- The initial colony is collected from leaves of peanut and maintained on broad bean in a controlled climate room(24 ± 1℃, 65 ± 5 % RH, photoperiod 16L:8D ).
- It has been 3 months that my aphid can't growing well, with slow growth rate and a few progeny. While no fungal infection and parasitism are found, and the plant grows well. There was no such a phenomenon before.
- I have replace several broad bean varieties and even the culture medium but without any improvement. At last I collected some wild Aphis craccivora to restore the colony, it grew well for 3 weeks but then bacame bad and can never recover again.
- I'm quite confused about this phenomenon.Can anybody help me? Thanks in anvance.
Dear Li Chao,
may be the temperature is a little high. Try to lower it to 20-22°C. At this temperature we used to rear Myzus persicae on Pisum sativa.
Best regards
though I have not experienced such case, however, as aphids are migratory insect give them alternate plant periodically and see.
also aphids get affected with the climatic changes so periodically change in the parameters could exert some positive effects I think
You should try another one or two host plants (e.g. peanut) as you may have a less favored variety. Also try increase temperature by 1-2C to increase reproduction rate.
Problems rearing aphids almost always begin with the plants. The most common problem I see is that the light intensity is not strong enough for good plant growth. The plants may look OK, but the aphids need them to be growing vigorously. If your aphids are really small and have few offspring, that is most likely the problem. You need to be using a growth chamber that is suitable for growing plants, with lots of lights and strong refrigeration also. Maria is right that a lower temp would be better - certainly not higher. All aphids thrive best between 20-24 deg C.
The problem may be the host plant. The aphid species known as "polyphagous" are "polyphagous" only apparently, because each population is closely related to a specific host plant. In my experiences with Aphis gossypii, I observed that a population collected, for instance, on Citrus fits very rarely to an other host plant (i.e., Gossypium, Cucurbita, etc.). In most cases, they survive on the new host very difficulty (as you described in your case) or succumb after some time. You said that the original population were collected on peanut and after you reared it on bean. Try to use the same plant where you are getting the initial population. Best wishes, G.
I recommend to check the media, which could be able more fermented and unpalatable to the aphids
Are you irrigating your plant culture enough to keep its growth vigor? Right kind of compost use is another crucial requirement of healthy plant culture. Bio-compost is the best. It is also important that aphid culture is periodically transferred to new plants, preferably within three weeks from the initial colonization. Your temperature, RH and light seem to be OK. Unlike pea aphid, Acyrthosiphon pisum, which is more adapt at rearing in controlled environment, most other aphids, Aphis species in particular, are quite sensitive to micro-environment. Periodical transfer of colony to new plants is likely to improve the performance of your culture on broad beans. Best luck.
Are your bean seeds certainly not-treated by any protectant? It could be fungicide or somewhat else.
I just wrote to a person who helped me out with another question. he works with leafhoppers and answered a problem similar to yours. I didn't want to violate his privacy but maybe he will write to you.
your A. craccivora is probably a strain specialized on peanut, not on other host plants. Try to find an originating strain from broad bean, and restart your rearing.
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