An olfactometer for measuring the repellent effect of chemicals on the stable fly Stomoxys calcitrans (L.)

An olfactometer is described that permits the evaluation of chemicals acting in the vapour phase against the stable fly Stomoxys calcitrans (L.). Hungry flies, held in a metal frame cage covered with soft gauze, are attracted to a target held adjacent to one side of the cage, and emitting an attractive airflow. Flies landing on the target are counted at intervals of 15s. Flies starved for 24h were tested in the olfactometer when 2, 3 and 4 days old. With the exception of the first exposure of the 4-day-old flies, all the flies of the three ages showed greater than 80% attraction to the olfactometer target after exposure for 2 min, for each of four successive exposures at 10-min intervals. For all ages there was a significant increase in attraction at the second exposure but no further increase with subsequent exposures. It is likely that the sensillae, stimulated by the first exposure, subsequently responded faster. Eight chemicals were incorporated into the airflow behind the target to test their effect on flies. Permethrin (a low vapour pressure pyrethroid) and crotoxyphos (a low vapour pressure organophosphate) did not act in the vapour phase. Empenthrin (a high vapour pressure pyrethroid) and dichlorvos (a high vapour pressure organophosphate) both exhibited the toxic effect of knock-down on the flies without repellency. Oil of citronella and citronellol, two known fly repellents, gave a general reduction of attraction that was dose dependent; fewer flies found the target and those that did stayed a shorter length of time. Natural pyrethrum gave a similar effect to these two at lower concentrations, but at higher concentrations, it also showed a repellent effect. N,N-Diethyl-m-toluamide gave a low reduction in attraction. The olfactometer shows potential for use with other flying insects, both to observe the effects of an insecticide and also to study the behavioural responses in the absence of insecticides.     

Dispersal of Ceratitis capitata Wied. on Procida Island 1)

A preliminary experiment, to relate the flight capability of Ceratitis to irradiation doses and to feeding, has shown that 9 Krads is a suitable dose for control programs and that feeding the newly emerged flies seems to affect their distribution over greater distances.     

Characteristics and implications of knockdown of the tsetse fly Glossina morsitans morsitans westw. by deltamethrin

Low doses of deltamethrin cause prolonged knockdown of the tsetse fly Glossina morsitans morsitans. Fifty per cent of female flies, treated with the LD₁₅-(48 h) of deltamethrin, failed to regain their capacity for normal flight for 30 h, compared with 6 h for bioresmethrin and 4 h for permethtin at the equivalent dose. Recovery after exposure to tetramethrin occurred within 1 h. The knockdown effect of deltamethrin on males was even more pronounced although, with both sexes, the onset of the effect was delayed for about 3 h. It is suggested that this prolonged knockdown effect of deltamethrin, at extremely low application rates, may make a significant contribution to the effectiveness of the compound against the tsetse fly.     

Effects of the essential oil constituent thymol and other neuroactive chemicals on flight motor activity and wing beat frequency in the blowfly Phaenicia sericata

BACKGROUND: The effects were evaluated of the plant terpenoid thymol and eight other neuroactive compounds on flight muscle impulses (FMIs) and wing beat frequency (WBF) of tethered blowflies (Phaenicia sericata Meig.). RESULTS: The electrical activity of the dorsolongitudinal flight muscles was closely linked to the WBF of control insects. Topically applied thymol inhibited WBF within 15–30 min and reduced FMI frequency. Octopamine and chlordimeform caused a similar, early‐onset bursting pattern that decreased in amplitude with time. Desmethylchlordimeform blocked wing beating within 60 min and generated a profile of continuous but lower‐frequency FMIs. Fipronil suppressed wing beating and induced a pattern of continuous, variable‐frequency spiking that diminished gradually over 6 h. Cypermethrin‐ and rotenone‐treated flies had initial strong FMIs that declined with time. In flies injected with GABA, the FMIs were generally unidirectional and frequency was reduced, as was seen with thymol. CONCLUSIONS: Thymol readily penetrates the cuticle and interferes with flight muscle and central nervous function in the blowfly. The similarity of the action of thymol and GABA suggests that this terpenoid acts centrally in blowflies by mimicking or facilitating GABA action. Copyright © 2009 Society of Chemical Industry     

Effect of gamma radiation on sterility ofliriomyza trifolii flies

The effect of low doses of gamma radiation applied toLiriomyza trifolii Burgess eggs or 1st-instar larvae, on the ensuing flies was studied. Doses of 50 or 40 Gy resulted in very few individuals reaching the adult stage; the life span of these flies was very short and they did not breed. A 25-Gy dose applied at the 1st instar allowed the development of many individuals into adults which emerged successfully, fed, and oviposited viable eggs which completed their development to adults. Contribution from the Agricultural Research Organization. No. 3024-E, 1990 series.     

