Copper is an essential metal that occurs chronically in the environment and affects the development and physiology of aquatic insects. In excess amounts, it can impair their nervous system and behaviour. We tested the anti-predatory behaviour of Cx. pipiens larvae after seven days exposure with several concentrations of copper up to 500 mg L⁻¹. We measured responses to non- consumptive (predation cues) and consumptive predation (dragonfly larvae) across two generations. We also tested the accumulated effect of copper on AChE enzyme activity. We exposed half of treated and control larvae to predation cues (water with predator odour and crushed conspecifics) and the other half to water without predation cues. We evaluated total distance moved and velocity. Copper reduced the distance moved and velocity, with stronger effects in the second generation. Copper had no significant effect on larvae eaten by dragonflies. Copper inhibited the AChE enzyme across both generations at 500 µg L⁻¹. Copper can affect the nervous system directly by inhibiting AChE activity, and possibly also by impairing the olfaction sensors of the larvae, resulting in larval inability to detect predation cues.

The larvae of Tuta absoluta are harmful leafminers that attacks different solanaceous plants such as tomato, potato, colour pepper, eggplant and many others. The life tables of a population are important to control pests because they give the most comprehensive description of the growth, survival and fecundity. Life tables of T. absoluta reared on tomato, potato and eggplant in the laboratory were determined and analysed using the age-stage, two-sex life tables. Developmental periods of eggs, larvae, pupae and adults, and pre-oviposition and oviposition periods of T. absoluta fed as larvae on tomato, potato or eggplant were estimated. Fecundity of a female fed on the same three hosts was 198.3, 172.2 and 133.7 eggs/female, respectively. Life table parameters such as the net reproductive rates (R0) (92.25, 76.25 and 67.82 days), the mean generation time (T0) (31.96, 36.06 and 36.94 days), the intrinsic rate of increase (rm) (0.142, 0.117 and 0.113/day) and the finite population increase (λ) (1.15, 1.12 and 1.12/day) were obtained for T. absoluta fed on tomato, potato and eggplant, respectively. The shortest doubling time (DT) was obtained with tomato leaves (4.9 ± 0.06 days), while the longest DT was obtained with eggplant leaves (6.30 ± 0.08 days). Based on the results herein, it appears that the development and reproductive potentiality of T. absoluta depends on its host plant; this pest can therefore be more dangerous to its suitable host (tomato) than other hosts.

The tomato leaf miner, Tuta absoluta (Meyric), second instar larvae were exposed for 1 day to LC50 of Bacillus thuringiensis (Berliner) subsp. kurstaki or Beauveria bassiana (Balsamo) on treated tomato foliages. Treated larvae had the longest development period while non-treated larvae had the shortest development period. The highest survivorship (l(x)) of adults was obtained by the non-treated larvae while the lowest survivorship was obtained by B. thuringiensis-treated larvae. The lowest age-specific fecundity (m(x)) of females was obtained by individuals treated as second instar larvae with B. bassiana. The intrinsic rate of increase (r(m)) reached its maximum with non-treated individuals while this value decreased to the minimum values with biopesticide-treated individuals. Therefore, development, survival, and reproduction of treated individuals were lower than those of non-treated individuals. The reproduction period and adult longevity were the shortest considering biopesticide-treated individuals. The highest and lowest net reproductive rates (R-0) were recorded for nontreated and treated individuals, respectively. The mean generation time was increased with biopesticide-treated individuals.