hatch rate
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Author(s):  
Abdullah A Alomar ◽  
Barry W Alto ◽  
Edward D Walker

Abstract Sugar is an essential source of nutrition for adult mosquitoes to acquire energy. Toxic sugar bait (TSB) provides a promising method for mosquito control by incorporating toxins into artificial sources of sugar (i.e., toxic baits) presented to wild populations. Spinosyns comprise a family of bacterial secondary metabolites with a unique mode of action against the insect nervous system, an appealing environmental safety profile, and potential for incorporation into sugar baits. This research evaluated acute and subacute effects of spinosad (spinosyns A and D) and spinetoram (spinosyns J and L) in sugar meals on survival, fecundity, and fertility of Aedes aegypti and Aedes albopictus. Acute toxicity of spinosyns doubled from 24 to 48 h of assessment, revealing a relatively slow and cumulative action of the formulated spinosyns. Median lethal concentrations at 48 h were lower for spinetoram than for spinosad, lower for Ae. albopictus than Ae. aegypti, and lower for males than females. When exposed to subacute LC50 concentrations of spinosad and spinetoram for 24 h, survival of males and females of both species was diminished compared with controls, fecundity of females was increased, but fertility as measured by hatch rate of eggs was decreased. The formulations may have increased the nutritive value of the sugar meals thereby boosting fecundity, while toxifying embryos, reducing fertility. The inclusion of subacute effects of spinosyns allows assessment of the broader consequences of TSB for adult mosquito control.


2022 ◽  
Vol 34 (2) ◽  
pp. 324
Author(s):  
L. Culpepper ◽  
D. Chen ◽  
I. Burger ◽  
S. Lampert ◽  
L.-D. Chen ◽  
...  

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2820
Author(s):  
Chenxu Zhu ◽  
Ming Zhao ◽  
Haibo Zhang ◽  
Fang Zhang ◽  
Yuzhou Du ◽  
...  

Clanis bilineata tsingtauica Mell, 1922 (Lepidoptera, Sphingidae), also known as “Doudan” in China, is an important pest in legume crops. As an edible insect, it is most commonly consumed in Jiangsu, Shandong, and Henan Provinces. Mass rearing requires access to large numbers of eggs. This stage, however, is of short duration and supplies are frequently not sufficient for insect production. Therefore, we identified the cold storage conditions for C. bilineata tsingtauica that can effectively prolong the storage time of the eggs, to make supplies more readily available. We found that when stored at 4 °C, only 7.5% of the eggs hatched after 7 days, while at 10 °C the hatch rate was 78.3%. At 15 °C, the egg hatch rate remained at this same level (77.8% even after 14–20 days). Considering various combinations, we found that optimal egg hatch occurred if eggs were stored at 15 °C for 11 days, and then held at 15–20 °C under dark conditions. Stored as described above, the egg hatch rate was not significantly different from the control group (at 28 °C). These conditions allow for easier mass rearing of C. bilineata tsingtauica by providing a stable supply of eggs.


Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1015
Author(s):  
Luiza Maria Grzyb Delgado ◽  
Jader de Oliveira ◽  
Amanda Ravazi ◽  
Fernanda Fernandez Madeira ◽  
Yago Visinho dos Reis ◽  
...  

Triatoma petrocchiae is a species morphologically similar to T. b. brasiliensis (which resulted in a synonymization event); despite this similarity, genetic, morphological, and experimental crossbreeding studies confirmed the specific status of T. petrocchiae. Considering that both species have been reported living in sympatry and that, for a long time, most species of the T. brasiliensis complex were considered only chromatic variants of T. b. brasiliensis, we carried out experimental crosses between T. b. brasiliensis and T. petrocchiae (to confirm whether these species are reproductively isolated) and between T. lenti and T. petrocchiae (to assess whether T. petrocchiae also presents prezygotic isolation with the other species of the T. brasiliensis complex). Reciprocal experimental crosses were conducted, and weekly, the eggs were collected, counted, and separated in new containers to assess the hatch rate. Neither cross resulted in hybrids, demonstrating that there are pre-zygotic reproductive barriers installed between T. petrocchiae and the other species of the T. brasiliensis complex. On the basis of the results above, we demonstrated that T. petrocchiae is reproductively isolated from T. b. brasiliensis and T. lenti. Furthermore, we suggest that T. petrocchiae is the species most derived from the T. brasiliensis complex.


