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Mosquito mass rearing: who’s eating the eggs?


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For the sterile insect technique, and other related biological control methods where large numbers of the target mosquito are reared artificially, production efficiency is key for the economic viability of the technique. Rearing success begins with high quality eggs. Excess eggs are often stockpiled and stored for longer periods of time. Any pests that prey on these eggs are detrimental to stockpiles and need to be avoided. Psocids of the genus Liposcelis (Psocoptera, Liposcelididae) are common scavengers consuming various types of organic material that are distributed globally and thrive in warm damp environments, making insectaries ideal habitats. In this short report, we investigated the species that has been found scavenging stored mosquito eggs in our insectary and identified it to be Liposcelis bostrychophila Badonnel, 1931. Additional observations were made to determine whether these predators indeed feed on mosquito eggs, and to suggest simple, effective ways of avoiding infestation. © H. Yamada et al., published by EDP Sciences, 2019.
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Mosquito mass rearing: who’s eating the eggs?
Hanano Yamada
, Carina Kraupa
, Charles Lienhard
, Andrew Gordon Parker
, Hamidou Maiga
, Danilo de Oliveira
, Minlin Zheng
, Thomas Wallner
, and Jeremy Bouyer
Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, International Atomic Energy
Agency, Vienna International Centre, P.O. Box 100, 1400 Vienna, Austria
Museum of Natural History, Arthropoda Department, C.P. 6434, CH-1211 Geneva 6, Switzerland
Benecial Insects Institute, Fujian Agriculture & Forestry University, Fuzhou, Fujian Province 350002, PR China
Received 4 November 2019, Accepted 5 December 2019, Published online 20 December 2019
Abstract – For the sterile insect technique, and other related biological control methods where large numbers of the
target mosquito are reared articially, production efciency is key for the economic viability of the technique. Rearing
success begins with high quality eggs. Excess eggs are often stockpiled and stored for longer periods of time. Any pests
that prey on these eggs are detrimental to stockpiles and need to be avoided. Psocids of the genus Liposcelis
(Psocoptera, Liposcelididae) are common scavengers consuming various types of organic material that are distributed
globally and thrive in warm damp environments, making insectaries ideal habitats. In this short report, we investigated
the species that has been found scavenging stored mosquito eggs in our insectary and identied it to be Liposcelis
bostrychophila Badonnel, 1931.Additional observations were made to determine whether these predators indeed feed
on mosquito eggs, and to suggest simple, effective ways of avoiding infestation.
Key words: Liposcelis bostrychophila, psocids, sterile insect technique, SIT, egg storage, Aedes.
´Élevage de masse de moustiques : mais qui mange les œufs ? Pour la technique des insectes stériles et
les autres méthodes de lutte biologique associées, dans lesquelles un grand nombre de moustiques cibles sont élevés
articiellement, lefcacité de la production est essentielle pour la viabilité économique de la technique. Le succès de
lélevage commence par des œufs de bonne qualité. Les œufs excédentaires sont souvent stockés pendant de longues
périodes. Tous les organismes nuisibles qui exploitent ces œufs nuisent à ces stocks et doivent être évités. Les psoques
du genre Liposcelis (Psocoptera, Liposcelididae) sont des charognards répandus qui consomment diverses matières
organiques, sont répartis dans le monde entier et prospèrent dans des environnements chauds et humides, ce qui
rend les insectariums des habitats idéaux pour eux. Dans ce court rapport, nous avons étudié lespèce qui mangeait
des œufs de moustiques stockés dans notre insectarium et nous avons déterminé quil sagissait de Liposcelis
bostrychophila Badonnel, 1931. Dautres observations ont été faites pour déterminer si ces prédateurs se nourrissent
effectivement des œufs de moustiques et suggérer des moyens simples et efcaces pour éviter linfestation.
Most people would probably wonder why nuisance insects
like mosquitoes should ever be reared. However, the rearing of
mosquitoes is important for species characterisation, retaining
of reference specimens, assessments of repellent and insecticide
efcacy and/or resistance, and other research. In fact, several
medically important mosquito species are mass reared for their
deployment in the framework of the sterile insect technique
(SIT), and other related biological control methods [5,10].
The SIT relies on the mass production of reproductively
sterilised male insects, which are released into a target area to
compete for, and mate with, wild females, who subsequently
lay infertile eggs gradually leading to a decline in the natural
population of that particular pest species [10].
The mass rearing of millions of mosquitoes can be a costly
undertaking and therefore production efciency is crucial at all
steps of the process, beginning with egg production and egg
hatch. Mosquito eggs, such as those of some Aedes spp.
