Hi Seenivasagan

I think the resolution of this problem is likely to be simpler with the species you are interested. Dengue vectors are reasonably consistent in their oviposition habits, requiring small containers, seasonal "flooding" of the containers so they can lay just above the water line, and largely peridomestic habitats. Within those parameters there will obviously be variations, so that in an urban environment they may select discarded food containers, old motor tyres, AC drip trays, or even flower containers; and in semi-rural these may be expanded to include tree holes, the water filled internodes on bamboo used for picket fences, etc. However, the primary selection appears to be related to the size and relative impermanence of the water.

Although there may also be chemical stimuli, such as presence of some organic matter, this type of characteristic is far simpler to observe or monitor than identifying the features likely to stimulate oviposition by vectors such as Anopheles spp. that are mainly rural and often use "open" and usually permanent water bodies.

Even in laboratory colonies we find there is some variation between generations with respect to "willingness" to oviposit in the same type of container so I am sure you will find similar differences in the same geographic population, and potentially more variation as populations become more geographically distant, especially as these species have such a short flight range and therefore largely rely on human intervention for their geographic spread. So I suppose some basic local surveillance work would be the first step with follow up using simulations of some natural options found in the locality to confirm the observations. Which fits in very well with the two points made by Vivek.

Good luck with this, Ian

Based on other insects (eg Delia species) I would suspect there to be intra-specific variation between geographically isolated populations which can be as great or greater than inter-specific variation; search for Delia papers by Erich Stadler on such an example. Regards, Nick Birch.

Two factors may influence oviposition behaviour of geographically isolated insect populations.

1. Does the oviposition cues or attractants used trigger an innate recognition template for oviposition?

If yes, then the geographic variation would not at all influence oviposition behaviour. As innate recognition templates are conserved and are transferred from parents to their offsprings of a given specie it is highly impossible for the insect to escape oviposition (traps).

2. Is the cue or attractant just a isolated compound from a particular geographical area?

If so then it is possible that the insect makes a plethora of testing before it lay eggs and the compound used may just inform the insect about a probable oviposition site and it is up to the insect to choose the site as favourable (trapping is weak).

So does your oviposition attractants or compounds instigate an innate recognition template of the insect?

Cheers

Vivek Kempraj

It looks like an interesting research question with no response until experimentation is done. Some genetic factors can evolve differently in geographically isolated pops, making them respond differently to an attractant, by a lot of possible mechanisms. And differences in their environment may cause individuals to acquire different preferences due to a lot of epigenetic factors.

I would say there is rather low probability that two populations behave exactly the same way, the point are their differences quantitavely matter with respect to your objectives ? It might be sufficient to address an eco-evo study, and not enough to affect conclusions for trapping.

I would guess there are chances to happen as some studies on Anopheline habitat have shown co existence of different species in the same environment or in the extreme cases displacement of species with others

Hi Seenivasagan

I think the resolution of this problem is likely to be simpler with the species you are interested. Dengue vectors are reasonably consistent in their oviposition habits, requiring small containers, seasonal "flooding" of the containers so they can lay just above the water line, and largely peridomestic habitats. Within those parameters there will obviously be variations, so that in an urban environment they may select discarded food containers, old motor tyres, AC drip trays, or even flower containers; and in semi-rural these may be expanded to include tree holes, the water filled internodes on bamboo used for picket fences, etc. However, the primary selection appears to be related to the size and relative impermanence of the water.

Although there may also be chemical stimuli, such as presence of some organic matter, this type of characteristic is far simpler to observe or monitor than identifying the features likely to stimulate oviposition by vectors such as Anopheles spp. that are mainly rural and often use "open" and usually permanent water bodies.

Even in laboratory colonies we find there is some variation between generations with respect to "willingness" to oviposit in the same type of container so I am sure you will find similar differences in the same geographic population, and potentially more variation as populations become more geographically distant, especially as these species have such a short flight range and therefore largely rely on human intervention for their geographic spread. So I suppose some basic local surveillance work would be the first step with follow up using simulations of some natural options found in the locality to confirm the observations. Which fits in very well with the two points made by Vivek.

Good luck with this, Ian

Dear Dr. Burgess,

Wonderful suggestion. I agree that some basic local surveillance work may help in understanding the ethology of mosquitoes in general and specific in case of targeted species.

Dr. Seenivasagan,

Consider the suggestion made by Dr. Burgess.

Is there any effect of change in photoperiod influence oviposition???

Interesting point Shashank. Of course photoperiod in tropical zones has relatively little variation but for the extended geographic range, especially of Aedes albopictus that is now distributed well into the northern temperate zone, photoperiod must play a role. As with many other insect species I would expect oviposition behaviour there to be influenced by season so that during the period when day length is shorter than night length many species cease oviposition and/or larvae enter diapause unless temperatures exceed a certain minimum level.

This will also be affected by newer/further observations of adult behaviour generally - see the REsearchGate questions and multiple answers in relation to whether Aedes albopictus exhibits host seeking behaviour at night. If they bite at night then surely they may seek oviposition sites at night also so there will be an impact on site characteristics due to identification cues.