Effects of soil moisture and sowing depth on the development of bean plants grown in sterile soil infested by <Emphasis Type="Italic">Rhizoctonia solani</Emphasis> and <Emphasis Type="Italic">Trichoderma harzianum</Emphasis>

The effects of soil moisture (varying from 15% to 42% (v/v)) and sowing depth (1.5–6.0 cm) on the development of bean plants grown in sterile soil infested by the pathogen Rhizoctonia solani and its antagonist Trichoderma harzianum were studied under greenhouse conditions. The four possible combinations of soil infestation with both fungi were tested. Disease severity, percentage of plants emerged, plant height and dry weight were evaluated 3 weeks after sowing. Emergence rate and growth of plants inoculated only with R. solani were not affected by soil moisture, but in the presence of both fungi, plant emergence, plant height and dry weight significantly decreased when soil moisture diminished. Deep sowing significantly reduced the emergence rate and growth of those plants that were inoculated with R. solani only. However, when the soil was infested with both fungi, the effect of sowing depth was not significant. At a sowing depth of 6.0 cm, the percentage of plants emerged was 50% in the presence of T. harzianum, but only 6.7% when the pathogen was inoculated alone. The antagonist protected bean seedlings from pre-emergence damping-off, reduced disease severity and increased plant growth in the presence of R. solani, especially in moist soil.     

Behavioural and electrophysiological investigation of 1-(7-ethoxygeranyl)-2-methylbenzimidazole on the house fly Musca domestica

The insecticidal properties of 1-(7-ethoxygeranyl)-2-methylbenzimidazole (EGMB) were investigated on larval and adult house flies. Unsynergised EGMB gave topical LD₅₀ values of 0.53 μg per female fly on NAIDM strain house flies. When flies were pretreated with 5.2 μg piperonyl butoxide, susceptibility was increased (LD₅₀ 0.12 μg per female fly). House fly larvae were less susceptible to EGMB (LD₅₀ 2.2 μg). Poisoning with EGMB resulted in a rapid reduction in locomotor activity of both larval and adult house flies. This reduction in locomotion was progressive and led to complete paralysis. Various parameters of larval nervous system function were investigated in larvae during these early phases of poisoning. As early as 15 min after dosing larvae with LD₉₅ doses of EGMB, sensory nerves were less responsive. Over a somewhat longer time (2–4 h), neurally evoked contractures were adversely affected by EGMB. In some cases, this effect appeared to be due to reduced postsynaptic potential amplitude; in other instances, it appeared to be due to an effect independent of neuromuscular transmission. The close temporal correlation between behavioural and electrophysiological observations suggests that the nervous and muscular systems are important sites of action of EGMB.     

Effects of inoculum density, leaf age, moisture, temperature, and wetness duration on black streak of edible burdock

Inoculum density, temperature, leaf age, and wetness duration were evaluated for their effects on the development of black streak (Itersonilia perplexans) on edible burdock (Arctium lappa L.) in a controlled environment. The effect of relative humidity (RH) on ballistospores production by I. perplexans was also evaluated. Symptoms of black streak on leaves increased in a linear fashion as the inoculum density of I. perplexans increased from 10² to 10⁶ ballistospores/ml. Rugose symptoms on young leaves were observed at densities of ≥10⁴ ballistospores/ml. Disease severity of I. perplexans in relation to leaf age followed a degradation curve when the leaves were inoculated with ballistospores. Disease severity was high in newly emerged leaves up to 5 days old, declined as leaf age increased to 29 days, and was zero when leaf age increased from 30 to 33 days. Disease development of edible burdock plants exposed to ballistospores of I. perplexans was evaluated at various combinations of temperature (10°, 15°, 20°, 25°C) and duration of leaf wetness (12, 24, 36, 48, and 72 h). Disease was most severe when plants were in contact with the ballistospore sources at 15° or 20°C. The least amount of disease occurred at 25°C regardless of wetness duration. Ballistospores required 24–36 h of continuous leaf wetness to cause visible symptoms by infection on edible burdock. Ballistospores production in infected lesions required at least 95.5% RH.     

