Head capsule widths of Conotrachelus perseae Barber (Coleoptera: Curculionidae) larvae extracted from avocado, Persea americana Mill. cv. Fuerte, were measured by computerized imagery. Head capsule widths ranged from 212 to 1,562 µm and, according to an analysis of frequency distribution using the HCAP program and Dyar's rule, formed five well-defined modal groups which suggests five larval instars. The mean head capsule widths were 264, 428, 642, 1,009, and 1,493 µm for the first through the fifth instars, respectively, with a probability of misclassification of instar below 3%.

Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a species complex that is one of the most devastating agricultural pests worldwide and affects a broad range of food, fiber, and ornamental crops. It is multivoltine and polyphagous, and vectors economically important plant viruses including those belonging to the family Geminiviridae. Therefore, understanding genetic variation among vector populations is important for its management. In order to gain insight into whitefly genotypes occurring on ash gourd, Benincasa hispida (Thunberg) Cogniaux, whitefly samples were collected from 18 locations in Tamil Nadu, and their mitochondrial cytochrome oxidase subunit I (mtCOI) genes were sequenced. Sequences generated in this study, when compared with sequences from the mtCOI data set, revealed that the whitefly populations TN1 Ja, TN2 Po, TN3 Ud, TN4 Ma, TN5 Ga, TN6 Co, TN9 Td, TN10 Gp, and TN11 El belong to Asia I genotype. Contrastingly, the populations TN7 On and TN8 Er were identified as Asia II 6 genotype. Interestingly, more than one genetic group was found coexisting in the same field.

The biological activity of extracts from Trichilia americana (Sesse and Mocino) T.D. Penn. (rind), Carica papaya L., Jatropha curcas L., Ricinus communis L., and Lupinus campestris Schldl. & Cham. (seeds), at 1% and 5%, were evaluated on neonates of Copitarsia decolora Guenée in ingestion bioassays. The plants that caused the highest percentage of larval mortality were T. americana at 1% and 5%, and Carica papaya at 5% with 98% and 100% and 100%, respectively. Trichilia americana was the plant with higher toxicological properties against C. decolora. Extracts in hexane, ethyl acetate, acetone, and methanol from T. americana were then evaluated at 10, 100, 300, and 1,000 ppm also in ingestion bioassays against C. decolora. Extracts of ethyl acetate and acetone at 1,000 ppm recorded the highest percentages of larval mortality of C. decolora (90% and 55%, respectively). In addition to larval mortality, feeding on T. americana extract also decreased mean larval weight, prolonged duration of the larval stage, resulted in malformed pupae and adults, and affected adult fertility and fecundity. Finally, these extracts were evaluated in a toxicity model, for which the crustacean Artemia salina Leach was used. The ethyl acetate, acetone, and hexane extracts showed no toxicity to A. salina, while the methanol extract caused 30% mortality, which is considered to be slightly toxic. Based on the results obtained, T. americana is a species with insecticidal and insectistatic activity against C. decolora and can be considered as a potential insecticide for the management of this or other insect pests.

The housefly, Musca domestica L. (Diptera: Muscidae), is a globally distributed synanthropic insect that must be controlled to maintain appropriate sanitary conditions for livestock and poultry. The efficacy of chlorfenapyr, a broad-spectrum insecticide, was tested against houseflies under laboratory conditions. In bioassays with a forced contact of adult flies with insecticide residues on the bottom of a glass cup, the chlorfenapyr contact toxicity was compatible to that of permethrin toxicity. When applied to surfaces, the chlorfenapyr contact toxicity was lower than that of pyrethroids and similar to neonicotinoids. In nonchoice feeding bioassays, chlorfenapyr demonstrated high intestinal toxicity to M. domestica: median lethal dose (LD₅₀) was 4.18 µg of active ingredient per gram of sugar. As a fly bait (3% and 6% wet powder), chlorfenapyr insecticidal efficacy was not less than 98% and 100% after 24 and 48 h of the exposure, respectively. The results indicate that chlorfenapyr, especially in the form of baits, may be recommended for fly control in livestock farms, and it may be useful for the development of insecticide resistance management strategies.

Mosquito resistance to insecticides remains a growing concern in North Africa. The heavy reliance on insecticides and their recurrent and oftentimes inappropriate application are key sources for resistance, which is a potential threat to the global public health. Four populations of Culex pipiens pipiens were sampled from four areas of Tunisia, with the areas characterized by contrasting agricultural activity and usage of insecticides for vector control. Bioassays were performed to determine the level of resistance in each population to pirmiphos-methyl insecticide. Comparison of resistance ratios among the populations suggested a possible link of pirmiphos-methyl resistance with agricultural activity and insecticide usage. Little or no cross-resistance was observed with pirmiphos-methyl and either organophosphates or pyrethroids commonly used in those areas. Detoxification enzymes and target site (acetylcholinesterase) were involved in the observed resistance. Overall, the results of the present study suggest the role of insecticide usage and other activities in the immediate area in impacting the development of insecticide resistance in mosquitoes, with a possible major factor being agricultural activities.

The coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), is a severe and ubiquitous pest of coconut plantations worldwide. Vegetable oils contain fatty acids that are active against a variety of agricultural pests; however, little is known about their efficiency in controlling A. guerreronis as well as their adverse effects on its natural enemies. Here, we assessed the chemical profile of palm oil as well as its toxicity and repellence to both A. guerreronis and Typhlodromus ornatus Denmark and Muma (Acari: Phytoseiidae), a natural enemy of the pest. Oleic, palmitic, and linoleic acids accounted for over 85% of palm oil fatty acid composition. Also, palm oil was approximately 4-fold more toxic to the coconut mite than to its predator. Furthermore, the lethal concentration percentage (LC)₅₀ and LC₉₉ of palm oil indicated greater activity against the coconut mite than to its predator. Therefore, by exhibiting higher toxicity and repellence to the coconut mite, with substantial selectivity to the predator T. ornatus, palm oil is a promising tool to be integrated in the control of A. guerreronis in coconut plantations.

Changing irrigation practices and rising global temperatures will impact pest insect populations, but limited knowledge of the thermal ecology of individual species prevents accurate modeling of their likely responses. Most studies focusing on temperature responses of the western tarnished plant bug, Lygus hesperus Knight (Hemiptera: Miridae), a major pest of cotton (Gossypium spp.), have been limited to constant conditions, whose relevance to the variable temperatures of field environments is unknown. To address this, newly emerged adults of L. hesperus were reared under environmentally relevant low (mean, 15°C), medium (mean, 22°C), or high (mean, 29°C) constant (±<0.5°C) or diurnally fluctuating (±8°C) temperatures. Females under the warmest conditions produced eggs sooner and at a faster rate than those reared under the coolest conditions but also had reduced lifespans. Variable temperatures shortened the preoviposition period under cool conditions and lengthened the duration under high heat. Lifetime egg production was unaffected by temperature regime. The adaptive responses of adult L. hesperus to environmental temperature indicate that implementing a control strategy that uses the thermal stress created by deficit irrigation may be difficult, although other developmental stages of this pest may be more susceptible.