The US Food and Drug Administration (US-FDA) uses the presence of filth and extraneous materials as one of the criteria in implementing regulatory actions and assessing food adulteration of public health importance. So far, 22 common pest species (‘Dirty 22’ species) have been considered by this agency for the spreading of foodborne illness, and their presence is an indicator of unsanitary conditions in food processing and storage facilities. Recently, we classified the ‘Dirty 22’ species into four groups: Group I (four cockroach species), Group II (two ant species), Group III (12 fly species), and Group IV (four rodent species), and described two molecular diagnostic methods for group-specific identification. We developed a PCR-RFLP assay based on rRNA gene for the detection and differentiation of Group I ‘Dirty 22’ species. Later, we designed three Group II ‘Dirty 22’ species-specific nested PCR primer sets and sequence characterized the rRNA, elongation factor 1-alpha (EF-1a), and wingless (WNT-1) loci. In this follow-up study, we have evaluated the robustness of five unique sets of published primers targeting the mitochondrial cytochrome oxidase I (COI) gene for insect barcoding. With modified PCR conditions, we successfully used COI barcoding for 18 members of Group I, Group II, and Group III ‘Dirty 22’ species. Results of this study reveal that COI barcoding is an effective tool for rapid identification of insects of Groups I, II, and III ‘Dirty 22’ species known to contaminate food and spread foodborne pathogens.

Dengue vector control programmes are mainly focused on insecticide fogging/space spraying to control adult Aedes mosquito vector populations. Due to the diurnal habit of the vectors, spraying is routinely conducted during the day when many other insect species are also active. This study reports the simultaneous effect of fogging on non-target insects by direct counting of knockdown in the insect population. Eight fogging treatments were conducted in two sites in Kurunegala District of Sri Lanka. Pesguard insecticide was sprayed in each treatment for 8 minutes according to the standard methodology and the ‘knockdown insects’ were collected on randomly spread polyethythene sheets (10 m2). A total of 3884 insects (24.3 insects per treatment per m2) belonging to 12 orders were collected and 12.44% of them recovered during a 24-hr recovery period. Diptera was the most affected insect order (36%) followed by Collembola (30%) and Thysanoptera (17%). Out of the 31 mosquitoes (<1%) collected, only two (<0.1%) belonged to the genus Aedes. Body length of 93% of the affected insects ranged from 0.35 mm to 1.8 mm. Positive controls using the WHO standard cage bioassays with the mosquito Ae. albopictus (n = 417) and the stingless bee Trigona iridipennis (n = 122) showed 100% initial knockdown, and 83.5% mosquito and 93.5% bee mortalities after the recovery period. The study shows that insecticide fogging does have a severe effect on non-target insects such as pollinators; therefore, fogging operations should be done in a controlled manner and indiscriminate fogging should be avoided.

Phytosanitary measures are a major barrier to trade in papaya. We assessed the infestation of tephritid fruit flies on different stages of maturity of papaya, to determine its non-host stage of maturity, for market access. Papaya fruits were collected from Kilifi and Embu counties, Kenya from March 2013 to December 2014, to assess the level of infestation by fruit flies according to the degree of fruit ripening. In all locations, no fruit fly infestation was recorded on papaya when fruits were at the 0, 25 and 50% yellow fruit ripening stage. Bactrocera dorsalis (Hendel) was, however, observed attacking fruits when papaya fruits were at 75 and 100% all yellow (fully ripe fruit ripening stage) with infestations of 0.19−0.51 B. dorsalis/kg fruit and 0.24−1.24 B. dorsalis/kg fruit, respectively, in all locations. Field cage exposure of B. dorsalis to fruits of five papaya cultivars—‘Papino’, ‘Neo Essence’, ‘Sunrise Solo’, ‘Tainung No. 1’ and ‘Tainung No. 2’ in Manica Province, Mozambique—showed that B. dorsalis did not infest fruits at 0, 25 and 50% yellow ripening stages at the densities of 50 and 100 flies per cage. However, at 75% yellow ripening stage, up to 13.1 pupae/kg of fruits was recorded at a density of 150 flies per cage in Tainung No. 1, and infestation ranged from 4.5 to 136 pupae/kg fruits at 100% yellow ripening stage across all the cultivars and infestation densities. Laboratory evaluation of volatiles emanating from freshly crushed papaya pulp of four cultivars: ‘Sunrise Solo’, ‘Red Lady’, ‘Papayi’ and ‘Apoyo’ on egg viability of B. dorsalis showed that at 0, 25 and 50% yellow, egg hatchability was inhibited, suggesting that semiochemical compounds present in green tissues of papaya prevent egg development, although this effect was variable across the four cultivars and ripening stages. Export papaya is harvested at less than 40% yellow ripening stage. Our results, therefore, suggest that quarantine treatment for fruits at this ripening stage is inconsequential, as B. dorsalis does not infest papaya fruits at this stage; thus, authorities should permit entry of these papaya cultivars of less than 40% yellow ripening stage to quarantine-sensitive markets.

Okra, Abelmoschus esculentus (L.) Moench, is an important vegetable crop grown throughout the tropical and temperate regions of the world. Spotted bollworm, Earias vittella (Fab.), is one of the most important insect pests of okra. The effects of insecticides (cypermethrin, imidacloprid, carbaryl and neem oil) were studied on the fitness of the F1 generation of E. vittella by a demographic method. Life table was constructed from the eggs obtained by the surviving individuals that had ingested insecticides. Survivorship and expectancy was highest with the commencement of age and gradually decreased with the progression of age in the treatment groups and control. However, it was reduced in the treatment groups in comparison to control groups. Highest numbers of unhatched eggs (17%) were recorded with imidacloprid and cypermethrin treatments, whereas all the eggs hatched in control groups. Larval mortality was high in the initial instars as compared to late instars. Potential fecundity was significantly reduced to 94 females/female/generation treated with cypermethrin as compared to 256 in the untreated females. Developmental time of pre-pupa and pupa was significantly decreased with cypermethrin treatment. The intrinsic rate of increase was reduced to 0.0201 females/female/day in cypermethrin groups as compared to 0.046 in the control groups. The generation time was 33.27 days in the control, which was reduced to 26.78 days with carbaryl treatment and was increased to 37.5 days with neem oil. Insecticides cause adverse effect on the surviving generation of E. vittella, and may be incorporated as a valuable component in the integrated management of E. vittella on okra.