I was checking on some wild collected Ipomoea lacunosa seed last night and discovered some guests in the plastic bag! About 8 or 9 seeds had these nice round holes in them and several of these beetles as well! I can't see any of my seed move.... but I imagine this is probably the same type of gig as the Mexican jumping beans!
Jumpin' MG seed!
So, when we trade MG seed, what to do? Wouldn't putting MG seed in the freezer turn it into mush? I sure would hate to import that little beasty.
AHH!!! The infamous Megacerus eulophus...how I know it well...this is a seed weevil that is relatively common and most often infect the larger perennial seeds of anything in the MG family...both of these weevils are already very widespread...
The larvae eat the embryo and when the beetle finally matures cuts it's way out leaving a telltale hole in the seedcoat with the embryo clearly eaten away...freezing the fully dried seeds can sometimes kill off the larvae,but these critters have adapted to the cold weather and although freezing fully dried seeds will not cause the embryonic cells to swell and rupture...
freezing seeds(especially quasi-tropical species) in refrigerators can often alter enzymes that may adversely affect viability...although the same seeds allowed to experience the natural wet cold of the natural environment will often improve germination by removing germination inhibitors...
Why there is a difference in the behavior of seeds subjected to refrigeration as compared to seeds which are naturally vernalized remains speculative...
Here is a link to some Ipomoea pandurata seeds showing signs of weevil damage
Arlan the first 2 photos you posted are Ipomoea lacunosa(the humpback shape is typical)...the 3rd photo is of Ipomoea cordatotriloba(notice the 2 winglike tabs visible on the top of the hilium of the seed just below the letter O of the quarter)...
Here is the photo of Megacerus eulophus I have shared
This message was edited Jun 30, 2008 1:09 PM
Ron, is there any method of control for these critters?
Do any other types of plants act as host for them if they for some reason can't find a MG to gnaw on? It's occurred to me, since some MG seed has a viability of at least 5 years or longer, that one might skip a year growing MGs and that that might starve out local populations of these weevils. But if they're versatile in the menu department or have some phase in their life cycle where they can just lie around dormant for a while waiting for their chops to grow out, then I suppose that wouldn't do.
Okay,here is the rundown on these...perhaps our resident entomologist can add some additional info...
These beetles are widespread and although there are apparently a few that are somewhat host specific,most will feed on a wide variety of various seeds,nuts and acorns...
These seed weevils are granivores,mainly those of legumes (beans,vetch,acacias, etc.), the adults attack legumes either in storage or in the field they depend almost entirely upon seeds for their development. Bruchidae over 1300 species are specialised in seed- and stem-boring.
The larvae live in seeds of legumes, notably peas and beans, and are often pests of stored leguminous seeds.
The adults are commonly found in flowers and on foliage.
The larvae of seed weevils are parasitised by little parasitic wasps such as species of Eupelmus (Hymenoptera: Eupelmidae).
Bruchinae are actually a beetle as they do not have the elongated snouts of true weevils
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Superclass Hexapoda (Hexapods)
Class Insecta (Insects)
Subclass Pterygota (Winged Insects)
Order Coleoptera (Beetles)
Suborder Polyphaga (Water, Rove, Scarab, Longhorn, Leaf and Snout Beetles)
Superfamily Chrysomeloidea (Long-horned and Leaf Beetles)
Family Chrysomelidae (Leaf Beetles)
Subfamily Bruchinae >formerly Bruchidae (Pea,Bean,nut,acorn and seed Weevils)
family Bruchidae > Large-horned Bruchid pea and bean weevils Large-horned Bruchid
Nicophorus which are usually known as carrion or burying beetles are mentioned in the full text >unfortunately only available for purchase
this mentions fumigation and heating the seeds to control the seed weevils and is suggestive of the possibilty of parasitic wasps in potential control of the seed weevils
photos of seed weevils
Seed beetles (Bruchidae) are by far the most numerous (in both numbers of species and individuals) and best known insects that feed in fruits of Prosopis in the New World (Kingsolver et al. 1977). The larvae of burchids feed in the seeds of a reported 32 plant families (Johnson 1981a) but most species feed in one of the families, the Leguminosae. Bruchids are closely related to the families Chrysomelidae and Cerambycidae. Although the other two families feed in a variety of plant parts, bruchids are known to feed only in seeds. At present the family Bruchidae consists of about 1 300 species, grouped into 56 genera in the subfamilies Amblycerinae, Bruchinae, Eubaptinae, Kytorhininae, Pachymerinae, and Rhaebinae (Johnson 1981a). Most (80%) species of bruchids are presently assigned to the subfamily Bruchinae.