(including potential vectors of dengue, chikungunya, yellow
fever, Zika, and more) require a substrate for oviposition (usu-
ally crepe, or germination paper), drying and storage for several
days for embryo maturation before they can be hatched. Excess
eggs are also stockpiled for production security.
At the Insect Pest Control Laboratory of the Joint FAO/
IAEA Division of Nuclear Techniques in Food and Agriculture,
the Human Disease Vectors group is carrying out crucial
research for the development of the SIT to manage mosquito
*Corresponding author:
Parasite 26, 75 (2019)
ÓH. Yamada et al., published by EDP Sciences, 2019 Available online at:
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (,
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vectors. Recent results include the cost reduction and optimisa-
tion of several components of the SIT package, including
mass-rearing cages, larval diet, irradiation, handling, and quality
control [3,4,8,15,16,24]. The insectary currently stocks
several mosquito strains for this research, and egg storage is
an important component of the facility. Recently, it was discov-
ered that some batches of mosquito eggs were hatching poorly,
and the possible reasons for this were investigated. Some
reasons for poor egg hatch in Aedes eggs are suboptimal storage
conditions (conditions that are too dry desiccate the eggs
making them collapse, killing the embryo; conditions that are
too humid can trigger premature hatching, and embryos die
shortly after) and mechanical damage of the eggs (mostly due
to poor collection methods). However, it was found when
checked under a stereomicroscope (Leica MZ 16 FA) that the
eggs had been severely damaged and had the appearance of
having been chewed by an unwanted guest (Fig. 1).
After a short search, the likely cause of the damaged eggs
was detected crawling across the egg papers (Fig. 2). Commu-
nication with various laboratories rearing insects indicated that
psocids have often been seen in insectaries, but there appears to
be only one prior report about their appearance in a mosquito
rearing environment [12]. Attempts to obtain the full text of this
report were not successful.
Psocids of the genus Liposcelis (Psocoptera: Liposcelidi-
dae) are common scavengers that are distributed globally and
are known for being a nuisance pest in households, libraries,
warehouses and food stores [9,11]. They are an important pest
found to damage valuable books, documents, and museum
specimens [6]. They thrive in warm damp environments, often
scavenging stored products, fungi, dead insect parts, starch
essentially any organic matter reecting their scientic name
which loosely means insects that like to chew(from the
Greek verb psochein = chew). They are also known to prefer
dark environments [13], making the black, damp egg storage
boxes containing papers with insect parts and eggs a luxury
all-inclusive habitat for these insects.
To gain an idea of their importance and possible dam-
age potential in mosquito rearing insectaries, a small test was
performed to verify these predators as the cause of egg
Materials, methods and results
Specimens were collected using a small brush and
preserved in 90% ethanol. Samples were sent to the Arthropoda
Department of the Museum of Natural History, Geneva,
Switzerland. They were identied as females and nymphs of
Liposcelis bostrychophila Badonnel, 1913 [1] (Psocoptera:
Figure 1. Mosquito egg showing severe damage. Photo by
M. Zheng.
Figure 2. Psocid Liposcelis bostrychophila Badonnel, 1931
(Psocoptera, Liposcelididae) as seen on an egg paper. Photo by
M. Zheng.
Figure 3. Treatment papers with heavy infestation (31 individual
psocids and 14 intact eggs within the eld of view). Photo by
M. Zheng.
2H. Yamada et al.: Parasite 2019, 26,75
Liposcelididae) (Fig. 2). Two microscopical slides containing
females and nymphs (identied by CL) are deposited in the
Psocoptera collection of the Geneva Natural History Museum.
The body length of the medium-brown females of this species
is about 1 mm. All species of the genus Liposcelis are apterous
(i.e. completely wingless) in both sexes and they are charac-
terised by their dorso-ventrally attened body and the strongly
enlarged hind femora.
Second, to verify that the psocids were truly responsible for
the reduced hatch rates and the damaged eggs, we transferred
10 L. bostrychophila (of mixed/unknown age) to each of
5 egg papers (i.e. 5 repetitions) holding 200300 eggs and
placed them in a petri dish and into the egg boxes for 12 weeks.
Two egg papers from the same mosquito cohort but without
psocids were kept as controls. The egg papers were then
checked periodically using a stereomicroscope. Damaged eggs
and numbers of psocids were recorded.
After three months, the contaminated egg papers were
heavily infested with the L. bostrychophila (~100 individuals
[103 ± 14]) while the control egg papers had none (Fig. 3).
The number of damaged eggs was also signicant (between
38.9% and 50.8%) compared to just a few collapsed eggs on
the control papers (<3%). The difference in damage was clear:
the eggs damaged by the psocids presented visible bite marks,
and the psocids appeared to be fat and numerous.