2021 ◽  
Vol 2 (2) ◽  
pp. 72-81
Author(s):  
P. A. Opute ◽  
C. A. Aisirhiowen

Embryo-larval toxicity test of selected anti-fungus chemicals used as prophylactic agents on the African catfish (Clarias gariepinus) was conducted to assess the comparative efficacy as well as the toxicity of the different chemicals. Measured endpoints included hatching, embryo and larval survival, and larval growth. Iodine (100 mg L-1), hydrogen peroxide (250 mg L-1), malachite green (5 mg L-1) and formalin (250 mg L-1) were used as prophylactic agents. The eggs were spread on an incubating raft and continuously dipped in the treatment chemical for 15 minutes. After 48 hours, the mean hatch rate was highest in formalin-treated embryos (70%). Iodine treatment resulted in a hatch rate of 36.7%, which was slightly less than half that of the formalin treatment. Both hydrogen peroxide and malachite green resulted in 60.0% hatch rates. The results indicate that formalin-treated embryos performed significantly better than all the other chemicals. The highest percentage survival rate of 63.3% was observed in formalin at 72hph and 56.7% after 168hph. The lowest survival rate (10%) was observed in the iodine treatment group and closely followed by the group treated with malachite green (16.7%). Except for malachite green, which inhibited growth, the prophylactic treatments did not affect the growth performance of fry. This study presents evidence that can be used to support the use of formalin and hydrogen peroxide as prophylactic treatments in the early stages of C. gariepinus, although caution should be exercised due to the possibility of toxicity at higher concentrations and for longer periods of exposure.


2021 ◽  
Vol 17 (8) ◽  
pp. e1009859
Author(s):  
Hua-Bao Zhang ◽  
Zheng Cao ◽  
Jun-Xue Qiao ◽  
Zi-Qian Zhong ◽  
Chen-Chen Pan ◽  
...  

Wolbachia is a group of intracellular symbiotic bacteria that widely infect arthropods and nematodes. Wolbachia infection can regulate host reproduction with the most common phenotype in insects being cytoplasmic incompatibility (CI), which results in embryonic lethality when uninfected eggs fertilized with sperms from infected males. This suggests that CI-induced defects are mainly in paternal side. However, whether Wolbachia-induced metabolic changes play a role in the mechanism of paternal-linked defects in embryonic development is not known. In the current study, we first use untargeted metabolomics method with LC-MS to explore how Wolbachia infection influences the metabolite profiling of the insect hosts. The untargeted metabolomics revealed 414 potential differential metabolites between Wolbachia-infected and uninfected 1-day-old (1d) male flies. Most of the differential metabolites were significantly up-regulated due to Wolbachia infection. Thirty-four metabolic pathways such as carbohydrate, lipid and amino acid, and vitamin and cofactor metabolism were affected by Wolbachia infection. Then, we applied targeted metabolomics analysis with GC-MS and showed that Wolbachia infection resulted in an increased energy expenditure of the host by regulating glycometabolism and fatty acid catabolism, which was compensated by increased food uptake. Furthermore, overexpressing two acyl-CoA catabolism related genes, Dbi (coding for diazepam-binding inhibitor) or Mcad (coding for medium-chain acyl-CoA dehydrogenase), ubiquitously or specially in testes caused significantly decreased paternal-effect egg hatch rate. Oxidative stress and abnormal mitochondria induced by Wolbachia infection disrupted the formation of sperm nebenkern. These findings provide new insights into mechanisms of Wolbachia-induced paternal defects from metabolic phenotypes.


