Interesting post. I was wondering if you could clarify what you’d include in the terrestrial insect herbivore grouping a bit more precisely. It’s not defined in your post and might be a bit ambiguous to non-biologists, for instance:
-Are freshwater aquatic insects (or those with aquatic juvenile forms) included?
-Are species with winged adult forms included?
-Are nectavores included?
-Are insects that switch between being carnivorous and herbivorous between juvenile and adult stages included (I’m not sure there are many examples of this, maybe some ants)?
Also, you mention parental care in the context of fecundity but not juvenile mortality. I assume that parental care would drastically reduce juvenile mortality, is that correct?
Sure, so included/excluded unless there is a specific statement otherwise WRT to a particular study: 1. strictly terrestrial species, no aquatic juveniles, 2. lots of species with winged adults, 3. nectavores in included. 4. As far as I know no species which switch between carnivorous and herbivorous.… I’m struggling to think of examples, but my guess would be that these belong to eusocial species, which are not really dealt with here.
Parental care in a particular group does reduce mortality in general compared to the average rates in that group. I can’t speak to comparisons across groups tho. So for example, don’t know, but don’t think that, in general, parental care in exophytics decreases mortality below that of endophytics.
Thanks! Ok terrestrial is pretty clear but herbivorous still throws up a lot of edge cases (although I do appreciate the focus of this article is on classic herbivores).
For instance, I thought of parasitic wasps/flies and social wasp with regards to the last point in my previous post. These often have nectivorous adults that predate other insects as food for their larvae.
-Consumers of animal waste products (I saw you included dung beetles as herbivores). There are also moths that drink the tears of sleeping birds, and dust mites eat shed skin cells.
-Insects that steal the stored plant products of other animals. Many bee species are known to raid honey from other bee colonies, although while some tropical species are known to do this frequently I’m not sure any do so exclusively. Bees on both sides are usually killed during the raids.
-Carnivorism that is primarily for aggressive reasons rather than to fulfill a dietary need. For instance, queens and worker in bee colonies will eat worker laid eggs they find.
We’ve tried to keep it clean with respect to data on herbivores, and in most cases have noted where the reference deals with other data as well.
For example, we do not include dung beetles in our definition, and you’ll see above where we note the fecundity of these reported by Gilbert and Manica (2010a), but then ferret out the herbivore-specific extremes from their supplemental data (their medians and stats DO include non-herbivores tho). (Note: my bad, I just spotted that sentence didn’t make the final cut… I’ve added it back into the post for greater clarity).
Dust mites would not be included here since we deal only with Insecta, although certainly some of the lifespan papers that are referenced in a more general way (e.g., Convey 1997, Danks 2006) also have data on mite species.
Not so sure that some of the edge cases really constitute a deviation from herbivory unless there is a significant portion of the diet involved (e.g., cows eat a lot of insects). However, Hawkins et al 1997 and Cornell & Hawkins 1995 claim all the species they examine are terrestrial herbivores as classified by larval stage. I can’t speak to these specific examples for bees, other than to note that the percentage of Hymenoptera in the review papers is small (mortality:6%; fecundity: ~12%).
On the other hand, I’ve started arguing in the scientific lit that this type of trophic classification is always context-dependent anyway.
Interesting post. I was wondering if you could clarify what you’d include in the terrestrial insect herbivore grouping a bit more precisely. It’s not defined in your post and might be a bit ambiguous to non-biologists, for instance:
-Are freshwater aquatic insects (or those with aquatic juvenile forms) included?
-Are species with winged adult forms included?
-Are nectavores included?
-Are insects that switch between being carnivorous and herbivorous between juvenile and adult stages included (I’m not sure there are many examples of this, maybe some ants)?
Also, you mention parental care in the context of fecundity but not juvenile mortality. I assume that parental care would drastically reduce juvenile mortality, is that correct?
Sure, so included/excluded unless there is a specific statement otherwise WRT to a particular study: 1. strictly terrestrial species, no aquatic juveniles, 2. lots of species with winged adults, 3. nectavores in included. 4. As far as I know no species which switch between carnivorous and herbivorous.… I’m struggling to think of examples, but my guess would be that these belong to eusocial species, which are not really dealt with here.
Parental care in a particular group does reduce mortality in general compared to the average rates in that group. I can’t speak to comparisons across groups tho. So for example, don’t know, but don’t think that, in general, parental care in exophytics decreases mortality below that of endophytics.
Thanks! Ok terrestrial is pretty clear but herbivorous still throws up a lot of edge cases (although I do appreciate the focus of this article is on classic herbivores).
For instance, I thought of parasitic wasps/flies and social wasp with regards to the last point in my previous post. These often have nectivorous adults that predate other insects as food for their larvae.
Some other questionable herbivores are:
-Opportunistic carrion foraging by tropical bees.
-Consumers of animal waste products (I saw you included dung beetles as herbivores). There are also moths that drink the tears of sleeping birds, and dust mites eat shed skin cells.
-Insects that steal the stored plant products of other animals. Many bee species are known to raid honey from other bee colonies, although while some tropical species are known to do this frequently I’m not sure any do so exclusively. Bees on both sides are usually killed during the raids.
-Carnivorism that is primarily for aggressive reasons rather than to fulfill a dietary need. For instance, queens and worker in bee colonies will eat worker laid eggs they find.
We’ve tried to keep it clean with respect to data on herbivores, and in most cases have noted where the reference deals with other data as well.
For example, we do not include dung beetles in our definition, and you’ll see above where we note the fecundity of these reported by Gilbert and Manica (2010a), but then ferret out the herbivore-specific extremes from their supplemental data (their medians and stats DO include non-herbivores tho). (Note: my bad, I just spotted that sentence didn’t make the final cut… I’ve added it back into the post for greater clarity).
Dust mites would not be included here since we deal only with Insecta, although certainly some of the lifespan papers that are referenced in a more general way (e.g., Convey 1997, Danks 2006) also have data on mite species.
Not so sure that some of the edge cases really constitute a deviation from herbivory unless there is a significant portion of the diet involved (e.g., cows eat a lot of insects). However, Hawkins et al 1997 and Cornell & Hawkins 1995 claim all the species they examine are terrestrial herbivores as classified by larval stage. I can’t speak to these specific examples for bees, other than to note that the percentage of Hymenoptera in the review papers is small (mortality:6%; fecundity: ~12%).
On the other hand, I’ve started arguing in the scientific lit that this type of trophic classification is always context-dependent anyway.