Psocids were also observed eating the egg chorions
(Fig. 4A). Parts of the black egg can be observed inside the
abdomen (Fig. 4B).
Liposcelis bostrychophila is a cosmopolitan species and is
the most common psocid in domestic settings, food processing
plants, and grain stores. A comprehensive review on its
biology, population dynamics and physiology was published
by Turner [20]. In particular, a case of egg predation in an
anobiid beetle by L. bostrychophila was studied in detail by
Williams [23] and predation on Indian meal moth eggs (Plodia
interpunctella) was recorded by Lovitt and Soderstrom [14].
The eggs of the cigarette beetle Lasioderma serricorne have
also been seen to be preyed upon by L. divinatoria [19]. Thus,
the predation on the eggs of other insects is not unusual for
some Liposcelis spp, but the signicance thereof in insect
rearing facilities has not been studied, or reported to date.
The species is usually parthenogenetic (thelytokous), can
diapause, is facultatively cannibalistic, and can survive without
food for up to 2 months [21]. For these reasons, these psocids
are hard to eradicate once established in the insectary.
The problem in the insectary is obvious and the egg damage
can be considerable if psocid infestation is not kept under
control. It seems that they only feed on the egg chorion and
not the embryo inside. However, damaging the chorion leads
to embryo mortality nonetheless, due to dehydration. In addi-
tion to this, they may cause a health issue such as asthmatic
reactions and allergies in insectary staff as they transfer
microorganisms with their faeces and cast skin [7,18,22].
The psocids also seem to feed on the fungi that sometimes
build up around dead adult mosquito parts that may be left on
the egg papers. We have caught psocids in the packages of
oviposition paper from suppliers, and they become established
in the cracks and creases of laboratory furniture (especially
when made of plywood). Cosy, warm and damp mosquito
rearing rooms seem to be a perfect environment for these
insects and they are difcult to eradicate once established.
Museums and libraries encounter similar problems with psocid
infestations in books and other important documents and
specimens. Their approaches to eliminating psocids include
fumigation with methyl bromide, phosphine or ethylene
dibromide, pyrethroid and carbamate insecticides, or mixtures
with piperonyl butoxide, or the placement of naphthalene balls
[6,13,17]. However, these insects are rapidly becoming
resistant to such chemical treatments. In the case of insectaries
or mass rearing facilities, most chemicals including essentially
all insecticides are banned for obvious reasons. Heat treatments
have also been used [2].
We advise the following procedures to prevent egg loss
due to predation by psocids: (i) maintain a clean insectary to
prevent psocids from entering the insectary on various paper
products or cardboard boxes to begin with; (ii) oviposition
papers (seed germination papers) that are used for mosquito
oviposition should be frozen (100% mortality is achieved at
0°C[13]), or heated in the microwave (mortality above
35 °C[25]) before entering the laboratories and before use;
(iii) egg storage boxes should be purged with boiling water
routinely to ensure the elimination of any psocids and their
Figure 4. Before (A) and after (B) a psocid meal. Small pieces of the egg chorion seen in the insects abdomen. Photo by H. Yamada.
H. Yamada et al.: Parasite 2019, 26,75 3
eggs. These simple preventive practices were efcient to ensure
minimal egg loss and to keep psocid numbers in check.
Competing interests
The authors declare that they have no competing interests.
1. Badonnel A. 1931. Contribution à l'étude de la faune du
Mozambique. Voyage de M. P. Lesne (19281929). 4e note.
Copéognathes. Annales des Sciences Naturelles, Zoologie, 10(14),
2. Beckett S, Morton R. 2003. The mortality of three species of
Psocoptera, Liposcelis bostrychophila Badonnel, Liposcelis
decolor Pearman and Liposcelis paeta Pearman, at moderately
elevated temperatures. Journal of Stored Products Research, 39,
3. Bimbilé Somda NS, Dabiré KR, Maiga H, Yamada H, Mamai
W, Gnankiné O, Diabaté A, Sanon A, Bouyer J, Gilles JRL.
2017. Cost-effective larval diet mixtures for mass rearing of
Anopheles arabiensis Patton (Diptera: Culicidae). Parasites &
Vectors, 10, 619.
4. Bimbilé Somda NS, Maïga H, Mamai W, Yamada H, Ali A,
Konzcal A, Gnankine O, Diabate A, Sanon A, Dabire KR,
Gilles JRL, Bouyer J. 2019. Insects to feed insects feeding
Aedes mosquitoes with ies for laboratory rearing. Scientic
Reports, 9(1), 11403.
5. Bourtzis K, Lees RS, Hendrichs J, Vreysen MJB. 2016. More
than one rabbit out of the hat: Radiation, transgenic and
symbiont-based approaches for sustainable management of
mosquito and tsetse y populations. Acta Tropica, 157, 115130.