Host species, age and sex as factors affecting the susceptibility of the African Tephritid fruit fly species,Ceratitis capitata, C. cosyra and C. fasciventris to infection by Metarhizium anisopliae

The effect of host age and sex on the susceptibility of 3 tephritid fruit fly species, Ceratitis capitata (Wiedemann), C. cosyra (Walker) and C. fasciventris (Bezzi) to the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin was studied in the laboratory. Three adult host ages, 0 (<1 day-old), 7-day-old and 14-day-old, were used. All 3 species were susceptible to fungal infection, although there were differences in the levels of susceptibility among the hosts. Age accounted for the largest variability in mortality followed by species, while sex had the lowest variability. Of the 3 host ages tested, the 0- and 7-day-old flies were more susceptible to fungal infection than the 14-day-old flies. Male and female C. fasciventris flies generally succumbed earlier to fungal infection than the other two species. Female flies of C. cosyra and C. fasciventris were also generally more susceptible to fungal infection than the males, although differences were apparent at 3 and 4 days after treatment but not 5 days after treatment. Age accounted for the largest variability in lethal time mortality values (LTs). Mean LT-values generally indicated that the speed of kill was faster among younger flies than the older flies. LT₉₅ ranged between 3.9–4.9 days in the 0-day-old flies, 4.3–6.1 days in the 7-day-old flies and 4.6–6.1 days in 14-day-old flies in the different species and sexes. The implication of this study for the management of fruit flies is discussed.     

The role ofPseudomonas spp. and competition for carbon,nitrogen and iron in the enhancement of appressorium formation byColletotrichum coccodes on velvetleaf

Colletotrichum coccodes is currently being investigated as a mycoherbicide against the weed velvetleaf (Abutilon theophrasti). Two isolates ofPseudomonas spp. (Ps2 and Ps5) reduced the percentage of germ tubes and increased appressorial formation ofC. coccodes on detached leaves of velvetleaf. A study was conducted to see whether this effect could be attributed to competition for nutrients or iron betweenC. coccodes andPseudomonas spp. Ps2 and Ps5 had no effect on early spore germination, but reduced the percentage of germ tubes at 24 and 30 h, compared to the nontreated control. This reduction was diminished by the addition of nutrients but not Fe³⁺. Ps2 and Ps5 stimulated the formation of dark-coloured appressoria without germ tubes (AWGT), but this stimulation was diminished by the addition of nutrients or Fe³⁺. Germ tube branching at 30 h was also inhibited by the bacteria, but was not diminished by the addition of nutrients or iron. EDTA stimulated conidial germination at 10 h, which was reduced by the addition of Fe³⁺. However, EDTA did not stimulate the formation of appressoria (AWGT). These results suggest that the reduction in the percentage of germ tubes and the increase in the percentage of appressoria induced by the bacteria may be due to the competition for carbon or nitrogen. Iron competition may also be involved in the stimulation of appressorial formation, but not in the reduction in germ tube percentage and branching. Phylloplane bacteria may compete for carbon, nitrogen and iron, limiting the saprophytic phase of the pathogen on the phylloplane and accelerating the development of the parasitic phase. This may enhance the field efficacy ofC. coccodes as a biocontrol agent against velvetleaf.     

Host species, age and sex as factors affecting the susceptibility of the African Tephritid fruit fly species,Ceratitis capitata, C. cosyra and C. fasciventris to infection by Metarhizium anisopliae

