Skip to main content

Anastatus Wasps

Description

Anastatus (species name currently unknown) females look much like black ants to the untrained eye, however, Anastatus wasps lay their eggs into the eggs of fruit spotting bugs, Amblypleta nitida and A. lutescens lutescens, the spined citrus bug, Biprorulus bibax, and green vegetable bugs (though only male Anastatus emerge from GVB eggs so it is not an ideal bio-control agent for this bug). There are currently 27 identified species from the genus Anastatus in Australia, and this particular species is commonly found in Queensland and northern NSW.

Anastatus adults are black, with strongly elbowed antennae and the females have one white abdominal segment and a characteristic clear boomerang shape through the middle of their wings. Females are approximately 4 mm in length while males are approximately 2.5 mm in length, their body all black with transparent wings.

Female Anastatus lay their eggs singly into a host egg using her ovipositor. The larvae then develop within the egg, killing the developing nymph, and after pupation the adult Anastatus chews through the egg to feed on nectar, mate and search for host eggs to parasitise. It takes from three weeks to a month for Anastatus to develop to adult within a bug egg, and adult females may live for over a month but do most of their parasitising in the first three weeks.

Anastatus move by walking (at a rapid pace), flying and doing short jumps. Temperature affects the movement of Anastatus, who will be slower and less likely to fly at temperatures below 20°C. Temperatures above 35°C also inhibit movement by Anastatus, who will seek shelter from the heat. Anastatus use their antennae in a drumming motion whilst walking on leaves to help them gather chemical cues to locate host eggs.

Unlike MacTrix, which primarily travels short distances in search of macadamia nutborer, Anastatus can fly relatively long distances to locate host bug eggs. In our trials we found that Anastatus located and parasitised spotting bug eggs 60 m away from their release point within 5 days, though they are likely to locate eggs at even greater distances (60 m was the point of our farthest sentinel bug egg). Anastatus uses chemical cues from hosts to locate host eggs and they are more likely to locate bug eggs that have adult bugs nearby.

CROPS SUITABLE FOR RELEASE

Crops Suitable for Release

All crops attacked by spotting bugs (banana spotting bug and fruit spotting bug) or spined citrus bug are suitable for Anastatus release, however, the best place to release Anastatus is close to where the bugs are breeding, which is often adjacent to the crop. Releasing Anastatus along the boundary of the crop often works well with crop management practices because it’s not so critical that chemical sprays be timed to avoid Anastatus releases. However, if spotting bug or spined citrus bug nymphs are found within your crop (spined citrus bugs typically breed within citrus crops) then Anastatus should be released close to these breeding areas.

Spined citrus bugs feed on lemon, orange and mandarin crops, feeding and breeding within the crop. Spotting bugs, Ambypelta lutescens lutescens and A. nitida, are highly polyphagous, meaning they feed (and breed) on a wide variety of plants. The main commercially grown hosts of spotting bugs are macadamia, avocado, mango, lychee, longan, custard apple, papaya, cashew and passionfruit. Waite and Huwer (1998) give an extensive list of host plants for spotting bugs, which has been collated into lists here (click for document).

RELEASE RATES AND STRATEGIES

Release Rates and Strategies

The aims of using Anastatus as a biological control agent of spotting bugs are slightly different to that of MacTrix for nutborer, because of the behaviour of spotting bugs within cropping systems. Spotting bugs tend to breed outside crop areas (though there are exceptions) and fly in as adults to feed. Therefore the aims of using Anastatus for biological control of spotting bugs are:

  • Increase the local Anastatus population to reduce locally breeding bug populations and so their migration into your crops
  • To reduce the dependency on chemical controls for spotting bugs and to move from whole block spraying to spot spraying where practical

 We recommend doing 8 or more releases of Anastatus, 3 weeks apart, from early spring to reduce summer bug activity through to late autumn/early winter to reduce numbers of overwintering bugs. Identify the boundaries or sites on-farm where spotting bug are likely to be breeding and release at least 1000 wasps per 100 meters of susceptible boundary or creek line per release (or ___ wasps per Ha within the crop).

Many farms to date show big reductions in bug damage after using Anastatus and many more have a moderate reduction. The release rate is the key factor. It may take several seasons to get the full benefit and it’s likely they will work better and faster at some sites than others. We therefore suggest that you continue your normal practices for controlling bugs and do not reduce your spraying until its deemed that bug numbers in your crop are low enough to do so. We recommend checking the crop for active bugs or fresh bug damage before spraying. The first step with the strategy is to reduce the migration of bugs into the crop then, if possible, to reduce spraying and in turn you will get more help from other natural enemies of FSB like spiders.

CHEMICAL USE & ANASTATUS

Chemical Use and Anastatus

Spotting bugs often need chemical management to some degree, however, to a large extent biological control of spotting bugs can happen concurrently with chemical management. Releasing Anastatus in non-crop vegetation surrounding the crop will reduce breeding populations which will in turn lower numbers of spotting bugs flying into your crop to feed. This can be done simultaneously whilst chemical control of spotting bugs is taking place within the orchard, if that is what is necessary.