6. Chin HC, Jeffery J, Ahmad NW, Kiang HS. 2010. First report of
Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelidae)
as a museum insect pest in Malaysia. Sains Malaysiana, 39,
7. Clemmons EA, Taylor DK. 2016. Booklice (Liposcelis spp.),
grain mites (Acarus siro), and our beetles (Tribolium spp.):
Other pestsoccasionally found in laboratory animal facilities.
Journal of the American Association for Laboratory Animal
Science, 55, 737743.
8. Culbert NJ, Balestrino F, Dor A, Herranz GS, Yamada H,
Wallner T, Bouyer J. 2018. A rapid quality control test to foster
the development of genetic control in mosquitoes. Scientic
Reports, 8, 16179.
9. Diaz-Montano J, Campbell JF, Phillips TW, Throne JE. 2014.
Evaluation of potential attractants for Liposcelis bostrychophila
(Psocoptera: Liposcelididae). Journal of Economic Entomology,
107, 867874.
10. Dyck VA, Hendrichs JP, Robinson AS. 2005. The sterile insect
technique: Principles and practice in area-wide integrated pest
management. Springer: Dordrecht.
11. Gautam SG, Opit GP, Shakya K. 2016. Population growth and
development of the psocid Liposcelis fusciceps (Psocoptera:
Liposcelididae) at constant temperatures and relative humidities.
Environmental Entomology, 45, 237244.
12. Gerberg EJ. 1961. Quarterly report no. 3, 1 July-30 Sep 61. U.S.
Government Research Reports, 36, 70.
13. Green PWC, Turner BD. 2005. Food-selection by the booklouse,
Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelidi-
dae). Journal of Stored Products Research, 41, 103113.
14. Lovitt AE, Soderstrom EL. 1968. Predation on Indian meal
moth eggs by Liposcelis bostrychophilus. Journal of Economic
Entomology, 61, 14441445.
15. Maiga H, Bimbilé-Somda NS, Yamada H, Wood O,
Damiens D, Mamai W, Balestrino F, Lees RS, Dabiré RK,
Diabaté A, Gilles JRL. 2017. Enhancements to the mass-rearing
cage for the malaria vector, Anopheles arabiensis for improved
adult longevity and egg production. Entomologia Experimen-
talis et Applicata, 164, 269275.
16. Maïga H, Mamai W, Bimbilé Somda NS, Konczal A,
Wallner T, Herranz GS, Herrero RA, Yamada H, Bouyer J.
2019. Reducing the cost and assessing the performance of a
novel adult mass-rearing cage for the dengue, chikungunya,
yellow fever and Zika vector, Aedes aegypti (Linnaeus). PLoS
Neglected Tropical Diseases, 13(9), e0007775.
17. Nayak M. 2006. Psocid and mite pests of stored commodities:
small but formidable enemies, in Proc. 9th Int. Work. Conf.
Stored Prod. Prot. Brazilian Post-harvest Association-ABRA-
POS, Campinas, Brazil, pp. 10611073.
18. Opit G, Ocran A, Shakya K. 2018. Population growth and
development of Liposcelis obscurus Broadhead (Psocodea:
Liposcelididae) at constant temperatures and relative humidities.
Julius-Kuehn-Archiv, 463, 151159.
19. Rao ChV, Rao N, Narasimha B, Ramesh BT. 2002. New
records of predation on the eggs of cigarette beetle, Lasioderma
serricorne (Fabricius) (Coleoptera: Anobiidae), a stored tobacco
pest. Journal of Biological Control, 16(2), 169170.
20. Turner BD. 1994. Liposcelis bostrychophila (Psocoptera:
Liposcelididae), a stored food pest in the UK. International
Journal of Pest Management, 40, 179190.
21. Turner BD, Maude-Roxby H. 1988. Starvation survival of the
stored product pest Liposcelis bostrychophilus Badonnel
(Psocoptera: Liposcelididae). Journal of Stored Product
Research, 24, 2328.
22. Turner BD, Staines N, Brostoff J, Howe CA, Cooper K. 1996.
Allergy to psocids in the UK, inProceedings of the 2nd
International Conference on Insect Pests in the Urban
Environment, Edinburgh, Wildey KB, Editor. p. 609
23. Williams LH. 1972. Anobiid beetle eggs consumed by a psocid
(Psocoptera: Liposcelidae). Annals of the Entomological
Society of America, 65(533), 536.
24. Yamada H, Maiga H, Juarez J, De Oliveira Carvalho D,
Mamai W, Ali A, Bimbile-Somda NS, Parker AG, Zhang D,
Bouyer J. 2019. Identication of critical factors that signi-
cantly affect the dose-response in mosquitoes irradiated as
pupae. Parasites & Vectors, 12, 435.
