Biological control of Cimex lectularius with Beauveria bassiana: Effects of substrate,dosage, application strategy,and bed bug physiology

Background

Cimex lectularius L. (bed bug) (Hemiptera: Cimicidae) is a serious indoor pest worldwide, and this nuisance needs to be controlled using different methods in integrated pest management (IPM). Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) kills bed bugs, and insect pathogenic fungi may be utilized to control bed bugs in IPM. To increase knowledge of this methodology, forced exposure experiments were conducted with different formulations, doses, and substrates, using bed bugs in variable physiological states.

Results

Both oil- and water-formulated fungal products showed significant improvement when conidial concentrations were raised in five steps from 0.02 to 2.0%. At low concentrations (0.02% in water) effects from substrate and application strategy were observed. Application on soft substrates (cotton and polyester) yielded significantly higher bed bug mortality rates than on harder substrates (paper, wood, and linoleum) with a final mortality of 35–63% against 8–10%. Multiple applications over time also improved B. bassiana's ability to kill bed bugs, and at low concentrations only a triple application on cotton showed 100% final mortality. Bed bug age and reproductive status significantly affected survival. Older and reproducing individuals showed higher mortality compared to newly emerged adults. Differences in feeding status also yielded differences in mortality timing, but only minor differences in final mortality rates. Egg production and hatching success were significantly reduced by some treatments.

Conclusion

B. bassiana appears to be an asset in the fight against bed bugs. Substrate, dosage, application strategy, and bed bug physiology are important factors to consider for optimal efficacy and safe indoor control with insect pathogenic fungi. © 2023 Society of Chemical Industry.     

Effects of juvenile hormone analog formulations on development and reproduction in the bed bug Cimex lectularius (Hemiptera: Cimicidae)

BACKGROUND: Bed bugs (Cimex lectularius L.) have become a common insect pest in urban areas and are often difficult to manage. Eradication is made more problematic by widespread insecticide resistance, raising interest in alternative control products. Juvenile hormone analogs (JHAs) such as methoprene and hydroprene are relatively harmless to non‐arthropods and have proved to be effective against other urban insect pests. Two JHA products (Gentrol^® and Precor^®, Central Life Sciences, Schaumburg, IL) were tested for efficacy against various bed bug stages as direct spray and as dry residue using three bed bug strains. RESULTS: At 1× and 2× the label rate, Precor^® [active ingredient (S)‐methoprene] had no significant effect on the development or fecundity of bed bugs. At 2× the label rate, confinement to residues of Gentrol^® [active ingredient (S)‐hydroprene] had no significant effect, but residues at 3× and 10× the label rate caused a reduction in fecundity and impaired development. Field strains were more susceptible to the reproductive effects of (S)‐hydroprene than a long‐maintained laboratory strain. CONCLUSIONS: While JHAs are attractive alternatives for pest management because of their inherent safety and distinct mode of action, these JHA formulations would have little impact on bed bug populations without relabeling to allow for higher application rates. Copyright © 2012 Society of Chemical Industry     

Surface contact toxicity and synergism of several insecticides against different stages of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae)

BACKGROUND: Five formulated insecticides (lambda‐cyhalothrin at 10 mg m^?2, bifenthrin at 50 mg m^?2, fipronil at 10 mg m^?2, fenitrothion at 50 mg m^?2, imidacloprid at 5 mg m^?2) and one active ingredient (DDT at 500 mg m^?2) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda‐cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed. RESULTS: The order of susceptibility of different stages of bed bugs was as follows: early stage ? lambda‐cyhalothrin > bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage—lambda‐cyhalothrin > bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult—lambda‐cyhalothrin > imidacloprid > bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT₅₀ among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects. CONCLUSIONS: Lambda‐cyhalothrin, bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus. Although imidacloprid demonstrated good initial response against C. hemipterus, the insects showed substantial recovery 72 h post‐treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation. Copyright © 2011 Society of Chemical Industry     

丝瓜花粉对少毛钝绥螨发育和繁殖的影响

丝瓜花粉是饲养捕食螨的常用替代食物,本研究旨在评价应用丝瓜花粉饲养少毛钝绥螨的可行性。在室内条件下,研究了25、30、35℃下少毛钝绥螨以丝瓜花粉为食物后的生长发育和繁殖能力。在25~35℃下,卵至成螨发育历期为3.63~6.96d,发育历期随温度升高逐渐缩短,存活率为82.69%~88.46%。30℃时,总产卵量最高,为41.27粒,净生殖率最高为18.15。产卵持续期随温度升高而降低。内禀增长率在30℃、35℃下显著高于25℃时,最高值为30℃下的0.203。本研究表明,丝瓜花粉是饲养少毛钝绥螨较好的替代食物。     