Insects -mosquito behavior - oviposition are selected based on aquatic bodies of both natural and artificial beedings sites ,availability host ,temperature and other abiotic factors also govern its selection behavior of geographical areas for oviposition .

Thank you Prof. Burgess, Renou, Birch and Vivek for adding newer dimensions to the query. I’m not sure weather we place “oviposition” under innate behaviors. The urge to oviposit in water by the mosquitoes, searching and orienting toward water bodies (or containers) may be considered to be innate. However, when an insect discriminate between suitable/unsuitable sites to effect oviposition on a particular water body (or containers in case of Aedes spp), do we say it as innate?

From my lab& semifield experiments, I found that both Anopheles and Aedes exhibited relatively similar preference to a chemical for egg laying despite the presence of other preferred water bodies of varying sizes mimicking natural conditions.

Hi Dr. Thangaraj,

"Oviposition site-selection" is an innate behavior and not "Oviposition". Insect can lay eggs, but selection of favorable oviposition sites by adult insects is essential for successful development and fitness of their progeny. Such behaviors like site selection cannot be learnt considering the short life span of insects, therefore, these behaviors are embedded into the genome and passed on from the mother to the off-springs.

You say Anopheles and Aedes prefer the same chemical for egg-laying. Then it is that the chemical you are using is triggering an "innate recognition template" in mosquitoes.

In our lab, we discovered a oviposition site-selection cue for B. dorsalis (Published in PLoS ONE and Journal of Chemical Ecology). Later, we conducted oviposition site-selection assays with 29 Tephritidae species using the same compound. To our astonishment, all tephritidae species responded in a similar manner as B. dorsalis. How is this possible when each of the 29 tephritidae species are different and use different oviposition sites in nature? E.g.: B. cucurbitae use cucurbits fruits as oviposition sites (Although cucurbit fruits do not contain the compound gamma-octalactone).

Species evolve and diverge from a single ancestor, there are possibilities that they may have carried certain crucial behaviors along even after divergence. Anopheles and Aedes should have had a common ancestor that might have used "your compound" as a cue for suitable oviposition site and may be carried on by these diverged species now. Hope this may help you.

Cheers

Vivek Kempraj

If typical host plants are absent there is a possibility of ''egg dumping'' in many species of insects. You have to be cautious about this also?

Douglas W. Tallamy. EGG DUMPING IN INSECTS. Annual Review of Entomology

Vol. 50: 347-370 (Volume publication date July 2005)

Yes Shashank we were cautious about this behavior during our experiments.

Vivek, your arguments are interesting. However, my mosquitoes are different from your fruit flies. Anopheles/Aedes/Culex lays huge number of eggs not in one particular chemical treated waters, but also shows relatively similar preference to other chemicals too, in the absence of former. In that case will you say the other chemical too trigger IRT in mosquitoes?

Lets confine our discussion only to "the influence of geographic isolation on oviposition response" of a moquito/any other insect to an oviposition stimulant/attractant.

I wonder why our western researchers who are working on the same line are not interacting?

Dear Dr. Thangaraj,

I think you have to read more papers about insect learning and memory. In insects there is something called "Behavioural plasticity". When insects do not find a suitable oviposition site according to its IRTs sensing, it is possible that insects try to find a site by learning and evaluating about better sites.

Yes the topic is confined to your question! However your work needs multi-disciplinary answer to make it robust.

I must also add that mosquitoes are no different from fruit flies as both are dipterens. So there may be similar behaviours as they have common ancestors.

Fruit flies also lay huge number of eggs not only to a single chemical !! There are other compounds also that are learnt by the process of behavioural plasticity.

The basic foundation of oviposition behaviour in all dipterens is the same.

if you are thinking of different populations of the same species, at the PRI,PARC, during mid eighties rearing of various populations drosophila (collected over the globe),not any notable difference of oviposition preference was observed in the same type of media offered for the egg laying on controlled temp. & RH etc.also not any notable difference of oviposition preference was found in respect of B.cucurbitael.

Dear Dr.Thangaraj:

The behavior of egg laying strongly associated with the adaptation of insects to specific ecological and geographical areas, and according to such ecological factors (ex: plant cover, soil, salinity...ect) the same species or genera of insects may prefer egg laying in such breeding sites than others.

BR

Sara

In the example I mentioned earlier, there was as much variation in oviposition preference within Delia radicum populations as between this specis and the closely related D. floralis (see papers by erich stadler et al). It was hypothesised that isolated populations (eg norwegian fjord areas) respond best to the most abundance hosts in the local area (assuming the vegetation is reasonably constant over time). With butterflies, host ranking shifted when the same population was moved to different areas, reflecting local abundance oif host plants (co-evolution studies by Thompson in USA). So there seems to be behavioural plasticity in some herbivore species at least, linked to local abundance of host plant species.

For this interesting discussion, here is a quiz problem. What is going to happen to a species if from the plains it lands at an altitude of 4000 m ??? will it survive in isolation ? perish? or adopt itself?

Please use your imagination... More about it latter... thanks

Ecology affects behavior and behavior affects Ecology vice versa. This is how the evolution works.

You will find different behaviors in one species grow in different geographic Regions.