Among botanical insecticides based on essential oils (EOs) or their main components, Carlina acaulis EO and the aromatic polyacetylene carlina oxide, constituting more than 90% of its EO, were recently proven to be effective against the larvae and adults of some insect vectors and pests. In this study, the toxicity of C. acaulis EO and carlina oxide were tested on Bactrocera oleae adults using a protein bait formulation. The LC₅₀ values of the C. acaulis EO and carlina oxide were 706 ppm and 1052 ppm, respectively. Electroantennographic (EAG) tests on B. oleae adults showed that both carlina EO and oxide elicited EAG dose-dependent responses in male and female antennae. The responses to the EO were significantly higher than those to carlina oxide, indicating that other compounds, despite their lower concentrations, can play a relevant role. Moreover, Y-tube assays carried out to assess the potential attractiveness or repellency of carlina oxide LC₉₀ to B. oleae adults showed that it was unattractive to both males and females of B. oleae, and the time spent by both sexes in either the control or the treatment arm did not differ significantly. Overall, this study points out the potential use of C. acaulis EO and carlina oxide for the development of green and effective “lure-and-kill” tools.

This study was conducted to characterize the Bacillus populations associated with dead Rhynchophorus ferrugineus, to develop a biological control for the red palm weevil. Dead adult beetles, collected throughout Sicily, were used for isolating internal and external spore forming bacteria (SFB) microbiota. The isolates, preliminarily allotted to the Bacillaceae family, were tested at four concentrations (10³ to 10⁶ CFU/mL) for their ability to inhibit hatching of eggs of R. ferrugineus and were used at 10⁶ CFU/mL to monitor their insecticidal activity against 10-day-old larvae. Total amounts of SFB measured outside the skeleton and in the inners part of the beetles were 5.59–6.94 and 5.17–7.05 Log CFU/g, respectively. Hatching was markedly inhibited by nine isolates, representing nine distinct strains of seven species (Bacillus amyloliquefaciens, Bacillus cereus, Bacillus licheniformis, Bacillus megaterium, Bacillus pumilus, Bacillus subtilis, and Lysinibacillus sphaericus), especially by the strains B. pumilus GC43 and GC51, which exhibited lethal concentrations 50 (LC50) values of 1.60 × 10³ and 9.84 × 10³ CFU/mL, respectively. Among all the strains tested, only B. licheniformis CG62 exhibited significant insecticidal activity against red palm weevil larvae. The Bacillus isolates characterized and tested in this study inhibited the hatching of red palm weevils in a contact-dependent manner. Thus, these isolates can be used as a preventive rather than as a curative treatment.

The two-spotted spider mite Tetranychus urticae is one of the most polyphagous and most damaging pests worldwide. The behaviour of the mite differs on its various host plants and this could influence crop defence strategies. We investigated the perception of leaf morphology by T. urticae in relation to the effects of visible light on the selection of sites on which females prefer to live and feed. Mite females chose the shaded surface when smooth and glabrous lemon leaves were offered as a surface for living and feeding, showing a photophobic behaviour. However, they clearly preferred the abaxial surface of bean leaves regardless of the presence or absence of visible light. As no differences were found regarding the food quality between the adaxial and abaxial leaf surfaces, mite behaviour seems to be related firstly to the perception of leaf morphology and secondly to visible light. As regards the first factor, T. urticae prefers the abaxial surface of leaves with a complicated architecture, i.e. veins in relief, on which they can easily build their dense web, and this factor has priority in comparison to the negative effect of the visible radiations. The second factor is important on smooth and glabrous leaves, these being unsuitable for building the complicated characteristic webs of T. urticae.

In the framework of integrated pest management, plant-based insecticides represent a promising tool for the control of insect pests. Indeed, N-alkylamides extracted from Acmella oleracea (L.) RK Jansen (Asteraceae) have been recently studied for their insecticidal properties. The encapsulation of these substances into stable formulations, like nanoemulsions (NEs), could boost their efficacy and stability. Herein, a N-alkylamide-enriched fraction (AEF) encapsulated into a stable NE was tested against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a key tomato pest, able to develop resistance towards chemical insecticides. Acmella oleracea was reported to be effective against many target species, but this is the first time that this extract was tested against T. absoluta in terms of toxicity against eggs, ingestion toxicity on larvae and repellence on adults. The AEF, containing 42.8% of spilanthol, was prepared by combining two eco-friendly techniques, namely supercritical CO₂ extraction and wiped-film short path molecular distillation, and then encapsulated into a stable NE. Preliminary tests on the phytotoxicity of the AEF-NEs at 0.25 and 0.5% (w/w) a.i., compared with a control NE solution (i.e., the AEF-free NE) and a negative control (distilled water), showed a negative effect on tomato plants at the highest concentration. On this basis, three concentrations (0.06, 0.125, and 0.25% a.i.) were evaluated against eggs (topical toxicity), larvae of 2nd instar (ingestion and topical toxicity), and adults (ovideterrence) of T. absoluta. The results showed that all adopted AEF-NE concentrations caused a significant inhibition in egg hatching (>20%). The larval survival, at the end of the evaluation (72 h), in ingestion toxicity tests were significantly different in the AEF-NEs at 0.06, 0.12, and 0.25% (56.7, 33.3 and 26.7%, respectively) compared with control NE and distilled water (100% both). Similar results were obtained in the adult emergence in ingestion toxicity comparing AEF-NEs at 0.06, 0.12, and 0.25% (64.7, 50.0 and 75.0%, respectively) with control NE and distilled water (100% both). Finally, a significant ovideterrent effect was shown by the concentrations 0.125 and 0.25% of the AEF-NEs (% of egg laid: 7.5 and 27.4% respectively), compared with distilled water. Overall, the AEF-NE tested showed promising and encouraging effectiveness as ovicidal and larvicidal against T. absoluta. This supports its potential use as an effective alternative to synthetic products for the control of this important pest.