25. Yusuf M, Turner B. 2004. Characterisation of Wolbachia-like
bacteria isolated from the parthenogenetic stored-product pest
psocid Liposcelis bostrychophila (Badonnel) (Psocoptera).
Journal of Stored Products Research, 40, 207225.
Cite this article as: Yamada H, Kraupa C, Lienhard C, Parker AG, Maiga H, de Oliveira Carvalho D, Zheng M, Wallner T & Bouyer J.
2019. Mosquito mass rearing: whos eating the eggs? Parasite 26, 75.
4H. Yamada et al.: Parasite 2019, 26,75
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H. Yamada et al.: Parasite 2019, 26,75 5
... The container walls must be covered with seed germination paper or moist filter paper as an oviposition substrate (Albeny-Simões et al., 2014). After 24 hours, egg paper is removed and air dried for 4 days and then it can be stockpiled in a dry environment inside plastic bags due to egg resistance to desiccation for long periods (Imam et al., 2014;Da Silva et al., 2019;Yamada et al., 2019). The eggs can be induced to hatch by placing them inside a water-filled container and a source of organic matter to initiate the process (Ponnusamy et al., 2011;Kroth et al., 2019). ...
... Insect eggs can be attacked by a great variety of predators and parasites, and information on invertebrate parasites or predators of Ae. aegypti eggs is scarce in the literature (Yamada et al., 2019). Aedes eggs, while stored under laboratory conditions, are susceptible to potential predators when the storage circumstances are suboptimal (e.g., storage containers are poorly closed, allowing unwanted organisms to invade these places). ...
... The species of the genus Liposcelis has a delicate and cylindrical body, and most measure less than 6 mm in length (Lyal, 1985). Liposcelis are known to prefer dark environments, which makes the storage boxes containing Ae. aegypti egg papers with insects parts an attractive habitat (Yamada et al., 2019). ...
For different research purposes, there is a need to mass rear mosquitoes, such as Aedes aegypti, under laboratory conditions. The rearing process begins with egg production followed by egg storage in a dry environment, inside containers. Stored eggs are susceptible to environmental threats when storage conditions are suboptimal. Some terrestrial insects can invade this environment and attack stored eggs. In this brief report, we assessed whether Ae. aegypti eggs exposed to Liposcelis sp. individuals had reduced hatching and immature development rates. We exposed 100 eggs in different treatment conditions (fixed in porous paper and loosed) to 30 Liposcelis sp. individuals for ten days and then we induced hatching. We observed a hatching rate of 99% reduced for those eggs adhered to porous paper and loosed eggs showed a hatching rate of 45% decreased for those eggs exposed to Liposcelis sp. The remaining larvae took longer to develop into pupae as well, showing a four-day delay on average to the final metamorphosis of the aquatic stage. These results reinforce the need to frequently monitor egg storage conditions to maintain laboratory colonies stable and free from pests that can interfere with mosquito life-history traits.
... Eggs collected on damp filter paper and sealed in plastic bags can be stored at ambient room temperature for up to 4 days [234]. Egg loss due to psocids of the genus Liposcelis (Psocoptera: Liposcelididae) that scavenge on mosquito eggs, needs to be prevented in rearing facilities [235]. ...
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... Physically induced hatching remains untested in most Culicid species, so it is unknown whether this trait is common across the family. Several animal taxa have been documented as potential predators of mosquito eggs (Bowatte et al. 2013, Blaustein et al. 2014, Byttebier and Fischer 2019, Yamada et al. 2019, and the effects of predator induced disturbances (e.g., surface water vibrations) on eggs remains unclear. ...
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Mosquitoes have developed specialized oviposition strategies that allow them to develop in a wide variety of aquatic habitats. Environmentally cued hatching traits may also play an important role in the successful colonization of some larval habitats, but this subject has remained largely unexplored in Culicidae. Aedes atropalpus (Coquillett) is an autogenous rock pool specialist that may maintain unique adaptations for oviposition and egg hatching. We investigated the egg-laying strategies of Ae. atropalpus exposed to standard (non-diapausing) rearing conditions and diapause-inducing conditions and tested the impact of physical agitation on egg hatch rates by exposing floating and submerged eggs to physical agitation treatments. The results of the oviposition experiment indicate that Ae. atropalpus females primarily lay non-diapausing eggs directly onto the water surface and lay diapausing eggs directly on solid surfaces. The egg-hatching experiment demonstrated that physical agitation significantly increases Ae. atropalpus hatch rates. Floating and submerged eggs responded similarly to the agitation treatment. These data suggest that oviposition behaviors based on both egg diapause status and environmentally-cued hatching strategies may be important adaptations for Ae. atropalpus in riverine rock pools. Journal of Vector Ecology 45 (2): 197-203. 2020.