Author(s):  
Zhong Qiu Xie ◽  
Jia Le Lv ◽  
En Dong Wang ◽  
Xue Nong Xu

Feeding experiences of predators during immature and adult stages may impact females’ reproduction. In the present study, we investigated reproductive performances of Neoseiulus californicus when both parents had different feeding experiences on Tetranychus urticae and Frankliniella occidentalis. Female and male immatures fed on either prey species. Each newly emerged female adult individually mated with a male had either the same or different feeding experience. Prey for mated females were either same as or different from that consumed during their immature stages. Therefore, eight reproductive treatments were created. The highest cumulative fecundity (57.5±3.3 eggs/female) was observed when both female and male fed on T. urticae with the lowest fecundity (34.2±2.7 eggs/female) observed when the parents fed on F. occidentalis. Daily fecundity and oviposition duration were mainly affected by prey of mated females. Mated females preyed on T. urticae had 56.6% higher daily fecundity and 22.3% shorter oviposition duration than those preyed on F. occidentalis. No significant difference in offspring sex ratio and egg hatch rate was detected between treatments. About 88% of the first-laid eggs developed to males. Impact of prey species consumed by male immatures was only observed on pre-oviposition duration. The average pre-oviposition duration of females who mated with males fed on T. urticae in their immaturity was 33.0% shorter than those females who mated with males fed on F. occidentalis in their immaturity. Results of the present study are valuable in optimizing N. californicus field release strategies, and will help further investigations into the nutritional requirements of this species.


Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 490
Author(s):  
Yi-Chai Chen ◽  
Tai-An Tian ◽  
Yi-Hui Chen ◽  
Li-Chen Yu ◽  
Ji-Feng Hu ◽  
...  

Pyemotes spp. are small, toxic, ectoparasitic mites that suppress Coleoptera, Hemiptera, and Lepidoptera plant pests. To explore their potential use as a biocontrol agent, we studied the reproductive development, paralytic process, time to lethality and mortality, and searching ability of Pyemotes zhonghuajia on different developmental stages of the oriental leafworm moth, Spodoptera litura. Pyemotes zhonghuajia gained 14,826 times its body weight during pregnancy. One single P. zhonghuajia female could rapidly kill one S. litura egg and first to third instar larvae, but not fourth to sixth instar larvae, prepupae, or pupae within 720 min. Pyemotes zhonghuajia could develop on eggs, first to sixth larvae, and pupae, but only produced offspring on the eggs and pupae. A single P. zhonghuajia female (an average weight of 23.81 ng) could paralyze and kill one S. litura third instar larvae (an average weight of 16.29 mg)—680,000 times its own weight. Mites significantly affected the hatch rate of S. litura eggs, which reduced with increasing mite densities on S. litura eggs. Releasing 50 or 100 P. zhonghuajia in a 2 cm searching range resulted in significantly higher mortality rates of S. litura first instar larvae within 48 h compared to second and third instar larvae in searching ranges of 4.5 and 7.5 cm within 24 h. To the best of our knowledge, this is the first study to reveal that P. zhonghuajia undergoes the greatest changes in weight during pregnancy of any adult female animal and has the highest lethal weight ratio of any biocontrol agent.


Author(s):  
Beverly D Catchot ◽  
F R Musser ◽  
J Gore ◽  
N Krishnan ◽  
D R Cook ◽  
...  

Abstract Tarnished plant bug, Lygus lineolaris Palisot de Beauvois (Hemiptera: Miridae), has become a primary pest of cotton in the Midsouthern United States. Insect growth regulators such as novaluron are an important part of L. lineolaris management. While novaluron is lethal to nymphs, it does not kill adults, so it has been used when nymphs are the primary stage present. However, cotton yield protection was observed from an application of novaluron when adults were the predominant stage present. To explain this, a series of studies were conducted to examine sublethal impacts of novaluron to L. lineolaris adults. Novaluron ingestion by adults reduced hatch rate and sometimes reduced oviposition rate. Ingestion by either males or females reduced hatch rates, but the reduction was greater from female exposure. Contact exposure of adults with novaluron residues within 1 d of application reduced hatch rate by about 50%, but the impact on oviposition was inconsistent. A field study showed reduced hatch rate from contact exposure to mixed-age natural populations, but the overall net reproductive rate was not reduced. Surface exposure of eggs to novaluron did not reduce hatch rate. Overall, exposure of tarnished plant bug adults to novaluron, regardless of adult age or exposure route, reduced egg viability. However, the impact on oviposition rate and net reproductive rate varied with adult age and exposure route. This understanding of sublethal impacts of novaluron, in addition to lethal impacts on nymphs, should be considered when choosing application times to maximize effects on L. lineolaris populations.


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