This study evaluated the insecticidal activity of garlic, Allium sativum Linnaeus (Amaryllidaceae) essential oil and their principal constituents on Tenebrio molitor. Garlic essential oil, diallyl disulfide, and diallyl sulfide oil were used to compare the lethal and repellent effects on larvae, pupae and adults of T. molitor. Six concentrations of garlic essential oil and their principal constituents were topically applied onto larvae, pupae and adults of this insect. Repellent effect and respiration rate of each constituent was evaluated. The chemical composition of garlic essential oil was also determined and primary compounds were dimethyl trisulfide (19.86%), diallyl disulfide (18.62%), diallyl sulfide (12.67%), diallyl tetrasulfide (11.34%), and 3-vinyl-[4H]-1,2-dithiin (10.11%). Garlic essential oil was toxic to T. molitor larva, followed by pupa and adult. In toxic compounds, diallyl disulfide was the most toxic than diallyl sulfide for pupa > larva > adult respectively and showing lethal effects at different time points. Garlic essential oil, diallyl disulfide and diallyl sulfide induced symptoms of intoxication and necrosis in larva, pupa, and adult of T. molitor between 20–40 h after exposure. Garlic essential oil and their compounds caused lethal and sublethal effects on T. molitor and, therefore, have the potential for pest control.

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The effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae) were studied at 25°C, relative humidity of 60 ± 10%, and photoperiod of 14 h light : 10 h dark. Development times of P. nigrispinus nymphs were similar when fed with third or fifth instar larvae of cotton leafworm (Alabama argillacea Hübner) (Lep., Noctuidae) or Tenebrio molitor L. (Col., Tenebrionidae). When fed with housefly larvae (Musca domestica L.) (Dipt., Muscidae) or artificial diet, the predator had a longer development time. Independent of diet, instar or sex, the females of P. nigrispinus showed a longer longevity than the males. The total survival of the nymphal stage, on the different diets, varied from 22.46 (fed with housefly) to 77.33% (fed with T. molitor larvae). P. nigrispinus males were heavier when fed with third or fifth instar cotton leafworm larvae than when fed with artificial diet. The weight of the females varied from 37.91 (with artificial diet) to 64.68 mg (with fifth instar cotton leafworm larvae). Independently of the diet, newly emerged females of P. nigrispinus were heavier than the males. Females of P. nigrispinus which were fed with fifth instar cotton leafworm larvae had heavier ovaries than those fed other diets.

The aim of this work was to study the feeding habits of the predator Brontocoris tabidus (Heteroptera: Pentatomidae) analyzing the salivary gland complex (SGC). The SGC was dissected and subjected to histological analyses and biochemical assays. Results showed that a pair of bilobed principal salivary glands and one pair of tubular accessory salivary glands form the SGC and different parts of salivary gland synthesizes similar substances.Lipases, α-amylase and trypsin-like enzymes were detected at both lobes of the principal salivary gland. These data together with observations related to the predator's diet suggested that it could be considered an obligate zoophytophagous.

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Pupae of Thyrinteina arnobia (Stoll) and

This study evaluated toxic effects, repellency and respiration rate caused by terpenoid constituents of cinnamon and clove essential oils and against Sitophilus granarius L. (Coleoptera: Curculionidae). The lethal concentrations (LC and LC), repellent effect, and behavior repellency response on adults of S. granarius after exposure to six concentrations of each essential oil and terpenoids were evaluated. The chemical composition of the cinnamon oil was also determined and primary compounds were eugenol (10.5%), trans-3-caren-2-ol (10.2%), benzyl benzoate (9.99%), caryophyllene (9.34%), eugenyl acetate (7.71%), α-phellandrene (7.41%), and α-pinene (7.14%). In clove essential oil, the primary compounds were eugenol (27.1%), caryophyllene (24.5%), caryophyllene oxide (18.3%), 2-propenoic acid (12.2%), α-humulene (10.8%), γ-cadinene (5.01%), and humulene oxide (4.84%). Cinnamon and clove essential oil was toxic to S. granarius. In toxic terpenoids compounds, eugenol has stronger contact toxicity in S. granarius than caryophyllene oxide, followed by α-pinene, α-humulene, and α-phellandrene. Insects reduced their respiratory rates after being exposed to essential oil terpenoids and avoided or reduced their mobility on terpenoid-treated surfaces. Cinnamon and clove essential oil, and their terpenoid constituents were toxic and repellent to adult S. granarius and, therefore, have the potential to prevent or retard the development of insecticide resistance.

No abstract