... Some projects cost approximately US$1.1 million [104], and some reports of failure have been published [105]. Mosquito egg production and mass rearing problems were also highlighted [106,107]. ...
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Deadly pathogens and parasites are transmitted by vectors and the mosquito is considered the most threatening vector in public health, transmitting these pathogens to humans and animals. We are currently witnessing the emergence/resurgence in new regions/populations of the most important mosquito-borne diseases, such as arboviruses and malaria. This resurgence may be the consequence of numerous complex parameters, but the major cause remains the mismanagement of insecticide use and the emergence of resistance. Biological control programmes have rendered promising results but several highly effective techniques, such as genetic manipulation, remain insufficiently considered as a control mechanism. Currently, new strategies based on attractive toxic sugar baits and new agents, such as Wolbachia and Asaia, are being intensively studied for potential use as alternatives to chemicals. Research into new insecticides, Insect Growth Regulators, and repellent compounds is pressing, and the improvement of biological strategies may provide key solutions to prevent outbreaks, decrease the danger to at-risk populations, and mitigate resistance.
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The risks of Aedes aegypti and Aedes albopictus nuisance and vector‐borne diseases are rising and the adverse effects of broad‐spectrum insecticide application has promoted species‐specific techniques, such as sterile insect technique (SIT) and other genetic strategies, as contenders in their control operations. When specific vector suppression is proposed, potential effects on predators and wider ecosystem are some of the first stakeholder questions. These are not the only Aedes vectors of human diseases, but are those for which SIT and genetic strategies are of most interest. They vary ecologically and in habitat origin, but both have behaviourally human‐adapted forms with expanding ranges. The aquatic life stages are where predation is strongest due to greater resource predictability and limited escape opportunity. These vectors' anthropic forms usually use ephemeral water bodies and man‐made containers as larval habitats; predators that occur in these are mobile, opportunistic and generalist. No literature indicates that any predator depends on larvae of either species. As adults, foraging theory predicts these mosquitoes are of low profitability to predators. Energy expended hunting and consuming will mostly outweigh their energetic benefit. Moreover, as adult biomass is mobile and largely disaggregated, any predator is likely to be a generalist and opportunist. This work, which summarises much of the literature currently available on the predators of Ae. aegypti and Ae. albopictus, indicates it is highly unlikely that any predator species depends on them. Species‐specific vector control to reduce nuisance and disease is thus likely to be of negligible or limited impact on non‐target predators. This article is protected by copyright. All rights reserved.
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SYNTHESIS OF PARTS 11-20 OF THE ADDITIONS AND CORRECTIONS TO LIENHARD & SMITHERS, 2002: "PSOCOPTERA (INSECTA) – WORLD CATALOGUE AND BIBLIOGRAPHY". Since the volume Psocoptera (Insecta) – World Catalogue and Bibliography was published by the Geneva Natural History Museum in 2002, twenty supplementary papers of additions and corrections have appeared in Psocid News. All available literature on Psocoptera was treated in the same style as the Catalogue (listed taxonomically, faunistically and thematically). For ease of use a synthesis of the first ten supplements was published as Special Issue 3 of Psocid News. The present compilation offers a synthesis of the supplements 11 to 20 (published annually between 2012 and 2021 in Psocid News No. 14-23) and it contains a complement to the Subject Bibliography published in Psocid News Special Issue 2, i. e. a synthesis of the annual subject bibliographies published in Psocid News No. 19-23. See:
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Introduction The widespread emergence of resistance to insecticides used to control adult Aedes mosquitoes has made traditional control strategies inadequate for the reduction of various vector populations. Therefore, complementary vector control methods, such as the Sterile Insect Technique, are needed to enhance existing efforts. The technique relies on the rearing and release of large numbers of sterile males, and the development of efficient and standardized mass-rearing procedures and tools is essential for its application against medically important mosquitoes. Methods In the effort to reduce the cost of the rearing process, a prototype low-cost plexiglass mass-rearing cage has been developed and tested for egg production and egg hatch rate in comparison to the current Food and Agriculture Organization/International Atomic Energy Agency (FAO/IAEA) stainless-steel cage. Additionally, an adult-index was validated and used as a proxy to estimate the mosquito survival rates by counting the number of male and female mosquitoes that were resting within each of the 6 squares at a given point of time each day in the cage. Results The study has shown that the prototype mass-rearing cage is cheap and is as efficient as the FAO/IAEA stainless-steel cage in terms of egg production, with even better overall egg hatch rate. The mean numbers of eggs per cage, after seven cycles of blood feeding and egg collection, were 969,789 ± 138,101 and 779,970 ± 123,042, corresponding to 81 ± 11 and 65 ± 10 eggs per female over her lifespan, in the prototype and the stainless-steel-mass-rearing cages, respectively. The longevity of adult male and female mosquitoes was not affected by cage type and, the adult-index could be considered as an appropriate proxy for survival. Moreover, the mass-rearing cage prototype is easy to handle and transport and improves economic and logistic efficiency. Conclusion The low-cost mass-rearing prototype cage can be recommended to produce Ae. aegypti in the context of rear and release techniques. The proposed adult-index can be used as a quick proxy of mosquito survival rates in mass-rearing settings.