The effect of host age and sex on the susceptibility of 3 tephritid fruit fly species, Ceratitis capitata (Wiedemann), C. cosyra (Walker) and C. fasciventris (Bezzi) to the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff) Sorokin was studied in the laboratory. Three adult host ages, 0 (<1 day-old), 7-day-old and 14-day-old, were used. All 3 species were susceptible to fungal infection, although there were differences in the levels of susceptibility among the hosts. Age accounted for the largest variability in mortality followed by species, while sex had the lowest variability. Of the 3 host ages tested, the 0- and 7-day-old flies were more susceptible to fungal infection than the 14-day-old flies. Male and female C. fasciventris flies generally succumbed earlier to fungal infection than the other two species. Female flies of C. cosyra and C. fasciventris were also generally more susceptible to fungal infection than the males, although differences were apparent at 3 and 4 days after treatment but not 5 days after treatment. Age accounted for the largest variability in lethal time mortality values (LTs). Mean LT-values generally indicated that the speed of kill was faster among younger flies than the older flies. LT₉₅ ranged between 3.9–4.9 days in the 0-day-old flies, 4.3–6.1 days in the 7-day-old flies and 4.6–6.1 days in 14-day-old flies in the different species and sexes. The implication of this study for the management of fruit flies is discussed.     

山东省樱桃主产区果蝇的调查与鉴定

为了解山东省樱桃主产区果蝇的发生情况,本研究选择了山东省主要樱桃产区的7个地点进行调查,并通过形态学特征和分子鉴定法对果蝇的种类进行鉴定。结果发现,山东省樱桃主产区有4种果蝇,通过形态特征与分子鉴定法最终确定4种果蝇,分别为斑翅果蝇Drosophila suzukii、黑腹果蝇D.melanogaster、海德果蝇D.hydei和伊米果蝇D.immigrans。这4种果蝇对樱桃的为害程度与种植地区、果实腐烂程度和樱桃的品种均有关系;莱芜和泰安地区果蝇分别有4种和3种;烟台和威海地区则只有斑翅果蝇和黑腹果蝇2种。烟台地区果蝇为害率最高,且数量最多,其中烟台丁家夼村樱桃为害率高达45.16%,在第2次采集中烟台薛家村每100粒樱桃中斑翅果蝇和黑腹果蝇的数量最多。美早和先锋2个品种樱桃对果蝇的吸引力较强;采摘后期腐烂的果实可吸引大量的果蝇产卵。因此,应对烟台地区进行重点预防、早期防治,并减少美早和先锋品种樱桃在山东省的种植。     

Toxicity of spinosad to susceptible and resistant strains of house flies,Musca domestica

The toxicity of spinosad, a new insecticide derived from the bacterium Saccharopolyspora spinosa, was evaluated against susceptible and resistant strains of house fly (Musca domestica L.). Spinosad was highly toxic to house flies based on 72-h LD₅₀ values and the symptoms of poisoning were consistent with a neurotoxic mechanism of action. Spinosad was relatively slow acting, with the maximum toxicity noted at 72 h. Piperonyl butoxide and S,S,S,-tribu-tylphosphorotrithioate synergized the toxicity of spinosad by 3·0- and 1·8-fold, respectively, while diethyl maleate had no significant effect. These results suggest that there is a small degree of monooxygenase-mediated spinosad detoxification in house flies, while hydrolases may be only minimally important and glutathione transferases may have no role. There were no substantial levels of cross-resistance detected, except in the LPR strain where a low 4·3-fold cross-resistance was observed. The cyclodiene-resistant OCR strain was 2·7-fold more sensitive to spinosad than the susceptible strain (CS). These results suggest that cross-resistance may not be a limiting factor for the use of spinosad against house flies. © 1998 Society of Chemical Industry     

Laboratory evaluation of natural pyrethrins, pymetrozine and triflumuron as alternatives to controlCeratitis capitata adults

Three insecticides, pyrethrins + piperonil butoxide (PBO), pymetrozine and triflumuron, were tested as potential alternatives for controlling the Mediterranean fruit flyCeratitis capitata (Wiedemann) (Diptera: Tephritidae). The compounds were administered to adult flies in the laboratory by different uptake methods at the recommended rates currently used in fruit crops in Spain. Pyrethrins + PBO (80 + 320 ppm a.i.) exhibited a comparable knock-down effect to malathion (1,500 ppm a.i.) in the laboratory, irrespective of the method of application used. After these results were obtained, the number of concentrations tested was increased to carry out a dose-response analysis. Pymetrozine (300 ppm a.i.) and triflumuron (150 ppm a.i.) did not kill adults at the concentrations tested. However, pymetrozine diminished the fecundity, especially when adults were fed the insecticide; egg hatch was decreased by 59.3% compared with controls. Further experiments showed that increased period of ingestion and higher concentrations had a clear effect in reducing both fecundity and fertility. The possible use of pyrethrins + PBO and pymetrozine to reduce populations ofC. capitata is discussed. http://www.phytoparasitica.org posting July 22, 2006. Corresponding author     