A typical life history of a bruchid is illustrated in Figure 1 but seed beetles attack seeds in a variety of ways (see below). Their life history is usually that the adult female via on ovipositor lays eggs on a seed or pod (Figure 1), the first stage larva chews through the egg shell, pod wall and/or seed coat and then into a seed. The first stage larva (Figure 1) is highly modified to enter seeds and has many spines, hairs, etc. for this purpose (Pfaffenberger and Johnson 1976). Shortly after entering a seed it molts into a leg-less grub that is very different from the first stage larva and is modified for feeding inside seeds. The larva usually feeds inside one seed, or in some bruchids, two to several seeds, molts usually three more times as it continues to feed and increase in size. It usually then pupates inside a single seed, although some species leave the seed and pupate in a cocoon, while other species glue several seeds together as a pupal chamber.
After pupation the adult completes a typical round exit hole (Figure 1) that was almost completed by the larva and leaves the seed to begin a new life cycle. The duration of the life cycle varies but it usually is about 30 days. Adult bruchids probably feed on nectar and pollen and are not known to feed on, or in seeds, except incidentally, such as when emerging from a seed or when a female chews a hole in a pod and then lays eggs in it. Some species of bruchids, especially those of economic importance, survive for many generations in containers of seeds in the laboratory or in storage without the adults feeding.
Finally, bruchids (Chrysomeloidea-Bruchidae/Bruchinae), with some 1700 species and whose larvae eat seeds, have diversified considerably on Fabaceae; they were perhaps first associated with Faboideae, then moved on to other groups following the chemistry of the plants involved (esp. Kergoat et al. 2005a, b; see also Johnson 1989, 1990 [Acanthoscelides], Birch et al. 1989 [chemistry of the interaction], and Janzen 1969 [the complexity of the association between plant and weevil]). Two clades, made up largely of New World Acanthoscelides and predominantly Old World Bruchidius, dominate, and they may have radiated contemporaneously with their hosts, largely Fabaceae-Mimosoideae and Faboideae (elsewhere also on some Malvaceae, in particular); they can detoxify the non-protein amino acid, L-canavine. Indeed, the diversity of "secondary metabolites" in Fabaceae, perhaps especially in Faboideae, is remarkable; for instance, about 28% of all known flavonoids and about 95% of the isoflavonoid aglycone structures - over 1,000 - identified in plants are known from Fabaceae, and the isoflavonoids from Faboideae alone; i.a. these latter compounds may be phytoalexins, and are perhaps also involved in nodulation (Hegnauer & Grayer-Barkmeijer 1993; Reynaud et al. 2004).
more in depth articles mostly on classification and impact on agriculture
Hope this initial info will be helpful...
This message was edited Nov 6, 2006 1:54 AM
Ron, thank you so much for such comprehensive information about this versatile little beastie. May I play back to you the plan of weevil "control" I've come up with for myself in case I've misconstrued something? Wuvie had an interesting suggestion, which see below, and I would be very interested to hear what others are deciding to do or not do.
From reading your links, I count 7 phases within some of these weevils' life cycles: adult to eggs to 4 instars (larva) to pupa to adult. Evidently, it's the 4th instar that gets through arctic winters, with more phases overwintering in warmer climes. Therefore, I can see why one method from your links says that these weevils can be controlled by being exposed to 145*F for 2 days, instead of freezing them. ( http://www.blackwell-synergy.com/doi/abs/10.1046/j.1570-7458.2003.00033.x?cookieSet=1&journalCode=eea ). I'd love to know how the morning glories we grow in our gardens would be affected by 145*F, let alone how a home gardener could achieve those temps in a foolproof way.
I also gather that some of these weevils aren't too particular about their host, which can include plants related to beans, morning glories, hollyhocks, golden rod, sunflowers and who knows what else. Supposing I were to bring in weevils with a batch of seeds from the garden, what might be the best type of container to store the seed in after it's been cleaned and dried so that they don't migrate from it to neighbors? I've been using paper envelopes. Would weevils have more difficulty gnawing through a plastic baggie?
So, after reading your links, I guess my methods of controlling weevils will include:
1) prevention - I'm going to capitalize on complexity; that is, keep growing as many different kinds of plants in our 1/4 acre as I can which will, in turn, nurture as many different kinds of other life forms. My theory here is that the more complex a system of life, the more checks and balances and hence the greatest chance at balance between the good guys and the bad guys. I'd rather be encouraging predatory behavior of birds, those tiny predacious wasps/flies that one of your links mentioned, spiders, etc. in my back yard than chemicals that seem to be so mindlessly used without regard for the consequences to complexities we don't understand.