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Background: The sterile insect technique (SIT) for use against mosquitoes consists of several steps including the production of the target species in large numbers, the separation of males and females, the sterilization of the males, and the packing, transport and release of the sterile males at the target site. The sterility of the males is the basis of the technique; for this, efficient and standardized irradiation methods are needed to ensure that the required level of sterility is reliably and reproducibly achieved. While several reports have found that certain biological factors, handling methods and varying irradiation procedures can alter the level of induced sterility in insects, few studies exist in which the methodologies are adequately described and discussed for the reproductive sterilization of mosquitoes. Numerous irradiation studies on mosquito pupae have resulted in varying levels of sterility. Therefore, we initiated a series of small-scale experiments to first investigate variable parameters that may influence dose-response in mosquito pupae, and secondly, identify those factors that potentially have a significantly large effect and need further attention. Methods: In this study, we compiled the results of a series of experiments investigating variable parameters such as pupal age (Aedes aegypti), pupal size (Ae. aegypti), geographical origin of mosquito strains (Ae. aegypti and Ae. albopictus), exposure methods (in wet versus dry conditions, Ae. albopictus) and subsequently in low versus high oxygen environments [submerged in water (low O2 (< 5 %)] and in air [high O2 (~ 21 %)] on the radiosensitivity of male pupae (Ae. aegypti, Ae. albopictus and Anopheles arabiensis). Results: Results indicate that radiosensitvity of Ae. aegypti decreases with increasing pupal age (99% induced sterility in youngest pupae, compared to 93% in oldest pupae), but does not change with differences in pupal size (P = 0.94). Differing geographical origin of the same mosquito species did not result in variations in radiosensitivity in Ae. aegypti pupae [Brazil, Indonesia, France (La Reunion), Thailand] or Ae. albopictus [Italy, France (La Reunion)]. Differences in induced sterility were seen following irradiation of pupae that were in wet versus dry conditions, which led to further tests showing significant radioprotective effects of oxygen depletion during irradiation procedures in three tested mosquito species, as seen in other insects. Conclusions: These findings infer the necessity to further evaluate significant factors and reassess dose-response for mosquitoes with controlled variables to be able to formulate protocols to achieve reliable and reproducible levels of sterility for application in the frame of the SIT.
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The black soldier fly, yellow mealworm and house fly are known for their wide distribution, ease of breeding, and environmental and nutritional attributes. Diets based on these fly proteins for the rearing of mosquito larvae are more accessible and affordable when compared to the reference IAEA diet which consists largely of costly livestock products such as bovine liver powder. Following a step-by-step assessment, we developed diet mixtures based on insect meal for the optimal mass production of Aedes albopictus and Ae. aegypti. Based on the assessed parameters including mosquito egg hatch, body size, flight ability, longevity and diet cost reduction, two mixtures are recommended: 1/2 tuna meal (TM) + 7/20 black soldier fly (BSF) + 3/20 brewer’s yeast and 1/2 TM + 1/2 BSF. These findings, which could be adapted to other mosquito species, provide alternative protein sources for mass rearing insects for genetic control strategies.
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Vector-borne diseases are responsible for more than one million deaths per year. Alternative methods of mosquito control to insecticides such as genetic control techniques are thus urgently needed. In genetic techniques involving the release of sterile insects, it is critical to release insects of high quality. Sterile males must be able to disperse, survive and compete with wild males in order to inseminate wild females. There is currently no standardized, fast-processing method to assess mosquito male quality. Since male competitiveness is linked to their ability to fy, we developed a fight test device that aimed to measure the quality of sterile male mosquitoes via their capacity to escape a series of fight tubes within two hours and compared it to two other reference methods (survival rate and mating propensity). This comparison was achieved in three diferent stress treatment settings usually encountered when applying the sterile insect technique, i.e. irradiation, chilling and compaction. In all treatments, survival and insemination rates could be predicted by the results of a fight test, with over 80% of the inertia predicted. This novel tool could become a standardised quality control method to evaluate cumulative stress throughout the processes related to genetic control of mosquitoes.