Raspberry ketone feeding makes Queensland fruit fly,Bactrocera tryoni (Froggatt), more vulnerable to desiccation but not starvation

Background

Queensland fruit fly (Qfly) males exhibit accelerated sexual maturation when their diet is supplemented with raspberry ketone (RK) for 48 h following emergence, which is beneficial for sterile insect technique operation. The present study tests whether RK supplementation makes Qfly more vulnerable to starvation or desiccation.

Results

Flies were fed for 48 h with a yeast hydrolysate and sugar diet (1:3) that contained 0% RK (control), 1.25% RK (low dose) or 5% RK (high dose) to test subsequent vulnerability to starvation and desiccation. RK feeding decreased body weight and water content in males and increased lipid levels in both sexes before exposure to any stress treatment. Under nutritional stress, flies fed the low RK dose, but not the high RK dose, had higher survival than controls. Under desiccation stress, flies fed both the low and high RK doses had lower survival than the controls. Body weight, water content and lipid reserves at death were all affected by RK dose when under nutritional stress, but not when under desiccation stress. In the absence of stress, body weight at death was higher than controls in flies provided with the high RK dose and lipids were lower than controls in flies provided with the low RK dose.

Conclusion

Feeding with RK makes Qflies more vulnerable to desiccation but not starvation. In most conditions, it is expected that the disadvantage of increased desiccation vulnerability would be outweighed by the benefits of accelerated sexual maturation in RK-fed young adult Qflies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

The effect of isoprothiolane on the emergence of infection pegs from appressoria of Pyricularia oryzae

The effect of isoprothiolane^a (di-isopropyl 1,3-dithiolan-2-ylidenemalonate), a systemic fungicide used for rice blast control, on the infection process of Pyriculuria oryzae was studied by micromanipulation in a scanning electron microscope. Whether or not infection pegs emerged from the appressoria was examined by inverting each appressorium contact surface. Infection pegs were observed on more than 80% of the appressoria, 48 h after inoculation, on both untreated rice leaves and cellophane film. Isoprothiolane, approximately 10 μg ml^?1 in the ambient water of inoculated conidia, reduced the emergence of infection pegs on rice leaves and cellophane film by 96 and 100%, respectively.     

Routine On-farm Soil Tillage Helps Control Asparagus Fly (Plioreocepta Poeciloptera)

Asparagus fly (Plioreocepta poeciloptera (Schrank, 1776)) is a serious pest in German asparagus (Asparagus officinalis L.) production. To evaluate the effects of different routine on-farm soil tillage measures on the number of flies emerging the following spring, asparagus fields in Lower Saxony, Germany, were investigated. Soil samples were taken before and after tillage in autumn 2017 and autumn 2018. Investigations were also conducted in both years on the effect that the soil depth at which asparagus fly pupae were buried had on the emergence of adult flies.

This study revealed that the number of emerging flies was not reduced by mulching, but was significantly reduced by subsequent tillage and/or tillage and dam formation. The emergence rate of adult flies was significantly reduced the deeper the pupae had been buried the previous autumn. The effects also depended on the year. The highest mean emergence rate observed was 68% and 45% for pupae buried at a depth of 10?cm and 20?cm, respectively. In conclusion, the key mechanism causing a decrease in asparagus fly population the following spring through routine on-farm tillage could be the burial of pupae when forming dams. Routine on-farm soil tillage can be regarded as a physical measure for controlling asparagus fly and is therefore an essential tool in the integrated pest management of asparagus production.

     

Genetic and biochemical studies of resistance to permethrin in a pyrethroid-resistant strain of the housefly (Musca domestica L.)

