The brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is a real agricultural pest. It’s native to East Asia and has invaded the United States, Canada, Europe, and Chile. When it comes to agriculture, it causes significant damage to many economically important crops. This damage happens in both its native and invaded ranges.
One of the reasons it’s so “successful” is that it can feed on over 100 different kinds of plants – it’s polyphagous. Unfortunately, this includes valuable agricultural crops.
Brown marmorated stink bug: an expensive pest
Recently, China reported brown marmorated stink bug outbreaks in kiwifruit orchards. So did Italy, with the pest causing around 30% production losses in certain kiwifruit orchards. In 2016, it caused a whopping US $60m damage to Georgia’s hazelnut crop. And as far back as 2010, the bug destroyed US $37m worth of apples in parts of the USA.
So, how are farmers in conventional agricultural systems controlling the pest? Mainly with chemical control using broad-spectrum insecticides. But these chemical controls are harmful to human health and the environment.
Researching the control of brown marmorated stink bug
As a science organisation, CABI researches ways to control pests naturally. We focus on using biological control or ‘biocontrol’. This is where we find natural enemies of crop pests and uses them to control the pest itself.
Dr Feng Zhang is CABI’s Regional Director, East & South-East Asia. He’s been leading research to control the brown marmorated stink bug naturally using tiny parasitoid wasps. Parasitoid wasps lay their eggs in or on another insect, in this case, the stink bug. As the parasitoids grow, they kill the host (the pest).
Research to the rescue
Dr Zhang’s research focused on the mass-rearing of an egg parasitoid, Anastatus japonicus Ashmead (Hymenoptera: Eupelmidae). The research team made an exciting discovery: a way to rear the wasps on alternative or factitious host eggs cost-effectively and efficiently for use against the stink bug.
The study involved scientists from the Joint Laboratory. This is a collaboration between the Chinese Ministry of Agriculture and Rural Affairs (MARA) and CABI. The research team included scientists from the Guangdong Academy of Agricultural Sciences and three universities – California, Hexi and Sun Yat-Sen.
The team believes mass rearing the wasp could sustainably manage the brown marmorated stink bug. Specifically, they think the wasp could control the bug long-term on economic crops such as kiwifruit.
The journal, Pest Management Science, published the study. The research stated that this type of biocontrol could help the environment. It could support more environmentally friendly, sustainable methods to control the brown marmorated stink bug.
Mass rearing wasps on oak silkworm hosts
Dr Zhang commented that the study was the first important step towards successfully mass-rearing the wasps. He described how the team assessed the reproductive attributes of the wasp.
They reviewed it being reared on a factitious host. In this case, they chose oak silkworm eggs – Antheraea pernyi (Guérin-Méneville) (Lepidoptera: Anthelidae). The wasps’ longevity and ability to reproduce offspring over time were of particular interest.
The team also evaluated how individual wasp females responded to different egg densities. The wasps’ attack ability increased with host density to an upper limit. This indicated the maximum daily per capita reproductive capacity of the wasps. They discovered the wasps reproduced more with increased longevity and were more likely to produce females at the beginning of production.
This discovery makes a rearing system between the oak silkworm eggs and the wasps more cost-effective. It also makes it more possible to use the wasp for inundative biocontrol against the stink bug. The wasps will be mass reared in ‘biofactories’. Then they will be released in large numbers to obtain rapid pest control over the short term.
Next steps for tackling the brown marmorated stink bug
The research team has suggested that large-scale mass wasp rearing can be cost-effective. Field testing is now needed to evaluate how and whether it works. And effects on non-target species need testing too. This research should happen before mass releases of the wasp are recommended to growers.
Read the full open-access paper here.
Mi, Q.-Q., Zhang, J.-P., Ali, M.Y., Zhong, Y.-Z., Mills, N.J., Li, D.-S., Lei, Y.-M. and Zhang, F. (2022), Reproductive attributes and functional response of Anastatus japonicus on eggs of Antheraea pernyi, a factitious host. Pest Manag Sci.
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