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Background: Larval nutrition, particularly diet quality, is a key driver in providing sufficient numbers of high quality mosquitoes for biological control strategies such as the sterile insect technique. The diet currently available to mass rear Anopheles arabiensis, referred here to as the "IAEA diet", is facing high costs and difficulties concerning the availability of the bovine liver powder component. To promote more affordable and sustainable mosquito production, the present study aimed to find alternative diet mixtures. Eight cheaper diet mixtures comprised of varying proportions of tuna meal (TM), bovine liver powder (BLP), brewer's yeast (BY), and chickpea (CP) were developed and evaluated through a step by step assessment on An. arabiensis larvae and adult life history traits, in comparison to the IAEA diet which served as a basis and standard. Results: Four mixtures were found to be effective regarding larval survival to pupation and to emergence, egg productivity, adult body size and longevity. These results suggest that these different diet mixtures have a similar nutritional value that support the optimal development of An. arabiensis larvae and enhance adult biological quality and production efficiency, and thus could be used for mass rearing. Conclusions: Our study demonstrated that four different diet mixtures, 40 to 92% cheaper than the IAEA diet, can result in a positive assessment of the mosquitoes' life history traits, indicating that this mosquito species can be effectively mass reared with a significant reduction in costs. The mixture comprised of TM + BY + CP is the preferred choice as it does not include BLP and thus reduces the cost by 92% compared to the IAEA diet.
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Mosquitoes (Diptera: Culicidae) and tsetse flies (Diptera: Glossinidae) are bloodsucking vectors of human and animal pathogens. Mosquito-borne diseases (malaria, filariasis, dengue, zika, and chikungunya) cause severe mortality and morbidity annually, and tsetse fly-borne diseases (African trypanosomes causing sleeping sickness in humans and nagana in livestock) cost Sub-Saharan Africa an estimated US$ 4,750 million annually. Current reliance on insecticides for vector control is unsustainable: due to increasing insecticide resistance and growing concerns about health and environmental impacts of chemical control there is a growing need for novel, effective and safe biologically-based methods that are more sustainable. The integration of the sterile insect technique has proven successful to manage crop pests and disease vectors, particularly tsetse flies, and is likely to prove effective against mosquito vectors, particularly once sex-separation methods are improved. Transgenic and symbiont-based approaches are in development, and more advanced in (particularly Aedes) mosquitoes than in tsetse flies; however, issues around stability, sustainability and biosecurity have to be addressed, especially when considering population replacement approaches. Regulatory issues and those relating to intellectual property and economic cost of application must also be overcome. Standardised methods to assess insect quality are required to compare and predict efficacy of the different approaches. Different combinations of these three approaches could be integrated to maximise their benefits, and all have the potential to be used in tsetse and mosquito area-wide integrated pest management programmes.
Innovations in mosquito mass-rearing techniques are essential in the quest to develop SIT (sterile insect technique) methods to fight mosquito vectors of disease. This study reports modifications to the Food and Agriculture Organisation/International Atomic Energy Agency (FAO/IAEA) mass-rearing cage (MRC) for mosquitoes to support the behaviour of adult Anopheles arabiensis Patton (Diptera: Culicidae) and to maximize egg production. The effects of an improved sugarfeeding device, and the addition of resting sites and a black cloth shroud to create an artificial horizon (visual contrast of light vs. dark at the edge) were assessed for their effect on adult longevity and egg production. Egg production of adults resulting from larvae reared in individual free-standing trays vs. those reared in the same trays in the FAO/IAEA larval rearing rack was also compared. Finally, the effect of blood feeding and frequency of egg collection from the MRC on average egg production per batch was investigated. Overall, the modifications to the MRC enhanced adult longevity, and the improved cage prototype allowed the collection of more eggs overall from a cohort of adults than was possible using the original and previous cage prototypes. These stepwise improvements are important for the development of economical and logistically efficient mass-rearing systems for the malaria vector An. arabiensis.
Pests that infest stored food products are an important problem worldwide. In addition to causing loss and consumer rejection of products, these pests can elicit allergic reactions and perhaps spread disease-causing microorganisms. Booklice (Liposcelis spp.), grain mites (Acarus siro), and flour beetles (Tribolium spp.) are common stored-product pests that have previously been identifed in our laboratory animal facility. These pests traditionally are described as harmless to our animals, but their presence can be cause for concern in some cases. Here we discuss the biology of these species and their potential effects on human and animal health. Occupational health risks are covered, and common monitoring and control methods are summarized. © 2016 by the American Association for Laboratory Animal Science.