2) good 'ol DG wiliness - In http://davesgarden.com/forums/t/667082/ , there's a link ( http://www.wuvie.net/hockdiseases.htm ) in which Wuvie advised leaving cleaned seed out in the sun on a plate that wind couldn't blow away. She says that apparently weevils prefer dark, so exposure to light makes them scamper off the plate.
3) paying attention - cleaning seed from chaff that can host critters and obscure visible effects of weevil damage. Hopefully Ron's links will help me to recognize weevils in their different stages along with signs of their activity in time to avoid major future snafus.
PS Here's a nifty dictionary for biological terms: http://www.biology-online.org/dictionary/Instar That's got to be my favorite new word from Ron's posts: instar. Can you imagine if we humans had a developmental cycle with phases so distinct from each other that one instar might have such a different identity from the next or previous instar that communication between them might not be possible? Now, who can ponder an instar without considering a fractal ( http://www.google.com/search?hl=en&lr=&q=fractal+%2B+definition )???
Ron, thanks again for another fascinating window upon morning glories and all that bugs them, and - dare I say it? - happy morphing.
I found a partially hollowed seed that looked chewed in a batch of Ipomoea nil 'Rose Silk' I received in a recent trade. There were a couple of tiny, snouty creatures in there, too, with some powdery substance that might have something to do with the excavation in that seed. I threw out all the seed and am contacting the trader and whoever I shared the seed with already. I really don't want me or people I've traded with to introduce Mr. Snoutnose to my garden. Fortunately, the seeds were in a plastic ziplock bag which seems intact and not chewed through.
My experience with this little guy included their ability to chew through the small plastic ziplock bag to escape. I keep my seed double bagged so they were still contained. They did not, however, chew to get into a new bag.
Thanks, Arlan - will double-bag my MG seed. I received this trade by 10/21/06 and discovered a seed looking exactly like your picture at the beginning of this thread on 12/12/06, which is more than the 30-day lifecycle attributed to many bruchid species. I haven't detected any further mischief in that packet's neighbors - yet.
I've gotta say, trying to propagate MG 'Chocolate Rose Silk' by seed is harder than other I. nil varieties. My vines only produced 2 pods, but they eventually produced healthy looking seeds. In addition to trader 1's Rose Silk seeds in the foregoing paragraph, a trader 2 sent me 5 Chocolate Rose Silk seeds. They were harvested from his garden this year and he had very few, too. Of those 5, the outer shells of 3 were absent by up to 1/2 of the seed's surface, so that you could see the cotyledon exposed inside. Does anyone know what could cause that? Doesn't sound like weevil damage, since the cotyledon doesn't seem damaged.
I hope I'm not hijacking this thread by asking another MG-seed, foe-related question here. Trader 1 also sent me a pack of MG seed labeled "Sunsmile Violet" with seed having surfaces almost completely mottled with something white. Any ideas what that could be?
bluespiral - I usually use the extra-large freezer ziplock bags > they are thicker and thick plastic tupperware containers and haven't found any bug that can chew through either one of those...
Leaving the seeds in the sun...for how long(?)...considering the multi-stage lifecycle...I don't know how long I'd be willing to leave my seeds in the open on a plate to be baked by the sun...
I had Ipomoea leptophylla that was infected and simply left it in a thich freezer bar for several years...all of the weevils hatched and I picked out the seeds with no damage...haven't had a single weevil from that batch of seeds again...
Exposing seeds to 145degrees farenheit might impair viability,but putting the seeds in a regular oven set to 145 degress for 2 days would do it...
LOL on the oven thing, Ron. If I keep hanging out on this forum, I'm going to have a hairdo just like Einstein's - or maybe Curly's of the 3 stooges... :)
Welp, I've got an appointment with yesterday's trash.
bluespiral - I have seen damage to the seed coat if/when I have harvested seed while yet immature or in very wet conditions. The seed coat is very soft in these conditions and easily damaged. The damaged coat will often shrink away from the cotelydon ( I know there is a proper "seed term!) leaving the interior exposed by cracks- but not by 50% as you described.
I don't have any explanation for it - only saw it on that one seed from a trader, not on any from my garden to that extent. Growing these unusual JMGs from EmmaGrace and The Fragrant Path seemed to be quite an anomalous experience overall just in the realm of awesome alone. Amazing what you see when you start paying attention.
I don't seem to be bothered by these weevils in my morning glory seed.
If you want to try distracting them, grow hardy hibiscus. They just cover the seed pods after they bloom. That orangish bug especially.
Since I usually don't use the seeds, and the hibiscus is hardy, it doesn't bother me to have them destroy the seed of the hibiscus.
I also control the Japanese beetle to some extent by letting the smart weed grow nearby my plants since they will devour this weed and leave other desireable plants nearby alone.
I second that eeeeeeew. There better not be any critters in my morning glory seed...yuk.