Interesting question without a clear answer. Maybe you can repeat some earlier surveys to address if this is the case. Keep in mind that most of the bee decline reports are from higher latitude where social wasps are not as abundant as in Brazil.

Hello Claus,

Thank you. I surveyed carrion-associated wasps in 2006-2007 and again in 2014-2015, in the same sites. I noted important declines in numbers for some species.

Hello Bruno,

Thanks for the feedback. Have you published these findings, by any chance?

Abraço,

Thiago

The abundance of social wasps are declining day by day at South American region, but here in South Asia, there's still presence of social wasps at a moderate level.

Dear Sahadat,

Thank you. After examining bibliographic records and interviewing residents in both tropical and temperate zones, it seems that the reduction of populations of some social wasp species is happening, inter alia, in Brazil, northwestern Costa Rica, French Guiana, Cameroon and Great Britain. Happy to know that at least in South Asia wasps seem to be ok!

Boa noite Thiago, tudo bem?

Eu trabalho com vespas sociais no Brasil, principalmente na região Amazônica e realmente a coleta das vespas sociais estão cada vez mais difíceis. Especificamente dentro da entomologia forense, percebemos recentemente as vespas sociais, principalmente Agelaia, Angiopolybia, poucas espécies de Polybia, Parachartergus e até mesmo Apoica chegam nas carcaças nas duas primeiras fases, ou seja, as fases mais frescas, pois não colonizam a carcaça, apenas buscam recursos, desta forma, o acompanhamento da carcaça logo após o início do experimento é muito importante. Ainda durante a coleta, além da coleta manual direta, utilizamos algumas armadilhas suspensas sobre a carcaça, o que auxilia na captura destas vespas.

Atenciosamente.

Hello Alexandre,

I am ok, how about you?

Thanks for your feedback. I am very excited to know that you are collecting carrion-associated social wasps in the state of Amazonas!

I am aware that Prof. Orlando and his group from MPEG, e.g. José Nazareno dos Santos, published a very good paper on social wasps collected from vertebrate carcasses in the state of Pará. It is the first time I hear about such an interest in the state of Amazonas, though.

You are absolutely right: I also could collect the wasps only using fresh baits. When the baits were colonized by calliphorid larvae or drying out, the wasps stopped hovering around the baits.

Because Apoica is primarily nocturnal, I wonder if you also carried out nocturnal collections.

Just checking if I understood you well: did you notice reductions ALSO in carrion-associated wasps?

Exato Thiago, o prof. Orlando desenvolveu este trabalho com iscas de carne lá na região de Belém, porém no estudo de uma mestranda do INPA, na Reserva Ducke, a intenção era Diptera, principalmente as moscas que colonizam a carcaças de porco de 60Kg, simulando um corpo humano, para estudar a bionomia, mas foi de grande surpresa quando começamos a coletas as vespas, no nosso caso espécies de Agelaia e Angiopolybia. No período noturno foi possível coletar Apoica, além disso, as espécies de Apoica, bem como as dos outros gêneros foram capturadas com esta armadilha suspensa, colocada sobre o cadáver. Ela foi de grande utilidade para verificarmos os momentos que cada táxon entraram na fase de decomposição, com isso percebemos que as vespas são ativas nas duas primeiras fases - fases fresca, enfisematosa, com o estágio mais avançado da decomposição, apenas moscas e coleópteros permaneceram.

Falando mais precisamente de armadilhas de isca, na Amazônia, coletamos com grande facilidade espécies de Agelaia, Angiopolybia e algumas Polybia utilizando tal método, porém, os outros grupos, que talvez possuam uma dieta diferente, não são tão atraídos e raramente são coletados. Para nós na Amazônia, a armadilha Malaise ainda é a mais eficiente nas coletas de vespas sociais, juntamente com o uso da armadilha suspensa pela altura do dossel.

I can’t speak from experience as I’ve been away from Brazil since a few years now but I read rumours about some entomological holocaust taking place. During my phd in Rio Claro there were many wasp nests to be found, of at least four different species in the university campus. Did you survey for their nests?

I am currently in China where I observe much less insects than expected (exception for cockroaches). Perhaps rumours are true and insects are indeed vanishing.

Hello again!

Sorry for not replying sooner and thanks for the comments.

The three of you (Bruno, Alexandre and Eduardo) raised interesting points:

Bruno: looking forward to reading your papers. Actually, one piece of meat, left on the ground for only a small amount of time, will surely attract several hundreds of ants, but also (at least) some specimens of social wasps. Your unsuccessful collections are perhaps a sign of the populational status for carrion-associated wasps in this specific geographical region.

Alexandre: the same happened to me. My original intention during my PhD was to deal with flies only (especially Calliphoridae and Sarcophagidae) but, given the reasonably high numbers of social wasps I came across during collections at that time, I decided to start collecting wasps too.

Eduardo: no, I did not survey for nests, I just collected specimens using carrion-baited traps. I am afraid that the rumors about the possible reduction of populations of insects in general can be true. If you simply google the terms insects are vanishing you will find many documents (including papers from very prestigious journals) dealing with the topic.

One final remark: Apart from everything we discussed, an issue should be taken into account: insects in general (whatever order they are in) are very prone to under-recording.

Thiago,

Podem verificar estas espécies de vespas sociais, caso precise de ajuda para identificá-las!

Abraços

Hello again,

Bruno: thanks for the comments. Could you please give me the reference of the study you mentioned at the end of your message?

