When we discovered the first specimen of the Red Palm Weevil(Rhynchophorus ferrugineus) in Malta, back in April 2006, it did not cause us much concern at the time. In fact, we were excited to see such a large weevil species locally.

Although we do not like encountering such alien species, we did not worry much, as we knew, or thought we knew, that this species was host-specific. In fact, when we researched the diet of this weevil, we found that besides its favourite host plant, the Canary Island Date Palm (Phoenix canariensis), only a few other host trees were listed, which were not indigenous to our islands and occurred here only as ornamental species.

In 2009, a study on this insect species showed that locally it was recorded feeding only on Canary Island Date Palm trees. This gave us mixed feelings about its presence locally and, in a way, we were pleased that something was getting rid of all these excess palm trees being planted everywhere instead of using indigenous trees.

Malta is always changing its landscape fashion. A few years ago, the islands looked like part of Australia, with its eucalyptus species, and lately we were metamorphosing into the Canary Islands with all these palm trees.

Everywhere was becoming saturated with palms, so when this pest showed up, we were sure that some nurseries heaved a sigh of relief that they would reap an economic gain as they would sell new trees to replace the dying palm trees, together with some pesticides to try to save the ones in existence.

We were very concerned for trees that had historical value, such as those growing in a number of private gardens, and also in public ones such as the Argotti Botanic Gardens and San Anton Gardens. Most of these were planted as seeds by the renowned Maltese botanist John Borg.

However, we always knew that this selective eradication was too good to be true. We frequently asked the most common question any naturalist would want to have a clear answer to: will it have a negative effect on the native species? Or, to be more precise, will it affect the only indigenous palm tree we have – the Dwarf European Fan Palm (Chamaerops humilis)?

This indigenous palm species has already almost become extinct in the wild. It is only due to careful reintroductions that the species is now thriving, though it is still critically endangered.

We did not find any evidence that this insect affects these trees; however, we are closely monitoring a few old trees, mostly at Buskett/Rabat area, that have not being affected. However, following tips received from a few farmers, we have recorded over 20 causalities of this palm species being devoured by this insect. It seems that till now, this insect species only attacks juvenile trees of the indigenous tree.

However, we are not putting our hopes very high as many experts (even some who are an authority in their respective fields) said that this species is host-specific, and now we have clear evidence that the Dwarf European Fan Palm is again in danger, and this time it could be the end of it.

The same goes for our fig trees (Ficus carica). The MulberryLonghorn beetle (PhrynetaLeprosa) was first recorded in Malta in 2002, feeding exclusively onmulberry trees (Morus nigra), and in one case, on white mulberry (Morus alba). Damage was also noted on some nearby fig trees.

Mulberry trees were already scarce in Malta. Now, these species have been decimated, and if it were not for human intervention, they would have become locally extinct.

Carrying out recent studies of the number of mulberry trees in Baħrija and Marsalforn, we quickly noticed that the appetite of the longhorn is not restricted to these trees, and since food is getting scarce, these insects are looking at fig trees as the next item on the menu.

Till now, we recorded over 20 cases of affected fig trees, which were close to mulberry trees. However, in over 13 cases, the insects were on trees over three kilometres away, which clearly indicates that this species is now becoming quite widespread.

Another possible reason why the Mulberry Longhorn is shifting to fig trees is because both trees belong to the same Moraceae family of trees. One might say that fig trees are a common archeophyte and there is no need for alarm.

It is already a privilege to taste a local mulberry, so observing the immediate impact this beetle has had on these 13 fig trees is quite alarming. We fear that over the next few years, the opportunities of tasting a local fig fruit will follow the same trend as that of the localmulberry today.

We have also found a number of adult Mulberry Longhorn beetles resting on olive trees (Olea europea). No damage on the latter trees was noted but it would be interesting to see why the insects were on this tree.

We are bringing these observations to light not only to document the new diet of these two pest insects but to increase awareness on precautions, and to call for action to be taken by the responsible authorities.

The authors are members of Nature Trust (Malta) and Permaculture Research Foundation Malta.

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