survival rate of each larval stage, female adult fecundity, egg hatch rate, or adult life span. The predatory ability of larvae in the third instar and the total larval stage of C. sinica that fed on A. gossypii were significantly lower in elevated CO₂ environments. The number of aphids consumed by first‐generation lacewing population did not change significantly with different CO₂ treatments; however, significantly fewer aphids were consumed by the second generation of the lacewing population with elevated CO₂. We speculate that A. gossypii may become a more serious pest under an environment with elevated CO₂ concentrations because of the reduced predatory ability of C. sinica on A. gossypii.     

A NEW AND PRACTICAL ARTIFICIAL DIET FOR THE COTTON BOLL-WORM*

Abstract A new and practical artificial diet for the cotton bollworm, Helicoverpa armigera (Hübner), containing canned tomato paste has been developed. The developmental duration of larvae fed on the diet was greatly shortened because most of them only went through 5 stadia before pupation. To add certain amount of mung bean flour to partly substitute for wheat germ in the diet was beneficial to the adult reproduction. During rearing period of 12 successive generations, 87. 5%-98. 7% of the larvae survived and only less than 5 % of the pupae failed to emerge. The number of egg laid by the adults of the 11th generation averaged about 1 000/female, with a hatching rate of 86. 5%. These results suggested that the vitality of the cotton bollworm did not decline obviously after reared with the diet for two years.     

The life parameters of a parasitoid Microplitis mediator (Hymenoptera: Braconidae), reared on cotton bollworm Helicoverpa armigera (Hübner) with Cry1Ac diet

Microplitis mediator (Haliday) is an important endoparasitoid of the cotton bollworm, Helicoverpa armigera (Hübner) in northern China. Interactions among H. armigera, its larval parasitoid M. mediator, and Cry1Ac over two generations were evaluated under laboratory conditions. The results indicated that the developmental period of M. mediator offspring's eggs and larvae were significantly delayed and pupal and adult weight were significantly less compared to the control when the female parasitoids parasitized H. armigera larvae that fed on diet containing 1, 2, 4 and 8 µg/g Cry1Ac. The female parasitoids emerged from the host fed diet containing 8 µg/g Cry1Ac could oviposit in healthy hosts, and their offspring's biological parameters (egg–larval period, pupal weight and adult weight), parasitism rate, abnormal cocoon rate and adult emergence were not significantly affected. Cry1Ac was detected in larvae and hemolymph of H. armigera, but not in the larvae of M. mediator. The results suggest that the observed significant effects on several fitness parameters of the F₁ M. mediator developed from H. armigera fed Cry1Ac diet most likely were host-quality mediated rather than direct effects of Cry1Ac.     

植物次生物质诱导作用对杀虫药剂毒力影响研究

通过培养基混药法测定了芸香甙、槲皮素和2—十三烷酮三种植物次生物质的诱导作力的影响。芸香甙的诱导作用提高了棉铃虫对甲基对硫磷和灭多威的耐药性,而对溴氰菊酯毒力的影响则随诱导时间的不同而异;槲皮素的诱导作用提高了棉铃虫F₂代对灭多威的毒力,槲皮素的诱导作用对溴氰菊酯的毒力无影响;2—十三烷酮的诱导作用提高了棉铃虫对溴氰菊酯的耐药性,提高F₁代对灭多威的敏感度,而对甲基对硫磷的毒力影响不大。     

Lethal and sublethal effects of thiacloprid on survival,growth and reproduction of Helicoverpa armigera (Lepidoptera: Noctuidae)

The cotton bollworm Helicoverpa armigera (Hübner) is the most destructive pest of cotton, tomato and chickpea in Iran. In this study, the lethal and sublethal effects of thiacloprid were evaluated against cotton bollworm under laboratory condition at 26?±?1?°C, 70?±?5% RH and a photoperiod of 16:8 (L:D). Bioassay experiments were conducted on first larval instars by mixing the insecticide dilutions with artificial diet. The LC₅₀ value of thiacloprid was 329?mg a.i./l. Sublethal effects of LC₃₀ concentration of thiacloprid was studied on biological parameters. In the study of sublethal effects, thiacloprid at LC₃₀ concentration significantly increased larval and pupal developmental times and reduced adults longevity compared with control but showed no significant effects on fecundity of cotton bollworm. Sublethal effects of thiacloprid also significantly reduced pupal weight compared with control. In general, sublethal effects studies showed that thiacloprid had adverse effects on biological parameters of the pest. Thus, our data suggest that thiacloprid had moderate potential against cotton bollworm.