高、低温处理对斜纹夜蛾生长发育、存活及耐寒性的影响

为探究短期高、低温对斜纹夜蛾的影响,将其3龄幼虫于35 ℃高温和13 ℃低温分别处理8、16、24、32 h后观察生长发育和存活情况,并比较其于-5 ℃胁迫下的耐寒性变化。结果表明,与对照温度相比,高温处理8 h的斜纹夜蛾3龄幼虫,其4～6龄各龄发育历期显著延长;处理24 h和32 h的幼虫其3、4、6龄发育历期缩短;各处理的预蛹期均缩短,3～5龄幼虫存活率显著降低。低温处理后3～6龄各龄发育历期显著延长,存活率显著降低。高、低温处理后幼虫化蛹率均降低,蛹重减小,且低温的伤害作用大于高温。高、低温处理8 h的3龄幼虫-5 ℃胁迫后耐寒性显著提高,存活率分别为对照的1.15和1.29倍;处理24 h和32 h的幼虫耐寒性及存活率均较对照显著下降。表明短期高、低温处理对斜纹夜蛾的生长发育和存活会产生不利影响,但一定程度上可提高其耐寒性。     

Effect of azadirachtin applied systemically through roots of plants on the mortality,development and fecundity of the cabbage aphid (<Emphasis Type="Italic">Brevicoryne brassicae</Emphasis>)

The effect of low concentrations of azadirachtin applied systemically through root tissues of rape plants (Brassica napus subsp.napus) on the mortality, period of development, longevity and fecundity of the cabbage aphid (Brevicoryne brassicae L.) (Sternorrhyncha: Aphididae) was studied. The concentrations of azadirachtin A tested were: 0.25, 0.05, 0.005, 0.0005 and 0.00005 mg ml⁻¹. The mortality of cabbage aphid nymphs, particularly during the period of ecdysis, increased significantly with increasing concentrations. Azadirachtin had no effect on the length of the development period of the respective immature stages of cabbage aphids. The average longevity of the cabbage aphids decreased with increasing azadirachtin concentration and time spent feeding. The fecundity of aphids decreased after the application of azadirachtin. http://www.phytoparasitica.org posting May 6, 2004.     

Protein digestibility, protease activity, and post-embryonic development of the velvetbean caterpillar (Anticarsia gemmatalis) exposed to the trypsin-inhibitor benzamidine

Protein digestibility, proteolytic activity, and post-embryonic development of Anticarsia gemmatalis (Hübner) (Lepidoptera: Noctuidae) were assessed in larvae reared on artificial diet containing 0.00, 0.25, 0.50, and 0.75% (w/w) of the synthetic trypsin inhibitor benzamidine. Diet consumption was affected by the inhibitor when the insects were exposed to 0.50% benzamidine showing a 4-day delay and a 70%-higher peak of consumption. Larva weight gain was also affected by benzamidine and again the results of 0.50% benzamidine were unexpected due to the worst performance of the insects at this inhibitor concentration and not at 0.75% benzamidine. These patterns of consumption and weight gain were however consistent with the results of protein digestibility, which affects larvae mortality and adult emergence. The insect proteolytic activity was also affected by benzamidine, particularly at 0.50%. These results indicate that the insects are able to circumvent the potentially harmful effects of the inhibitor since at the highest concentration the negative impact is mitigated.     

新烟碱类等杀虫剂对葱蝇的毒力及其对生长发育和繁殖的影响

采用定量滴加法和浸渍法测定了8种药剂对葱蝇1龄和3龄幼虫的毒力,用噻虫胺和噻虫嗪等新烟碱类杀虫剂的亚致死浓度分别处理葱蝇1龄和3龄幼虫,观察其对葱蝇生长发育和繁殖的影响,并进行了田间药效试验。结果表明,噻虫胺和噻虫嗪对3龄幼虫48 h的LC₅₀分别为14.7839 mg/L和13.3055 mg/L,毒力为毒死蜱的0.41倍和0.50倍。但LC_30-40剂量处理葱蝇3龄幼虫后,第6天存活幼虫体重分别较对照降低35.47%和36.34%,幼虫发育历期延长3.68天和3.98天,化蛹率降低71.91%和78.65%,雌蛹重降低13.36%和14.72%,雄蛹重降低15.97%和18.32%,羽化率降低12.50%和17.86%,单雌产卵量降低47.71%和51.68%。噻虫胺和噻虫嗪处理1龄幼虫,对其生长发育也有显著不利影响。田间药效试验结果显示,1 200 g/hm²噻虫胺和噻虫嗪处理后7天防效分别达98.16％和92.46％,表明这两种药剂对葱蝇防治效果高、推广应用价值大。