 

Reduction in chemical use within your crop, especially broad-spectrum insecticides, will allow for increases in predatory arthropods, especially spiders which are excellent at catching bugs as they fly through the orchard. Harbouring higher numbers of other un-economic insects within your orchard will also feed a higher population of spiders and in turn catch more bugs.

ORDERING & DELIVERY

Ordering and Delivery

Anastatus are sold by the 1,000 wasps. They are delivered as parasitised sterile silkworm eggs on cards. You’ll get about 5 sheets per 1,000 wasps ordered. Each sheet is 90 mm x 370 mm with a big hole in each end and perforations along the sheet. You can break the sheet in half and hang off a twig through the hole or stapled around a small branch. Or break into smaller strips if you wish.

Anastatus are usually despatched on a Monday via Australia Post Express Post, to arrive on Tuesday to Thursday depending on location. Upon despatch, we send an email notification and tracking number for your parcel.

Please ensure that the package is not left in a hot place, especially in direct sunlight or in a closed car! Typically there are some emerged wasps in the bag on arrival.

If Anastatus have not begun to emerge its best to wait until they start to do so, otherwise some Anastatus pupae may be eaten by predators before the wasps emerge. We suggest you place the cards in the field when, for example 50 of the wasps have emerged within the bag. This will minimise predation. If you keep emerged wasps in the bag for more than a day or so they will need some food. You can streak a very little bit of honey on the inside of the bag. Fresh air should also be allowed into the bag upon arrival and then the bag resealed.

STALLING EMERGENCE

Stalling Wasp Emergence

There are likely some live Anastatus in the ziplock bag when you receive your parcel. This is good as they are ready to go and those still within the eggs will be soon out. The Anastatus cards and the wasps that emerge cope well with wet weather as long as it’s not too prolonged. If necessary, you can stall their emergence by slowing their development by placing them in a fridge (between 8 and 14°C) or in an esky with a couple of ice bricks. This will delay their emergence. Do not refrigerate for more than 4 days because their fitness will decline. If there are a lot of wasps out in the bag you can give them a fine streak of honey to keep them happy until release. Note, dont put in a domestic fridge as its a bit cold.

HOW AND WHERE TO RELEASE

How and Where to Release

Anastatus cards are stapled onto either the upper or under-side of tree leaves at about head height, preferably not in direct sunlight if temperatures are extremely hot. If severe rain is predicted it is best to staple cards within an upturned plastic takeaway cup, or a 2L plastic milk container with a piece of wire passed through to hook the cards on, so that they are more protected. An office type stapler can be used but we suggest you obtain a good plier type stapler especially if you have a big area to cover.

 Where you should release Anastatus will depend on where the pest bug is breeding (either outside or within your crop), and the chemical usage within your crop. If, for example, the bugs are breeding within your crop then you should aim to release them near to where the bugs are breeding and releases be timed around the application of any chemicals. However, if the bugs are breeding in non-crop areas and flying in to feed within your crop, a good place to release Anastatus will be within the non-crop vegetation along the boundaries or creek lines of your crop/property. House gardens and nearby abandoned orchards are also ideal places to release Anastatus to target bug populations residing there.

AFTER RELEASE & MONITORING

After Release and Monitoring

Measuring Anastatus activity directly is very difficult as spotting bug eggs are hard to find and their breeding sites are not necessarily within the crop. We therefore need to rely on the assessment of changing bug damage levels over time within your crop, both at harvest and prior to harvest.

We have had great results with Anastatus through our trials, some of which were done in conjunction with the University of Queensland. We know that Anastatus is highly capable of searching and parasitising spotting bug eggs in dense vegetation and over relatively long distances. As more farms in a particular area make Anastatus releases, this will reduce the over-wintering spotting bug populations, resulting in district-wide benefits for biological control of spotting bugs.

Monitoring for spotting damage takes practice, so if you don’t have time we suggest you employ a crop consultant.

CULTURAL PRACTICES TO AID ESTABLISHMENT

Cultural Practices to Aid Establishment

Anastatus wasps perform best in moderately warm temperatures (20-32°C) without extreme rain or wind. However, extreme weather events often only mean a short delay in Anastatus activity whilst they shelter in micro-habitats until environmental conditions improve.

 Like all hymenopteran parasitoids, Anastatus drink nectar to give them fluids and energy to search and parasitise bug eggs. Without a source of ‘food’, Anastatus will not survive as long, nor parasitise as many host eggs. Crop environments can often be quite barren in terms of floral resources and alternate hosts for our ‘good bugs’, simply because there often aren’t many other plant species other than the crop itself. Leaving vegetation ‘strips’ to grow out within the inter-row can be a small step that can bring about a well-functioning ecosystem of invertebrates, and provide nectar and pollen for biological control agents at the same time. Planting cover crops within the inter-row can further enhance beneficial activity within your crop.