One or more weak factors of resistance on autosome 2, and barely detectable resistance on autosome 3, confer moderate resistance to several pyrethroids (5–13-fold) in the field-collected Ipswich strain of houseflies. In these flies, which unlike other pyrethroid-resistant strains lack kdr or super-kdr, pyrethroid resistance probably developed in response to prolonged treatment of buildings for animals with pyrethrins synergised with piperonyl butoxide. Substrains, isolated genetically from Ipswich flies and with resistance only on autosome 2, degraded permethrin more rapidly than susceptible flies and produced larger amounts of very polar metabolites. In this, they differed from flies with kdr or super-kdr which resembled susceptible flies in their metabolism of permethrin. NIA 16388 (propyl prop-2-ynyl phenylphosphonate) was a better synergist and reduced the metabolism of permethrin more than piperonyl butoxide in both the susceptible and resistant insects. The slight increase in synergism and minimal decrease in metabolism when piperonyl butoxide was applied with NIA 16388 indicated that the latter also inhibited detoxication that was sensitive to piperonyl butoxide.     

Knockdown by pyrethroids: Its role in the intoxication process

Using techniques for treating the insects unanaesthetised, knockdown of aduit Musca domestica by pyrethrin I applied topically to or injected into the thorax was assessed by measuring the ED₅₀s on 13 occasions 1 min-48 h after treatment. From 1 min to approximately 1 h after treatment, ED₅₀s for topical application decreased quickly with increasing time. During this “knockdown phase” ED₅₀ values were probably determined mainly by rate of penetration of the insecticide into the insect, but the rate of elimination of the insecticide probably determined the increasing ED₅₀ values during the “recovery phase” which followed. ED₅₀s for injected pyrethrin I were initially much smaller than after topical application but increased continuously until 24 h after treatment. From 100 min onwards ED₅₀s by topical application and injection were similar. These results indicate (1) that the site affected during knockdown is within the insect rather than superficial, and (2) that detoxication and excretion processes determine the ultimate toxicity of the insecticide apparently independently of the method of treatment. Additional tests with a strain of flies having the penetration delaying factor and with the cockroach Periplaneta americana L. supported these conclusions. Speed of knockdown after topical treatment was also affected by the site of application and the solvent in which pyrethrin I was applied. Bioresmethrin was about as effective as pyrethrin I in knocking down flies when applied topically or when injected, but because the ED₅₀ increased very little during the recovery phase it was ultimately much more toxic.     

五种药剂对黏虫卵的室内触杀效果及胚胎发育的影响

为有效防控黏虫Mythimna separata,选用灭多威、苦参·印楝素、苏云金芽胞杆菌Bacillus thuringiensis、甲维盐和高效氯氟氰菊酯5种药剂对其卵进行室内触杀试验,比较这5种药剂对黏虫卵和初孵幼虫的触杀效果及对卵的毒力,测定不同药剂处理后黏虫卵初孵幼虫存活率、发育历期、化蛹率、蛹重和羽化率;并通过冷冻切片技术观察不同药剂处理后黏虫卵的外部形态和胚胎发育情况。室内触杀试验结果表明,苦参·印楝素浓度大于0.1 mg/L时,对产后不同时间黏虫卵的校正死亡率介于42.89%～97.34%之间,苏云金芽胞杆菌浓度为0.01 mg/L时对产后72 h黏虫卵的校正死亡率已达71.99%;各浓度苦参·印楝素和苏云金芽胞杆菌处理产后24、48和72 h黏虫卵后,其初孵幼虫校正死亡率介于39.02%～83.59%之间。苦参·印楝素对产后24、48 h黏虫卵的毒力最大,致死中浓度LC_(50)分别为0.018、0.109 mg/L;苏云金芽胞杆菌对产后72 h黏虫卵的毒力最大,LC_(50)为0.004 mg/L。黏虫卵经5种药剂处理后,幼虫化蛹率、蛹重和羽化率分别介于91.07%～93.64%、0.272～0.284 g和86.60%～87.78%之间,与对照差异不显著,幼虫存活率较对照显著下降43.02%～60.27%,幼虫发育历期较对照延长0.23～0.88 d,其中灭多威、苦参·印楝素、苏云金芽胞杆菌处理的幼虫发育历期较对照显著延长。苦参·印楝素、苏云金芽胞杆菌使胚胎无法形成正常胚带,同时会使已发育的虫体出现蜷缩、腹部皱缩;高效氯氟氰菊酯会延缓胚胎发育时间,使已形成的虫体畸形或使其肠道断裂;甲维盐影响虫体对营养物质的吸收,造成虫体萎缩,使其不能正常孵化。在黏虫卵防治中推荐使用苏云金芽胞杆菌和苦参·印楝素。