Alexandre: I am not sure if it was a question. If so, please consider sending your samples to experts in the field (e.g. Prof. Orlando at MPEG)

Abs.

Hello,

Just a brief update on this question. The following two papers, from the same issue of Sociobiology (v. 65, i.2, June 2018), deal with fall in numbers of some social wasps in Brazil:

M Detoni, BC Barbosa, TT Maciel, SJL dos Santos, F Prezoto (2018) Long- and short-term changes in social wasp community structure in an urban area. 65(2): 305-311

A Raw (2018) A founder-controlled, social wasp assemblage, and a recent severe fall in numbers. 65(2): 325-329.

Hello again,

I would like to take the opportunity to attach an abstract I presented during the XIII meeting of the European Association for Forensic Entomology in 2016. Feel free to look and share your thoughts.

I am no longer working on social wasps. I now live in Ilhéus where I saw few social wasps and there are even less now.

However, it is clear that their numbers are dropping, as are those of many species.

Thank you for the feedback, Anthony.

Em minhas coletas na região do Cariri Paraibano, consegui um número muito reduzido em abundância e riqueza de vespas sociais. Esse tipo de ambiente pode revelar uma tendência para o grupo. É notória a dependência de água por vespas sociais. No período em que coletei, a região estava passando por seis anos de seca drástica, a maior da história. O problemas é não existir estudos anteriores na região para comparações.

Hello Thiago!

Sorry for not replying earlier. Thank you for your interesting comment, and I am glad to hear that you have collected in the Cariri Paraibano!

I agree with you: I also think that very dry periods may reduce the numbers of social wasps.

Could you please tell us what type of bait you used, or even better: provide us with the reference of the paper in which you presented these data?

Cheers,

Thiago

Hello Thiago,

I'm not sure if you're familiar with our latest publication. If you're not, you can read it through this link: Article Long- and short-term changes in social wasp community struct...

Our study compares wasp diversity in an urban area in Southeastern Brazil for two instances within a 15-year lapse. While richness seemed to be quite stable, we did record an impressive drop in wasp abundance in the most recent assessment. Although we did not include macroclimate data in our analysis (and they are likely to play a role, as suggested by Dejean et al. 2011),

Article Climate Change Impact on Neotropical Social Wasps

we have discussed how the availablity of nesting substrates and the reduction of urban green areas may directly and indirectly affect wasp abudance in such.

I hope this helps your question in some way!

Best regards,

Mateus

Hello Mateus,

Thank you for your help!

Yes, in fact I am familiar with both publications you are referring to. Bruno Barbosa recommended me the first one (whose first author is you, I just noticed). Dr. Dejean´s paper was perhaps the first study on the subject I put my eyes on.

All the best,

Thiago

The work of Mateus was done in altered habitats and the changes might account for the drops in numbers.

My work was done in a habitat which didn't change. That makes it difficult to explain the drops in numbers

Hello Thiago

The wasp are known to adapt for changing environment year by year. For any insect, the food source, shelter, nesting material are necessary. In case of wasps we have to look in two aspect of their life. one is the solitary life and the other is social life.

In case of social wasp the food selection by adults are specific to sweet liquid material. this source can be anything from nectar, fruit juice, plant sap and also any source of food that are used by humans. But the range of prey selection by social wasp for their developing larva is wide. Here in social wasp the insect prey or any carrion is first masticated and then given to the larvae. thus the population size of social wasp will maintain itself because of wider selection of food source.

I would also like to mention that in my past four years study on wasp, i have observed an increase population of wasp in close proximity of human settlements where in the surroundings are covered with sub natural ecosystem that is urban gardens.

Hello Anthony,

The point you raised makes the things even more interesting!

Dear Kiran,

Thank you for your comment.

Would you mind answering these questions:

1. Where exactly did you collect?

2. What type of baits did you use?

3. Did you survey for nests, or just collected specimens?

Cheers,

Thiago

The difficulty is that we have baseline data on very few groups.

We need to have data from decades ago to see how the situation is changing

I commented on this problem in my 2016 paper.

Hello Thiago, answers for you quarries...

1. Where exactly did you collect?

A. The live wasp insects were collected in the urban areas, specifically from the public gardens. in simple words any place where there is man made constructions surrounded by vegetation forms the ideal study area (for my studies on wasps).

2. What type of baits did you use?

A. I used fruit's which are cut open to expose the inner content. the wasps are attracted to the fruits and visit them to masticate the fruit pulp, so as to drink the fruit juice.

3. Did you survey for nests, or just collected specimens?

A. Yes.... My survey was based on the wasp which are involved in nesting. Because the selection of wasp nesting place for survey is ideal. identifying the wasp species during nesting provides vital information on interaction between wasp insects and Biotic & Abiotic factors of the environment.

understanding wasp and its interaction with the environment is complex. Hope the above information will be helpful.

Regards

Kiran

Hello Thiago,

Our group here from MS is also having this difficulty, here we work mainly with social insects and this problem has been recurring in recent years. It is increasingly difficult to find wasp colonies and the locations to which we find them is limited. Close to any kind of culture is practically impossible to find.

I think the wasps are going into a collapse, as reported to the bees ...

Unfortunately we have not recorded this fact in any study of our group.

Hope the above information will be helpful.

Regards

Hello Georgios Gastouniotis,

Thank you so much for the information.

Cheers,

Thiago